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Metal-contaminated soils: in-situ inactivation and phytorestoration
... Such technologies can be excavation and landfilling, insitu vitrification, ex-situ solidification/ stabilization, ex-situ soil washing & soil flushing, creating a subsurface barrier to protect groundwater from contamination, thermal treatment, electrokinetic method etc. (Vangronsveld and Cunningham 1998). All these technologies, though quicker and provide a relatively long-term solution, are cost and energy intensive and applicable to a limited volume and area of soil body. ...
... Most of the chemical approaches aim at reducing both total and free ion activity of the metals in soil solution so that their uptake by plant and toxicity to organisms are reduced. Among the chemical methods, application of amendments like phosphates, liming material, Fe/Mn oxyhydroxides, organic materials, zeolites, modified aluminosilicates (beringite) etc. has been advocated (Vangronsveld and Cunningham 1998 Application of chelates like EDTA has been found to enhance metal extraction by the hyperaccumulators (Huang et al. 1997, Nowack et al. 2006. Rock phosphate has been found to accelerate arsenic removal by hyperaccumulator Pteris vittata (Fayiga and Ma 2006). ...
... Several plants have also been used for the phytostabilization purpose (inactivation of soluble forms of metals in the rhizosphere) in order to prevent metal contamination of deeper soil layers and groundwater (Cunningham et al. 1995). Some researchers have demonstrated the potential of microbes for removal of metals from soil using 'Bio metal slurry reactor' technique (Vangronsveld and Cunningham 1998) and indirectly by microbially generated biosurfactant (Wang and Mulligan 2004). However, the feasibility of such technologies is yet to be proved at field level. ...
... Such technologies can be excavation and landfilling, insitu vitrification, ex-situ solidification/ stabilization, ex-situ soil washing & soil flushing, creating a subsurface barrier to protect groundwater from contamination, thermal treatment, electrokinetic method etc. (Vangronsveld and Cunningham 1998). All these technologies, though quicker and provide a relatively long-term solution, are cost and energy intensive and applicable to a limited volume and area of soil body. ...
... Most of the chemical approaches aim at reducing both total and free ion activity of the metals in soil solution so that their uptake by plant and toxicity to organisms are reduced. Among the chemical methods, application of amendments like phosphates, liming material, Fe/Mn oxyhydroxides, organic materials, zeolites, modified aluminosilicates (beringite) etc. has been advocated (Vangronsveld and Cunningham 1998 Application of chelates like EDTA has been found to enhance metal extraction by the hyperaccumulators (Huang et al. 1997, Nowack et al. 2006. Rock phosphate has been found to accelerate arsenic removal by hyperaccumulator Pteris vittata (Fayiga and Ma 2006). ...
... Several plants have also been used for the phytostabilization purpose (inactivation of soluble forms of metals in the rhizosphere) in order to prevent metal contamination of deeper soil layers and groundwater (Cunningham et al. 1995). Some researchers have demonstrated the potential of microbes for removal of metals from soil using 'Bio metal slurry reactor' technique (Vangronsveld and Cunningham 1998) and indirectly by microbially generated biosurfactant (Wang and Mulligan 2004). However, the feasibility of such technologies is yet to be proved at field level. ...
... There is an increasing concentration of metals in our earth due to the re-allocation of mineral deposits and metals as a result of various industries (including mining and smelting), thermal power plants, combustion of fossil fuel and various industrial activities that might cause a danger to the health of human beings and the ecosystem [1].Anthropogenic emission of high concentrations of heavy metals on earth include both the hydrosphere and the biosphere. As a result of the industrial revolution there is a huge and rising requirement for heavy metals [2].In the present world heavy metal contamination in water is an extremely significant problem. Contamination of toxic heavy metals in water bodies such as ponds, ditches and river water have an effect on the life of local communities that rely on these water bodies for their daily necessities [3]. ...
The study focused on the assessment of metal accumulation in certain aquatic macrophytes to be used as biomonitors. The macrophytes and water samples were collected from January to December 2017 from three selected water bodies-Keerat Sagar, Kalyan Sagar and Madan Sagar of the Mahoba district, central India. Hot digested samples of macrophytes and water were analysed for metal concentration using AAS-200. In the macrophytes and water samples, five metals were investigated: Zn, Pb, Ni, Cu, and Cd. Based on the accumulation levels in the macrophytes, the selected metals were arranged in the order of Zn> Pb> Cd> Ni > Cu>.
... As bioavailability represents the fraction that can be taken up by soil organisms and/ or leached to other environmental compartments, it is a much more significant element for effective soil protection and risk assessment than total contaminant concentrations. Soil properties, including pH, redox potential, moisture content, organic matter content, clay content, anionic molecule presence, and so on, have a significant impact on the bioavailability of metals [6]. Solubility, hydrophobicity, and interaction with the mineral and organic fractions of the soil matrix through physicochemical processes including sorption and complexation impact the bioavailability and mobility of organic contaminants [5]. ...
... Contaminant bioavailability is a considerably more important element for adequate soil protection and risk assessment than total contaminant concentrations since it represents the fraction that can be taken up by soil organisms and/or leached to other environmental compartments. Metal bioavailability is primarily influenced by physicochemical features of the soil, such as pH, redox potential, moisture content, organic matter content, clay content, anionic compound presence, and so on (Vangronsveld 1998). Organic pollutants' bioavailability and mobility are largely determined by their solubility, hydrophobicity, and interaction with the mineral and organic fractions of the soil matrix via physicochemical processes such as sorption and complexation (Megharaj et al. 2011). ...
... As bioavailability represents the fraction that can be taken up by soil organisms and/ or leached to other environmental compartments, it is a much more significant element for effective soil protection and risk assessment than total contaminant concentrations. Soil properties, including pH, redox potential, moisture content, organic matter content, clay content, anionic molecule presence, and so on, have a significant impact on the bioavailability of metals [6]. Solubility, hydrophobicity, and interaction with the mineral and organic fractions of the soil matrix through physicochemical processes including sorption and complexation impact the bioavailability and mobility of organic contaminants [5]. ...
The soil is one of the most valuable resources since it forms the foundation for many important life processes and ecosystem purposes. Worldwide, soil pollution is a result of human activities that are not sustainable, such as the use of dangerous inorganic chemicals. The mining, production, transportation, end-user use, disposal, and accidental discharge of chemicals all contribute to soil contamination, which in turn jeopardizes human life, livestock, wildlife, and entire ecosystems. Purifying and decontaminating soil with conventional procedures is labor-intensive and time-consuming and can modify the soil's physical, chemical, and biological properties. Furthermore, they do not always ensure that all impurities are eliminated. Sustainable and cutting-edge technology has developed over the last few decades. Biological soil remediation solutions, also known as soft remediation options, are being developed to integrate, namely efficient removal of soil contaminants, mitigation of soil ecotoxicity, and reduction of legally and ethically mandated hazards to the environment and human health. Soil remediation methods should not only repair soil health and provide necessary system services but also reduce noxious waste concentrations in the soil to below regulatory limits. The microorganisms have shown promise in the clean-up of soils contaminated with radioactive contaminants, heavy metals, chemical fertilizers in excess, trichlorethylene, trinitrotoluene, herbicides such as atrazine, and organophosphates. The cost of cleaning up environmental pollutants with eco-friendly technology is inexpensive when compared to other approaches, including conventional ones. The focus of the current manuscript is on using beneficial bacteria to clean up polluted farmland to ensure the longevity of the subsequent generation.
... As bioavailability represents the fraction that can be taken up by soil organisms and/ or leached to other environmental compartments, it is a much more significant element for effective soil protection and risk assessment than total contaminant concentrations. Soil properties, including pH, redox potential, moisture content, organic matter content, clay content, anionic molecule presence, and so on, have a significant impact on the bioavailability of metals [6]. Solubility, hydrophobicity, and interaction with the mineral and organic fractions of the soil matrix through physicochemical processes including sorption and complexation impact the bioavailability and mobility of organic contaminants [5]. ...
