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Chlorinated pesticides in the marine sediments
... Thus, the contamination of seafood with such toxic contaminants poses a serious threat to human health thereof. Persistent organic pollutants have been detected in different segments of the marine environment such as water, sediments and biota [5,[17][18][19][20]. The natural capacity of coastal zones to disperse and to assimilate pollutants varies according to the tidal zones and the seasonal variation in the physico-chemical characteristics of coastal zones. ...
In this article, we present an overview on the role of marine pollutants in impairment of DNA integrity in marine gastropods exposed to xenobiotics released from various sources into the coastal ecosystem. We provide an insight into the impact of various types of genotoxic compounds on the physiologic status of marine organisms, with specific focus on DNA integrity. DNA damage in marine gastropods was found to be highly correlated to the level of contaminants prevalent in the marine environment. DNA integrity in marine organisms was significantly affected upon exposure to genotoxicants such as polycyclic aromatic hydrocarbons (PAH), persistent organic pollutants, cadmium, lead, manganese, chromium, copper, etc. The prevalence of persistent xenobiotic contaminants in the marine environment coupled to their deleterious impact on marine organisms, exemplifies the measurement of DNA integrity as a prognostic tool for marine pollution assessment, control and policy-making.
... Concentrations of DDTs in Bay of Bengal ranged from 0.04 to 4.79 ng/g. These concentrations were several orders of magnitude lower than the highest concentrations reported for same areas 15 years earlier possibly reflecting a significant decline in DDT usage and exposure in that area (Sarkar and Sen Gupta, 1988). ...
Persistent organic pollutants (POPs) have been used in a wide range of agricultural and industrial commodities, resulting in vigorous deterioration of environment and human health. A number of studies on the occurrence of POPs confirm their presence in various environmental compartments and human body. In order to deal with this global concern, India has recently prepared the National Implementation Plan (NIP) of the Stockholm Convention. Common beliefs point at India as a hot spot of POP contamination and human exposure; however no systematic analysis was ever performed so far considering all available past data on POP occurrence. This review aims to examine the distribution pattern of POPs in multicompartment environment and human samples, meta-analysis of time trends in exposure levels to environment and humans, and cross country comparison of POP contamination with China. Based on this review, it can be concluded that the Indian environment and human population are highly contaminated by DDTs and HCHs; however scarcity of data on other POPs makes it challenging to assess their nationwide human and environmental exposure. No evidence of a general decline in DDT and HCH residues in the environment and human body come out from the meta-analysis of time trend. While comparing contamination levels between India and China, tendency towards decline in POP contamination is visible in China, unlike India.
... Although the low levels of OCCs detected in most of the sediments surveyed supported the popular view that chemical pollution of the New Zealand marine environment is lower than is the situation for more industrialised and highly populated overseas countries, the concentrations of OCCs at some sites within the Waikareao Estuary, (e.g., Wl, W5, and W8) had OCC levels similar to those reported in sediment from San Francisco Bay, California (Phillips & Spies 1988) and Rio de La Plata, Argentina (Colombo et al. 1990). Other studies outside New Zealand have, however, also recorded levels much higher than those determined in the Waikareao sediments (Turk 1980;Sarkar & Sen Gupta 1988). ...
DDT, DDE, and DDD (up to 0.5 ng gper compound) and traces of dieldrin (< 0.1 ng g), were detected in surficial sediments collected from four sites in the greater Tauranga Harbour. An elevated level of PCBs (19.9 ng g) was identified in a Waikareao Estuary sample. PCB and DDT levels of up to 24.1 ng g and 5.38 ng grespectively, were subsequently detected in other eastern shore Waikareao Estuary sediment samples. Higher levels of PCBs (68.6 and 73.8 ng g) and DDTs (total 7.52 and 19.2 ng g) were detected in sediments from two eastern shore stormwater drains identified as the likely sources of the PCB and DDT burden entering the Waikareao Estuary. Black, carbonaceous, coal‐ and asphalt‐like, paniculate material (98% loss of organic carbon on ignition), isolated by sieving a representative sediment sample, exhibited DDT and PCB levels which were respectively 85 and 6 times higher than was the case for other sieved fractions.
