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Soil Invertebrates and Micro‐Organisms
Abstract
IntroductionDiversity of Soil Organisms and their FunctionsSoil Factors Influencing ToxicityMicrobial TestsTests on Microfauna and MesofaunaMacrofaunal TestsMicrocosm TestsRisk Assessment for Soil ContaminantsReferences
... They may however, be used, e.g., to indicate potential effects of chemical pollutants on the filter function of the soil [4]. Long-term bioassay methods, focusing on sublethal endpoints and testing the soil as such, are more relevant from an ecological point * To whom correspondence may be addressed (gestel@bio.vu.nl). of view [5] and may provide information on potential effects on the habitat function of the soil [4]. Such chronic tests are much more expensive and time consuming and have therefore only rarely been applied to polluted and remediated soils. ...
... To obtain useful information on potential ecological risks of polluted or remediated soils, it is recommended to use a battery of tests [3,4], including a number of different test species representative of the ecosystem to be protected [5]. Species selected for such a battery of tests should be taxonomically different, play different roles in (soil) ecosystem(s), and have different routes of exposure [5]. ...
... To obtain useful information on potential ecological risks of polluted or remediated soils, it is recommended to use a battery of tests [3,4], including a number of different test species representative of the ecosystem to be protected [5]. Species selected for such a battery of tests should be taxonomically different, play different roles in (soil) ecosystem(s), and have different routes of exposure [5]. Besides this, also the availability of test organisms, their tolerance to variations in physicochemical soil properties, and the availability of suitable test methods have to be taken into consideration when selecting test methods and species [7]. ...
To compare the effectiveness of acute and chronic bioassays for the ecological risk assessment of polluted soils, soil samples from a site with an historical mineral oil contamination (<50–3,300 mg oil/kg dry soil) at the Petroleum Harbour in Amsterdam, The Netherlands, were screened for ecological effects using acute and chronic bioassays. A two-step 0.001 M Ca(NO3)2 extraction at a final solution-to-soil ratio of 1:1 was used to prepare extracts for the acute bioassays. Acute bioassays (≤5 d) applied to the 0.001 M Ca(NO3)2 extracts from the polluted and reference soils included growth tests with bacteria (Bacillus sp.), algae (Raphidocelis subcapitata), and plants (Lactuca sativa), immobility tests with nematodes (Plectus acuminatus), springtails (Folsomia candida), and cladocerans (Daphnia magna), and the Microtox® test (Vibrio fischeri). Chronic bioassays (four weeks) performed on the same soil samples included tests with L. sativa, F. candida, and earthworms (Eisenia fetida) and the bait-lamina test (substrate consumption). The acute bioassays on Microtox showed a response that corresponded with the level of oil pollution. All other acute bioassays did not show such a consistent response, probably because pollutant levels were too low to cause acute effects. All chronic bioassays showed sublethal responses according to the contaminant levels (oil and in some soils also metals). This shows that chronic bioassays on soil samples are more sensitive in assessing the toxicity of mineral oil contamination in soil than acute bioassays on soil extracts. A pilot scale bioremediation study on soils taken from the two most polluted sites and a control site showed a rapid decline of oil concentrations to reach a stable level within eight weeks. Acute bioassays applied to the soils, using Microtox, algae, and D. magna, and chronic bioassays, using plants, Collembola, earthworms, and bait-lamina consumption, in all cases showed a rapid reduction of toxicity, which could be attributed to the degradation of light oil fractions.
... The sorption of organic compounds and metals in the soil increases over time. Laboratory experiments in which the exposure time is short may give too pessimistic results and too high toxicity values (van Straalen and van Gestel, 1993). ...
... The major problem in tests with nematodes and protozoans is extrapolation of the results for environmental risk assessment of hazardous compounds. Usually the tests are performed with arti"cial media; the composition of the media thus has a bearing on the results (van Straalen and van Gestel, 1993). ...
... Organisms in soils may be exposed to contaminants through soil pore water, by direct ingestion of soils, by ingestion of organic matter, or by ingestion of contaminated food resources. Few standard methods for testing soil organisms exist [1] and the ones available primarily address phytotoxicity [2] and earthworm survival [3]. ...
... Soil protozoa, which occur at high densities in surface soils and litter layers, play an important ecological role in nutrient cycling and regulation of bacterial population densities [24]. Van Straalen and Gestel [1] stressed the importance of testing a wide range of soil organisms in ecological risk assessment, as well as the inclusion of sublethal endpoints. For these reasons, we have 212 Environ. ...
The toxicity of elutriates from 25 putatively contaminated soils was evaluated using the standard seed (Lactuca sativa) germination test and a recently developed soil ciliate (Colpoda inflata) growth test. Correspondence in the identification of presence or absence of toxicity in the 25 soil elutriates between the two tests was 60% and concordance in ranking of toxicity between the two tests was significant (p < 0.05) using Spearman`s rank correlation test (r{sub s} = 0.3831). Stepwise multiple regression analysis of toxicity results against soil elutriate chemistry indicated that pH explained the greatest amount of variation in response in both tests, despite high concentrations of several metals in the elutriates. For the germination test, a multiple regression model that included pH and cadmium explained 58.5% of response variation, whereas over 83% of response variation in the ciliate growth test could be explained by pH, copper, and cadmium. Differences in the response of the plant and protozoan models appeared to be due primarily to differences in their sensitivity to elutriate pH. In addition to better correspondence between elutriate chemistry and ciliate response compared to the seed germination test, lower response variability associated with the measure of ciliate growth compared with seed germination provided greater statistical sensitivity for detecting toxic effects.
... Organisms in soils may be exposed to contaminants through soil pore water, by direct ingestion of soils, by ingestion of organic matter, or by ingestion of contaminated food resources. Few standard methods for testing soil organisms exist [1] and the ones available primarily address phytotoxicity [2] and earthworm survival [3]. ...
... Soil protozoa, which occur at high densities in surface soils and litter layers, play an important ecological role in nutrient cycling and regulation of bacterial population densities [24]. Van Straalen and Gestel [1] stressed the importance of testing a wide range of soil organisms in ecological risk assessment, as well as the inclusion of sublethal endpoints. For these reasons, we have 212 Environ. ...
The toxicity of elutriates from 25 putatively contaminated soils was evaluated using the standard seed (Lactuca sativa) germination test and a recently developed soil ciliate (Colpoda inflata) growth test. Correspondence in the identification of presence or absence of toxicity in the 25 soil elutriates between the two tests was 60% and concordance in ranking of toxicity between the two tests was significant (p < 0.05) using Spearman's rank correlation test (rs = 0.3831). Stepwise multiple regression analysis of toxicity results against soil elutriate chemistry indicated that pH explained the greatest amount of variation in response in both tests, despite high concentrations of several metals in the elutriates. For the germination test, a multiple regression model that included pH and cadmium explained 58.5% of response variation, whereas over 83% of response variation in the ciliate growth test could be explained by pH, copper, and cadmium. Differences in the response of the plant and protozoan models appeared to be due primarily to differences in their sensitivity to elutriate pH. In addition to better correspondence between elutriate chemistry and ciliate response compared to the seed germination test, lower response variability associated with the measure of ciliate growth compared with seed germination provided greater statistical sensitivity for detecting toxic effects.
... 24) In environmental toxicology, these annelids are the recommended organisms in soil toxicity testing and in the field monitoring of metal pollution. 25,26) Thus, many reviews have examined different aspects of earthworm ecotoxicology such as biomarkers, [27][28][29] or practical issues when these organisms are used in toxicity testing. 30,31) Historical Overview of Earthworm Esterases as Ecotoxicological Biomarkers ...
... However, the sensitivity of earthworms to pesticides is the main limitation in their use as enzymatic bioreactors. A threshold of viability based on acute and chronic toxicity tests 25) and avoidance behaviour bioassays 56) should be firstly defined for the pesticides of interest. Alternatively, vermicompost (a nutrient-rich material that is the result of the biooxidative, fragmentation and stabilization of the organic matter by earthworm activity) 121) could be an attractive source of extracellular CEs if compost's earthworms (e.g., Eisenia species) are able to secrete these esterases as L. terrestris do. ...
Chemical control of pests is still necessary in agriculture, despite the growing efforts to introduce biocontrol-based strategies. Many studies have evidenced the harm of pesticide side-effects on natural populations of pest enemies and other non-target organisms. Moreover, pesticide-contaminated soils can act as a secondary pollution source causing contamination in environmental compartments of critical concern to public health (water resource). These environmental risks need to be assessed and monitored for decision-making related to the post-authorization management of pesticides. Under these considerations, earthworm esterases can be a suitable tool for these regulatory and environmental purposes. Herein, it is suggested the use of earthworm esterases as biomarkers to be included in a field toxicity test. Furthermore, the potential role of gut carboxylesterases (CEs) in the modulation of pesticide toxicity is discussed in view of their contribution to the natural tolerance of earthworms to pesticides, and consequently the appropriate selection of earthworm species for regulatory toxicity testing. Finally, it is postulated that CE secretion into the earthworm gut could be an environmental friendly methodology in the enzymatic bioremediation of pesticide-contaminated soils. (C) Pesticide Science Society of Japan
... It is important also to consider the different exposure pathways, mainly the ingestion of soil particles and dermal exposure to the soil solution (García-G omez et al., 2014). There is not an agreement about this topic, some authors found exposure via soil pore water is considered the most important, promoting dermal uptake by earthworms (Van Straalen and Van Gestel 1993;Vijver et al., 2003), but other studies point out the importance of intestinal absorption via ingestion (García-G omez et al., 2014;Nannoni et al., 2011). Furthermore, the role that earthworms play on soils during bioassays is a key factor to consider since they may influence on elements increasing their mobility and availability (Sizmur and Hodson, 2009), so these mechanisms have to be studied in more detail. ...