The soil is one of the most valuable resources since it forms the foundation for many important life processes and ecosystem purposes. Worldwide, soil pollution is a result of human activities that are not sustainable, such as the use of dangerous inorganic chemicals. The mining, production, transportation, end-user use, disposal, and accidental discharge of chemicals all contribute to soil contamination, which in turn jeopardizes human life, livestock, wildlife, and entire ecosystems. Purifying and decontaminating soil with conventional procedures is labor-intensive and time-consuming and can modify the soil’s physical, chemical, and biological properties. Furthermore, they do not always ensure that all impurities are eliminated. Sustainable and cutting-edge technology has developed over the last few decades. Biological soil remediation solutions, also known as soft remediation options, are being developed to integrate, namely efficient removal of soil contaminants, mitigation of soil ecotoxicity, and reduction of legally and ethically mandated hazards to the environment and human health. Soil remediation methods should not only repair soil health and provide necessary system services but also reduce noxious waste concentrations in the soil to below regulatory limits. The microorganisms have shown promise in the clean-up of soils contaminated with radioactive contaminants, heavy metals, chemical fertilizers in excess, trichlorethylene, trinitrotoluene, herbicides such as atrazine, and organophosphates. The cost of cleaning up environmental pollutants with eco-friendly technology is inexpensive when compared to other approaches, including conventional ones. The focus of the current manuscript is on using beneficial bacteria to clean up polluted farmland to ensure the longevity of the subsequent generation.
... Loparite ore enrichment tailings were added to plastic containers (S = 0.02 m 2 , height 5 cm) in the amount of 400 g (control) and the same amount of a mixture of tailings with reagents according to the experimental scheme (experimental variants), as presented in Table 3. Seeds of red fescue were used to form a single-species seeded phytocenosis. This species was chosen for this laboratory experiment because it is native to the Kola Peninsula [46] and is widely used for restoring vegetation in technogenically disturbed areas [47,48]. It is known that Festuca rubra L. is tolerant to high concentrations of metals through an exclusion strategy, which confirms its recognized potential for phytostabilization [49]. ...
This paper presents an assessment of the effect of various reagents on the qualitative indicators of anti-deflationary single-species sowing phytocenosis on enrichment waste from rare earth ores. It has been established that tailings of loparite ores are not suitable for biological reclamation due to low values of hygroscopic moisture (0.54–2.85%) and clay particles (17.6 ± 0.6%) and high content of bioavailable forms of aluminum (504 ± 14 mg/kg). Seeds of red fescue (Festuca rubra L.) were grown on the tailings of loparite ore enrichment with the addition of opoka (O), brucite (B), and vermiculite (V). The quality of the seed cenosis was assessed by the dry biomass of the above-ground parts of the plants and the plant height. A positive effect (one-way ANOVA followed by Tukey’s HSD test (p < 0.05 and p < 0.01)) of the considered combinations of reagents on the growth of above-ground biomass from 31.5% (V) to 70.3 (V + O), 82.4% (V + B), and 81.8% (V + O+B) and on plant height from 53.8% (V) up to 78.6 (V + O), 83.8% (V + B), and 75.4% (V + O+B) was revealed. The use of a combination of V + O and V + B reagents made it possible to significantly reduce the content of Al (by 19.0% and 52.8%), Sr (by 16.5% and 12.9%), La (by 65.2% and 40.6%), and Ce (by 66.8% and 41.9%) in the aerial part of the sowing phytocenosis compared to control. The results obtained here can become the basis for development of a combined sorption technology for the reclamation of technogenically disturbed lands.
... Currently, a variety of physical, biological and chemical remediation technologies, as well as phytoremediation, have been established to remediate contaminated soils [9][10][11]. Among them, in situ immobilization is regarded as a cost-effective contaminated soil remediation approach with its advantages of low investment, short cycle, quick effect, and easy implementation [12]. ...
To explore the feasibility of biochar for reducing mobility and bioavailability of heavy metals in different contaminated soils, batch incubation experiments including column leaching and pot experiments were conducted to investigate the effects of biochar input on soil pH, the bioavailability of heavy metals (Cd, Zn, and Pb) and their species in three different contaminated soils treated with different swine biochar application rates. The results show that biochar has more potential for pH improvement in acidic soils than neutral and alkaline soil. After 42 d incubation, the pH values of the acidic soils increased from 5.90 to 7.23, while the pH values of neutral/alkaline soils did not change significantly. The available heavy metals showed a decreasing trend as the biochar application rate increases. The order of the immobilization effect is Pb>Zn>Cd. Possible immobilization mechanisms are mainly ion exchange, complexation, π bond action and precipitation on the surface of biochar.
... The latter are the most used, as they potentially allow economic returns to be obtained (Vangronsveld et al., 2009;Meers et al., 2010). This technique has notable advantages over traditional technologies originated in civil engineering given that its environmental burden and economic costs are notably lower (Glass, 2000;Masciandaro et al., 2014), and it does not destroy the edaphic properties, which allows the subsequent use of the soil for food production (Vangronsveld and Cunningham, 1998). ...
It is known that any environmental remediation process must be approached as a system and that the transport of materials is key to determining its sustainability. The aim of this work is to establish how far it was possible to transport plant material from a phytoextraction process in such a way that the environmental gain of the remediation process is not compromised. In the absence of a general methodology to answer our question, a new methodology based on spatial analysis and the life cycle perspective is proposed to calculate, under different hypotheses and depending on the type of remediation, the maximum distance that a lorry can travel, taking as a limit the distance in which the environmental benefit would be equal to 0.
The results obtained show that there are significant differences depending on the type of optimisation proposed for the transport route as well as the type of valorization of the plant material to be carried out. Thus, in the case of bioethanol, biomass could be transported up to 25 km. For biodiesel, it can be shipped over distances between 255 and 415 km and finally, if it is valorized by anaerobic co-digestion, biodigesters up to 267 km away could be sought for the most favourable case.
... Emerging economies as India mostly accelerated mining activities that causes the unpleasant environmental conditions with extreme physico-chemical and biological impediments like low cation-exchange capacity, decreased water holding capacity, low available nutrients, poor organic matter and insufficient soil microorganisms [1] and ultimately leads to land degradation. The real problem of land degradation on open cast mine sites, which were either restored badly or restoration process has become stopped due to unseen natural or anthropogenic reasons (2,3,4).Vigorously mined land, disturbed with metal contaminants usually do not have the capability to possess sufficient surface soil for vegetation (5,6) which not only limited to the site but also expanded to the surroundings through acid mine drainage and tailings deposit [7].Long term exposure to metal contaminated mine spoil has been reported to disequilibriate the ecosystem structure and functioning through detrimental effect on microbial activity (8,9). Besides, short term exposures to noxious metals have also been reported to reduce the microbial activity [8]. ...
... The phytostabilization technique refers to apply plants, separately or in combination with soil improvers, to immobilize trace element-contaminated soil by restricting the element's mobility and phytoavailability [65]. Dissimilar to phytoextraction, during a phytostabilization process, plants usually do not concentrate the contaminants in their shoots, which could be consumed by human or ecological receptors [74]. Generally, the phytostabilization technique is useable in soils with extensive surficial pollution where trace elements exist in the soils at low concentrations. ...