... A comparison with data from tropical coastal areas was also made. Previously reported residue concentrations of pesticides in sediments along the west coast of India decreased as dieldrin < aldrin < HCH < DDT with the highest values of total DDT ranging from 32 to 43 lg/kg wet wt (Zitko and Hanlon, 1991) while the east coast had the concentration ranges of aldrin: (10-210), dieldrin: (50-510) and total DDT: (0.020-0.780), all in lg/kg wet weight (Sarkar and Gupta, 1988). These values are relatively higher than the ones obtained in this study. ...
... The cumulative effects of these pesticides on the coastal environment can be expected to be considerable as is evident from their accumulation in the marine organism (Kannan & Sen . Few data on the residue levels of various organochlorine pesticides in the seas around India are available (Kannan & Sen Gupta, 1987;Sarkar & Sen Gupta, 1986, 1988a,b, 1989 Arabian sea at an average depth of 50-250 m along the west coast of India with a Peterson grab during Cruise ...
An average of 55,000 t of pesticides (including or organochlorine compounds) are used every year in India for agricultural purposes. The cumulative effects of these pesticides on the coastal environment can be expected to be considerable as is evident from their accumulation in the marine organism. Few data on the residue levels of various organochlorine pesticides in the seas around India are available. However, the residue levels of different organochlorine pesticides in the sediments from the Arabian Sea along the west coast of India is Dieldrin Aldrin HCH DDT.
... Sarkar and Sen Gupta (1988a,b) determined residues of organochlorine pesticides in sediments from the Bay of Bengal. The compounds and concentrations detected were aldrin at 20 to 530 ng/g (all sample weights expressed as ww), γ-HCH at 10 to 210 ng/g, dieldrin at 50 to 510 ng/g (Sarkar and Sen Gupta 1988b), and ΣDDT at 20 to 790 μg/g (Sarkar and Sen Gupta 1988a). The variability in pesticide residue concentrations was attributed to the presence of numerous rivers along the east coast of India including the Hugli, Mahanadi, Vamsodhara, Godavari, Krishna, Pennar and Palar Rivers, as evidenced in Fig. 1. ...
Organochlorine pesticides (OCPs) are an important potential component of chemical pollutants used extensively for agriculture and sanitation purposes in India as these are comparatively cheap and effective. These persistent organic compounds such as HCH isomers, DDT and its metabolites are the predominant chemical contaminants found along the Indian coast and thus constitute both alluring and grave areas of scientific research. Our objective in the paper is to provide a comprehensive account of the distribution of organochlorine pesticides in biotic and abiotic compartments of the Indian coastal environment, make some comments on their environmental sources, their movement through the food chain and possible ecotoxicological risk of health in biota including humans. The prevalent HCH, DDT and HCB concentrations differ markedly in eastern and western coast of India reflecting differing agricultural and other usage and their ultimate input into the coastal environment by several rivers and the bioturbation activities of macrozoobenthos (bivalve mollusks, polychaetous annelids, etc.). In several cases, the DDT levels exceeded the effects range-low (ER-L) and could thus cause acute biological impairments, in comparison with the sediment quality guidelines. Contributions of DDT metabolites (DDT, DDD and DDE residues) vary in different Indian coastal regions predominated by pp'-DDT and pp'-DDD. Measured concentrations of HCHs were lower than DDTs that might be due to higher water solubility, vapor pressure and biodegradability of the latter. HCH and DDT residues in fish in India were lower than those in the temperate countries indicating a lower accumulation in tropical fish, which might be related to rapid volatilization of this insecticide in the tropical environment. The concentrations of other chlorinated pesticides (aldrin, dieldrin, eldrin, methoxychlor, endosulfan sulphate) were lower and not generally of great concern.
Indiscriminate use of pesticides will lead to their accumulation in soil and may impart an adverse impact on human and environmental health. Due to the intensification of agriculture, usage of pesticide is inevitable in India; however, in the absence of a strong legal framework and lack of awareness of the farmers, inappropriate use of pesticides contributed to the pollution of soil and sediments and induced health problems for human and aquatic lives. Some of the pesticide molecules and its derivatives persist in the soil for a longer period which disturbs soil ecological balance and sustainability. Moreover, traces of pesticides may cause threat to the aquatic endangered species. This is a serious concern for both soil and aquatic environments. Reviewing various literature it was found that the level of contamination in soil and sediment does not reflect the present pesticide usage scenario of India and further highlighted the widespread use of banned pesticides. Under these circumstances, this chapter describes the occurrence, distribution and source of pesticides in the Indian scenario based on the numerous studies conducted over the past decades in both soil and sediment environments. The impact of these pesticides on soil ecology is also discussed along with the mention of novel and effective bioremediation methods invented by team of researchers to overcome the problem of pesticide residues.