A long-term case of residual pollution is studied after 20 years since the largest mining accident in Spain (the Aznalcóllar spill) happened. This pollution is manifested through a surface zoning consisting of bare soils (B0), sparsely vegetated soils (B1), and densely vegetated and recovered soils (B2). A biopiles treatment with a mixture of contaminated soils (B0 and B1) with recovered soils(B2) at 50 % (w/w), and vermicompost addition (50 tons ha-1) was evaluated. To assess the effectiveness of treatments, total, water-soluble, and bioavailable fractions of the most polluting elements in the zone (Cu, Zn, As, Pb, Cd, and Sb) was analysed. To evaluate the potential risk of contamination for the ecosystem, a bioassay with earthworm Eisenia andrei was carried out. Twenty years after the accident, there are still soils where total As and Pb exceed the regulatory levels and water-soluble Zn and As exceed the toxicity guidelines. According to toxicity bioassay, weight variation and juvenile production of earthworms showed an improvement after biopiles treatment, with values that trend to be similar to those of recovered soils. The only bioaccumulated element in earthworms was Cd (BAF>1), both in polluted as in treated soils, which indicates the possible existence of exclusion mechanisms of the other pollutants by earthworms. The comparison between biopiles and polluted soils showed no significant differences for the bioaccumulation factor of trace elements, with the exception of Zn and Cu, which slightly increased after treatment. According to our results, biopiles treatment combined with vermicompost addition is a good technique for the recovery of residual contaminated areas, by the improvement of soil properties and the reduction of the potential toxicity; anyway, monitoring of soils and organisms is needed to prevent the increase of bioavailability of some potentially pollutant elements over time.
... Collembola are useful as indicator organisms because of their short life-cycles, and high individual and species numbers. A single-species Collembola reproduction bioassay is in the process of undergoing international-standardisation (OECD, 1990;ISO, 1996b and Tullbergia granu/ata (Van Straalen and Van Gestel, 1993). None of these species is common in local soils; therefore, the tests based on these species lack ecological relevance to Australian ecosystems. ...
... Considering that collembolans continue molting after reaching sexual maturity (Mari Mutt and Soto-Adames 1987;Son et al. 2009), adverse effects on the molting process need to be studied as a biological endpoint. Although the existing toxicity test method with Collembola is easy to carry out because it evaluates toxicity with only live juveniles produced after 4 weeks of exposure (Van Straalen and Van Gestel 1993), the specific effects on juvenile reproduction, such as egg productions and egg hatching, cannot be observed directly. Furthermore, because collembolans live under the surface of the soil, molting cannot be directly investigated using the standardized test methods proposed by the ISO (1999). ...
Tebufenozide is an insect growth regulator used to control pest caterpillar populations. As an ecdysone agonist, tebufenozide is equally toxic to several non-target arthropod species, binding the receptor sites of the molting hormone 20-hydroxyecdysone and causing premature and lethal molting. In this study, the toxic effects of tebufenozide were assessed, and biomarkers of tebufenozide exposure were identified, in the non-target soil collembolan species Yuukianura szeptyckii. Adult mortality and reproduction in Y. szeptyckii exposed to tebufenozide were evaluated after 28 days of exposure and were used to calculate LC50 and EC50, respectively. The LC50 could not be determined, because the mortality values observed were below 50%, even when exposed to the highest concentration tested (700 mg/kg), but the EC50 was 95.5 mg/kg. Effects on hatching and molting rates were evaluated using compressed soils, to prevent experimental individuals from burrowing; thus, all eggs and exuviae were detectable on the soil surface. Significant negative effects of tebufenozide exposure on the hatching rate and molting frequency were observed only at the highest concentration tested (700 mg/kg). Proteomic analyses were conducted to detect the cryptic effects of toxicity in adult collembolans exposed for 28 days to 43.8 mg/kg of tebufenozide, a concentration at which no toxicity effects were observed. The production rates of two ribosomal proteins, as well as proteins involved in apoptotic cell signaling, were higher in collembolans exposed to tebufenozide than in the control group. However, the production of proteins involved in glycolysis and energy production was downregulated. Therefore, the ecotoxicoproteomic approach is a promising tool for measuring the cryptic effects of tebufenozide exposure in Y. szeptyckii at low concentrations.
... To investigate soil toxicity, organisms such as microbes, earthworms, enchytraeids, springtails, mites, and insects have been utilised (van Straalen and van Gestel 1993;Van Gestel and van Straalen 1994;Lokke and van Gestel 1998). Nematodes are also widely employed to study soil contamination and there has been considerable research into their role in ecotoxicology and ecology. ...
This study set out to determine the suitability of the nematode Steinernema feltiae as a bioindicator for heavy metal pollution, specifically chromium VI.
Nematodes were introduced into sand contaminated with concentrations of CrVI+, in a range between 10 and 100ppm, in increments of 10. Reproductive potential, development times and infectivity vs exposure times to Cr VI were employed as endpoints.
It was observed that infective juveniles (IJ) from this nematode can survive and successfully infect host insects in the presence of Cr VI for as much as 13 days, and that the nematode increases its reproductive potential at concentrations up to 100ppm Cr VI+. Conversely, development times (time in days taken for progeny to emerge after larval host death) and IJ infectivity rates were observed to reduce with increasing concentrations of Cr VI.
The ability of this nematode to survive in the presence of high concentrations of Cr VI, and its ability to increase progeny numbers at the early stages of Cr VI exposure may provide a survival advantage for this nematode at contaminated sites. It may also demonstrate potential for development as a model species for toxicological assessment in in situ field sampling.
... To acquire complete and useful information in an ecotoxicological assessment and to determine the effectiveness of bioremediation treatments, it is suggested that a battery of tests be used (Keddy et al. 1995;Van Gestel et al. 2001;Tigini et al. 2011). The battery should include a number of reference organisms that are representative of the different trophic levels, in order to select species with different roles in ecosystems, and different exposure conditions (Van Straalen and Van Gestel 1997). Moreover, environmental risk assessment must integrate chemical characterization, ecotoxicity and bioremediation data, in order to accurately assess the ecological hazard. ...
Pesticides can help reduce yield losses caused by pests, pathogens, and weeds, but their overuse causes serious environmental pollution. They are persistent in the environment and are biomagnified through the food chain, becoming a serious health hazard for humankind. Bioremediation, where microbes are used to degrade pesticides in situ, is a useful technology. This review summarizes data on the fungi involved in the biodegradation of chemical pesticides and their application in soil and water bioremediation. Indications for future studies in this field are given.
... Earthworms also play a crucial role in nutrient cycling in soil ecosystem as well as the biological activity enhancement (Parmelee et al., 1998). In view of extensive use of pesticides in agricultural fields, earthworms may be used as indicator/biomarker for total soil metabolism, soil pollution or toxicity testing (Peakall, 1994;Van Straalen and Van Gestel, 1998;Paoletti, 1999;Spurgeon and Hopkin, 1999;Lock and Janssen, 2003;Brady and Weil, 2004). ...
The toxic effect of common pesticides i.e. cypermethrin and locally used Neem (Azadirachta indica) fruit extract has been investigated on adult earthworm (Pheretima posthuma) and compared with another commonly used pesticide imidacloprid. The earthworms were treated with the test compounds using feeding cum contact method to establish LD 50 values. Major organs of the LD 50 treated surviving earthworms were subjected to total protein extraction, estimation, SEC FPLC and SDS-PAGE analysis. The total protein contents of cypermethrin (which was found to be the most toxic, LD 50 = 0.14 ppm) treated earthworms was 25.2, 37.2 and 38.5 mg/ml in the peristomium, clitellum and abdominal regions, respectively. Whereas Neem fruit extract treatment (which was found to be the less toxic LD 50 = 0.48 ppm) demonstrated moderate effect on total protein concentrations (37.8, 54.8 and 66.4 mg/ml). Imidacloprid which is also a commonly used pesticide was found to be more toxic (LD 50 = 0.24 ppm) to earthworms as compared to Neem fruit extract and showed protein concentrations of 27.7, 26.1 and 30.3 mg/ml in the peristomium, clitellum and abdominal regions, respectively. The untreated or control animals showed protein concentration of 63.9, 76.8 and 78.7 mg/ml in peristomium, clitellum and abdomen regions, respectively. These results were further confirmed by SEC FPLC profiles which demonstrate drastic differences in terms of the proteins and peptides compared to their respective controls. These results were further complemented by SDS PAGE analysis of extracted proteins of peristomium (head) region which revealed that cypermethrin is selectively more toxic to proteins of the head region as compared to imidacloprid and Neem fruit extract suggesting different mode of action of these pesticides on different organs of the earthworms. In conclusion, our results demonstrate for the first time not only the toxic effect of these commonly used pesticides but also the differential action on the secondary target organisms such as earthworms.
... Tel.: +82 2 2049 6090; fax: +82 2 2201 6295. Earthworms are also standard species used in soil ecotoxicology for evaluating the adverse effects of soil contaminants (Van Straalen and van Gestel, 1998), which focus on measuring mortality, behavior, pathological symptoms, body weight change, and reproductive activity by established methods (ISO, 2008(ISO, , 2012aOECD, 2004;USEPA, 2012). Previous studies on earthworms have investigated the effects of toxicants on the lysosomal stability of coelomocytes by assessing neutral red retention (Svendsen et al., 2007), phagocytosis (Fuller-Espie et al., 2010), DNA damage (Manerikar et al., 2008;Li et al., 2009), and enzymatic responses (Li et al., 2009). ...
... Earthworms also play a crucial role in nutrient cycling in soil ecosystem as well as the biological activity enhancement (Parmelee et al., 1998). In view of extensive use of pesticides in agricultural fields, earthworms may be used as indicator/biomarker for total soil metabolism, soil pollution or toxicity testing (Peakall, 1994;Van Straalen and Van Gestel, 1998;Paoletti, 1999;Spurgeon and Hopkin, 1999;Lock and Janssen, 2003;Brady and Weil, 2004). ...
The toxic effect of common pesticides i.e. cypermethrin and locally used
Neem (Azadirachta indica) fruit extract has been investigated on adult
earthworm (Pheretima posthuma) and compared with another commonly
used pesticide imidacloprid. The earthworms were treated with the test
compounds using feeding cum contact method to establish LD50 values.
Major organs of the LD50 treated surviving earthworms were subjected to
total protein extraction, estimation, SEC FPLC and SDS-PAGE analysis. The
total protein contents of cypermethrin (which was found to be the most toxic,
LD50 = 0.14 ppm) treated earthworms was 25.2, 37.2 and 38.5 mg/ml in the
peristomium, clitellum and abdominal regions, respectively. Whereas Neem
fruit extract treatment (which was found to be the less toxic LD50 = 0.48
ppm) demonstrated moderate effect on total protein concentrations (37.8,
54.8 and 66.4 mg/ml). Imidacloprid which is also a commonly used pesticide
was found to be more toxic (LD50 = 0.24 ppm) to earthworms as compared to
Neem fruit extract and showed protein concentrations of 27.7, 26.1 and 30.3
mg/ml in the peristomium, clitellum and abdominal regions, respectively.
