Phytoextraction and dissipation of lindane by Spinacia oleracea L

Metabolome regulation and restoration mechanism of different varieties of rice (Oryza sativa L.) after lindane stress

There is a lack of studies on the ability of plants to metabolize chlorinated organic pollutants (COPs) and the dynamic expression changes of metabolic molecules during degradation. In this study, hybrid rice Chunyou 927 (CY) and Zhongzheyou 8 (ZZY), traditional rice subsp. Indica Baohan 1 (BH) and Xiangzaoxian 45 (XZX), and subsp. Japonica Yangjing 687 (YJ) and Longjing 31 (LJ) were stressed by a typical COPs of lindane and then transferred to a lindane-free culture to incubate for 9 days. The cumulative concentrations in the roots of BH, XZX, CY, ZZY, YJ and LJ were 71.46, 65.42, 82.06, 80.11, 47.59 and 56.10 mg·kg-1, respectively. And the degradation ratios on day 9 were 87.89 %, 86.92 %, 94.63 %, 95.49 %, 72.04 % and 82.79 %, respectively. On the 0 day after the release of lindane stress, the accumulated lindane inhibited the normal physiological activities of rice by affecting lipid metabolism in subsp. Indica BH, amino acid metabolism and synthesis and nucleotide metabolism in hybrid CY. Carbohydrate metabolism of subsp. Japonica YJ also was inhibited, but with low accumulation of lindane, YJ regulated amino acid metabolism to resist stress. With the degradation of lindane in rice, the amino acid metabolism of BH and CY, which had high degradation ratios on day 9, was activated to compound biomolecules required for the organism to recover from the damage. Amino acid metabolism and carbohydrate metabolism were disturbed and inhibited mainly in YJ with low degradation ratios. This study provides the difference of the metabolic capacity of the metabolic capacity of different rice varieties to lindane, and changes at the molecular level and metabolic response mechanism of rice during the metabolism of lindane.

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.

An insights of organochlorine pesticides categories, properties, eco-toxicity and new developments in bioremediation process

Organochlorine pesticides (OCPs) have been used in agriculture, increasing crop yields and representing a serious and persistent global contaminant that is harmful to the environment and human health. OCPs are typically bioaccumulative and persistent chemicals that can spread over long distances. The challenge is to reduce the impacts caused by OCPs, which can be achieved by treating OCPs in an appropriate soil and water environment. Therefore, this report summarizes the process of bioremediation with commercially available OCPs, considering their types, impacts, and characteristics in soil and water sources. The methods explained in this report were considered to be an effective and environmentally friendly technique because they result in the complete transformation of OCPs into a non-toxic end product. This report suggests that the bioremediation process can overcome the challenges and limitations of physical and chemical treatment for OCP removal. Advanced methods such as biosurfactants and genetically modified strains can be used to promote bioremediation of OCPs.

Potential use of Solanum lycopersicum and plant growth promoting rhizobacterial (PGPR) strains for the phytoremediation of endosulfan stressed soil

This study aimed to assess the role of Solanum lycopersicum and plant growth promoting rhizobacterial (PGPR) strains to remove endosulfan present in the soil. S. lycopersicum was grown in endosulfan amended soil (5, 10, 25, and 50 mg kg^-1) inoculated with PGPR strains for 40, 80, and 120 days. The influence of PGPR inoculation on endosulfan accumulation in plant tissues, endosulfan degradation in soil, and plant growth parameters were evaluated. The oxidative stress tolerance was assessed by determining the malondialdehyde formation in S. lycopersicum planted in endosulfan stressed soil inoculated with PGPR strains. The results showed that uptake of endosulfan followed root > shoot pathway in association with a reduction in endosulfan accumulation in inoculated plants as related to un-inoculated plants. Moreover, inoculation of PGPR strains showed a beneficial influence on the degradation of endosulfan, Bacillus sp. PRB101 showed maximum degradation (89% at 5 mg kg^-1 of soil) of endosulfan at 120 days after sowing. Furthermore, the content of malondialdehyde was lower in inoculated plants as related to un-inoculated plants. Inoculation of PGPR strains efficiently enhanced plant biomass. The findings showed the effectiveness of PGPR strains to increase the decontamination of endosulfan stressed soil and decline endosulfan concentration in the plant tissues.