Concentrations of six organochlorine pesticide residues (lindane, heptachlor, aldrin, pp'DDE, pp'DDD y pp'DDT) wereanalized in surface mangrove sediments at four sites at Ciénaga Grande de Santa Marta and in one site in Bahía de Chengue, Colombian Caribbean. Analyses were carried out by gas-liquid chromatography. Samples were taken between March and December 1993, corresponding to four climatic seasons (dry, minor rainy, minor dry and major rainy). Significant differences in lindane, heptachlor and pp'DDE concentrations among seasons were determined by multifactorial analysis of variance; the other three compounds (aldrin, pp'DDD an pp'DDT) did not show significant differences for any of the likely sources of variation. Highest concentrations of lindane were in dry season and those of heptaclore and pp'DDE were in rainy season. A canonical correlation was run between the groups formed with organochlorine concentratios and water salinity plus relative organic matter content. The correlation coefficients indicate that only pp'DDT presented a inverse correlation with the percentage of organic matter.
Over the past few decades there has been a steady increase in the use of many pesticides for agricultural and disease control purposes in developing countries including India. Apart from this, India is now becoming an industrially developed nation, compelling it to use several other man-made chemicals for its ongoing industrial development. In spite of the fact that India has promulgated several laws for the control of such chemicals, in practice, there has been little control over their production and usage. As a result, there has been widespread contamination of the Indian environment and biota, including human, by all these chemicals. Most recent studies have shown that, in contrary to the popular belief that the developed nations are the prime sources of the highly toxic chemicals such as PCDDs/DFs, India is also contributing such chemicals to the global environment in considerable quantities. Many popular articles and scientific publications have shown a grim situation in several sectors of human life in India with regard to xenobiotic chemical contamination. Our group at the Center for Marine Environmental Studies (CMES), Ehime University has been carrying-out monitoring and toxicological studies of many of those chemicals in India for the past three decades. Apart from our works, sizable literature is available on the status of contamination of persistent toxic substances (PTS) such as DDTs, PCBs, PCDDs/DFs, PBDEs, HBCDs, OTs, etc. Viewing from a global pollution point of view, a detailed review of the available information on PTS pollution in India is necessary for planning and executing control measures to restrain their expansion on a wide scale. With this view in mind, this review provides information on the history of usage of PTS in India, their occurrence in the aquatic and terrestrial environment and in the flora and fauna. Finally the review provides a brief account of the laws governing the manufacture and usage and the management practices of those chemicals.
Persistent organic pollutants (POPs) are semivolatile organic compounds of special concern because of their toxicity, persistence, long-range transport and bioaccumulation potential. They are present in the marine environment, notably in coastal areas affected by municipal sewage, agricultural and aquaculture effluents, industry and shipping traffic. The 7,555 km-length coastal region of India is the most vulnerable zone facing frequent geohazards, e.g. tsunami and flooding. It is contaminated from direct discharge of wastes from the densely populated coastal areas, runoff of fertilizers, dumping by vessels, oil spills, deforestation and ill-planned river basin developments. This chapter summarizes the knowlegde on residues of 5 classes of persistent organic pollutants (POPs) such as dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane and its isomers (HCHs), polycyclic aromatic hydrocarbon and its congeners (PAHs), polychorinated biphenyl and its congeners (PCBs) and polybrominated diphenyl ether and its congeners (PBDEs) in the sediments and in selective biota: bivalve mollusks, fishes and marine mammals. Their potential ecotoxicological impacts on biota have also been assessed based on the sediment quality guidelines (SQG) specified by USEPA (The incidence and severity of sediment contamination in surface waters of the United States, vol 1, National sediment quality survey. EPA 823-R-97-006, Washington, DC, 1997a: Environmental protection agency, National Sediment Quality Survey, App D, Washington DC, 1997b) and by Canadian Council of Ministers of the Environment (CCME, Canadian quality guidelines for the protection of aquatic life-summary tables. Available from. http://www.ccme.ca/assets/pdf/sed summary_table.pdf, 2002).