The untreated or control animals showed protein concentration of 63.9, 76.8
and 78.7 mg/ml in peristomium, clitellum and abdomen regions,
respectively. These results were further confirmed by SEC FPLC profiles
which demonstrate drastic differences in terms of the proteins and peptides
compared to their respective controls. These results were further
complemented by SDS PAGE analysis of extracted proteins of peristomium
(head) region which revealed that cypermethrin is selectively more toxic to
proteins of the head region as compared to imidacloprid and Neem fruit
extract suggesting different mode of action of these pesticides on different
organs of the earthworms. In conclusion, our results demonstrate for the first
time not only the toxic effect of these commonly used pesticides but also the
differential action on the secondary target organisms such as earthworms.
... Earthworms can be exposed to contaminants present in the soil by two major routes: ingestion of soil particles and dermal exposure to the soil solution. Although the exposure via soil pore water is considered the most important (Van Straalen and Van Gestel 1993; Vijver et al. 2003), the correlation found between the total concentrations and the body concentrations pointed toward the hypothesis that, due to soil ingestion, earthworms may access less labile metal pools than plants (Nannoni et al. 2011). In contrast, Fordsmand et al. (2004) found that earthworms and plants access the same fraction of soil Zn; however, a wider range of soil concentrations was used in our study. ...
The interactions and relevance of the soil (total and available) concentrations, accumulation, and acute toxicity of several essential and non-essential trace elements were investigated to determine their importance in environmental soil assessment. Three plant species (T. aestivum, R. sativum, and V. sativa) and E. fetida were simultaneously exposed for 21 days to long-term contaminated soils collected from the surroundings of an abandoned pyrite mine. The soils presented different levels of As and metals, mainly Zn and Cu, and were tested at different soil concentrations [12.5, 25, 50, and 100 % of contaminated soil/soil (w/w)] to increase the range of total and available soil concentrations necessary for the study. The total concentrations in the soils (of both As and metals) were better predictors of earthworm uptake than were the available concentrations. In plants, the accumulation of metals was related to the available concentrations of Zn and Cu, which could indicate that plants and earthworms accumulate elements from different pools of soil contaminants. Moreover, Zn and Cu, which are essential elements, showed controlled uptake at low concentrations. The external metal concentrations predicted earthworm mortality, whereas in plants, the effects on growth were correlated to the As and metal contents in the plants. In general, the bioaccumulation factors were lower at higher exposure levels, which implies the existence of auto-regulation in the uptake of both essential and non-essential elements by plants and earthworms.
... Plants support the organisms in the second trophic level by producing organic matter, which feeds the soil bacteria and some fungal species. Plant roots directly feed both symbiotic and saprophytic fungi as well as nematodes (USDA NRCS 2013; Kennedy and Smith 1995; van Straalen and van Gestel 1998; Ferris et al. 2001). The diversity of native plants on rangeland sites contributes to the maintenance and enhancement of above-and belowground biological interactions that keep the ecological interactions described in ecological site descriptions (ESD) intact. ...
... Plants support the organisms in the second trophic level by producing organic matter, which feeds the soil bacteria and some fungal species. Plant roots directly feed both symbiotic and saprophytic fungi as well as nematodes (USDA NRCS 2013; Kennedy and Smith 1995;van Straalen and van Gestel 1998;Ferris et al. 2001 the introduction of exotic species affect the dynamics of these ecological sites and degrade sites into alternate states. Presence of the right species in the right proportions based on site potential and management objectives is important for maintaining above-and belowground ecosystem health. ...
... TNO is initiator en coördinator van dit netwerk. SedNet beoogt primair om de probleembezitters die verantwoordelijk zijn voor het beheer van verontreinigde sedimenten (waterkwaliteitsbeheerders, havenbedrijven, normstellers, baggeraars etc.) in contact te brengen met de probleemoplossers (universiteiten, onderzoeksinstellingen, adviesbureaus etc. Gestel, 1993;Løkke & Van Gestel, 1998;Förster et al., 1999). Ook is veel gewerkt aan het inzetten van toetsmethodes in de vorm van bioassays voor verontreinigde grond . ...
... Many field and laboratory studies have considered the important roles played by invertebrates in ecosystem structure and functioning, and their abiotic and biotic environmental interactions. A number of studies have focussed on the decomposition of litter (Seastedt, 1984;Heneghan et al., 1999), seasonal and temporal dynamics (Cepeda-Pizarro and Whitford 1989;Bengtsson, 1994), moisture and temperature (Huhta and Hanninen, 2001), abundance and suc- cession ( Purvis and Curry, 1980;Newell, 1984;Dilly and Irmler, 1998), and inter- relationships with other biota (Visser, 1985;Harris and Boerner, 1990;van Straalen and van Gestel, 1993;Gange, 2000). There have also been a number of studies focusing on the implications of agricultural and forestry practices, ecological in- teractions and overall functioning of invertebrates in the soil and litter environ- ment (Sohlenius, 1990;Faber and Verhoef, 1991;Bardgett et al., 1993;Heisler and Kaiser, 1995;Kovac and Miklisova, 1997;Cancela da Fonseca and Sarkar, 1998;Kovac et al., 1999;Garrett et al., 2001;Filser et al., 2002). ...
The micro and meso-invertebrate abundance was measured, together with forest litter composition, in eight plots of differing vegetation (dominated by beech and birch) over a winter-spring period. The litter moisture content was a mean of 76% during the sampling period and the beech sites were the driest. The results were analysed using a suite of statistical techniques, together with data on protozoa, fungi and bacteria available from parallel research. Nematodes were analysed according to the trophic levels, which included microbial feeders, plant feeders and predators. The majority of arthropods found were the collembolan, Folsomia candida and cryptostigmatid mites, with very small quantities of other micro-and mesoarthropods (such as larvae and mesostigmatid mites). The microarthropod populations peaked in January and fell during subsequent months, while population numbers of nematodes showed a decrease between January and February, followed by an increase in March. ANOVA showed a significant date effect, but no site-date interactions for the population abundance of both nematodes and microarthropods. Ecological interactions of meiofauna were analysed by ANCOVA, stepwise regression, and correlation analysis. Examples of relationships revealed include positive relationships of plant-feeding nematodes (PFN) with microbial feeding nematodes (MFN), and of F. candida with cryptostigmatid mites. Other positive interactions were found for PFN, MFN, F. candida, cryptostigmatid and mesostigmatid mites with litter components, such as beech leaves and litter thickness, moisture and grass, and protozoa. Negative interactions were recorded for PFN, MFN, F. candida, cryptostigmatid and mesostigmatid mites with beech leaves, fungi, protozoa and bacteria. The results have highlighted a very complex structure of factors influencing the temporal and spatial dynamics of the forest litter community. It is suggested that temperature and moisture content particularly influence the invertebrates present. The invertebrates appear to be present in a range of microhabitats, which may have resulted in a reduced level of competition and a high level of positive interactions revealed.
... In earthworms, the presence of isoproturon was not simply due to contaminated soil in the animals since they were allowed to void gut content before extraction of the pesticide. Absorption of pesticides by earthworms may occur via ingestion but also by dermal uptake of lipophilic molecules because of the permanent contact between the worms and the soil interstitial water (van Straalen and van Gestel, 1993;Belfroid et al., 1995). The latter route is probably important in the case of isoproturon since its relatively low adsorption coefficient (K OC = 120 l/g; Lafrance et al., 2001) suggest that availability was not limited by adsorption of the pesticide to soil particles and its octanol/water partition coefficient (log K OW = 2.5) indicates a moderate hydrophobicity. ...
This study was conducted to investigate the effects of isoproturon on mature earthworms (Lumbricus terrestris L.) and its fate under laboratory conditions. Earthworms were exposed for various durations to soils contaminated with concentrations that were chosen to mimic an accidental spill of the herbicide. Residues were monitored in soil and earthworms after 7, 15, 30, 45, and 60 days of exposure to different isoproturon concentrations. Effects of the herbicide on mortality, relative growth rate, and total soluble protein content of earthworms were determined. No lethal effect of isoproturon was observed even at the highest concentration tested (1.4 g/kg soil) after 60 days of exposure. Residues of isoproturon caused a significant reduction in the growth rate (maximum −27.9%). Additionally a reduction in total soluble protein was observed in all treated worms (maximum −36.1%). The decrease in isoproturon concentration in the soil depended on initial concentration: it was slower at higher concentrations. In the worms, it increased during the first 15 days and decreased thereafter. It was concluded that an accidental spill of isoproturon may have localized consequences very different from those observed in cases of diffuse pollution, in terms of herbicide degradation and toxicity.
... Only few natural stresses were associated with recovery times longer than 60 days and these could potentially have critical ecological consequences. The concept of Domsch et al. (1983) has been widely used, but also criticised since the evaluated stress effects occur in addition to natural stresses and the combined effect therefore could be more severe (Van Straalen and van Gestel, 1993). ...
Band-steaming of arable soil at 80–90 °C kill off weed seeds prior to crop establishment which allows an extensive intra-row weed control. Here we evaluated the side-effects of in situ band-steaming on soil respiration, enzyme activities, and numbers of culturable bacteria and fungi in an organic field soil. The results showed that mechanical disturbance created by band-steaming could be neglected as a mediator of microbial changes. Also, soil pH and water content was unaffected by band-steaming. Effects of band-steaming on in situ soil respiration and basal respiration, respectively, were insignificant or slightly stimulatory (P < 0.05). Fluorescein diacetate hydrolysis and arylsulfatase activity were significantly (P < 0.001) inhibited by 25 and 38%, respectively, and only showed weak recovery during 90 days after band-steaming. Bacterial colony-forming units increased after soil steaming whereas the number of fungal propagules was reduced by 50% (P < 0.001). This reduction persisted at a level of 38% after 90 days (P < 0.001). Evaluated in relation natural environmental stresses, band-steaming showed ecologically tolerable short-term effects, but with weaker recovery potential and therefore possible long-term effects. However, band-steaming affects only a minor volume of the plough layer (<10%) and long-term effects may be minimal due to annual tillage (mixing) of the soil. In conclusion, the side-effects on soil microbiology may not disqualify band-steaming as an option in organic farming systems.
... In addition, ground reservoirs and tanks of creosote lay abandoned with creosote seeping into surrounding soil and groundwater (Conrad et al., 1999). Among microinvertebrates, nematodes (Bongers, 1990), Collembola (van Straalen and van Gestel, 1993; Frampton, 1997), and mites (Ruf, 1998) are popular candidates as bioindicators because of their role in essential ecological processes of soil including nutrient cycling and decomposition (Wasilewska et al., 1975; Ingham et al., 1985; Beare et al., 1992). The relative abundance and ubiquitous nature of soil invertebrates contribute to their usefulness in comparing their community structure among ecosystem types and land management practices (Neher, 1999aNeher, ,b, 2001 ). ...