An analysis of the versatility and effectiveness of composts for sequestering heavy metal ions, dyes and xenobiotics from soils and aqueous milieus

The persistence and bioaccumulation of environmental pollutants in water bodies, soils and living tissues remain alarmingly related to environmental protection and ecosystem restoration. Adsorption-based techniques appear highly competent in sequestering several environmental pollutants. In this review, the recent research findings reported on the assessments of composts and compost-amended soils as adsorbents of heavy metal ions, dye molecules and xenobiotics have been appraised. This review demonstrates clearly the high adsorption capacities of composts for umpteen environmental pollutants at the lab-scale. The main inferences from this review are that utilization of composts for the removal of heavy metal ions, dye molecules and xenobiotics from aqueous environments and soils is particularly worthwhile and efficient at the laboratory scale, and the adsorption behaviors and effectiveness of compost-type adsorbents for agrochemicals (e.g. herbicides and insecticides) vary considerably because of variabilities in structure, topology, bond connectivity, distribution of functional groups and interactions of xenobiotics with the active humic substances in composts. Compost-based field-scale remediation of environmental pollutants is still sparse and arguably much challenging to implement if, furthermore, real-world soil and water contamination issues are to be addressed effectively. Hence, significant research and process development efforts should be promptly geared and intensified in this direction by extrapolating the lab-scale findings in a cost-effective manner.

Comparative analysis of the seed germination of pakchoi and its phytoremediation efficacy combined with chemical amendment in four polluted soils

The seed germination plant growth parameters and level of heavy metal accumulation were investigated in pakchoi cultured in four contaminated soils with different levels of heavy metals supplemented with citric acid (CA) or calcium phosphate (CP). Results showed that the seed germination energy, germination percentage and germination index parameters were similar, while the seed vigor (SV) significantly (p < 0.05) decreased as the soil pollution level increased. The lengths of the shoots and roots presented the same trend as SV. All the seedlings grew in heavily polluted soil without any amendments before harvesting; therefore, no plant material was available for subsequent analyses. The photosynthesis parameters of pakchoi cultured in lightly polluted soil without amendment (LPS), lightly polluted soil with CA (LPSA) and moderately polluted soil with CP (MPSP) were similar. The concentrations of Pb, Zn, Mn, Cu and Cd in the shoots, roots and whole plants were in the order of MPSP > LPSA > LPS. Pakchoi cultured in MPSP showed the most promising results in terms of plant height, biomass and heavy metal accumulation. Pakchoi presented the highest translocation and bioaccumulation factors for Cd and the lowest for Pb.HighlightsSoil pollution and the type of chemical amendment had no effect on the seed germination of pakchoi.Citric acid addition in lightly polluted soil improved pakchoi growth and heavy metal extraction.Pakchoi cultured in moderately polluted soil with calcium phosphate amendment presented the highest biomass and heavy metal concentration.

Restoring HCHs polluted land as one of the priority activities during the UN-International Decade on Ecosystem Restoration (2021-2030): A call for global action

The United Nations General Assembly has recently declared 2021-2030 as the 'International Decade on Ecosystem Restoration' for facilitating the restoration of degraded and destroyed terrestrial and marine systems for regaining biodiversity and ecosystem services, creating job opportunities and also to fight against climate change. One of the prime focus is the restoration of ~350 mha of degraded land across the world for attaining the UN-Sustainable Development Goals. Pesticides are one of the major causes of land pollution and hexachlorocyclohexanes (HCHs, including technical-HCH and γ-HCH) is one of the widely used organochlorine pesticides during the past seven decades before α-, β-, and γ-HCH was listed in the Stockholm Convention in 2009. The widespread pollution of HCHs has been reported from every sphere of the environment and ~7 Mt of HCHs residues have been dumped worldwide near the production sites. HCHs isomers have higher volatility, water solubility and long-range atmospheric transport ability which further facilitates its entry into various environmental compartments. Therefore, the restoration and management of HCHs polluted land is urgently required. Despite various pilot-scale studies have been reported for the remediation of HCHs polluted land, they are not successfully established under the field conditions. This is mainly due to the high concentration of HCHs residues in the contaminated soil and also due to its toxicity and highly persistent nature, which increases the complexity of the onsite remediation. Here we provide a novel approach i.e. sequential and integrated remediation approach (SIRA) for the restoration of HCHs contaminated land by the integrated use of agroresidues along with the application of HCHs degrading microorganisms and chemical amendments followed by the plant-based clean-up techniques using grasses, herbs, shrubs and trees in a sequential manner. SIRA provides cost effective solution with enhanced ecological and socioeconomic benefits for the sustainable restoration of HCHs contaminated sites.

