Distribution Of Organochlorine Pesticides Research Articles

Organochlorine pesticides and chlorpyrifos in the sea anemone Bunodosoma zamponii (Actiniaria: Actiniidae) from Argentina's southeastern coast

Temporal and spatial distribution of organochlorine pesticides (OCPs) and the organophosphate pesticide chlorpyrifos, one of the main insecticides used in Argentina, was evaluated in two populations of the sea anemone Bunodosoma zamponii living under different anthropological stressors: Las Delicias (LD) adjacent to a wastewater plant, and Punta Cantera (PC) a reference site. Pesticides were analyzed throughout the year in water, sediments and whole organisms. Chlorpyrifos represented 50% of the total pesticide found in water samples during winter. HCHs and drins were predominant in sediment samples, mainly in LD. Total pesticide concentration in anemones from LD was higher than those from PC during winter (mainly associated with HCHs, endosulfans, DDTs and chlorpyrifos levels), coincident with the main period of effluent discharge to the coast after pesticide applications and also the rainiest season. Dissimilarities among anemones populations could stem from a differential input of pesticides in each site and/or a contrasting physiological status of the populations.

Distribution and flux of organochlorine pesticides in sediment from Prydz Bay, Antarctic: Implication of sources and trends

Surface sediments were collected from Prydz Bay, Antarctica to investigate the distribution patterns, origins, annual fluxes, and trends of organochlorine pesticides (OCPs) in the marginal sea of polar areas. The concentrations of OCPs ranged from 0.80 to 7.90 ng/g dry weight, with dichlorodiphenytrichloroethanes (DDTs) as the main components. Levels of hexachlorocyclohexanes (HCHs) and DDTs in sediment from Prydz Bay were comparable to the majority of marine sediment worldwide. The distributions of OCPs were characterized by a distinct “quasi-concentric circle” pattern, which has significantly positive relationship with total organic carbon (TOC) of sediment and controlled by the local hydrodynamic conditions and sources of organic matter. Source apportionment demonstrated that HCHs and chlordanes in Prydz Bay were mainly derived from the long range atmospheric transport (LRAT) of these compounds from off regions. However, current inputs of DDT-based compounds and lindane are suggested to exist either as a result of the LART from the neighbouring countries or re-emission from melting glacier. The annual sedimentary fluxes of OCPs were 0.007 to 7.12 pg/cm2/yr, about one to three orders of magnitude lower than some data from the Arctic areas. Based on a rough calculation of r-HCH, only 0.3–1.5% of the air-seawater net deposition would be buried in sediment, implying a long active lifetime of OCPs in Antarctica. We preliminarily indicate an increase of OCP contamination in Antarctic environment afterwards when considering the possible occurrence of “fresh” sources and low proportion of sedimentary sink.

Event loading drives distribution of the organochlorine pesticide metabolite DDE in a sub-tropical river system, Brisbane River, Australia

Past catchment practices can contribute to environmental impacts for decades following their cessation. We examine the distribution of the prevalent organochlorine pesticide, dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDE, DDD) in the sediments of a sub-tropical river system (Brisbane River, Australia). This study aimed to identify sources of DDT, DDE, DDD into the lower reaches of the Brisbane River. Annual sediment sampling of the lower Brisbane River over a period of 15 years (2001–2015) revealed a significant increase in sediment DDT, DDE and DDD content following major floods. A regional survey detected elevated sediment DDT, DDE and DDD content at 32 of 79 sites sampled; however, these were generally below guideline trigger values. DDE was the sole fraction at all but one site with creek systems dominated by intensive cropping practices identified as legacy sources and major flood events as a driver of elevated sediment DDE content in the lower reaches.

