Phytoextraction of endosulfan a remediation technique

Research progress on remediation of organochlorine pesticide contamination in soil

Deteriorated soil pollution has grown into a worldwide environmental concern over the years. Organochlorine pesticide (OCP) residues, featured with ubiquity, persistence and refractoriness, are one of the main pollution sources, causing soil degradation, fertility decline and nutritional imbalance, and severely impacting soil ecology. Furthermore, residual OCPs in soil may enter the human body along with food chain accumulation and pose a serious health threat. To date, many remediation technologies including physicochemical and biological ways for organochlorine pollution have been developed at home and abroad, but none of them is a panacea suitable for all occasions. Rational selection and scientific decision-making are grounded in in-depth knowledge of various restoration techniques. However, soil pollution treatment often encounters the interference of multiple factors (climate, soil properties, cost, restoration efficiency, etc.) in complex environments, and there is still a lack of systematic summary and comparative analysis of different soil OCP removal methods. Thus, to better guide the remediation of contaminated soil, this review summarized the most commonly used strategies for OCP removal, evaluated their merits and limitations and discussed the application scenarios of different methods. It will facilitate the development of efficient, inexpensive and environmentally friendly soil remediation strategies for sustainable agricultural and ecological development.

Remediation of endosulfan-contaminated water by hairy roots: removal and phytometabolization assessment

Although many countries banned the insecticide endosulfan, it is still an environmental pollutant. Plants metabolize the two diastereomers of the formulations known as technical grade endosulfan (TGE) by two phase I pathways: hydrolysis leading to less toxic derivatives and oxidation giving endosulfan sulfate which is as toxic as endosulfan itself. We assessed the removal, bioaccumulation and phase I metabolization of TGE from water matrices using hairy root clones (HRs) of three edible species, Brassica napus, Raphanus sativus and Capsicum annuum. B. napus and C. annuum HRs removed 86% of TGE from the bioreaction media in 2 and 96 h, respectively, whereas R. sativus HRs removed 91% of TGE within 6 h of biotreatment. In the experiments with B. napus, only endosulfan sulfate was detected in both biomass and medium, whereas R. sativus and C. annuum accumulated endosulfan sulfate and endosulfan alcohol. Besides, endosulfan lactone was detected in C. annuum reaction medium. Acute ichthyotoxicity assays toward Poecilia reticulata showed that media contaminated with TGE lethal levels did not produce mortality after the phytotreatments. This research highlights the feasibility of using HRs to evaluate plant enzymatic abilities toward xenobiotics and their potential for the design of ex situ decontamination processes.

Phytoremediation of organochlorine pesticides: Concept, method, and recent developments

Rapid increase in industrialization of world economy in the past century has resulted in significantly high emission of anthropogenic chemicals in the ecosystem. The organochlorine pesticides (OCPs) are a great risk to the global environment and endanger the human health due to their affinity for dispersion, transportation over long distances, and bioaccumulation in the food chain. Phytoremediation is a promising technology that aims to make use of plants and associated bacteria for the treatment of groundwater and soil polluted by these contaminants. Processes known to be involved in phytoremediation of OCPs include phytoaccumulation, rhizoremediation, and phytotransformation. Vegetation has been accounted to considerably amplify OCP elimination from soil, in contrast to non-planted soil, attributable to both, uptake within plant tissues and high microbial degradation of OCP within the root zone. Developing transgenic plants is a promising approach to enhance phytoremediation capabilities. Recent advances in the application of phytoremediation technique for OCPs, including uptake by plants and plant-microbe association in the rhizosphere for the enhanced degradation and mineralization of these pollutants, is presented in this review. Additionally, some attempts to improve this technique using transgenesis and role of certain enzymes are also discussed.

Assessing the dynamic changes of rhizosphere functionality of Zea mays plants grown in organochlorine contaminated soils

The persistent organochlorine pesticides (OCPs) in soils are suspected to disturb soil biogeochemical cycles. This study addressed the dynamic changes in soil functionality under lindane and chlordecone exposures with or without maize plant. Decreases in soil ammonium concentration, potential nitrogen mineralization and microbial biomass were only OCP-influenced in bulk soils. OCPs appeared to inhibit the ammonification step. With plants, soil functionality under OCP stress was similar to controls demonstrating the plant influence to ensure the efficiency of C- and N-turnover in soils. Moreover, OCPs did not impact the microbial community physiological profile in all tested conditions. However, microbial community structure was OCP-modified only in the presence of plants. Abundances of gram-negative and saprophytic fungi increased (up to +93% and +55%, respectively) suggesting a plant stimulation of nutrient turnover and rhizodegradation processes. Nevertheless, intimate microbial/plant interactions appeared to be OCP-impacted with depletions in mycorrhizae and micro/meso-fauna abundances (up to -53% and -56%, respectively) which might have adverse effects on more long-term plant growth (3-4 months). In short-term experiment (28days), maize growth was similar to the control ones, indicating an enhanced plasticity of the soil functioning in the presence of plants, which could efficiently participate to the remediation of OCP-contaminated soils.