Pesticide residue levels in the aquatic systems are scattered and fragmentory in India. A systematic analysis of the distribution pattern of the common organochlorine pesticide Hexachlorocyclohexane (HCH) and its isomers in the waters of the tropical positive estuarine system (the Cochin Estuarine System) has been carried out for the first time. The average concentrations of HCH ranged between 0.013 and 1.125 μg 1−1. α‐HCH was found to be at an appreciable concentrations throughout the study area and formed the highest percentage (90%) of all isomers of the HCH family
Concentration levels of various organochlorine pesticides and their derivatives — namely, hexachlorocyclohexanes (HCH) and the DDT compounds pp'-DDT, op'-DDT, pp'-DDE, op'-DDE, pp'-DDD, and op'-DDD — were determined in the sediments from eight different lakes of the Schirmacher Oasis, near Dakshin Gangotri, the Indian station (70° 45'S, 11° 44'E) during the Sixth Indian scientific expedition to Antarctica (December 1986 to February 1987). Concentration levels of HCHs (α, β, γ)and t-DDT (pp'-DDT + op'-DDT + pp'-DDE + op'-DDE + pp'-DDD + op'-DDD) in sediments of these lakes were found to be in the ranges of 37.7–155 pg/gand 512.9–1131 pg/g, respectively. Among the isomers of HCH, gamma-HCH was most prominent, followed by alpha-HCH, whereas in the case of metabolites of DDT and its isomers, pp'-DDT was found to be dominant over others. However, all the other compounds of the DDT family were present in considerable amounts in all the lakes. There was no significant change in the monthly variation of the concentration levels of HCHs and DDTs in the lakes.
This paper reports on the results of systematic analyses carried out to assess the distribution of dichlorodiphenyltrichloroethane (DDT) and its metabolites, o,p′-DDT, p,p′-DDE, and p,p′-DDD in a tropical waterway, the Cochin Estuarine System. Six sampling stations along the system were studied. Analyses were carried out during premonsoon, monsoon, and postmonsoon seasons. ΣDDT concentrations as high as 55.422 μg L−1 were detected. The predominant DDT metabolite was found to be p,p′-DDE. During the monsoon season, o,p′-DDT was not detected at any of the sampling Stations. Station 1 (riverine) and station 6 (coastal zone barmouth) emerged as DDT-free zones and the analytical results have enabled the identification of DDT “hot spots” in the estuary. © 1994 by John Wiley & Sons, Inc..
The levels of contamination of various organochlorine pesticides such as HCHs, DDTs, aldrin, dieldrin and endrin were determined in marine and estuarine sediments along the west coast of India. The concentration of various pesticides in sediments from the mouth of different estuaries along the coast were in the range of 0.85–7.87 ng/g (t-HCH), 0.10–0.26 ng/g (aldrin), 0.70–3.33 ng/g (dieldrin), 0.42–0.95 ng/g (endrin) and 1.47–25.17 ng/g (t-DDT), whereas those in the offshore sediments in the range of 0.10–6.20 ng/g (t-HCH), 0.09–0.26 ng/g (aldrin), 0.20–1.41 ng/g (dieldrin), 0.39–0.78 ng/g (endrin) and 1.14–17.59 ng/g (t-DDT). Among the organochlorine pesticides, t-HCH and t-DDT were most dominant in both the estuarine and offshore sediments. The highest concentration of t-HCH was estimated at station 8 near the mouth of Netravati estuary (7.87 ng/g) while that of t-DDT at station 7 near the mouth of Kali estuary (21.16 ng/g). Among the cyclodiene compounds, aldrin was in abundance in most of the sediments whereas dieldrin and endrin could be detected at the mouth of Zuari, Damanganga, Diu, Cannanore and Ponnani estuaries along the west coast of India. The mean concentrations of t-HCH, aldrin, dieldrin, endrin and t-DDT increased in the estuarine sediments by factors of 2.95, 1.13, 3.60, 2.26 and 2.18, respectively, with respect to those in the offshore sediment. The most predominant metabolites of DDT and HCH in both the estuarine and the offshore sediments were found to be pp'-DDE and α-HCH respectively.