Soil organisms are useful for quantification of ecological impact of chemical contamination of soils. This study examined the effects of creosote (complex mixture of polycyclic aromatic hydrocarbons) on composition and abundance of soil invertebrates (nematodes, collembolans and mites) and decomposition processes. Thirty intact soil cores and adjacent litter samples were collected each of three times during the 1998 growing season from soil contaminated with creosote for 50 years. Each core was divided evenly into two subsamples. Abundance of nematodes (by family), Collembola (by family), mites (by Oribatida and others), total bacterial biomass, and active fungal biomass were quantified in the first subsample; soil properties including polycyclic aromatic hydrocarbon (PAH) concentration, organic carbon, pH, electrical conductivity (EC), bulk density, soil moisture and soil texture were measured in the second subsample. Creosote affected soil food webs and decomposition more by altering habitat of microinvertebrates and their prey, fungi and bacteria, than by direct toxicity. We hypothesize that nematodes were affected directly by PAH, more than collembolans or mites, because of their intimate contact with contaminated soil particles and permeable cuticles. Collembola and mites explained decomposition of 100% cellulose and mixed cellulose/lignin substrates better than nematodes because of their co-location in the litter layer. This is the first study to examine effects of PAH contamination on soil food webs and ecological processes.
... Land allein auf industrielle Aktivitäten zurückgeführt [Anonymus 1995]. Gestel 1993]. Die Wahl des Testorganismus bzw. des Testkriteriums hat somit maßgeblichen Anteil an der Aussagekraft eines Testverfahrens [Fent 1998]. Um möglichst viele Wirkungsmechanismen abdecken zu können, wird in der Regel der Einsatz von Testbatterien vorgeschlagen, welche Testorganismen verschiedener Trophiestufen heranziehen [Keddy et al. 199 ...
Zur Bewertung der mikrobiellen Lebensraumfunktion von Böden ist der Einsatz biologischer Testverfahren von großer Bedeutung. Ein wichtiges Testkriterium ist dabei der Umsatz von Sauerstoff und Kohlenstoffdioxid der autochthonen Mikroorganismenpopulation, der in der Regel in Form des Summenparameters Bodenatmung erfaßt wird. Die Gesamtumsätze der mikrobiellen Bodenatmung setzen sich aus verschiedenen Stoffwechselvorgängen wie z. B. der aeroben Atmung, der Nitrifikation und der Ureaseaktivität zusammen. Im Rahmen dieser Arbeit wurden Einflüsse von Schadstoffen auf die Basalatmung und die substratinduzierte Atmung unter besonderer Berücksichtigung der Nährstoffsituation untersucht. An Hand schadstoffbedingter Abweichungen von der typischen Bodenatmung unkontaminierter Böden wurden Auswertungskriterien abgeleitet, die zur Bewertung der mikrobiellen Lebensraumfunktion herangezogen werden können. Als Kriterien zur Erfassung toxischer Wirkungen auf die Bodenmikroorganismen wurden Schwellenwerte für einen Mindestumsatz der kumulierten Basalatmung, für den zeitlichen Verlauf der Umsatzrate der substratinduzierten Atmung, für die maximale Steigung und für den Höchstwert der Umsatzrate der substratinduzierten Atmung vorgeschlagen. Desweiteren können mit Hilfe eines oberen Schwellenwertes für die kumulierte Basalatmung und eines Schwellenwertes für die zeitliche Reaktion der Mikroorganismen auf die Ammoniumzudosierung bei der Erfassung der substratinduzierten Atmung (D tN bzw. D tNP) aerob abbaubare Substanzen angezeigt werden. Ein Mangel der Makronährstoffe Ammonium und Phosphat kann zu ähnlichen Auswirkungen auf die Bodenatmung führen wie eine Belastung mit Schadstoffen. Aus diesem Grund ist die Nährstoffsituation einer Bodenprobe unbedingt bei der Auswertung der Atmungsmessung zu berücksichtigen. An Hand von Limitierungsquotienten für die Basalatmung (qBNPn) und für die substratinduzierte Atmung (qSXn) können Limitierungen und Hemmungen durch zudosierte Nährstoffe quantifiziert und falsch negative Ergebnisse bei der Bewertung der mikrobiellen Lebensraumfunktion durch Nährstoffmangel bzw. hemmende Wirkungen der zudosierten Nährstoffe ausgeschlossen werden. Für Böden, die vorwiegend mit Schwermetallen belastet waren, wurden hohe Werte für die Limitierungsquotienten qSNO2 bzw. qSNCO2 ermittelt. Es wird eine Auswertungsstrategie vorgestellt, die die Ergebnisse der vorgeschlagenen Kriterien kombiniert und eine weitergehende Bewertung der Lebensraumfunktion von Böden ermöglicht. Eine zuverlässige quantitative Bestimmung der Ammoniumoxidation an Hand des Sauerstoffverbrauchs konnte nicht realisiert werden, da diese spezielle Stoffwechselaktivität nicht vollständig vom Prozeß der Bodenatmung trennbar war. Obwohl die Ammoniumoxidation im Boden durch den Hemmstoff N-Allylthioharnstoff zu 100% hemmbar ist, wie mittels der photometrischen Bestimmung der Nitritbildungsrate bewiesen werden konnte, war die Hemmwirkung auf den Sauerstoffverbrauch der Ammoniumoxidation nicht eindeutig zu belegen. Durch den Vergleich des Sauerstoff- und des Kohlenstoffdioxidumsatzes konnte die Ammoniumoxidation aber qualitativ erfaßt werden und führte bei der Bewertung der Lebensraumfunktion der Versuchsböden zu einer weitgehenden Übereinstimmung mit der Messung der Nitritbildungsrate. Einzige Ausnahme bildete der Boden BMKW 1a, der eine ungewöhnlich hohe Stickstofflimitierung der Basalatmung aufwies und damit ein falsch positives Ergebnis anzeigte. Das Verfahren kann somit nur als Ergänzung zur Bodenatmungsmessung eingesetzt werden, da deutliche Nachteile im Vergleich zur Bestimmung der Nitritbildungsrate festgestellt wurden: Wesentlich längere Inkubationszeit, keine eindeutige Quantifizierung und falsch positive Ergebnisse in Ausnahmefällen. Die Ureaseaktivität der Versuchsböden konnte mittels des Kohlenstoffdioxidumsatzes bestimmt werden, da eine eindeutige Trennung der Kohlenstoffdioxidproduktion durch die Ureaseaktivität von der der Bodenatmung mit Hilfe des spezifischen Hemmstoffes NBPT möglich war. Das Verfahren bietet gegenüber der photometrischen Bestimmung der Ammoniumproduktion verschiedene Vorteile: Inkubation der Bodenprobe ohne Pufferlösung möglich, keine Elution der testrelevanten Substanz notwendig, geringerer Chemikalienverbrauch und bessere Reproduzierbarkeit der Ergebnisse. Die Ureaseaktivität erwies sich als senisitver Parameter zur Beurteilung der mikrobiellen Lebensraumfunktion, da für einen Großteil der kontaminierten Versuchsböden sehr geringe bzw. keine Ureaseaktivität festgestellt werden konnte. Vor allem wurden Böden auf Basis des vorgeschlagenen Schwellenwertes als bedenklich eingestuft, die an Hand der potentiellen Ammoniumoxidation als unbedenklich bezüglich der Lebensraumfunktion eingeordnet wurden. Auch der umgekehrte Fall konnte beobachtet werden, so daß durch die Verwendung beider Testverfahren die Wahrscheinlichkeit eines falsch positiven Ergebnisses bei der Beurteilung von Schadstoffeinflüssen auf die mikrobielle Lebensraumfunktion offensichtlich stark reduziert werden kann. Demnach ist eine Ergänzung der Untersuchung der mikrobiellen Lebensraumfunktion mittels Bodenatmung und Ammoniumoxidation durch die Ureaseaktivität zu empfehlen. Eine vollständige Validierung der Testverfahren bzw. der Gültigkeit der Auswertungskriterien und Schwellenwerte stehen noch aus. Die vorgeschlagenen Schwellenwerte sind demnach als Arbeitsgrundlage für weitere Untersuchungen zu verstehen. The application of biological tests for the assessment of the habitat function of soils is of great importance. Soil respiration measured as oxygen consumption or carbon dioxide release is used frequently for the evaluation of contaminated sites. The oxygen and carbon dioxide turn over in soil respiration is composed of different metabolic activities, for example aerobic respiration, nitrification and urease activity. First of all the influence of pollutants on basal respiration and substrate induced respiration was investigated with special consideration of nutrient supply (nitrogen and phosphorus). For the derivation of evaluation criteria, respiration of uncontaminated soils was compared to the respiration of contaminated soils. It was shown that the following criteria can be used for the assessment of the habitat function: Cumulated basal respiration, maximum of substrate induced respiration rate, maximum slope of substrate induced respiration rate, the space of time, which is needed to reach the maximum substrate induced respiration rate. Furthermore it was possible to detect organic pollutants, which are degradable under aerobic conditions, by high cumulated basal respiration and by the influence of nitrogen supply for the time span, which is needed to reach the maximum substrate induced respiration rate (D tN and D tNP). The symptoms, which are caused by a lack of nutrients like ammonia and phosphate, are comparable to the effects caused by pollutants. For this reason the nutrient supply of a soil sample has to be considered for evaluation of soil respiration data. The positive (promotion) or negative (inhibition) influence of nutrients can be quantitatively estimated using the limitation quotients for basal respiration (qBNPn) and for substrate induced respiration (qSXn). Limitation quotients (qSNO2 and qSNCO2) for soils which had high contents of heavy metals were significantly higher than for soils without heavy metal contamination. Standard values and a strategy for a combined evaluation were proposed for the above mentioned criteria, which allows for an exact interpretation of the achieved data. A reliable quantitative measurement of ammonia oxidation by oxygen consumption could not be realized, because the specific process of ammonia oxidation could not be separated from soil respiration. The photometrical test with the specific inhibitor allylthiourea showed that the production of nitride in a soil sample could be stopped completely, but the inhibition of the oxygen consumption caused by ammonia oxidation could not definitely be proved. But the direct comparison of oxygen consumption and carbon dioxide release offers the possibility of a qualitative measurement of ammonia oxidation. In most cases the results of the two methods were corresponding. One exception occured with the soil BMKW 1a, which showed a very high nitrogen limitation of basal respiration. Therefore the result of measuring oxygen consumption seemed to be a very high ammonia oxidation, but the result of the measurement of nitride production was very low. For these reasons the measurement of oxygen consumption in testing ammonia oxidation can only be used as complementary investigation for soil respiration: Much longer incubation time, no reliable quantification possible and in special cases wrong results are obtained. The urease activity of soils could be measured by the carbon dioxide release. By using NBPT as specific inhibitor, it was possible to seperate the carbon dioxide which was produced by urease from the carbon dioxide which was produced by soil respiration. The developed method offers some important advantages in comparison to the photometrical measurement of ammonia: Incubation of a soil sample without using buffer solution, no extraction of ammonia from the soil sample necessary, less chemical consumption and better reproduction of results. Urease activity has proved to be a sensitive parameter for the assessment of microbial habitat function, because most of the contaminated soil samples showed low or no urease activity. Soils, which were classified as not critically influenced relative to the ammonia oxidation measured as nitride production, were graded as critical by the urease activity measured as carbon dioxide release. The reverse case could be observed, too. Therefore the use of both assays avoids the possibility of achieving misleading results if the influence of pollutants on the microbial habitat function has to be tested. As consequence the widespread use of soil respiration and ammonia oxidation should be completed by the urease activity measured as carbon dioxide release. The complete validation of the proposed assays, the validity of criteria of evaluation and proposed standard values have to be seen as basis for future investigations and have to be proved by investigating a greater amount of soil samples.