Synergistic influence of Vetiveria zizanioides and selected rhizospheric microbial strains on remediation of endosulfan contaminated soil

Application of endosulfan tolerant rhizospheric bacterial strain isolated from pesticide contaminated area, Ghaziabad in combination with V. zizanioides for the remediation of endosulfan is described herein. The dissipation of endosulfan from soil was considerably enhanced in the presence of bacterial strain and Vetiveria zizanioides together when compared to the dissipation in presence of either of them alone. Four strains- EAG-EC-12 (M1), EAG-EC-13(M2), EAG-EC-14(M3) and EAG-EC-15(M4) are used for this purpose. V. zizanioides was grown in garden soil spiked with 1500 µg g(-1) of endosulfan and inoculated with 100 ml of microbial culture of above motioned strains. Effect of microbial inoculation on plant growth, endosulfan uptake and endosulfan removal efficiency were analyzed. The microbial inoculation significantly enhances the growth of test plant and endosulfan dissipation from soil (p < 0.05). The addition of bacterial strain M1, M2, M3 and M4 in treated pots showed enhanced root length by 13, 33 35, 20.2 and 4.3 %, above ground plant length by 16.38, 35.56, 24.92 and 9.8 % and biomass by 33.69, 49.63, 39.24 and 17.09 % respectively when compared with endosulfan treated plants. After 135 days of exposure, a decline in endosulfan concentration by 59.12, 64.56, 62.69 and 56.39 % was obtained in the spiked soil inoculated with bacterial strains M1, M2, M3 and M4 respectively whereas, decrease in endosulfan concentration by 72.78, 85.25, 76.91 and 65.44 % in the vegetative spiked soil inoculated with same strains was observed during same exposure period. After 135 days of growth period, enhanced removal of endosulfan from experimental soil by 13.66, 20.69, 14.22 and 9.05 % was found in vegetative experiment inoculated with same strains when compared with non vegetative experiment. Result of the study showed that use of toletant plant and tolerant bacterial strains could be the better strategy for the remediation of endosulfan contaminated soil.

Treatment of endosulfan contaminated water with in vitro plant cell cultures

Endosulfan is a Persistent Organic Pollutant insecticide still used in many countries. It is commercially available as mixtures of two diastereomers, α- and β-endosulfan, known as technical grade endosulfan (TGE). A laboratory model based on the use of axenic plant cell cultures to study the removal and metabolization of both isomers from contaminated water matrixes was established. No differences were recorded in the removal of the two individual isomers with the two tested endemic plants, Grindelia pulchella and Tessaria absinthioides. Undifferentiated cultures of both plant species were very efficient to lower endosulfan concentration in spiked solutions. Metabolic fate of TGE was evaluated by analyzing the time course of endosulfan metabolites accumulation in both plant biomass and bioremediation media. While in G. pulchella we only detected endosulfan sulfate, in T. absinthioides the non-toxic endosulfan alcohol was the main metabolite at 48h, giving the possibility of designing phytoremediation approaches.

Effectiveness of vetiver grass (Vetiveria zizanioides L. Nash) for phytoremediation of endosulfan in two cotton soils from Burkina Faso

The influence of vetiver grass (Vetiveria zizanioides) on the fate of endosulfan was studied using a vertisol and a lixisol soils from cotton-growing areas of Burkina Faso. Endosulfan adsorption isotherms were prepared for planted and unplanted soils. Pot experiments were then conducted for six months. For both soils, endosulfan adsorption was higher on planted soils (K(f) = 6.53-9.73 mg(l-n) L(n) kg(-1)) than on unplanted soils (6.27-7.24 mg(l-n) L(n) kg(-1)). In unplanted soils, vertisol adsorbed more endosulfan than lixisol. From the pot experiments, the estimated half-lives of endosulfan in unplanted soils (40.6 to 43.1 days) were higher than in planted soils (34.5 to 40.6 days) containing a greater number of endosulfan-degrading microorganisms. Six months after treatment, endosulfan was not detected in soils. The effectiveness of vetiver in promoting adsorption and the disappearance of endosulfan in both studied soils should be validated on the cotton plot scale in Burkina Faso.