Occurrence and distribution of OCPs and PAHs in water, soil and sediment of Daye lake

To elucidate the concentrations, spatial distribution, sources, and risk of sixteen polycyclic aromatic hydrocarbons (PAHs) and twenty-four organochlorine pesticides (OCPs), thirteen sites were chosen for collecting water, sediment, and soil samples from Daye lake in April 2019. All pollutants were frequently observed in three media of Daye lake. Higher concentrations of OCPs were determined in the soil whereas PAHs were dominant among sediment samples. However, the water of Daye lake is contaminated with both of the pollutants. In water, ΣDRINs, ΣDDTs, ΣHCHs and LMW PAHs accounted for 22.1%, 19.6%, 17.9% and 85.5%, respectively. Among sediments, OCPs and PAHs were ranged from 1.53–51.38 ng·g−1 and 14.38–4659.66 ng·g−1, respectively. While soil accounted for a larger percentage of heptachlorepoxide i.e. 96.5% and HMW PAHs i.e. 82.7%. Furthermore, the low α-to γ-HCH ratio suggested fresh input of HCH and the higher ratio of (DDE + DDD)/DDT determined the historical use of DDT. Additionally, diagnostic molecular ratio along with principal component analysis evaluated that PAHs mainly came from fossil fuel, biomass, and coal combustion. Moreover, ecological risk assessment of Daye lake indicated that the carcinogenic PAHs in water and soil can pose 10% risk to the environment also OCPs in sediments has a visible effect on ecology. According to incremental lifetime cancer risks (ILCRs) evaluation, OCPs have negligible to low cancer risk among all sites for water, soil, and sediments while PAHs value fluctuate in the midst of 10−6 to 10−2 which shows the potential risk of cancer on children as well as adults. Therefore, measures should be taken to control them in time.

Residues of organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in waters of the Ili-Balkhash Basin, arid Central Asia: Concentrations and risk assessment

Release and transport of contaminants in watersheds can have adverse effects on aquatic organisms and human health. Little attention, however, has been paid to chemical contamination of aquatic environments in arid regions by persistent organic pollutants. We analyzed the concentrations and distributions of organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in waters of the Ili-Balkhash Basin, in arid central Asia. ΣOCP concentrations ranged from 4.02 to 122.80 ng L−1 and ΣPAH concentrations were between 7.58 and 70.98 ng L−1. On a global scale, OCP and PAH concentrations in waters of the Ili-Balkhash system were relatively low, with only a few exceptions, i.e., highest concentrations near cities and relatively high values in some headwater areas. Source identification revealed that the dichlorodiphenyltrichloroethanes (DDTs) may come from recent use, whereas endosulfans stem from historic applications. Lindane, a common insecticide, may be responsible for hexachlorocyclohexanes (HCHs). Low-molecular-weight PAHs, primarily originating from wood and coal combustion and petroleum-derived sources, were the primary components of PAHs in waters. Furthermore, the primary sources of PAHs at different sites were identified using a Positive Matrix Factorization model: 1) oil leakage (33.9%), 2) biomass burning (29.5%), 3) coal combustion (22.6%), and 4) petroleum-powered vehicles (14.1%). Agricultural, industrial and domestic activities are all potential pollution sources. Besides, contaminated headwater areas indicate that long-range transport has probably become a non-negligible mechanism for pollutant distribution. Risk assessment showed low to moderate toxicity for aquatic organisms, but no marked carcinogenic or non-carcinogenic risks for human health.

Occurrence and partition of organochlorine pesticides (OCPs) in water, sediment, and organisms from the eastern sea area of Shandong Peninsula, Yellow Sea, China

To evaluate the occurrence and partition of organochlorine pesticides (OCPs), hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), water, sediment, and organisms were sampled from the eastern sea area of Shandong Peninsula (Yellow Sea, China) across all four seasons in 2016. There were three OCP hotspots in the sediment, mainly caused by the transportation of lindane and dicofol from adjacent Swan Lake and Guhe River. Waterborne OCP levels were highest in winter and lowest in spring, without vertical variability, suggesting that the Yellow Sea Cold Water Mass was governing the spatio-temporal distribution of OCPs in seawater. There was substantial accumulation of HCHs and DDTs in organisms via sediment, as indicated by the relatively low fraction of sedimental fugacity, high bio-sediment accumulation factor, and a positive linear correlation between logΣHCHs and trophic level. This is the first study that has focused on the accumulation of OCPs in entire sediment-seawater-organism system involving multi-phyla of species.