... The ecological concept of functional redundancy was brought forward in the original assessment. This concept states that the loss of a few vulnerable species will not affect system functionality (quoted from Van Straalen and Van Gestel (1993)). This concept was used as an argument for omitting an assessment factor. ...
A critical appraisal of the data used for the establishment of the trigger values for the exposure of the aquatic environment to human medicines and the terrestrial environment to veterinary medicines leads to the recommendation to change these values. The (draft) technical guidance documents in support of the European registration procedure for human and veterinary medicines demand no risk assessment for substances with an exposure level below a certain trigger value for water (10 ng/L) and soil (100 ug/kg), respectively. However, the EU Scientific Committee on Toxicity, Ecotoxicity and the Environment did not consider the proposed number of the aquatic trigger to be scientifically valid. The EU Scientific Steering Committee also considered the soil trigger value as non-scientific. The critical appraisal of available data and methodology, complemented with readily available public information, leads to considerably lower trigger values of 0.4 ng/L for the water compartment and 1 ug/kg for the soil compartment Een kritische beschouwing van de wetenschappelijke onderbouwing van bestaande drempelwaarden voor blootstelling aan humane geneesmiddelen in water en diergeneesmiddelen in bodem leidt tot de aanbeveling deze waarden te herzien. Het gebruik van drempelwaarden is opgenomen in de (concept) richtsnoeren voor de milieurisicobeoordeling als onderdeel van de Europees geharmoniseerde registratie van (dier)geneesmiddelen. Op basis van het overschrijden van deze drempelwaarden wordt besloten of een risicobeoordeling voor het milieu noodzakelijk is. In de opinie van het Europese Wetenschappelijk Comite voor Toxicologie, Ecotoxicologie en het Milieu is de bestaande waarde voor water (10 ng/l) wetenschappelijk ondeugdelijk. Volgens de Europese Wetenschappelijke Stuurgroep is de bestaande waarde voor bodem (100 ug/kg) evenmin wetenschappelijk onderbouwd. De kritische beschouwing van de gebruikte gegevens en de toegepaste beoordeling, met inachtneming van gegevens uit de openbare literatuur, leidt tot beduidend lagere drempelwaarden van 0,4 ng/L voor water en 1 ug/kg voor bodem.
To reveal the changes in the interactions between invertebrates and microbes in decomposing litter with seasonal rainfall, litterbags containing camphor (Cinnamomum longepaniculatum) and Masson pine (Pinus massoniana) litter were therefore in situ incubated on the floor of Masson pine-camphor mixed plantations in the subtropical region of China. Different mesh sizes of litterbags were used to control the access of the invertebrates. The invertebrates in litterbags were collected by funnel method, and microbial communities were detected by phospholipid fatty acid (PLFA) method in slightly rainy season (SRS; November 1–December 24), micro rainy season (MRS; December 25–March 7), early rainy season (ERS; March 8–June 15) and rainy season (RS; June 16–October 31) during two decomposition years. The abundance and composition of microbial and invertebrate communities varied significantly with seasonal rainfall and tree species. Invertebrate exclusion generally decreased the bacterial and fungal biomass, and the biomass of Gram-positive bacteria and Gram-negative bacteria in Masson pine needle litter, but generally increased these indices in camphor foliar litter. Invertebrate exclusion decreased the mass loss rate of Masson pine litter, but increased the mass loss rate of camphor litter. Total microbial biomass and bacterial biomass in both foliar litters were generally higher in SRS and MRS than these in ERS and RS during the first decomposition year, whereas the situation reversed during the second decomposition year. The abundance of invertebrates increased gradually from the first SRS to the second SRS and decreased gradually afterwards. Briefly, the interactions between invertebrate and microbial communities varied greatly with litter types and seasons. Positive and negative interactions between invertebrate and microbes were respectively observed in Masson pine and camphor litters, and differential responses of microbial biomass and mass loss rate to invertebrate exclusion were found in two litter types. In turn, the interactions between invertebrates and microbes run the litter decomposition.
h i g h l i g h t s Different species of springtails were compared for their sensitivity to two neonicotinoids. Two new model species are introduced: Heteromurus nitidus and Sinella curviseta. Exposing adults of Folsomia candida for 21 days is as effective as exposing juveniles for 28 days. Females of Sinella curviseta were more sensitive than males. Populations of springtails are already at risk at a normal field application rate of imidacloprid. a b s t r a c t Collembolans comprise one of the most abundant groups of soil invertebrates within the arthropods. The parthenogenetic species Folsomia candida (Willem, 1902) is the most well-studied representative, being used since the beginning of the 1960s as a model organism for assessing toxicity of chemicals in soil. In this paper we aimed at answering three questions by exposing four different species of springtails (F. candida, Folsomia fimetaria, Sinella curviseta and Heteromurus nitidus) to the neonicotinoids imida-cloprid and thiacloprid: i) How representative as a model organism is F. candida for species of springtails that reproduce sexually? (ii) How suitable are other species of springtails to be used as model organisms for ecotoxicological testing? (iii) Is it possible to use the life history of these species to extrapolate the impact of neonicotinoids on the population level? Our results showed that F. candida is a good model organism, despite being the most sensitive species tested, when analysing both endpoints e survival and reproduction. The tests performed with S. curviseta and H. nitidus showed that they could be used as surrogates in ecotoxicity tests, and also to predict how their population might be affected after being exposed to chemicals. The adjustments made to the test performed with F. candida: introducing adults (20e22 days old) into the test jars and exposing them for 21 days instead of 28 days, proved to be as efficient as the standardized test guideline (OECD 232, 2009).
La recherche était destinée, dans un premier temps, à comprendre les conditions de mobilisation des polluants associés à des matériaux solides, tels que les terres ou les déchets, puis, dans un second temps, à élaborer une démarche et à proposer des méthodes pour caractériser les dangers et les risques, à court et à long terme, liés à la présence de composés toxiques, organiques et/ou métalliques. Dans ce but, des échantillons de terre contaminés au laboratoire ou prélevés directement sur des sites industriels ainsi que des déchets ont été constitués. Une batterie de tests biologiques (vibrio fischeri, pseudokirchneriella subcapitata, daphnia magna et vibrio fischeri m169) a été appliquée sur des extraits obtenus par lixiviation statique en faisant varier le solvant (eau, méthanol, tampons phosphate et borate) et les conditions de l'extraction (rapport massique solide/liquide, durée de lixiviation, et filtration) ainsi que par percolation dynamique en colonne. Afin de prévoir l'évolution de la toxicité et de la génotoxicité, des essais de dégradation ont également été réalises. Les résultats montrent que le rendement d'extraction et l'intensité de la réponse toxique dépendent des conditions de la lixiviation. En général, la toxicité des échantillons contaminés au laboratoire est plus forte que celle d'échantillons prélevés sur des sites industriels, traduisant l'influence des conditions et de la durée de vieillissement sur l'état et la mobilité des polluants dans les terres et les déchets. La percolation en colonne a permis de mettre en évidence une migration différentielle des polluants en fonction de leur solubilité dans l'eau, de plus, elle évalue la durée sur laquelle s'effectue leur relargage. La toxicité et la génotoxicité mesurées après 30 semaines de percolation démontrent l'existence d'une réserve polluante toxique qui est aussi révélée par les lixiviations statiques montrant une différence de toxicité entre les extraits aqueux et au méthanol. Enfin la toxicité et la génotoxicité des échantillons sont diminuées ou amplifiées par la dégradation, en fonction des conditions imposées. En conclusion, la caractérisation du danger toxique et génotoxique à court et à long termes devrait reposer sur l'utilisation d'une gamme de lixiviations statiques à l'eau et à d'autres solvants comme le méthanol, couplée à une batterie de tests biologiques complémentaires. Elle pourrait ensuite être complétée par des essais de percolation et/ou d'incubation, afin d'acquérir des informations sur l'évolution de la toxicité.
Problems associated with mining are the disposal of wastes on tailing disposal facilities (TDFs). The aim of this study was to determine the ecotoxicity of gold mine tailings by using earthworm bioassays, earthworm biomarkers and enzymatic analyses. End points included changes in biomass, reproduction, lysosomal membrane stability, tissue metal concentrations, and selected enzymatic activities. Results indicated high concentrations of Ni in the material as well as bioaccumulation of lead and arsenic in the earthworm body tissue after exposure. Enzymatic activity was higher in revegetated tailings than in unrehabilitated tailings. It was concluded that TDF and surrounding areas have an acidic pH which affects earthworms and metal bioavailability. Soil enzymatic activities were a sensitive indicator of metal pollution in mining areas. Growth, reproduction and lysosomal membrane stability of earthworms have also been shown to be sensitive end points to assess the ecotoxic effects of gold TDF.
[...] The aim of this thesis is to study the mechanisms that modulate metal bioavailabilityfor the garden snail Cantareus aspersus (= Helix aspersa) a soil invertebrate living at the interfacesoil‐plant‐air (saprophagous and phytophagous intermediate link in the food chain).[...] These data underline the necessity to take into account the factors and mechanisms that modulate themetal bioavailability for snails to better model accumulation and assimilation of metal by snails. As nounique chemical method to assess metal bioavailability was determined, we recommend the use ofbiological measures that identify the real metal bioavailability rather than the use of chemical measures.