There are many anthropogenic activities that have caused the accumulation of potentially toxic metals (e.g., lead, cadmium, chromium, nickel, arsenic, cobalt, and mercury) in the environment. Lead (Pb) is known as a very toxic and non-biodegradable element that has no metabolic function in living creatures. It can be easily taken up and transferred within plant tissues; consequently, it can easily enter the food chain, causing phytotoxicity, which in turn through different biochemical and enzymatic reactions, can result in severe threats to public health. After entering soil and sediments, Pb may be diffused among soil components and associated with them through different geochemical fractions, which determine the final fate of Pb in terms of bioavailability and uptake by plants. Metal bioavailability in soils is largely dependent on the soil and plant properties and interactions with other elements. In spite of the fact that there are numerous studies on the influence of heavy metals on public health but there are limited studies that consider the role of the soil-plant chain on the final fate of potentially toxic metals in respect to threat the public health. This manuscript defines a joint challenge between agricultural and medical sciences and shows that the soil (as the base of agriculture) affects human health in a variety of ways, with human health being linked to the health of the soil.
... Traditionally, the phytostabilizing plants can be found through systematization of wild species growing on soils with excess content of heavy metals, followed by the analysis of their distribution in plant organs (Cetinkaya & Sozen, 2011). At phytostabilization, the plant species should have a greater ability to accumulate metals in the roots, while their transfer to aerial parts tissues is very limited (Fagnano et al., 2020); therefore, such plants can be potentially consumed by living organisms (Vangronsveld & Cunningham, 1998). There are even a number of crops that can be grown on contaminated soils without any risk to human health (Yakovyshyna, 2011). ...
The article discusses the creation of a methodological approach and the specific technologies based on it in terms of the phytostabilization of urban soils contaminated with heavy metals, taking into account the peculiarities of urban ecosystems functioning in order to ensure the environmental safety of industrial wastelands. Based on the analysis of existing soil restoration methods, a mechanism for creating an integrated phytostabilization technology was developed by involving the components differing in action, aimed at reducing the migration ability of heavy metals in soil and their translocation into plants. It was suggested to increase the phytoremediation potential of phytostabilizers through the stimulation of internal defence mechanisms of plants, and through additional application of an ameliorant to bind heavy metal cations in soil, as well as through the use of microbiological preparation in order to restore soil protective functions. The practicability of phytostabilization using alfalfa (Medicago sativa) plants combined with detoxification with an aqueous solution of potassium carbonate and the BTU-r multipurpose biocomplex microbiological preparation was experimentally confirmed by means of an example of lead contamination of urban ecosystem soils in the city of Dnipro. It was concluded that their combination provides the lowest Pb2+ removal from the soil by alfalfa (Medicago sativa) plants and a significant reduction in the availability of the metal compounds in soil.
... However, the total metal content is generally giving an insight about the possible enrichment of the sediment with metals, but it is not enough to assess their environmental impact and the estimation of the bioavailable fraction (Marmolejo-Rodríguez et al., 2007). This bioavailable fraction is thus defined as the amount of metal that can be exchanged with biological organisms and incorporated into their structure (Cunningham et al., 2019;Vangronsveld & Cunningham, 1998). Thus, the sequential extraction procedure has been applied to evaluate the potential mobility and the possible transfer of metals from sediments to the surrounding environment (Kaasalainen & Yli-Halla, 2003;Shokr et al., 2016). ...
Sediments from Lake Mariut, Egypt, after its rehabilitation, and its anoxic diverted polluted drains were subjected to five sequential steps to define different geochemical fractions of eight studied metals. Results cleared out that 30–50% of its total Cd and total Co contents are easily bioavailable with a high-risk assessment code (RAC) to enter the food chain in the lake basin. Whereas Cu and Fe are safe and the remaining studied metals, i.e., Mn, Zn, Pb, and Cr are of medium risk for the environment. Individual contamination factor (ICF) is high (> 6) for all the studied metals except for Fe and Cu which are tightly held in sediments confirming their safeness to biota. Cadmium accounted for > 94% of the total risk in the study area. Metal pollution loading (MPL) from the sediments was found in the order: Fe > Mn > Zn > Pb > Cu > Cr > Co > Cd.
... However, the total metal content is generally giving an insight about the possible enrichment of the sediment with metals, but it is not enough to assess their environmental impact and the estimation of the bioavailable fraction (Marmolejo-Rodríguez et al., 2007). This bioavailable fraction is thus defined as the amount of metal that can be exchanged with biological organisms and incorporated into their structure (Cunningham et al., 2019;Vangronsveld & Cunningham, 1998). Thus, the sequential extraction procedure has been applied to evaluate the potential mobility and the possible transfer of metals from sediments to the surrounding environment (Kaasalainen & Yli-Halla, 2003;Shokr et al., 2016). ...
... This can facilitate upgrading of the land through phytoremediation, which is described as the use of plants to extract, sequester and detoxify environmental contaminants from the soil (Ali et al., 2017). In phytoextraction, a subprocess of phytoremediation, plants uptake and concentrate potentially contaminants, such as metals, in their harvestable parts for subsequent recovery (Salt et al., 1998;Vangronsveld and Cunningham, 1998). Although phytoextraction was originally restricted to a class of plants described as metal hyperaccumulators, i.e. plants which have the ability to uptake and tolerate high levels of metals, studies have since been extended to other plants, such as fibre plants, which can demonstrate sufficient phytoextraction potential while simultaneously producing a biomass of economic value (Schwitzguébel et al., 2002;Pandey et al., 2016). ...
Post-mining land use for the production of industrial crops has the potential to mitigate environmental and socioeconomic impacts of mine closure and stimulate post-mining economic growth. Fibre-rich plants are of particular interest due to their multi-product potential. The South African context, where there are many abandoned and end-of-life mines near human settlements, presents an opportunity to assess the feasibility of transforming post-mining land into productive land and building resilient communities through the development of multi-product value chains from fibre-rich plants such as kenaf, hemp or bamboo. This paper provides an overview of the plant selection criteria, phytoremediation potential and the downstream options for the recovery of products and value from bast fibre plants (hemp and kenaf) and bamboo. Based on findings from a comprehensive review of the published literature, as well as interviews with relevant experts within South Africa, it appears that bast fibre plants are the best downstream option for producing "green" textiles and high-end niche products, whereas bamboo is more suitable as a replacement for conventional timber. Although fibre plants have the potential to extract metals from soils, high concentrations may inhibit plant growth and affect the quality of the final fibre product. Further site-specific studies would thus be required to select the best route for both land remediation and optimal product recovery.
... Its bioavailability is determined by the oxidation state: Cr(VI) is highly soluble and, therefore, available and potentially (eco)toxic; on the contrary, Cr(III) has low solubility and is easily adsorbed by soil minerals (Polti et al. 2007;Aldmour et al. 2019). Soil physicochemical properties, such as clay content, organic matter (OM), pH, redox potential, and moisture content, strongly influence metal mobility and bioavailability in soil (Vangronsveld and Cunningham 1998). Soil OM plays a key role in Cr(VI) immobilization by means of reduction and/or sorption (Banks et al. 2006;Choppala et al. 2018). ...
Chromium is considered an environmental pollutant of much concern whose toxicity depends, to a great extent, on its valence state, with Cr(VI) being more soluble, bioavailable, and toxic, compared to Cr(III). Nanoremediation is a promising strategy for the remediation of metal pollutants by changing their valence state. However, among other aspects, its effectiveness for soil remediation is seriously hampered by the interaction of nanoparticles with soil organic matter. In this study, soil was (i) amended with two doses of a municipal solid organic waste and (ii) artificially polluted with 300 mg Cr(VI) kg−1 DW soil. After a period of aging, a nanoremediation treatment with nanoscale zero-valent iron particles (1 g nZVI kg−1 DW soil) was applied. The efficiency of the remediation treatment was assessed in terms of Cr(VI) immobilization and recovery of soil health. The presence of the organic amendment caused (i) a decrease of redox potential, (ii) Cr(VI) immobilization via its reduction to Cr(III), (iii) a stimulation of soil microbial communities, and (iv) an improvement of soil health, compared to unamended soil. By contrast, nZVI did not have any impact on Cr(VI) immobilization nor on soil health. It was concluded that, unlike the presence of the organic amendment, nanoremediation with nZVI was not a valid option for soils polluted with Cr(VI) under our experimental conditions.