Residues of various organochlorine pesticides were determined in the water off the central west coast of India using anin-situ sampler. Y-BHC and the two cyclodiene compounds, Aldrin and Dieldrin were found to be more consistent than the compounds of the DDT family. Y-BHC ranged from 0.26 to 9.4 ng l−1 whereas Aldrin and Dieldrin were from 1.4 to 9.8 and 2.1 to 50.9 ng l−1, respectively. Among the compounds of the DDT family,pp′-DDT was found to be more abundant than the others in the southern part of the region, whereasop′-DDT was present in a fairly considerable amount off Ratnagiri coast. Among the metabolites of DDT,pp′-DDE was found to be present in every alternate station with increasing concentration (2.5–20.39 ng l−1) whereas op′-DDE could be detected occasionally in the northern part of the region. Presence of op′-DDD was observed only in one sample off the Ratnagiri coast, whereas pp′-DDD was not detected at all.
Water and sediment samples were collected from eight different locations along the River Nile and its branches. Residues of hexachlorocyclohexane (HCH's), hexachlorobenzene (HCB), DDT's, cyclodienes and polychlorinated biphenyls (PCB's) were analyzed by GLC. Data on Grand Total (GT) concentration values pointed out that Rosetta Branch was more polluted with all components than Demietta Branch. Kafr El-Ziate was the most polluted location showing 1355.8 ng/L for water and 7396.9 ng/g for sediments, while Delta Barrage was the least polluted site. The concentrations of gamma-HCH were higher than the other isomers (alpha- and beta-HCH) in all studied sites. The results showed that HCB was the smallest pollutant at all locations on comparison with other chlorinated hydrocarbons. El-Mansoura, Rosetta and Kafr El-Ziate sites contained the highest concentrations of DDT's in both water and sediment samples. P,P'-DDE was dominate in all locations of water samples, but P,P'-DDT was in sediment samples. Also, the results showed the prominent presence of cyclodienes when compared with the other OC's compounds in sediment samples, especially Aldrin. Kafr El-Ziate was the most polluted location by PCB's, particularly the Ar1242. However, there were increasing levels of chlorinated hydrocarbons in the sediment samples parallel to percentage extractable organic matter (% EOM). Sediment/water ratios were calculated for all locations.
BuU. Environ. Contam. Toxicol. (1988)41:664-669
�9 1988 Springer-Vedag New York Inc.
Bulletin of Environmental Contamination and Toxicology
DDT Residues in Sediments from the Bay of Bengal
A. Sarkar and R. Sen Gupta
Chemical Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403004, India
Abstract
The large scale use of persistent organochlorine pesticides in developing countries has caused serious concern due to the presence of their residues in the environment. Organochlorine compounds are characterised by their stability for long periods and may lead to marked changes in the aquatic ecosystem (Addison,1976). Uptake and accumulation of such chlorinated hydrocarhons hy sediments, micro-organisms and fish led to build up of such compounds in the food chain (Mecek and Korn, 1970). In developing countries like India organochlorine insecticides, especially DDT are extensively being used in agriculture and vector control programmes. High concentration of DDT �8 in the marine environment has led to a total ban on its use in USA, Europe and Japan and restricted the use of other chlorinated pesticides (Harvey, 1974). About 55000 tons of pesticides are used every year in India for agricultural purposes (Sen Gupta and Qasim,1985). The cumulative effects of these chlorinated pesticides over time on our coastal environment can he expected to be considerable. A very few data is available on their levels of concentration from the seas around India (Jenson et a1.1972; Tanahe et al. 1980; Kureish~ et a1.1978; Kannan and Sen Gupta 1987; Sarkar and Sert Gupta 1987, 1988) This work aims to asses the prevailing levels of DDT and its metabolites in the sediments from the Bay of Bengal off the East coast of India.
The concentrations of organochlorine residues of lindane, aldrin, alpha-endosulfan, dieldrin, endrin, p,p'-DDE, p,p'-DDD and p,p'-DDT in samples of seawater, sediment, fish and seaweed from different locations along the coast of Kenya are discussed in relation to the geographical location of the sampling sites and potential sources of residue over a period of two years. All sediment samples were found to contain very low levels of organic carbon except those sampled from Sabaki River that had high (4.7%) organic carbon due to greater primary activity. Most of the pesticides residues (112 samples analysed in 1997 and 258 analysed in 1998/99) were detected in fish, water, sediments and seaweed. The concentration of some residues was higher during the wet season than the dry season in 1997, but no marked seasonal variation was observed in 1998/99. Lindane, aldrin, p,p'-DDT and p,p'-DDE were the most frequently observed residues in all samples while alpha-endosulfan, dieldrin, p,p'-DDD and endrin were either present low concentrations or absent in most samples. Water samples had the lowest concentrations of residues (range 0.503 - 9.025 ng g(-1)). Sediments had the second highest levels of pesticides residues with a range of 0.584 - 59.00 ng g(-1) while fish lipid content had the highest levels of residues in 1989/99 with p,p'-DDT concentration of 1011 ng g(-1) and 418 ng g(-1) p,p'-DDD in Siganus rivulatus.