Residual Characteristics and Health Assessment Analysis of OCPs and PCBs in Karst Groundwater

Residual levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in karst groundwater in Nanshan Laolongdong were measured using a gas chromatograph equipped with a micro-63Ni electron capture detector to determine the residual characteristics including concentration, distribution, and source of OCPs and PCBs. Results revealed that the total concentration range of OCPs was 34.8-623.2 ng·L-1, and the mean value was 215.6 ng·L-1, among which the total concentration ranges of HCHs, DDTs, and other OCPs were 8.2-23.6, 4.5-363.7, and 22.2-235.9 ng·L-1, respectively, and the mean values were 15.9, 104.5, and 95.3 ng·L-1; the total concentration range of PCBs was 6.0-40.7 ng·L-1, and the mean value was 16.8 ng·L-1. Overall, the pollution of OCPs and PCBs was above average; the results of multiple comparisons revealed that statistically significant differences occurred in the concentration of some OCPs and PCBs. The pollution levels in the water of each sampling point in the study area were quite different; however, the seasonal distribution of OCPs and PCBs was relatively uniform. Source analyses revealed that HCHs' source was the input of lindane in the surrounding environment, DDTs recently originated from illegal use of industrial DDT, other OCPs originated from atmospheric deposition and agricultural input, and PCBs' sources included both historical remains and enterprise production processes. The results of Pearson correlation analyses revealed that some organo-halogen pollutants were homologous or had similar sources and decomposition mechanisms. According to health risk assessment model, drinking water in the study area would not cause obvious harm to human health, but children were more sensitive to pollutants than adults.

Concentrations and regularities of disperse-phase distribution of organochlorine pesticides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in natural water

<div><p>This article presents the monitoring results of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in surface water of the Dnieper River for the period 2011–2019. Total levels of OCPs, PCBs and PAHs consist of 1,4–17,1; 2,8–57,2; and 7,5–378,6 ng/L, respectively. A significant increase in pollution levels was not identified. Research results of the disperse-phase distribution of these substances in water were also provided. Less than half of the total contents of pollutants were in the water phase. Average water-soluble parts of OCPs, PCBs, and PAHs accounted for 32, 42, and 44 %, respectively. It was shown that water-soluble parts of individual pollutants decrease with the increase in <span style="text-decoration: line-through;">the</span> coefficients of hydrophobicity of compounds. The clearest reliable, relevant correlation between water-soluble parts of individual congeners and coefficients of hydrophobicity was obtained for PCBs.</p></div><p align="center"><strong><br /></strong></p>

Spatial distribution and sources of organochlorine pesticides in surface waters of Shanghai, China

The concentrations, distribution, influencing factors, and sources of 26 organochlorine pesticides (OCPs) were investigated in surface waters of Shanghai. Surface waters in this study refer to the freshwater that contains particles smaller than 0.45 μm in size. Total concentrations of OCPs ranged from 5.90 to 158.16 ng/L with a mean value of 78.11 ng/L. The OCP concentrations were generally low, but with a few relatively high concentrations at sites in the northern and southern regions of Shanghai. Dissolved oxygen, electrical conductivity, pH and oxidation–reduction potential had an important impact on the distribution of OCPs, which showed a significant negative correlation (p HCHs > Endosufan and Methoxychlor > Propachlor > Heptachlor and DDTs > Dacthal and Chlordane. The contribution of historic residual HCHs in Shanghai’s surface waters was not significantly different from that of atmospheric deposition, and a part of HCB was likely from the degradation of HCHs. DDTs were mainly from historical residues, although some were derived from recent inputs, and the main sources of heptachlors were also the historical residues. However, the recent input and historical residues of aldrins were both noticeable. The fluctuation of OCPs pollution levels and source differences among different intensive land-use types were relatively insignificant (p > 0.05).