... In agriculture, toxic levels of various elements may contaminate the groundwater as a result of an excessive application of fertilizers, pesticides, insecticides, and through leaching of trace elements in the soil after irrigation (Alloway, 1995;Kabata-Pendias and Mukherjee, 2007). Therefore, finding suitable treatment technologies to clean up contaminated water and soil is of great importance (Vangronsveld and Cunningham, 1998). Among many technologies considered to treat trace element-polluted soils, stabilization methods, such as in-situ immobilization techniques by means of organic (Chiu et al., 2006;Farrell and Jones, 2010;Liu et al., 2018) and inorganic amendments (Alvarez-Ayuso and Garcia-Sanchez, 2003a, 2003bAnsari Mahabadi et al., 2007;Zanuzzi et al., 2013), appear as cost-effective and environment-friendly approaches for remediation of polluted soils. ...
information about the application of clay minerals (e.g. sepiolite) at nanoscale levels for stabilization of potentially toxic trace elements in soils and wastewaters is very limited. Therefore, this study was carried out to: (i) determine how removal of Pb and Cu from aqueous solutions (containing 150 mg/kg Pb and Cu) differs between microparticles (< 10 μm) and nanoparticles (< 100 nm) of sepiolite, and (ii) find out the kinetic parameters of Pb and Cu adsorption onto micro-and nano-sized particles of sepiolite. Batch experiments at eleven contact times (5, 10, 20, 30, 60, 120, 240, 480, 720, 1440 and 2880 min) with three replications were conducted and the data were evaluated using pseudo-first order, pseudo-second order, and intraparticle diffusion models. The results indicated that the sorption of Pb and Cu onto both microparticles and nanoparticles of sepiolite follows an increasing trend with contact time, and it is a three-stage process that is well described by the pseudo-second-order kinetic model. Intraparticle diffusion modeling showed that intraparticle diffusion was not the only mechanism that influenced the rate of Pb and Cu uptake by the nano-and microparticles of se-piolite. The maximum adsorptions of Pb and Cu by sepiolite nanoparticles were 34.70 and 24.50 mg g −1 , respectively , higher than those of the microparticles (27.17 and 17.10 mg g −1). To identify how the addition of sepiolite nanoparticles (10 and 20 g/kg soil) would function as a soil amendment relative to Pb and Cu pollution, the leaching potential of Pb and Cu was also tested, using distilled water and 1 M NH 4 NO 3 solutions from the two soils with clay loam and sandy loam textures. The results implied that the addition of sepiolite nanoparticles to both the sandy loam and clay loam soils increased their ability to retain Pb and Cu elements in comparison with the control. In both the clay loam and sandy loam soils, the amounts of Pb and Cu leached using the 1 M NH 4 NO 3 solution were significantly higher than those with distilled water. The amounts of metals eluted using 1 M NH 4 NO 3 solution from the sandy loam and clay loam soils treated with 20 g kg −1 nanoparticles of sepiolite were 7.15% and 5.33% for Cu, and 6.44% and 4.55% for Pb, respectively. The results also illustrated that using water and NH 4 NO 3 solutions, the metal extraction yield was greater in the sandy loam soil than in the clay loam soil. The highest amounts of Pb (9.76%) and Cu (9.88%) leached from the soils were observed in the sandy loam soil, using 1 M NH 4 NO 3 solution, but without any addition of sepiolite nanoparticles. In contrast, the clay loam soil leached with water and amended with 20 gkg −1 sepiolite nanoparticles showed the least amount of Pb (3.49%) and Cu (3.93%) in the leachates. In conclusion, sepiolite nanoparticles improved the efficiency of Pb and Cu removal from aqueous solutions and their immobilization in soils with sandy loam and clay loam textures. The findings also emphasize the importance of extracting agents in evaluating the amounts of Pb and Cu leached from the soils.
... A variety of biological resources have been employed widely in developed and developing nations for cleanup of the metal-polluted sites. These technologies have gained considerable momentum in the last decade and are currently in the process of commercialization [9][10][11][12][13][14][15][16][17][18][19]. The U.S. Environmental Protection Agency's remediation program included phytoremediation of metals and radionuclides as a thrust area during the year 2000. ...
Metals, radionuclides and other inorganic contaminants are among the most prevalent forms of environmental contaminants, and their remediation in soils and sediments is rather a difficult task [1]. Sources of anthropogenic metal contamination include smelting of metalliferous ore, electroplating, gas exhaust, energy and fuel production, the application of fertilizers and municipal sludges to land, and industrial manufacturing [1,3]. Heavy metal contamination of the biosphere has increased sharply since 1900 [4] and poses major environmental and human health problems worldwide [5]. Unlike many organic contaminants, most metals and radionuclides cannot be eliminated from the environment by chemical or biological transformation [6,7]. Although it may be possible to reduce the toxicity of certain metals by influencing their speciation, they do not degrade and are persistent in the environment [8]. The various conventional remediation technologies used to clean heavy metal-polluted environments are soil in situ vitrification, soil incineration, excavation and landfill, soil washing, soil flushing, solidification, and stabilization electrokinetic systems. Each conventional remediation technology has specific benefits and limitations.
... Smith and Bradshaw (1979) and Williamson and Johnson (1981) discussed the reclamation of metalliferous mine wastes with plants. Other key references are: Chaney (1983), McGrath (1990), Baker et al. (1991), Brown et al. (1994), Vangronsveld and Cunningham (1998), Van der Lelie et al. (2001), Barceló and Poschenrieder (2003) and Bech (2015), among other. ...
... As a consequence of the industrial revolution there is an enormous and increasing demand for heavy metals that leads to high anthropogenic emission of heavy metals in the biosphere. [1] Their accumulation in soil becomes dangerous to all kind of organisms including plants. [2] These are a unique class of toxicants since they cannot be broken down to non-toxic forms easily. ...
... Especially for contaminated kitchen garden soils, which are complex due to the presence of many pollutants (organics and inorganics) and their heterogeneity, a first method consists of removing the contaminated materials and replacing with uncontaminated soils (Hajdu and Licsko, 1999;Lanphear et al., 2003;Nielsen and Kristiansen, 2005;Douay et al., 2008). With the aim of maintaining remediated soils for plant production without great modifications of their physicochemical and biological parameters, chemical remediation can be a promising technology for the immobilisation of metals in kitchen garden soils and may provide a long-term remediation solution if low solubility minerals and/or stable precipitates are produced (US Environmental Protection Agency, 1997;Vangronsveld and Cunningham, 1998). Natural organic amendments like sheep manure, biosolid compost, vegetable waste, waste compost, vermicompost and biosolid compost (McCoy, 2015;Wiszniewska et al., 2016), industrial products like fly ash, lime mud from papermaking process and biochar (Janus et al., 2015;Brännvall and Kumpiene, 2016;Rizman et al., 2016;Zhang et al., 2016) and inorganic compounds like lime, metal oxides and phosphates (Miretzky and Cirelli, 2010;Komárek et al., 2013;Gul et al., 2015;Hafsteinsdóttir et al., 2015;Mahar et al., 2015) have been widely used for the chemical immobilisation of As, Cd, Pb and Zn. ...