Over a period of two weeks in September, 1983 a high biomass macroepifauna community characteristic of a greater part of the Gulf of Trieste suffered mass mortality. The affected area is estimated to cover several hundred km2. Within 2–3 days all sponges and the brittle star Ophiothrix quinquemaculata, which together make up over 60 % of the community biomass, were dead. Benthic fish, mostly gobiids, were already affected on the first day and littered the bottom in great numbers. Concurrently the complete spectrum of macroinfauna species including (in order of emergence) holothurians, burrowing shrimp, echinoids, polychaetes, sipunculids and bivalves appeared on the sediment surface. Within one week sea stars and all remaining ophiurids had died. At this time hermit crabs were found lying dead next to their shells. Several anemones survived into the last week, although many showed signs of severe stress and lay on the surface with exposed pedal discs. Oxygen deficiency is the apparent immediate cause of this phenomenon and several possible factors leading to anoxic conditions in the Gulf are discussed. This ecological catastrophy provides evidence that the affected community, considered to have achieved relative stability by developing a strategy effectively dampening the effect of physical oscillations, has a distinct tolerance limit to stress. The Gulf of Trieste, among the most productive areas in the Mediterranean Sea, must be considered as sensitive; September is a particularly critical month.
The boundaries as well as the macro-epibenthic biomass distribution and composition of a North Adriatic benthic community, dominated by the brittle star Ophiothrix quinquemaculata (D.Ch.), the sponges Reniera ssp., and the ascidians Microcosmus ssp. were determined. Transects totalling more than 80 km (i.e., a recorded area of approximately 150 000 m2) were taken by means of a combined TV- and photocamera sled. The observations, TV-recordings, and photos, together with 392 diver-collected quantitative samples were evaluated. The biomass values were used to establish isobenths. Within the community, the mean biomass, measured as wet weight, amounted to 370 (73) g/m2 with maxima of more than 1000 g/m2. 64% of the biomass was due to the designating group Ophiothrix-Reniera-Micrcosmus, 87.5% were represented by filter- and suspension-feeding species alone. The mean biomass in the peripheral areas was evaluated at 166 (62) g/m2. Biomass distribution and composition is examined, and the ecological function and meaning of the observed patterns is discussed.
Anoxic conditions in the near-bottom layer below the pycnocline were observed in September 1983 causing mass mortality of benthic macrofauna in the central part of the Gulf of Trieste. The vertical transport of particulate organic matter and decomposition of abundant pelagic and benthic organic matter during the summer produced a low oxygen level in the near-bottom layer below the pycnocline when this layer was sufficiently close to the bottom. A high sea water temperature and vertical stability contributed to the development of anoxic conditions in September 1983 in the near-bottom layer.
In the Northern Adriatic Sea, the occurrence of anoxic events near the bottom has considerably increased in frequency during the last 15 years. Although it has been suggested that increasing nutrient inflow from land-based sources has caused the phenomenon, there has been no direct evidence for this. An analysis of the oxygen distribution in the Northern Adriatic Sea between 1911 and 1982 clearly demonstrates that the probability of anoxic events near the bottom has increased in time. This process is related to the increasing primary production near the surface. There is strong evidence that the long-term nutrient enrichment of the Northern Adriatic Sea forces the above changes.
Trends of dissolved oxygen content of the surface and bottom layers of the northern Adriatic Sea are analysed for the period 1911–1984. An increase in the surface layer and a decrease in the bottom layer are observed in all seasons except winter. Although the oxygen content of the water column as a whole has not changed significantly, it is inferred, from the increasing difference between the surface and the bottom layer, that the primary productivity of the northern Adriatic Sea is increasing. As the average midsummer oxygen content of the bottom layer decreases, the frequency of mass mortality in the benthic fauna is expected to increase, especially in the northern and western subareas.