Occurrence and distribution of HCHs and DDTs in surface water and groundwater from the Gajulamandyam region along the Swarnamukhi river basin, Andhra Pradesh, India

ABSTRACT Organochlorine pesticides (OCPs) are growing concern and ubiquitous in the environment due to their chronic toxicity, persistence, bioaccumulation, and biomagnification properties. The concentration levels of selected organochlorine pesticides (OCPs) like HCH (hexachlorocyclohexane) isomers (α, β-, γ-, δ- HCH) and DDT (dichlorodiphenyltrichloroethane) family (p,p′ – DDT, p,p′ – DDE, p,p′ – DDD) and their distribution patterns in surface water and groundwater of the study area have been investigated. Gajulamandyam region has chosen as a study area that is lying on the banks of Swarnamukhi River basin in Andhra Pradesh, India. Water samples were extracted using the SPE procedure and determined using gas chromatography-mass spectrometer (GC-MS). Concentration profile of total HCH isomers in surface water and groundwater samples have ranged from n.d.- 2970 ng/L (mean 795 ng/L) and n.d.- 2150 ng/L (mean 649 ng/L) respectively. Similarly, the concentrations of ƩDDT in surface water in the range of n.d.- 2020 ng/L (mean 653.6 ng/L) and groundwater n.d.-1540 ng/L (mean 527.3 ng/L) had been observed. The concentration distribution of ƩHCH in surface water and groundwater varied significantly with different sampling sites that indicated their sources of contamination are diverse. The OCP residue levels, namely α – HCH/γ – HCH ratios in the water indicating that it might be from long historical to a recent mixed source of the technical grade of HCHs as well as lindane. Besides, the ratios of (DDE+DDD)/DDT metabolites reveal that the source of contamination may be due to technical DDT. The residue levels of DDTs found in this investigation signifying 63% of groundwater samples exceeded the WHO recommended drinking water limits, thereby affecting human health. The spatial distribution of OCPs demonstrated the variations in pesticide burden in water bodies. The present investigation on the occurrence of HCHs and DDTs in water has advantageous because it provides baseline data for the management of water resources.

Occurrence of organic micropollutants and human health risk assessment based on consumption of Amaranthus viridis, Kinshasa in the Democratic Republic of the Congo

The contamination of water resource and food chain by persistent organic pollutants (POPs) constitutes a major environmental and human health concern worldwide. The aim of this study was to investigate the levels of POPs in irrigation water, soil and in Amaranthus viridis (A. viridis) from different gardening sites in Kinshasa to evaluate the potential environmental and human health risks. A survey study for the use of pesticides and fertilizers was carried out with 740 market gardeners. The levels of POPs (including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs)) were analyzed in irrigation water and 144 vegetable samples collected from different gardening sites. The assessment of potential human health risk was estimated by calculating daily intake and toxic equivalency to quantify the carcinogenicity. The results show highest PAH levels in A. viridis from all studied sites. The concentrations of the sum of seven PCBs (Σ7PCBS) congeners in analyzed plants ranged between 15.89 and 401.36 ng g−1. The distributions of OCPs in both water and A. viridis were congener specific, chlorpyrifos-ethyl and p,p′-DDE were predominantly detected. Among PBDEs, only BDE47 was quantified with noticeable concentration in A. viridis, while no PBDEs were detected in irrigation water. Higher estimated daily intake values indicate that consuming leafy vegetables might associate with increased human health risks. However, calculated incremental lifetime cancer risk values indicates no potential carcinogenic risk for the local population. The results of this study provide important information on A. viridis contamination by POPs and strongly recommend implementing the appropriate measures to control the use of chemicals used in studied gardening areas. Thus in Kinshasa, urban agriculture control programs for POPs and fertilizers is very important in order to protect the public health through direct and dietary exposure pathways.