The behaviour of metals mainly depends on soil pH, carbonate contents and contamination level, which should be considered for the management of contaminated soils. In this study, kitchen garden topsoils (0–25 cm) were sampled from the area around three smelters in France, with different Cd and Pb contamination levels. Effect of a phosphate amendment (a mixture of diammonium phosphate and hydroxyapatite) on the environmental availability and phytoavailability of Cd and Pb was evaluated by different chemical extractions and cultivating lettuce (Lactuca sativa L.), respectively. Changes in the distribution of Cd and Pb were found in most contaminated soils after phosphate amendment. An increase of Cd and Pb in the residual phase was highlighted in almost all carbonated contaminated soils, whereas a decrease of Pb in the exchangeable, water and acid-soluble phase was observed in most contaminated soils with the lowest carbonate contents. The concentrations of extractable Cd and Pb using calcium chloride and acetic and citric acids generally decreased after the soil amendment. Lettuces grown on amended soils were acceptable for human consumption as regard to Pb concentration. In contrast, some lettuces were unacceptable for human consumption, since the concentrations of Cd in the leaves were higher than the European legislation limit. Surprisingly, in carbonated soils with very low concentration of Cd, the Cd concentrations in lettuce reached up to the European legislation limit, making the lettuce unacceptable for human consumption. Our study highlighted the fact that the total metal concentration in soils does not always allow to predict the metal accumulation in the edible parts of vegetables in order to make a judgement about their acceptability or unacceptability for human consumption.
... Especially for conta- minated kitchen garden soils, which are complex due to the presence of many pollutants (organics and inor- ganics) and their heterogeneity, a first method consists of removing the contaminated materials and replacing with uncontaminated soils ( Hajdu and Licsko, 1999;Lanphear et al., 2003;Nielsen and Kristiansen, 2005;Douay et al., 2008). With the aim of maintaining remediated soils for plant production without great modifications of their physicochemical and biological parameters, chemical remediation can be a promising technology for the immobilisation of metals in kitchen garden soils and may provide a long-term remedia- tion solution if low solubility minerals and/or stable precipitates are produced (US Environmental Protec- tion Agency, 1997;Vangronsveld and Cunningham, 1998). Natural organic amendments like sheep ma- nure, biosolid compost, vegetable waste, waste com- post, vermicompost and biosolid compost (McCoy, 2015;Wiszniewska et al., 2016), industrial products like fly ash, lime mud from papermaking process and biochar (Janus et al., 2015;Brännvall and Kumpiene, 2016;Rizman et al., 2016;Zhang et al., 2016) and inorganic compounds like lime, metal oxides and phos- phates ( Miretzky and Cirelli, 2010;Komárek et al., 2013;Gul et al., 2015;Hafsteinsdóttir et al., 2015;Mahar et al., 2015) have been widely used for the chemical immobilisation of As, Cd, Pb and Zn. ...
The most recent in vitro tests used to determine metal bioaccessiblility are generally time-consuming and expensive. This study aimed at determining potential relationships between the concentrations of metals extracted using single-extraction methods and the concentrations of bioaccessible metals assessed by a harmonised in vitro test, the Unified BARGE Method (UBM). A total number of 27 soil samples were collected from kitchen gardens and lawns with various physicochemical parameters and contamination levels. Significant relationships were obtained between Cd, Pb and Zn extracted in gastric and gastrointestinal phases and using single extractions. The best relationhips were established using acetic and citric acids for Cd, whereas for Pb, citric acid and ethylenediaminetetraacetic acid (EDTA) were identified as the best extractants. These relationships were improved by means of a linear multiple regression with a downward stepwise procedure involving agronomic parameters (soil cation exchange capacity and assimilated P). This method highlighted the fact that the cation exchange capacity and P contents in soils were the two main parameters that controlled the human bioaccessibility of Cd, Pb and Zn in the gastric phase. Besides, the metal concentrations extracted with the acetic and citric acids correlated well with the metal concentrations in the gastric and gastrointestinal phases, suggesting that the bioaccessible metals were mainly in a soluble form, weakly bound to the organic matter and associated with the carbonates and the Fe and Mn oxides/hydroxides in soils.
... It has been shown that trees can effectively reduce the contamination of the soil, in addition to their economic benefits (French et al., 2006). It has previously been reported that trees can immobilize contaminants in the soil or accumulate them in their tissues (Dickinson, 2000;Pulford and Watson, 2003;Vangronsveld and Cunningham, 1998). Woody plants, Terminalia arjuna, Prosopis juliflora, and Dendrocalamus strictus, growing on tannery sludge dumps accumulated appreciable amounts of metals in their tissues, which led to a reduction in the contamination levels in the tannery sludge (Shukla et al., 2011). ...
Our project was aimed at improving a brownfield in the city of Kladno, where an old steel producing facility used to be in operation. Ecological risk is mainly caused by the processing of co-products during coal production (tars, oils). Knowledge of toxicology and environmental aspects can help us protect human health and the environment. Primarily, we focused on soil sampling and identification of pollutants. Results showed that organic contamination on the site is very high. Average concentration of total petroleum carbon in the soil was about 13g/kg DW, which is much more than the maximum allowed concentration. For selection of suitable plant species for phytoremediation at the site, experiments were conducted in a greenhouse. Biomass growth, root morphology, and pigment content in the leaves of Brassica napus var. Opus-C1 and Sorghum×drummondii var. Honey Graze BMR plants were studied. Plant analysis confirmed that polyaromatic hydrocarbons (PAHs) accumulated in the shoots of both plant species. B. napus plants grown on Poldi soil in a greenhouse were able to survive the toxicity of PAHs in soil, and their ability to accumulate PAHs from soil was evident. However, more studies are needed to decide if the plants are usable for phytoremediation of this brownfield.
... The Bio Metal Slurry Reactor (BMSR) is a technique proposed of removal of heavy metals using microbes from excavated soil (Vangronsveld and Cunningham 1998). This technique operates by accumulating contaminants in bacterial biomass, and thereafter by removing the contaminated biomass. ...
Soils perform several important ecosystem functions and therefore polluted land requires remediation and appropriate management for restoration of its life sustaining functions. Several technologies have been developed for their remediation based on clean-up, detoxification and risk minimization approaches. All of these technologies have both advantages and disadvantages in respect of the extent of applicability, side-effects on other components of environment, cost & ease of adoption, speed & effectiveness of remediation etc. While removal of contaminants and the risk minimization are the major approaches for heavy metal polluted soil, degradation to non toxic or less toxic compounds is the most common approach for soils polluted with organic pollutants. Plants, microorganisms, nanotechnology have also been used for remediation of polluted sites with varying degree of success. Waste products from agriculture, industries, city etc. have also exhibited their potential in minimizing risk from pollutants. Growers may minimize risks from polluted land through modification of soil, crop and nutrient managements. This chapter also discusses examples of a remediation approaches followed in case of different polluted sites worldwide.
... Аммонификаторы Азотфиксаторы ИУК N Н и т р и ф и к а т о р ы Д е н и т р и ф и к а т о р ы С в я з ы в а н и е C d м и к р о б н ы м и м е т а б о л и т а м и З а щ и т н а я м и г р а ц и я могут способствовать увеличению накопления ТМ в растениях, и это свойство микроорганизмов используется в технологии фитоэкстракции (Lasat et al., 2002). Для фитостабилизации (перевода химических соединений в менее подвижную и активную форму) могут быть использованы растения, обладающие высокой устойчивостью к ТМ и локализующие ТМ преимущественно в корневой системе (Vangronsveld, Cunningham, 1998;Zhang et al., 2012). Предполагают, что регуляция поступления ТМ в растения с помощью микроорганизмов может лежать в основе стратегий преодоления экологических последствий загрязнения. ...
... Thus, the growth of plants with an ability to tolerate adverse conditions found on derelict mine sites increases soil organic matter, which plays an important role in immobilizing heavy metals, improving soil structure, increasing soil fertility and reducing erosion . This process may also include the use of nontoxic metalimmobilizing or fertilizing soil amendments to improve plant growth (Vangronsveld and Cunningham 1998;Sellers 1999). Among four native shrubs (Myrtus communis, Retama sphaerocarpa, Rosmarinus officinalis and Tamarix gallica) field-trialed over a 2-year period for phytoremediation of toxic metals (As, Al, Zn, Cu, Cd) in a pyritic waste contaminated soil, R. sphaerocarpa showed highest survival and depletion of available metals with low metal transfer to shoot under prevailing conditions. ...