biphenyls (PCBs) are world-wide distributed organic pollutants. Such compounds are characterized by their stability for long periods and may lead to marked changes in the aquatic ecosystem (Addison 1976). Uptake and accumulation of such chlorinated hydrocarbons by sediments, microorganisms and fish led to the build up of such compounds in the food chain (Macek and Korn 1970). In Egypt and some other Mediterranean countries, wastewaters are discharged into the sea directly, or via agricultural drains. This work aims to assess the prevailing levels of organochlorine insecticides and PCBs in the sea water,sediments and some fish species collected at Port-Said. This location was selected as an example of an important recreational area, charaterized by high fish productivity, growing industrial and navigable ac tivi ties. MATERIALS AND METHODS Water, sediments and fish samples were collected from the Mediterranean sea, at Port-Said, from an area i0 km into the sea defined by latitude 31 ~ 20 ~ and Longtitude 32 ~ , 20 (Fig i). Sub-surface grab water samples were collected into 2-L glass stoppered bottles previously cleaned with a mixture of 15% methylene chloride in n-hexane (v:v). An adequate volume of water samples (IL) was extracted twice with 60 mL of 15% methylene chloride in n-hexane. The combined extracts were dried over anhydrous sodium sulphate and concentrated to 10 mL in a rotating evaporator. Sediments were collected by Ekman dredge sampler (Standard Methods 1980) from three sites namely, No. 1,2 and 3, from a depth of about 20 meter. A known weight of the air dried sediments (50g) was mixed with 50g of anhydrous sodium sulphate. The mixture was transferred
SAMPLES of zoo- and phytoplankton were collected in Stockholm harbour during an investigation into levels of polychlorinated biphenyls (PCBs). The samples were taken in September and October 1971 and in June 1972 at the localities shown in Fig. 2a and b. The opportunity was taken to check the possibility that contamination of plankton samples might occur from the anti-fouling paint, containing PCB, used on the boat.
Oceanography of Northern Adriatic Sea. 1. Hydro-logic features
- P Franco
Franco, P. (1970). Oceanography of Northern Adriatic Sea. 1. Hydro-logic features. Cruises July-August and October-November 1965. Archo Oceanogr. Limnol. 16 (suppl.), 1-93.
Oceanography of Northern Adriatic Sea. Data from the cruises of the years
- P Franco
Franco, P. (1982). Oceanography of Northern Adriatic Sea. Data from the cruises of the years 1978 and 1979. Archo Oceanogr. Limnol. 20 (suppl.), 1-207.
Annuario statistico ltaliano
- Istituto Centrale
- Statistica
Istituto Centrale di Statistica (1959-1985). Annuario statistico ltaliano. Edizioni 1959-1985, Roma.
Berichte tiber die Terminfahrten Osservazioni sulla mortalita di pesci c di ahri organismi verificatasi nel 1969 in Adriatico
- S M S Najade
- Najade
Najade (1911-1914). Berichte tiber die Terminfahrten 1911-1914, S. M. S. Najade, 2-12, 1-102, Vienna. Piccinetti, C. & Manfrin, G. (1969). Osservazioni sulla mortalita di pesci c di ahri organismi verificatasi nel 1969 in Adriatico. Note del Laboratorio di Biologia Marina e Pesca--Fano 3, 73-92.
Crociera talassografica Adriatica 1955. III Tabele delle osservazioni fisiche, chimiche, biologiche e psammografiche
- M Picotti
Picotti, M. (1960). Crociera talassografica Adriatica 1955. III Tabele delle osservazioni fisiche, chimiche, biologiche e psammografiche. Archo Oceanogr. Limnol. 11,372-420.
Secchi disk science: Visual optics of natural waters Hydrographical and biotical conditions in the North Adriatic. II Penetration of light into the sea
- R W Preisendorfer
Preisendorfer, R. W. (1986). Secchi disk science: Visual optics of natural waters. Limnol. Oceanogr. 31,909-927. ~krivani& A., Pu~ar, Z. & Ke~ke~, S. (1969). Hydrographical and biotical conditions in the North Adriatic. II Penetration of light into the sea. Thalassia Jugosl. 5,329-334.
The Indian Oceans. An environmental overview in ocean realities and prospects
- Sen Gupta
Sen Gupta, R. & Qasim, S. Z. (1985). The Indian Oceans. An environmental overview in ocean realities and prospects, pp. 7-40. R. C.
Sbarma, Rajesh Publications, New Delhi.
PCB contamination from boat bottom paint and levels of PCB in plankton outside a polluted area
- Jenson
DDT contamination in zoo-plankton from the Arabian sea
- Kureishy