Spatio-temporal distribution of organochlorine pesticide residues in water and sediments of tropical reservoirs: a case study of Bui Reservoir, Ghana

This study investigated the spatio-temporal distribution of organochlorine pesticides (OCPs) in water and sediments of the Bui Reservoir from June 2017 to May 2018, to provide baseline data for monitoring contamination in the Reservoir. Samples were collected during four seasons reflecting levels of rainfall and from five sites around the Reservoir. Water and sediment samples were subjected to liquid-liquid separation and ultrasonic extraction, respectively. GC-ECD was used to identify and quantify the pesticide residues. Eight OCPs each for water and sediment were detected and their concentrations in water and sediment range from 0.1–4.6 µg l−1 and 1.38–104.86 ng g−1 dry weight, respectively. α-Hexachlorocyclohexane and trans-chlordane dominated with mean concentrations of 3.2 ± 0.08 µg l−1 and 70.91 ± 3.47 ng g−1 dry weight in water and sediment, respectively. There were non-significant differences (p > 0.05) in the spatial distribution of OCPs in water and sediments, but significant differences (p < 0.001) in the temporal distribution of the contaminants in water and sediments, with the wet season samples accounting for the highest concentrations. This indicated that the distribution, behaviour and fate of OCPs the the reservoir have close links with meteorological properties beyond their chemical composition.

Levels and distribution pattern of organochlorine pesticide residues in eggs of 22 terrestrial birds from Tamil Nadu, India.

Long-term monitoring is essential to assess the patterns and distribution of the residues of organochlorine pesticides (OCPs) in biota. Bird eggs have several advantages than other environmental matrixes, which have been used extensively to portray the accumulation and distribution of OCPs. The present study investigated the organochlorine pesticide (OCP) residues in eggs of 22 species of terrestrial birds collected from Tamil Nadu, India. Eggs found abandoned were collected during nest monitoring between 2001 and 2008 and analyzed for the presence of organochlorine pesticide residues. The results showed that the mean concentrations of total hexachlorohexane (∑HCHs), total dichlorodiphenyltrichloroethane (∑DDTs), heptachlor epoxide, and dieldrin ranged from non-detectable (nd) to 2800ng/g, nd to1000 ng/g, nd to 700ng/g, and nd to 240ng/g on a wet mass (wm) basis, respectively. The variation in magnitude of contamination among the species and feeding guilds were not significantly different (p > 0.05). Among the OCPs analyzed, the residues of β-HCH and p,p'-DDE were found to be the abundant in concentration. Similarly, among various bird species studied, the highest concentrations of ∑OCPs (> 5000ng/g wm) were recorded in the eggs of gray junglefowl, scaly-breasted munia, and red-whiskered bulbul. This may be due to their widespread occurrence of their habitat at proximity to the agricultural fields, where organochlorines were in use until recently. Among the various contaminants analyzed, concentrations of p,p'-DDE and heptachlor epoxide exceeded the threshold levels of toxicity for wild birds in > 5% of the egg samples. Hence, this study indicates the need for continued monitoring and further systematic ecotoxicological investigation of these compounds not only in eggs but also in other environmental media.

Sources, distribution, and risk assessment of organochlorine pesticides in Nairobi City, Kenya

The distribution and sources of organochlorine pesticides (OCPs) in air and surface waters were monitored in Nairobi City using triolein-filled semipermeable membrane devices (SPMDs). The SPMDs were extracted by dialysis using n-hexane, followed by cleanup by adsorption chromatography on silica gel cartridges. Sample analysis was done by GC-ECD and confirmed by GC–MS. Separation of means was achieved by analysis of variance, followed by pair-wise comparison using the t-test (p≤ 0.05). The total OCPs ranged between 0.018 – 1.277 ng/m3 in the air and <LOD – 1391.000 ng/m3 in surface waters. Based on the results, the means of Industrial Area, Dandora and Kibera were not significantly different (p≤ 0.05), but were higher (p≤ 0.05) than those of City square and Ngong’ Forest. The results revealed non-significant (p≤ 0.05) contribution of long-range transport to OCP pollution in Nairobi City. This indicated possible presence of point sources of environmental OCPs in the city. The water-air fugacity ratios indicated that volatilization and deposition played an important role in the spatial distribution of OCPs in Nairobi City. This indicated that contaminated surface waters could be major sources of human exposure to OCPs, through volatilization. The incremental lifetime cancer risks (ILCR) determined from inhalation of atmospheric OCPs were 2.3745 × 10−13 – 1.6845 × 10−11 (adult) and 5.5404 × 10−13 – 3.9306 × 10−11 (child) in the order: Dandora > Kibera > Industrial Area > City Square > Ngong’ Forest. However, these were lower than the USEPA acceptable risks, 10−6 – 10−4. This study concluded that atmospheric OCPs did not pose significant cancer risks to the residents.