Influence of plant growth promoting rhizobacterial strains Paenibacillus sp. IITISM08, Bacillus sp. PRB77 and Bacillus sp. PRB101 using Helianthus annuus on degradation of endosulfan from contaminated soil

Endosulfan is a broad spectrum insecticide used in agriculture for protection of various food and non-food crops. It is persistent in nature and hence found in soil, air and water. The potential use of plants and microorganisms for the removal of endosulfan from soil was studied. Helianthus annuus plant was grown in soil spiked with 5, 10, 25 and 50 mg kg^-1 concentrations of endosulfan and inoculated with plant growth promoting rhizobacterial strains Paenibacillus sp. IITISM08, Bacillus sp. PRB77 and Bacillus sp. PRB101 for 40, 80 and 120 days. Potential of plant for endosulfan uptake was evaluated by investigating the endosulfan levels in plant tissues (root and shoot). The results indicated that endosulfan accumulation followed the pattern of root > shoot as well as decrease in uptake of endosulfan in root and shoot of a plant grown in bacterial inoculated soil as compared to un-inoculated soil. Bacterial inoculation had a positive effect on endosulfan degradation. Maximum degradation of 92% at 5 mg kg^-1 of endosulfan in soil was observed on inoculation with PRB101 after 120 days of inoculation. The results showed that plant growth promoting bacteria enhances plant biomass production. Lipid peroxidation was also estimated by determining the malondialdehyde (MDA) production, which is a biomarker of oxidative damage. Decrease in MDA formation by root and leaves of plants grown in the bacteria inoculated plant was also observed. The results suggested the effectiveness of plant growth promoting rhizobacteria to boost accumulation potential, biomass production and enhance remediation of endosulfan contaminated soil.

Lindane and hexachlorobenzene sequestration and detoxification in contaminated sediment amended with carbon-rich sorbents

Sediment represents a sink for toxic and persistent chemicals such as hexachlorobenzene (HCB) and lindane (γ-HCH). This paper investigates the possibility of reducing the risks associated with the presence of these pollutants in sediments by amending the sediment with carbon-rich materials (activated carbon (AC) and humus (HC)) to sequester the contaminants and render them biologically unavailable. The effects of the dose and contact time between the sediment and the carbon-rich amendments on the effectiveness of the detoxification are estimated. Four doses of carbon-rich amendments (0.5-10%) and four equilibration contact times (14-180 days) were investigated. Results have shown that the bioavailable fraction of γ-HCH and HCB decreased significantly in comparison to the unamended sediment. Regarding the AC amendments, almost 100% for both compounds; and for HC amendments around 95% for γ-HCH, and 75% for HCB. Aging caused further reductions in the bioavailable fraction, compared to the untreated sediment. Phytotoxicity tests showed that Zea mays accumulated significantly higher amount of γ-HCH and HCB from unamended sediment, comparing to Cucurbita pepo and Lactuca sativa. Toxicity of HC and AC amended sediment assessed by Vibrio fischeri luminescence inhibition test and by measuring Zea mays germination and biomass yield was significantly reduced in the amended sediment samples. γ-HCH and HCB accumulation in the Zea mays biomass in the unamended sediment were a significantly higher than in the all HC and AC amended sediment. Both sorbents show potential to be used as remediation agents for organically contaminated sediment, but AC exhibited the better performance.

Effect of endosulfan tolerant bacterial isolates (Delftia lacustris IITISM30 and Klebsiella aerogenes IITISM42) with Helianthus annuus on remediation of endosulfan from contaminated soil

Endosulfan contaminated soil has become an important risk to the environment and human health worldwide. In the present study, endosulfan tolerant bacterial strain Delftia lacustris IITISM30 and Klebsiella aerogenes IITISM42 were isolated from pesticide stressed agricultural soil and tested for plant growth promoting activities. A pot experiment was performed using Helianthus annuus, grown in soil supplemented with endosulfan and inoculated with pure and consortium of bacterial strain IITISM30 and IITISM42. Inoculation increased plant biomass production and endosulfan degradation, maximum degradation (90% at 5 mg kg^-1 of soil) was observed by inoculation with a consortium of bacterial strain IITISM30 and IITISM42. Moreover, there was significantly less endosulfan accumulation was observed in roots and shoots of bacterial inoculated plants as compared to uninoculated plants. Decrease in production of malonialdehyde (MDA) was noticed on inoculation of a bacterial strain. The study demonstrated that inoculation of a consortium of endosulfan tolerant plant growth promoting bacterial isolates could more effectively remediate endosulfan contaminated soils and decrease endosulfan residues in plants, than individual strains. Moreover, it revealed that combined use of H. annuus and endosulfan tolerant bacterial isolates IITISM30 and IITISM42 has great potential for remediating endosulfan contaminated soil.