The lack of awareness for timely management of the environment surrounding a metal mine site results in several adverse consequences such as rampant business losses, abandoning the bread-earning mining industry, domestic instability and rise in ghost towns, increased environmental pollution, and indirect long-term impacts on the ecosystem. Although several abandoned mine lands (AMLs) exist globally, information on these derelict mines has not been consolidated in the literature. We present here the state-of-the-art on AMLs in major mining countries with emphasis on their impact towards soil health and biodiversity, remediation methods, and laws governing management of mined sites. While reclamation of metalliferous mines by phytoremediation is still a suitable option, there exist several limitations for its implementation. However, many issues of phytoremediation at the derelict mines can be resolved following phytostabilization, a technology that is effective also at the modern operational mine sites. The use of transgenic plant species in phytoremediation of metals in contaminated sites is also gaining momentum. In any case, monitoring and efficacy testing for bioremediation of mined sites is essential. The approaches for reclamation of metalliferous mines such as environmental awareness, effective planning and assessment of pre- and post-mining activities, implementation of regulations, and a safe and good use of phytostabilizers among the native plants for revegetation and ecological restoration are discussed in detail in the present review. We also suggest the use of microbially-enhanced phytoremediation and nanotechnology for efficient reclamation of AMLs, and identify future work warranted in this area of research. Further, we believe that the integration of science of remediation with mining policies and regulations is a reliable option which when executed can virtually balance economic development and environmental destruction for safer future.
... Remediation of heavy metal polluted soils has therefore become an urgent necessity. Current remediation operations are generally associated with civil-engineering techniques or some environmentally friendly options using phytoremediation (Vangronsveld and Cunningham, 1998;Lasat, 2000;Wong, 2003). A new generation of remediation techniques proposes the use of organic matter and earthworm additions to polluted soils. ...
We tested the effect of an addition of organic matter (OM: 10% of a mixture of coconut bran and cattle dung) and/or earthworm inoculation (15g fresh weight kg-1 soil) in a soil polluted by metals on microbial activities and concentrations of metal DTPA extractable fractions. The experiment, conducted under laboratory conditions, lasted for 60days. Soil organic C and total N in control were 15.3and 1.47mgkg-1, and total Zn, Cd, Pb and Cu contents, 405, 0.639, 439 and 394mgkg-1, respectively. The native earthworm species Amynthas morrisi exhibited 91.5% mortality in the un-amended polluted soil, whereas only 20% of Eisenia fetida individuals died. In the OM treatment the native species performed much better showing reproduction and a higher soil ingestion rate than E. fetida. In both amended and non-amended soils, casts exhibited higher concentrations of total organic C (+15.7 to 46.5%) and N(+13.3 to 59.3%) and alkali hydrolysable N (+78.0 to 133%), but not dissolved organic C. Microbial enzymatic activities were significantly increased when OM was added to the soil (+142 to 456%), with the sole exception of acid phosphatase activity. The addition of earthworms had contrasting effects on microbial activities: N-acetyl glucosamine activity was enhanced (+559 to 829%) while no significant difference was noted for other measured enzymatic activities. Introduction of earthworms in OM amended treatments tended to decrease all activities (-30.6 to -59.3%) although they were still higher than in the non- amended soil, especially for β-glucosidase (+182 to 230%). We noted no significant differences between the effects of the two earthworm species. Increased microbial activities resulting from the addition of organic matter did not substantially alter the availability of Zn, Cd, Pb and Cu assessed by their association with DTPA. Earthworm increased the availability of Zn (up to +31%), Cd (+78 to 193%) and decreased Pb (down to -16.4%) in the non-amended treatment. In the amended treatment earthworms induced an increase in Cd (up to 18.8%), but a decrease in Zn availability. Total Cd available concentrations in the experimental units (in soil and casts when earthworms were present) increased from 36.2% in control soil to up to 46.1% after 60days depending on treatments, while no significant changes were observed for other metals. This rather important change obtained for Cd in such a short amount of time indicates a possible environmental risk.
... Glass (1999) U.S. and international markets for phytoremediation Vangronsveld and Cunningham (1998) Metal-contaminated soils: in-situ inactivation and phytorestoration Panin (1998) Influence of antropogenic activity and human argochemical activity on migration of heavy metals in system "soil-plant" Lan et al. (1998) Reclamation of Pb/Zn mine tailings at Shaoguan, Guangdong Province, People's Republic of China: the role of river sediment and domestic refuse Brooks (1998) Plants that hyperaccumulate heavy metals Rao and Tarafdar (1998) Selection of plant species for rehabilitation of gypsum mine spoil in arid zon Kraemer et al. (1997) Nickel localization in leaves of the hyperaccumulator plant Alyssum lesbiacum by micro-PIXE technique Leblanc et al. (1996) Accumulation of arsenic from acidic mine waters by ferruginous bacterial accretions (stromatolites) Singh (1996) Prosopis juliflora in an alkali soil Gonsalves et al. (1997) Mycorrhizae in a portuguese serpentine community Mesjasz-Przybylowicz et al. ...
Rapid urban growth and industrial development led to irreversible changes in the landscape, especially the natural vegetation. The fly ash dumps at thermal power plants, in the Middle Ural region occupy a large area. These fly ash dump sites are the main source of air and soil pollution. To restore these fly ash-ravaged sites and to prevent harmful effects on the environment, biological reclamation has been carried out. The key objective of this exercise is to create a biological reclamation on the surface of dump sites by transforming them through biogeocenosis into productive areas for agriculture, forestry, and recreation.
... Additionally, bio-litter, ferro-and manganese oxihydroxides (Lombi et al., 2003), natural and artificial clay minerals (aluminium silicates) and alkalizers (lime, dolomite) (Bolan et al. 2003) are well applicable. Sewage sludges, manures, composts, biosolids, digestates, and some industrial wastes (slags, ashes) are likely amendments (Vangronsveld and Cunningham, 1998). The potential use of red mud as a chemical stabilizer for HMs was published by Feigl et al. (2012). ...
Anthropogenic contamination of soils with potential toxic metals has become a global environmental problem. Metal pollution affects crop yield, composition of microbial community and fertility of soils and it is a potential health risk appearing in food production. Phytoremediation is a group of new and promising methods to decrease the harmful effect of soil and water pollution. Phytoremediation, which is also called green or botanical remediation (phyto (gr) means plant, remedium (lt) means healing, restoration), consists of technologies that applies plants or plant-microbe associations to reduce the concentration or transport of organic or inorganic pollutants to a tolerable level. Research on phytoremediation is diverse because the methods depend on the interaction of the pollutant, the plant, the polluted medium and the climate. Above all, phytoremedial technologies are presented with their advantages and disadvantages, including the requirements and difficulties of practical application. Both ecological and human health aspects should be considered in planning the effective and efficient phytotechnology of the metal contaminated sites. Phytoremediation is primarily used for the restoration of metal polluted soils, so this chapter is focused on the treatment of heavy metal polluted media. As the part of the soilplant interface, the rhizosphere microbial community has a significant role in the practice of soil remediation and field restoration. Soil microorganisms have a potential to improve the efficiency of phytoremedial processes through their effects on heavy metal mobility, availability and transport to plants. Nowadays, phytoremedial methods assisted by heavy metal-tolerant soil microorganisms are obtaining significant attention. Managed mycorrhization significantly promotes phytoremediation and reuse of damaged fields. The results of our research on enhancing phytoremedial technologies with the application of arbuscular mycorrhizal fungi are also presented.
The aim of this chapter was to identify the benefits for sustainability from green pharmaceutical production activities. Green manufacturing to produce green products is now increasing in response to the national and international environmental laws and the pressure from local communities where the industry is located.