Current environmental risk assessment (ERA) related to the soil contamination by metal consider neither the physico-chemical properties of soil nor the biological mechanisms that modulate metal bioavailability. The aim of this thesis is to study the mechanisms that modulate metal bioavailability for the garden snail Cantareus aspersus (= Helix aspersa) a soil invertebrate living at the interface soil-plant-air (saprophagous and phytophagous intermediate link in the food chain). Bioavailability is assessed by the metal accumulation (internal concentration of metals after 28 days of exposure) and assimilation fluxes. The influence of soil characteristics on availability and bioavailability of metal in soil and contribution of the contamination sources (soils/plants) of snails are the studied variables in two exposure protocols:
In situ, on the twelve sites of the ADEME bioindicator 2 program, multivariate equations have identified organic carbon (Corg), oxides (iron and aluminium) and CEC as modulating parameters of accumulation of Cd, Pb, Cr and Zn and assimilation of Cd and Pb. However, soil properties do not influence neither As assimilation and accumulation nor Sb accumulation. These studies highlight the low bioavailability of As and Sb in soil. Total metal concentration and characteristics of soil allow the explanation of 40 to 67% of accumulated metal in snails. The addition of other variable like plant contribution on snails contamination may improve the understanding of metal bioavailability modulation for snails. These results have led to the establishment of internal concentration of reference (CIRef) of snails exposed on uncontaminated site. Determined for As, Cd, Cr, Cu, Pb and Zn, these CIRef, compared to the internal concentration of snails exposed on various contaminated sites have permit the characterization of the variable bioavailability of metals. The proposed methodology of interpretation (SET: Sum of Excess of Transfer) may define environmental management priorities not based on total metal concentration in soil but on a biological risk assessment intregrating the soil properties influence on metal bioavailability to snails.
In laboratory, by using an agricultural field soil manually modified (contamination, pH and organic matter content) we have determined that the main assimilation source of Pb is the soil (90%) whereas the one of Cd is the lettuce (80%). For both meals, a decrease of two-pH-unit increases the lettuce contribution since an increase of organic matter content increases the soil contribution. By using 17 other soil coming from a contaminated site we identified pH, CEC and oxides (iron and aluminium) as modulating parameter of Cd, Pb and Zn bioavailability for snails. For these soils, total soil metal concentration and EDTA extractable fraction are usable to assess respectively Pb and Cd bioavailability for snails. It signifying that metals strongly bound on the solid phase of soil are bioavailable for snails. For Zn, none chemical method alone allows its bioavailability assessment, its assessment can be only done by using total metal concentration and properties of soil (pH and Al and Fe oxides).
These data underline the necessity to take into account the factors and mechanisms that modulate the metal bioavailability for snails to better model accumulation and assimilation of metal by snails. As no unique chemical method to assess metal bioavailability was determined, we recommend the use of biological measures that identify the real metal bioavailability rather than the use of chemical measures.
The risk assessment of chemicals for ecosystems is generally based on the results of laboratory toxicity tests. For an overview of tests available or under development for the soil ecosystem, refer to Van Straalen and Van Gestel (1993). To derive ‘safe’ levels of chemicals in soil ecosystems, a number of extrapolation methods have been developed. These extrapolation methods all assume a certain distribution (log-logistic, log-normal or triangular) of sensitivities of organisms in the field, and aim at deriving a so-called 95% protection level, i.e. the hazardous concentration for 5% of the species, the so-called HC5 value. For a critical overview of extrapolation methods see Suter (1993)
A study was conducted in 13 years of Organic Fertilizer (OF) and nofertilizer CU) field experiment in a winter wheat-summer maize rotation agroecosystem in the North China plain. The study was also included an Greenhouse (GH) experiment in cucumbers and kidney bean rotation in the North China Plain. Researchers aimed to evaluate the changes in soil physico-chemical parameters and the abundance and community structure of soil protozoan, under Greeubouse (GH), Organic Fertilizer (OF) and nofertilizer (U) different treatments, compared to difference management measure soil as the control CD). Soil organic matter content, available potassium (K) and hydrolyzable N were significantly higher in the plots under the GH treatment than under the other treatments. Available Phosphorus (P) content of OF was significantly higher than control treatment. After continuous many years organic application treatment and GH treatment which both increased the abundance soil protozoa. Both types of organic fertilizer and GH reduced the relative abundance of amoeba whereas increased relative abundance of flagellate in experiment. However, relative abundance of amoeba in the three treatments have occupied the overall majority. This result was positively related to the high level of phosphorus in this experiments which probably suppressed fungi thus increasing the food resources for bacterivorous protozoa, especially in flagellate. The GH and organic fertilizer treatments remarkably increased the overall abundance of protozoa. While the GH and organic fertilizer application treatments did not increase the relative abundance difference groups of soil protozoa, respectively especially amoeba increasing the relative abundance of flagellate, the increase in flagellate reflected enhanced biological activity and functioning of the bacterial decomposition pathway especially in the food web of this treatment.
Bioremediation is a natural process, which relies on bacteria, fungi, and plants to degrade, break down, transform, and/or essentially remove contaminants, ensuring the conservation of the ecosystem biophysical properties. Since microorganisms are the former agents for the degradation of organic contaminants in soil, the application of organic matter (such as compost, sewage sludge, etc.), which increases microbial density and also provides nutrients and readily degradable organic matter (bioenhancement–bioaugmentation) can be considered useful to accelerate the contaminant degradation. Moreover, the organic matter addition, by means of the increase of cation exchange capacity, soil porosity and water-holding capacity, enhances the soil health and provides a medium satisfactory for microorganism activity. Plants have been also recently used in soil reclamation strategy both for their ability to uptake, transform, and store the contaminants, and to promote the degradation of organic contaminants by microbes at rhizosphere level. It is widely recognized that plant, through organic materials, nutrients and oxygen supply, produces a rich microenvironment capable of promoting microbial proliferation and activity.
An increasing number of ecotoxicological field studies are being submitted in the European Union procedure for authorization of pesticides. Although there is some guidance on how these studies can be used for risk assessment, not all aspects of field tests are covered and the guidance differs per type of test and per non-target group. To facilitate a more uniform approach by the regulatory authorities in the EU, a basic scheme is proposed with qualitative tools to: (i) assess the scientific reliability of individual field tests, and (ii) to assess the usefulness of field tests for regulatory risk assessment of the pesticide under registration. In this way, the treatment, evaluation, and the mutual comparability of field data for regulatory purposes is harmonized. It thereby provides a more consistent foundation for further risk assessment.
Soil enzymatic activities (phosphatases, arylsulphatase and dehydrogenase) were measured in microcosm systems designed for the study of the impact of a commercial mixture of Linear Alkylbenzene Sulphonate (LAS) homologues on a xerofluvent agricultural soil. The soil microcosms consisted of glass columns filled with 800 g of dry soil which were fed with sterile commercial LAS solutions at concentrations of 10 or 50 mg l−1 for periods of time up to 21 days. A soil microcosm fed with sterile distilled water was included in this study and considered as control. Our results showed that the continuous application of the anionic surfactant to soil increased the values of the enzymes acid and alkaline phosphatases and arylsulphatase. On the contrary, the dehydrogenase activity was decreased by the continuous application of 10 or 50 mg l−1 LAS when compared with control microcosms. In addition, a statistically negative correlation was found between this enzymatic activity in the upper portion of the soil columns amended with LAS and the viable counts of heterotrophic aerobic microorganisms. Moreover, in order to test the influence of LAS on nutrient availability and, consequently, on bacteria populations and soil biological activities, phosphate concentration was regularly determined in the microcosm leachates. The phosphate concentration tested in the leachate of the microcosm continuously amended with 50 mg l−1 LAS solution was significantly lower than the concentrations detected in the leachate of the microcosms continuously amended with 10 mg l−1 LAS throughout the experiment.
The demography of Paronychiurus kimi (Lee), a dominant springtail in the paddy fields of Korea, was studied under the influence of glufosinate-ammonium (GA), a herbicide, on two different substrates: plaster-charcoal and artificial soil.On plaster-charcoal substrate with brewer’s yeast provided as food, survival rate of eggs, juveniles and adults, and life table statistics of P. kimi did not reveal any significant influence of GA except at an extremely high concentration (1572.70μg/cm2). The EC50 of GA for reproduction of P. kimi was estimated to be 446.21μg/cm2. In artificial soil with brewer’s yeast, P. kimi was susceptible to GA. Reproduction of P. kimi was significantly reduced at 0.5mg/kg and the adult survival rate decreased at 50mg/kg. The life table statistics showed significant influences of GA even at low concentration, and the EC50 was estimated to be 0.039mg/kg. The fact that acute toxicity of GA to the springtail is negligible does not guarantee negligible impact of the herbicide on springtail populations in the field.
Despite their significance in soil ecosystems and their use for investigations of soil ecosystem functioning and in bioindication elsewhere, springtails (Collembola) have not been well investigated in South Africa. Early recognition of their role in soil systems and sporadic systematic work has essentially characterised knowledge of the southern African fauna for some time. The situation is now changing as a consequence of systematic and ecological work on springtails. To date this research has focused mostly on the Cape Floristic Region and has revealed a much more diverse springtail fauna than previously known (136 identifiable species and an estimated 300 species for the Cape Floristic Region in total), including radiations in genera such as the isotomid Cryptopygus. Quantitative ecological work has shown that alpha diversity can be estimated readily and that the group may be useful for demonstrating land use impacts on soil biodiversity. Moreover, this ecological work has revealed that some disturbed sites, such as those dominated by Galenia africana, may be dominated by invasive springtail species. Investigation of the soil fauna involved in decomposition in Renosterveld and Fynbos has also revealed that biological decomposition has likely been underestimated in these vegetation types, and that the role of fire as the presumed predominant source of nutrient return to the soil may have to be re-examined. Ongoing research on the springtails will provide the information necessary for understanding and conserving soils: one of southern Africa's major natural assets.
Two Australian Collembola species were selected for use in toxicity testing because they are more ecologically relevant to Australian soils than Folsomia candida Willem. A number of easily-collected local species were assessed but were not suitable for toxicity tests because they were too difficult to maintain in culture or their reproduction rates in artificial soil were too low. Two species, Sinella communis Chen & Christiansen and Proisotoma minuta (Tullberg, 1871), reproduced rapidly in culture and compared favourably with F. candida, the standard test species in Europe. Proisotoma minuta was found to be more difficult to count than S. communis because of its smaller size and less conspicuous colour. Sinella communis was easy to count and found to be more sensitive to most toxicants and contaminated soils than F. candida, so is the preferred species for toxicological testing of soils in Australia. All three species are near cosmopolitan and probably introduced to Australia but F. candida is very rare while S. communis and P. minuta are common in Australian soils. The use of avoidance as an endpoint for toxicity assessment of soils was also investigated.