HCH phytoremediation potential of native plant species from a contaminated urban site in Turda, Romania

Current physical or chemical methods used for remediation of soils contaminated with hexachlocyclohexane (HCH), leave behind significant levels of pollutants. Given the compound's volatility and persistence in the environment, sites contaminated with HCH remain a concern for the population living in nearby areas. By making use of both the recovery capacity and the pollutant uptake ability of spontaneously growing vegetation, our study aimed to identify native plant species able to cover and moreover take up the HCH left at a former lindane production unit in Turda, Romania. The results showed that dominant species across the study site like Lotus tenuis, Artemisia vulgaris or Tanacetum vulgare, were capable of taking up HCH in their tissues, according to different patterns that combined at the scale of the plant community. Regardless of the proximity of the HCH contamination hotspots, the development of the plant cover was characteristic for vegetation succession on disturbed soils of the Central European region. Finally, we conclude that plant species which grow spontaneously at the HCH contaminated site in Turda and are capable of taking up the pollutant, represent a self-sustainable and low maintenance phytomanagement approach that would allow for the reintegration of the site in the urban or industrial circuit and nevertheless would reduce the toxicity risk to the neighboring human inhabitants.

Accumulation and toxicity of organochlorines in green microalgae

Toxicity of mine dump effluent containing five hexachlorocyclohexane (α, β, γ, δ and ε-HCH, sum 159.4 μg/L) and two trichlorobenzene (TCB, sum 65.2 μg/L) isomers to two microalgae (Scenedesmus quadricauda and Coccomyxa subellipsoidea) was studied over 24 h exposure and also with 2- and 10-fold diluted stock solution (i.e. 1×, 0.5× and 0.1× strength). Individual isomers revealed rather dose-dependent accumulation typically higher in Scenedesmus than in Coccomyxa (max. sum of HCH 14.99 μg/g DW with bioaccumulation factor 94) and δ-HCH was dominant isomer. TCB isomers showed low accumulation in algae. 0.1× dose elevated chlorophylls and carotenoids in Coccomyxa while enzymatic activities (SOD, CAT, and APX), thiols (glutathione and phytochelatin 2) and ascorbic acid were rather elevated by 1× dose in both species. Malic acid, rather than citric acid, increased in response to 0.5× and 1× concentration. Sum of fatty acids was higher in Coccomyxa than in Scenedesmus with palmitic, oleic, linoleic and α-linolenic acids being dominant compounds in both species. Detailed profiling revealed that saturated and monounsaturated fatty acids increased in Coccomyxa while polyunsaturated fatty acids in Scenedesmus in response to increasing dose of organochlorines. Accumulation of organochlorines and metabolic responses in algae are reported here for the first time.

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.

Microbial-enhanced lindane removal by sugarcane (Saccharum officinarum) in doped soil-applications in phytoremediation and bioaugmentation

The aim of this study was to examine the effect of lindane-degrading yeast on the growth and lindane uptake by Saccharum sp., in doped garden soils. The rhizosphere of Saccharum plant was amended with yeast Candida VITJzN04 by root-inoculation. The bio-augment yeast was applied in two different forms viz., planktonic form and cells immobilized on sugarcane-bagasse, in the pot experiments. Garden soils (lindane∼100 mg/kg) exposed to various treatments were monitored for a period of 30 days, for residual lindane by gas-chromatography analysis. The lindane-removal rates in soil were expressed in terms of half-life period and were recorded as 13.3 days (yeast), 43.3 days (Saccharum), 9.8 days (free yeast-plant) and 7.1 days (immobilized yeast-plant). Additionally, Candida sp., was also identified as a plant growth promoting yeast due to its ability to produce growth hormone and solubilize insoluble phosphates in the soil for better uptake by the plant species. Bio-stimulation of the soil with yeast immobilized on sugarcane bagasse further enhanced the total yeast activity in the soil which in turn had a positive influence on lindane-removal. Combined treatment with bagasse immobilized yeast and plant showed the best lindane degradation. Results suggested that the synergistic activity of plant and yeast resulted in fast and efficient degradation of lindane. Thus, it can be concluded that Saccharum plant in combination with Candida VITJzN04 is an effective alternative for the conventional remediation strategies.