Rejony przemysłowe, szczególnie te silnie zurbanizowane, wykazują niedostatek terenów inwestycyjnych, w tym również takich, które można przeznaczyć na tereny zieleni. Parki i zieleńce bywają zakładane nawet na gruntach silnie skażonych. Przedmiotem pracy jest analiza możliwości adaptacji metody PAR (Prediction, Adaptation, Resilience) w dostosowaniu terenów skażonych do użytku społecznego z zachowaniem warunków bezpieczeństwa i rozwiązań opartych na naturze (Nature-Based Solutions) w relacji do usług ekosystemowych. Celem pracy jest wskazanie przy tym drogi do zachowania lokalnych wartości przyrodniczo-kulturowych przy remediacji i rekonstrukcji lokalnych warunków środowiskowych i przy różnym stopniu zainwestowania. Bezpieczeństwo użytkowników jest najważniejsze, ale stopień tego bezpieczeństwa nie w każdym miejscu musi być taki sam. Trzeba umiejętnie równoważyć izolację, remediację, fitostabilizację i sukcesję. Efekty analiz tworzą fenomenologiczny opis cech, których znaczenie dla obiektu projektant może dostosować do swojej wizji. Znając uwarunkowania i mając ideę, należy jeszcze sporządzić listę celów dla porównania i sprawdzenia słuszności podejmowanych decyzji.
Crumb Rubber Concrete has negative impact on the mechanical properties of concrete. This negative impact is attributed to the smoother surface of Crumb Rubber. To make the surface of Crumb Rubber rougher in order make adhesion better and recover strength loss 24 hour lime treatment has been carried out. This treatment helped to recover the strength loss by making the surface of Crumb Rubber rougher as compared to untreated Crumb Rubber. Concrete cylinders of 150 x 300 mm were prepared to investigate the compressive and tensile strength of Crumb Rubber Concrete. The compressive strength was investigated at 7 and 28 days of curing and tensile strength was investigated at 28 days of curing. Effect of pre-treated and untreated Crumb Rubber at replacement levels of 0%, 5%, 10%, 15% and 20% with the replacement of sand as fine aggregate by volume was investigated. The results showed that the compressive and tensile strength of Crumb Rubber Concrete was improved when treated with lime.
In this study, a life cycle assessment (LCA) method was used to examine the environmental impact of the rice
pulse production system (RPPS) in Cauvery Deltaic Region (CDR), Tamil Nadu, India. The LCA considered
the entire system required to produce 1 t of rice and 1 quintal of the pulse. The analysis included resource
utilization and greenhouse gases emissions (GHGEs) under two different rice cultivation methods followed by
a residual pulse crop. The result shows the significance of environmental impacts, followed by eutrophication,
water depletion, global warming, and energy depletion. As such, reducing nitrogen (N) fertilizer intensity and
increasing utilization efficiency are the key points to control the life cycle environmental impacts of rice and its
fallow crops, which would decrease resource consumption and emissions in the upstream production stages.
Streamlinig water management, particularly in the early growth stage, and reduction of rice field water
discharge are also significant measures with which to minimize nitrogen and phosphorus runoff losses and
control eutrophication and GHGEs so as to reduce life cycle environmental impacts of the rice-based cropping
system.
Keywords: Eutrophication, Global warming, Greenhouse gases, Life cycle assessment, Rice-pulse
The Royal Netherlands Meteorological Institute (KNMI) published the KNMI’06 Climate Scenarios in 2006. These scenarios give the possible states of the climate in The Netherlands for the next century. Projections of changes in precipitation were made for a time scale of 1 day. The urban drainage sector is, however, more interested in projections on shorter time scales. Specifically, time scales of 1 hour or less. The aim of this research is to provide projections of precipitation at these shorter time scales based on the available daily scenarios. This involves an analysis of climate variables and their relations to precipitation at different time scales. On the basis of this analysis, one can determine a numeric factor to translate daily projections into shorter time scale projections. Eventually, these synthetic data can be used as an input for an urban drainage model. With such a drainage model and synthetic data for design storms the effects of climate change on the systems’ performance can be assessed and the efficiency of adaptive measures can be investigated.
The earth is currently dealing with a variety of issues and is losing its potential as a result of climate change brought on by increasing industrialization and urbanization. Harmful metals wastes generated by anthropogenic processes such as household, municipal, agricultural, industrial, and military operations penetrate the soil, decreasing its quality and usefulness. Because soil is the foundation of life, it necessitates excellent remediation activity. The problem of soil pollution is no longer being ignored because it is limited or no new land to replace. Therefore, the objective of this review paper is to explore the concepts and promises of basic phytoremediation approaches for heavy metal-contaminated soils. The use of living organisms, particularly plants (phytoremediation), is one of the remediation approaches that is now being used. In comparison to other soil remediation approaches, phytoremediation is an effective and affordable technology that can work with few maintenance costs once established, is suited for vast regions with low to moderate amounts of contaminants, and is ecologically benign. Phytoremediation, on the other hand, is a long-term remediation option, and not all of its remediation procedures are optimal. For example, in the case of phytovolatilization, air pollution may occur, while in the case of phytoextraction, pollutants collected in leaves may be released back into the environment during litterfall. Therefore, future concerns should be directed toward the modification and improvement of phytoremediation technologies that are likely to improve metal-binding abilities in plant tissues and phyto-transform toxic metals. Finally, it is critical to minimize or avoid the release of harmful compounds into the environment, in addition to enhancing and adapting various techniques.
Soil degradation by metal and metalloid (metal[loid]) contamination represents a widespread environmental threat. Most studies investigating soil metal(loid) contamination have disregarded the soil quality concept. Enzyme activities (EAs) are good soil quality indicators due to their direct connection to functions related to C, N, P, and S cycles and their sensitivity to metal(loid) contamination. This review (a) provides an overview of the development of soil quality indices (SQIs) based on EAs in metal(loid) contaminated soils, and (b) evaluates the effects of individual metal(loid)s and their combinations on the activities of the most common enzymes involved in the C, N, P, and S cycles. Four intracellular mechanisms dominate the inhibition of EAs by metal(loid)s: (a) transcription inhibition, (b) protein denaturation, (c) cell division inhibition, (d) cell membrane disruption. These mechanisms can also be further exacerbated in soil by nonspecific exoenzyme inhibition. The main EAs used as indicators for metal(loid) contaminated soils are dehydrogenase (DHA), arylsulfatase (ARY), urease (UA), acid phosphatase (Pacid), alkaline phosphatase (Palk), and catalase (CAT). These enzymes are sensitive to metal(loid) contamination, with DHA and ARY being the most sensitive indicators (62 and 56% inhibition, respectively, when averaged over all metal[loid] contamination levels). Other enzymes are inhibited by 32% (UA), 23% (Palk), 18% (Pacid), and 18% (CAT). We suggest principles for the development of SQIs considering biotic soil functions via the use of EAs. This review is the first presenting SQIs based on EAs for metal(loid) contaminated soils, and represents the first quantitative analysis of metal(loid) effects on EAs.
Heavy metals are biologically magnified due to continuous accumulation in the natural resources which not only threatens the plants and animals survival but also puts mankind at higher risk lacking excellent defense mechanism. Even at a lower concentration these metals may interact with several biomolecules thereby hampering the physicochemical processes in plants resulting in enzyme deactivation, protein denaturation, or disruption of various metabolic activities. Plants have been continuously known to adapt themselves under any of the prevailing environmental stress condition since their origin on this terrestrial planet through various physical and cellular defense mechanisms. Plants in association with the arbuscular mycorrhizae also limit the translocation of these heavy metals in the shoot system, thus immobilizing these metals in soil. Maximum arable acreage is being degraded by the heavy metals accumulation in the soils thereby reducing the cropping intensity, therefore the faulty practices leading to the biomagnification of these heavy metals should be avoided both at primary and secondary stages of its accumulation. This chapter summarizes the growth and development of plants under heavy metals stress condition, the defense mechanisms, and the mitigation options involved.