Present statistical analysis of survivorship data obtained from bioassays using nonpersistent toxicants does not explicitly take into account that exposure decreases with time due to degradation of the toxicant. Such a situation typically occurs in static aquatic toxicity tests and in soil tests. We develop a model for the analysis of survival data obtained in such experiments and show how estimates for the initial LC50, the degradation rate constant, and the elimination rate constant may be obtained from observations on time-dependent survival rates. The model assumes linear one-compartment toxicokinetics with exponentially decreasing input. The probability of dying is assumed to be directly proportional to the internal concentration. An explicit expression for time- and concentration-dependent survival is obtained. The model predicts that, with increasing exposure time, survival will approach a nonzero baseline value for certain initial concentrations. Application of the model is illustrated by curve-fitting to experimental observations, made over 6 weeks, for the effect of diazinon on the terrestrial isopod Porcellio scaber. The fit to data is fairly good, but the parameter estimates tend to have a high coefficient of variation. A considerable increase of precision may be obtained if the degradation rate constant is given a fixed value (for example, following from chemical residue analysis of the medium). The approach is applicable to all situations where, due to loss of the toxicant during the test, mortality shows no further increase after a certain exposure period.
Oribatid mites are a group of arthropods that have had remarkable evolutionary success with regard to species richness, variety of habitats colonized, life-cycle variation and reporductive patterns. The aim of this paper is to review some of the important features of Oribatida in relation to the possible use of these animals in ecotoxicological experiments. Their often sedentary way of living, combined with a narrow dependence on microhabitats qualify oribatids as potential indicator organisms for air and soil quality. Some species have been shown to be extremely sensitive to air pollutants such as SO2 and NO2. A low metabolic rate may be the driving force for slow development, low fertility, iteroparity and long adult life. Given these life-cycle characteristics, oribatids may be particularly vulnerable to intoxication by persistent contaminants. Work done on heavy metals suggests that the capacity for accumulation differs greatly between species. The camisiid Platynothrus peltifer accumulates high amounts of trace metals, specifically Mn. The toxicity of Cd, Cu and Pb has been studied in P. peltifer, demonstrating the necessity to consider egg production as a sensitive criterion. It is concluded that oribatid mites hold a great potential for use in ecotoxicology, due to the structural and functional complexity of their communities, and several peculiarities not found in other arthropods. The possibilities offered by this diverse group have not yet been fully employed by ecotoxicologists.
“Evolution Canyon” is a typical Mediterranean-basin canyon with a summer dry stream at the bottom and large differences in
vegetation cover and solar radiation between the north-facing slope (NFS) and the south-facing slope (SFS). It is known to
act as an abiotic mediator influencing the community structure of soil fauna. The aim of this study was to determine the spatial
dispersion of soil microbial and free-living nematode communities in the open sites (between shrubs) in the upper (0–10 cm)
soil layer at four altitudes on both slopes. The combination of relative soil moisture availability and temperature, known
to be one of the main triggers for soil biota activity, was explained by slope orientation. The above-mentioned differences
were found to significantly affect microbial biomass and CO2 evolution resulting in temporary stress, corresponding to higher values in metabolic quotient (qCO2) values. These differences may represent microbial investment in energy in order to overcome stress resulting from the microclimatic
differences between the two slopes. Moreover, the degree of substrate limitation (primary production due to the differences
in plant cover) of microbial activity was explained by the difference in microbial functional groups. The total abundance
of soil free-living nematodes was found to be 2-fold higher on the SFS than on the NFS. Thirty-nine genera, including 12 bacteria-feeders,
5 fungi-feeders, 12 plant-parasites, and 10 omnivore-predators, were found at the study site, with 34 genera on the NFS and
29 on the SFS. The generic diversity of the bacteriafeeding nematodes was higher on the SFS than on the NFS. This study elucidates
the importance of slope orientation and its effect on the structural levels of soil microbial and nematode communities.
Internationally there is a gradual decline in availability of fresh water to be used for irrigation. As a consequence, the
use of drain water for irrigating agricultural lands is on the rise particularly in urban areas of developing countries especially
Egypt. On the other hand, there is increasing concern regarding the exceedance of statutory and advisory food standards for
trace metals throughout the world. A study was undertaken to assess the long-term effect of irrigation with drain water on
heavy metal content in soils and diversity of terricolous biota. An agroecosystem in Bahr El-Baqar area, south of Port Said,
Egypt were selected where various cereals, vegetable and fodder crops have successfully been grown. During the period from
September (2004) to February (2005), 25 soil profiles, 100 soil and 30 water samples were collected from cultivated soil and
drain of Bahr El-Baqar. Soil heavy metals content (Zn, Pb, Cd, Co, Mn and Cu), gypsum, organic matter, total calcium carbonates,
cations, anions, electric conductivity and pH were determined. Water samples has been subjected to various analyses including
water temperature, pH, total soluble salts, electric conductivity, total nitrogen, total phosphate, heavy metals and organic
loads (chemical oxygen demand and biological oxygen demand). For isolation and examination of total mycobiota, arbuscular-mycorrhizal
fungi (AMF) and nematodes from rhizosphere soils, samples were collected from dominant plant species in the study area. Obtained
data were subjected to multivariate analysis by using Canonical Correspondence Analysis to find out the relationship between
biota and environmental variables. Results indicated that concentrations of heavy metals exceeded the maximum allowable limits
while water analyses showed that organic load values are slightly increase in all examined samples and samples were not complying
with the standard value given by law 48/1982 for ambient water quality in the drain. It was possible to encounter as many
as 43 fungal species belonged to twenty-one genera from five sites in the agroecosystem in south Port Said. The results show
that Zygomycota represented by six species (7.59% of the total isolate number), teleomorphic Ascomycota (3 species, 3.78%),
anamorphic Ascomycota (31 species, 86.96%) and mitosporic fungi (3 species, 1.67%). The AM fungal spores obtained belonged
to the three genera namely Acaulospora, Gigaspora, and Glomus and eight species. While family Glomeraceae accommodates the greatest range of species (6 species), the other family Gigasporaceae
accommodate the lowest range (two species). Twelve species belonging to eight genera and six families of plant-parasitic nematodes
were identified throughout the study. Total levels of heavy metals showed a trend relationship between metal concentration
in soil and long term of irrigation assuming that there is a continuous deposition of heavy metals on the soils due the continuous
use of Bahr El-Baqar drain in watering soil for many years in which both living and non-living components of ecosystem are
hazardly affected. Detailed studies to minimize the quantity and improve the quality of wastewater discharged should be carried
out for each industry. Research must take the objective of sustainability into consideration. Legislation sensible to environmental
control should depend on a thorough knowledge of the existing situation and careful assessment of its likely impact on the
development. On the other hand activation of law 4/1994, for the protection of environment in Egypt, is urgently needed.
The risk assessment process planned for the S. Domingos mine, an abandoned cupric pyrite mine (Southeast Portugal), established as a task the assessment of soil microbial parameters to evaluate the long-term effects of heavy-metal contamination on the microbial community activity and subsequently on some important soil functions (e.g. nutrients cycling, decomposition of organic matter). Total metal contents as well as physical and chemical parameters (e.g. organic matter, moisture, pH and conductivity) were measured. In the study area, the levels of As, Cd, Cr, Cu, Ni and Pb were above soil quality criteria defined by some European countries. Nevertheless, sub-areas from the mining area with high concentrations of As, Cu and Pb and low soil pH levels were separated from the rest, along the first axis of a principal component analysis (PCA). The most sensitive microbial parameters were dehydrogenase activity (DHA) and potential nitrification (POTNI), which were highly depressed in the mining area. According to the redundancy analysis (RDA) of the microbial parameters and environmental variables, and Spearman rank order correlations, pH was positively correlated with these microbial parameters (DHA: rs = 0.733, p < 0.01; POTNI: rs = 0.676, p < 0.01). These results suggested that the contamination with some of the most toxic elements and low pH values adversely affected the biomass and the activity of soil microorganisms in the mining area. Therefore, the results of this study provided evidence about the importance of the assessment of microbial parameters, as a tool for the evaluation of direct impacts of heavy metals in contaminated sites.
Earthworms are standard test organisms in soil toxicity testing. They have been broadly used to assess environmental impact from heavy metal pollution; however, the knowledge on toxic effects from pesticides upon these organisms is still very limited. One of the ecotoxicological approaches to assess pollutant bioavailability and sublethal effects is the use of molecular and biochemical biomarkers. This review focuses on five issues that need further investigation: 1) field validation of earthworm biomarkers of pesticide exposure (e.g., cholinesterases) as well as testing and development in earthworms of those biomarkers of pesticide exposure currently used in other organisms (e.g., carboxylesterases), 2) the impact of environmental and biological interfering factors upon biomarker responses, 3) the development of biomarker-based approaches to assess long-term pesticide exposure, and 4) the need to develop biomarkers of behavioural and reproductive disruption with direct implications at individual and population levels. (C) Pesticide Science Society of Japan.
This article gives a brief overview on soil biotests as ecotoxicological tools for the evaluation of the impact of substances on soil quality. Soil biotests or bioassays use biological indicators of bioaccumulation and effect. Toxicity tests evaluating the effect are described with some of their advantages and disadvantages. Their integration into the risk assessment of substances and of contaminated soils or sites is outlined.
The herbicide 2,4,5‐T is commonly used in forests and nature reserves in the Netherlands for the control of the black cherry ( Prunus serotina ) and birch ( Betula spp.). To investigate possible side effects of 2,4,5‐T on the soil fauna, laboratory experiments were carried out with the isopod Philoscia muscorum , a primary decomposer of litter in woods. After direct treatment with 0.12 ml/dm ² herbicide, the survival time of the isopod was shorter. There were some indications that a high moisture content in the substrate increases mortality. When offered treated and untreated substrate at the same time, the isopod did not show a clear preference for or avoidance of the treated part at first contact (15 min). However, at a high dose (0.05 ml/dm ² ) the activity of the isopod decreased, and at a low dose (0.006 ml/dm ² ) there was a slight increase. When 0.012 ml/.dm ² was applied to the treated half of the substrate, most of the isopods stayed on the untreated part from the fifth day on. Notwithstanding this repellent action of the herbicide, the survival duration was shorter. The herbicide also influenced the isopod via its food. Sprayed black cherry leaves, prepared under controlled conditions, were consumed well. The isopod also showed a preference for sprayed leaves. Consumption of sprayed leaves for 5 weeks did not alter longevity or weight gain; consumption of unsprayed leaves coincided with a weight loss. Possible causes of this difference in consumption include the following changes caused by the 2,4,5‐T treatment: a high protein content, a low C/N ratio, a looser leaf structure, and a reduced penetration resistance. When fresh Prunus leaves were offered to isopods over a longer period (20 weeks), more treated leaves were consumed too, but the survival time did not change significantly. The consumption of fresh birch litter treated with 2,4,5‐T was half that of untreated litter, and the survival time of the isopods was reduced significantly. Since the amounts of 2,4,5‐T found on the forest floor and calculated as ppm‐content of the upper part of the litter layer correspond with the 2,4,5‐T content of the food used in the experiments, side effects of the herbicide 2,4,5‐T must be expected in the field. It is not clear what influence the enhanced break‐down of treated Prunus leaves has on the soil fauna.
Zusammenfassung
Nebenwirkungen des Herbizids 2,4,5‐T auf die Assel Philoscia muscorum Scopoli
Gegen Prunus serotina und Betula spp. wird in den Niederlanden das Unkrautbekämpfungsmittel 2,4,5‐T zur Zeit noch in großen Mengen angewandt. Zur Prüfung, welche Veränderungen durch die Einwirkung von diesem Mittel auf der Bodenfauna möglicherweise hervorgerufen werden, sind Laborversuche mit der Assel Philoscia muscorum als Versuchstier ausgeführt worden. Diese Tiere sind als primäre Zersetzer der Laubstreu zu betrachten.
Bei einer Spritzung mit einer Dose von 0.012 ml/dm ² kam es in den Versuchen schon zu einer abgekürzten Lebensdauer der Tiere. Weiterhin schienen sie in dieser Hinsicht unter feuchten Umständen empfindlicher zu reagieren. Das Herbizid hatte beim ersten Kontakt keine abwehrende Wirkung auf die Asseln. Durch eine Dose von 0.05 ml/dm ² konnte doch eine Abnahme der Mobilität festgestellt werden und eine leichte Steigerung bei einer geringen Dose (0.006 ml/dm ² ). Wenn die Asseln während einer längeren Zeit auf einem teilweise gespritzten Boden waren, dann hatten Sie eine deutliche Präferenz für die nicht gespritzten Teile, trotzdem war auch bei diesen Tieren eine abgekürzte Lebensdauer zu beobachten. Weiterhin konnte ein Zusammenhang zwischen der Vergiftung mit dem Herbizid und der Ernährung der Versuchstiere festgestellt werden. So wurde das gespritzte Fallaub von Prunus serotina , das nach jeweils spezifischer Methodik präpariert wurde, in größeren Mengen konsumiert als das nicht gespritzte Fallaub. Es hat sich herausgestellt, daß bei den Asseln, die während fünf Wochen damit genährt wurden, keine schädlichen Folgen in der Lebensdauer und dem Gewicht nachweisbar waren.
Dagegen verursachte das unbehandelte Fallaub zwar keine abgekürzte Lebensdauer, obwohl das Gewicht der Asseln deutlich abnahm. Für eine Beurteilung dieser Untersuchungsergebnisse ist anzuführen, daß ein hoher Eiweißgehalt des Fallaubes sowie auch ein niedriges C/N‐Verhältnis und eine lockere Blattstruktur dem Abbau der organischen Substanz durch die Asseln zu gute kommt.
Es hat sich auch ergeben, daß frischgesammelte, gespritzte Blätter während einer Periode von 20 Wochen besser konsumiert wurden als Blätter von unbehandelten Sträuchern. Diese Untersuchungen gaben aber keinen Unterschied in Lebensdauer. Wenn aber zum Beispiel frische Birchblätter in Laborversuchen gespritzt wurden mit dem Herbizid, so wurde der Konsum durch Asseln auf die Hälfte reduziert und wurde ihre Lebensdauer ziemlich gekürzt.
Die Herbizide‐Akkumulationen, die in der Praxis auf Waldböden gefunden wurden, waren fast ähnlich wie der Herbizidgehalt bei den Laborexperimenten. Deshalb ist es wahrscheinlich, daß bei der Verwendung des Unkrautbekämpfungsmittels 2,4,5‐T ebenfalls schädliche Nebenwirkungen zu berücksichtigen sind.
The effects of an organotin pesticide, fentin hydroxide (triphenyltin (IV) hydroxide; TPTH) , on the soil fauna mediated decomposition of poplar leaf litter were examined. The responses of micro‐ecosystems (MES) containing soil animals were compared to MES without fauna. The isopod Porcellio scaber Latr. was chosen as a representative saprotrophic soil fauna species.
TPTH was added in four concentrations, ranging from 0.1 to 100 μg (g dry litter) ⁻¹ . MES respiration was used as a measure of decomposition rate. To measure the nitrogen mineralisation by microflora and isopods, ammonium and nitrate concentrations in the litter were determined.
Analyses of the litter showed that TPTH was not degraded during the experiment. TPTH had a short‐term effect on microbial respiration, which diminished after two days. Ammonium production by isopods within the system was the most sensitive parameter for the effects of TPTH . The No Observed Effect Concentration (NOEC) was 10 μg g ⁻¹ . It was concluded that, while TPTH is a fungicide, it does not seem to be very toxic to microbial respiration and ammonification as measured within the micro‐ecosystem; isopod activities are more sensitive.
The herbicide 2,4,5‐T is widely used in forestry and nature reserves against black cherry ( Prunus serotina ) and birch ( Betula spp.). When adult specimens of the springtail Onychiurus quadriocellatus Gisin (taken as a representative of the important group of the soil fauna, the Collemboles) in laboratory experiments were continuous exposed to the herbicide, a dose of 0.003 ml/dm ² already caused a significant increase in mortality.
Not only the active ingredient of the herbicide (2,4,5‐T isooctylester), but also the formulation fluid itself proved to be toxic, be it to a lower extent.
The toxic action of the herbicide is mainly caused by direct contact; there was only a slight effect after application as a vapour.
Juvenile springtails proved to be more susceptible than adults. The herbicide also influenced the mobility of the springtails. A high dose (0.025 ml/dm ² ) decreased mobility, whereas a low dose (0.003 ml/dm ² ) gave an increased mobility.
Moreover the herbicide excercised a repellent action on springtails; these were able to avoid treated sections of the substrate, as well as to escape from them.
In spite of this repellency a considerable proportion of the springtails tested died, although given the opportunity to escape. They died on the treated substrate or after escape from it.
The amounts of herbicide found on the soil under and between black cherry shrubs after practical applications, varied from 0.0005 to 0.017 ml/dm ² . From this and the above mentioned results of laboratory experiments, in the field side effects of the herbicide 2,4,5‐T are to be expected.
Zusammenfassung
Nebenwirkungen des Herbizids 2,4,5‐T auf den Springschwanz Onychiurus quadriocellatus Gisin (Collembola)
Die Anwendung des Mittels 2,4,5‐T zur Bekämpfung von Prunus serotina und Betula spp. hat in den Niederlanden sowohl in Wäldern als auch in Naturreservaten in der letzten Zeit mehr und mehr zugenommen.
Es stellte sich heraus, daß in Laborversuchen, wo erwachsene Tiere von Onychiurus quadriocellatus Gisin — als Vertreter der Collembolengruppe — ständig dem Einfluß des Mittels ausgesetzt waren, eine Dosis von 0,003 ml/dm ² schon eine ziemlich hohe Mortalität verursachte. Die schädliche Wirkung war dabei nicht nur der wirksamen Substanz (2,4,5‐T isooctylester) des Mittels zuzuschreiben, sondern auch den Formulierungsbestandteilen.
Die Toxizität wurde hauptsächlich durch direkte Berühung mit dem Mittel verursacht, jedoch nahm bei Ausbringung in Dampf‐Form die toxische Wirkung ab.
Die Jungtiere zeigten größere Empfindlichkeit als die Adulten. Das Unkrautbekämp‐fungsmittel beeinflußte weiterhin die Mobilität der Springschwänze. Bei hoher Dosis (0,025 ml/dm ² ) kam es zu einer Abnahme der Mobilität, bei geringer Dosis (0,003 ml/ dm ² ) zu einer Zunahme. Außerdem zeigte das Herbizid eine abschreckende Wirkung auf die Springschwänze. Dennoch starben die meisten Versuchstiere, weil es ihnen nicht gelang, den vergifteten Stellen zu entrinnen. Die Herbizid‐akkumulationen, die in der Praxis in Waldböden gefunden wurden, wechselten wie in den Laborversuchen zwischen 0,0005 und 0,017 ml/dm ² . Deshalb ist es sehr wahrscheinlich, daß bei der Verwendung des Unkraut‐bekämpfungsmittels 2,4,5‐T in unseren Böden ebenfalls schädliche Nebenwirkungen auf‐treten.
The following topics are discussed: the advantages of an interdisciplinary approach to ground water studies; the porous aquifer as an open system; the problem of the terminology used in ground water ecology; the interest of ecologists in hydrogeological terminology; biological activity in the unsaturated zone of porous aquifers; the distribution of ground water fauna in the saturated zone of porous aquifers; ground water animals as environmental indicators; the manipulation of ground water ecosystems; basic lines for the further development of ground water ecological studies.
Increasingly stringent environmental requirements for pesticides mean that both biological activity and favourable environmental behaviour must be assessed at an early stage in pesticide discovery. Soil behaviour is governed by the physical properties of the molecule: partition coefficient, dissociation constant, vapour pressure and melting point, which control potential movement under particular soil and environmental conditions and the soil persistence. Established chemical structure-physical property correlations generally allow physical properties to be estimated for the large number of compounds in a synthesis programme with adequate precision. Stability to chemical or biological transformations in soil is more difficult to estimate but a combination of measurement for a few compounds and analogy with known chemical and biological transformation rates for various functional groups can give useful structure-stability correlations.
Spreading treated municipal wastes on agricultural and forest lands is becoming an established method of disposal (LOEHR 1977). However, there is concern about the deleterious effects of toxicants, particularly cadmium, in the sludges. Cadmium concentrations in sewage sludge have been reported as high as 1500 ppm (BERROW & WEBBER 1972). The work reported here is a part of a larger project to investigate the ecological effects of municipal wastes on forest lands. Snails, Helix aspersa, were chosen to examine the entrance of cadmium into terrestrial food chains. This experiment was designed to determine cadmium accumulation, acute toxicity, and behavioral, reproductive and growth responses with increasing levels of cadmium.