Soil acts as a sink for a number of organic and inorganic pollutants, through which these enter into the food chain and become a potential source of human diseases. Heavy metal (Cd, Cu, Cr, Fe, Ni, Pb, Zn) and metalloid (As, Sb) contamination of soil resources is increasing due to natural and anthropogenic activities. Currently, metal(loid) accumulation is one of the most serious environmental concerns owing to their toxicity to crops. Agronomic crops, mainly cereals (wheat, Triticum aestivum; maize, Zea mays; rice, Oryza sativa), are cultivated on large area and, thereby, are more vulnerable to metal(loid) toxicity, affecting crop growth (seed germination, root/shoot length, and biomass), physiology (water relation, pigmentation, photosynthetic machinery), and metabolic processes (reactive oxygen species (ROS), lipid peroxidation, protein degradation). However, to counter these anomalies, crops are equipped with antioxidants (CAT, POD, SOD, APX, GR, proline, phenolics) to detoxify metal-induced ROS and proteins (phytochelatins, PCs; metallothioneins, MTs) to sequester metal(loid)s. Thus, further insight into these processes is important to exploit better metal-contaminated areas for raising crops, generate revenue, and feed ever-increasing population. Therefore, we present an overview of heavy metal(loid) pollution in soil; their toxicity to cereals (wheat, maize, rice) at morphological, physiological, and cellular levels; and their tolerance mechanisms. At the end, we explore the symbiotic association of cereal crops to a microbe in scavenging metal toxicity.
Plant communities that can grow on mine spoils and are capable of accumulating metals in their parts have immense scope for mine reclamation and for biogeochemical exploration. The chemical composition of these plants is usually correlated with the mineral composition of the soil in order to fetch biogeochemical prospecting [1]. Thus, the plant community established on a mine spoil can be useful in mineral exploration as well as in remediation to minimize the impacts of mining [2-4]. Therefore, considering the diversity of plants and their responses in metal-contaminated sites having different levels of metals, it is important to study the composition of the plant communities of abandoned mines or mine spoils, which would serve as a basic approach for initiating steps for mine reclamation and remediation.
This chapter reviews fly ash typology, composition, treatment, deposition, recycling, functional re-use, and metals and organic pollutants abatement. Fly ash is a by-product of power and incineration plants operated either on coal and biomass, or municipal solid waste. The growing of environmental awareness and increasing energy and material demand will foster recycling. Recycling will help to reuse valuable materials which would otherwise be wasted, and reduce energy consumption and greenhouse gas emissions from extract ion and processing. Fly ash is world’s fifth largest material resource because of the large amount of ash produced in the world. Fly ash can be classified into several categories: coal fly ash obtained from power plant burning coal; flue gas desulphurisation fly ash, that is the byproduct generated by the air pollution control equipment in coal-fired power plants to prevent (reduce) the release of SO2; biomass fly ash produced in the thermal conversion of biomass; and municipal solid waste incineration (MSWI) fly ash, that is the finest residue obtained from the scrubber system in a municipal solid waste incineration plant.
Fly ash often contains pollutants such as heavy metals and organic compounds. The composition of fly ash is very variable, depending on their origins, then also the pollutants can be very different. For example, MSWI fly ash are the most problematic ash in terms of contaminant content. We review existing techniques for fly ash inertization, separately considering heavy metals entrapment or organic abatement. We show that fly ash is a valuable resource with potential use in several applications like agriculture, synthesis of zeolite and geopolymer, adsorbent and building materials. Finally all advantages in fly ash recovery and re-use are discussed. It is shown that fly ash recycling will reduce landfilling disposal, raw materials employ, greenhouse gas emission and water consumption.
The data on heavy metal (HM) accumulation and detoxification by plants and bacteria in plant–microbial systems (PMS) are reviewed. Bacteria are shown to be the labile component of the system, responsible for a considerable amelioration of HM stress impact on plants and for improved PMS adaptation to heavy metals. Simulation of plant–microbial interactions under conditions of soil contamination by HM revealed the protective role of bacterial migration from the rhizoplane to the rhizosphere.
Total suspended particle (TSP) and fine particulate matter (PM2.5) samples were collected continuously using an atmospheric particulate matter sampler at sampling points in a tailings reservoir in the south from October 28 to November 3, 2013. The mass concentrations of particulate matter in the air, the contents, and morphological analysis of heavy metal elements (Pb, Cd, U, Cu) were also studied. The results indicate that the air particulate matter concentrations exceed the mass concentration limits of national Grade II ambient air quality standard (GB3095-2012); The heavy metals content in air particulate matter from high to low order is: Pb > Cu > U > Cd and heavy metals are easier to be concentrated on fine particulate matter (PM2.5); heavy metal elements (Pb, Cd, Cu) exist mainly in the exchangeable morphology, especially the element Cd.
In its soluble ionic forms, lead (\({\rm Pb}\)) is a toxic element occurring in water and soil mainly as the result of human activities. The bioavailability of lead ions can be decreased by complexation with various materials to decrease their toxicity. \({\rm Pb}\) chemical immobilization using phosphate addition is a widely accepted technique for immobilizing \({\rm Pb}\) from aqueous solutions and contaminated soils. The application of different P amendments causes \({\rm Pb}\) in soils to shift from forms with high availability to the most strongly bound \({\rm Pb}\) fractions. The increase of \({\rm Pb}\) in the residual or insoluble fraction results from formation of pyromorphite \({\rm Pb}_5 ({\rm PO}_4)_3{\rm X}\), where \({\rm X} = {\rm F}\), \({\rm Cl}\), \({\rm Br}\), \({\rm OH}\), and the most stable environmental \({\rm Pb}\) compounds under a wide range of \({\rm pH}\) and \({\rm Eh}\) natural conditions. Accidental pyromorphite ingestion does not yield bioavailable lead, because pyromorphite is insoluble in the intestinal tract. Numerous natural and synthetic phosphate materials have been used to immobilze \({\rm Pb}\): apatite and hydroxyapatite, biological apatite, rock phosphate, soluble phosphate fertilizers such as monoammonium phosphate (MAP), diammonium phosphate (DAP), phosphoric acid, biosolids rich in P, phosphatic clay, and mixtures. The identification of pyromorphite in phosphate-amended soils has been carried out by different nondestructive techniques such as x-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), x-ray absorption fine structure (XSFS), transmission electron microscopy (TEM), and electron microprobe analysis (EMPA). The effectiveness of in situ \({\rm Pb}\) immobilization has also been evaluated by sequential extraction (SE), by the toxicity leaching procedure (TCLP), and by a physiologically-based extraction procedure simulating metal ingestion and gastrointestinal bioavailability to humans (PBET). Efficient \({\rm Pb}\) immobilization using P amendments requires increasing the solubility of the phosphate phase, and of the \({\rm Pb}\) species phase, by inducing acid conditions. Although phosphorus addition seems to be highly effective, excess P in soil and its potential effect on the eutrophication of surface water, and the possibility of arsenic enhanced leaching remains a concern. The use of mixed treatments may be a useful strategy to improve their effectiveness in reducing lead phyto- and bioavailability.
Although Canada, like many other NATO countries, spends hundreds of millions of dollars annually to remediate contaminated sites, many still remain and continue to represent an economic and environmental liability as well as a technical challenge. Site owners and managers alike are constantly confronted by the need for innovative and cost effective technological solutions to address the more recalcitrant environmental contaminants. One of the more promising environmental technologies on the horizon is that of phytoremediation. Phytoremediation is defined as the in situ use of plants to immobilize, remediate, reduce, or recover contaminants from soil, sediment, or water.
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