The occurrence of organochlorine pesticides (OCPs) in riverine sediments of hilly region of southern China: Implications for sources and transport processes

Rivers serve as important water resources for socio-economic development as well as the sink of anthropogenic pollutants—especially pesticides, thus being responsible for the riverine transport and distribution of such chemicals. Therefore, the spatial-temporal distribution of organochlorine pesticides (OCPs) was investigated based on their content in major rivers located in the hilly region of southern China. The research objective was to identify this region's riverine transport of OCPs and their potential affecting factors. Higher concentrations of OCPs were detected in the wet season (52.0 ± 46.5 ng/g dw) than in the dry season (24.9 ± 26.5 ng/g dw). Wet-season OCP input from tributaries was associated with increased water runoff and sediment discharge. Dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) were the major OCP contributors, accounting for 30.4% ± 20.4% and 24.3% ± 10.9% of the total OCPs, respectively. These results corresponded well with the historical production and application of OCPs in China. The spatial differences among rivers and basins were ascribed to the regional usages in history, while the transport of OCPs in rivers was along the water flow direction and related to suspended substances. Moreover, black carbon (BC) played a crucial role on retention and accumulation of OCPs in sediments. Ecological risk assessments based on sediment quality guidelines (SQGs) suggested that γ-HCH, p,p′-DDE, and p,p′-DDD posed high ecological risks, especially in the lower reaches of rivers. Additionally, the human health risk assessment revealed negligible carcinogenic risk associated with OCP contamination.

First account of spatio-temporal analysis, historical trends, source apportionment and ecological risk assessment of banned organochlorine pesticides along the Ganga River

We conducted the first comprehensive assessment of the presence, source, and ecotoxicological implication of 13 banned and restricted organochlorine pesticides (OCPs) in the surface water along the Ganga River for two different seasons. Surface water samples were collected along the 2525 km stretch of the Ganga through 43 sites representing five zones of diverse land-use pattern, pesticide consumption rate, and varied flow. The mean concentrations of ΣOCPs were significantly higher (∼2–5 times) in the post-monsoon or wet season [range: 0.126 to 10.402 μg/L (mean: 2.482 μg/L ± 3.589 and median: 1.433)] than in the post-winter or dry season [range: 0.053 to 3.010 μg/L (mean: 0.765 μg/L±1.033 and median: 0.399)]. Lindane (γ-HCH) was the dominant and most frequently detected pesticide at all the sites, indicating possible continued use of this banned pesticide in agricultural practices. The spatial distribution of OCPs revealed non-significant difference amongst different zones and indicate that point source pollution from the open drains along the Ganga could be responsible for observed trend. Ratio diagnostic analysis highlighted the fresh inputs and potential illegal use of lindane and chlordane at all the zones whereas, historical use of DDT was revealed at the majority of sites. Interestingly, fresh inputs of DDT were observed in the relatively pristine high altitude Upper zone (UZ) suggesting long-range atmospheric transfer and its continued use in the zone. Risk quotient (RQ) analysis revealed high ecotoxicological risks (>1), at all the studied sites for p, p’ DDE. The lower zone (LZ) emerged as a high ecological risk zone. The study highlights that though the OCPs analysed in this study are banned/restricted in India, still the implementation of the ban is poor and delayed and the country requires stricter adherence to its National Implementation Plan (NIP) on pesticides.

Levels and enantiomeric signatures of organochlorine pesticides in Chinese forest soils: Implications for sources and environmental behavior

We investigated the levels and distributions of organochlorine pesticides (OCPs) in 159 background soil samples collected from 30 forested mountain sites across China. The sum of DDT was the most abundant OCP, with the concentrations of 0.197–207 ng/g and 0.033–122 ng/g in the O-horizon and A-horizon, respectively. High concentrations of OCPs usually occur near agricultural regions or high consumption areas. The spatial distribution was mainly influenced by the emission sources and soil total organic contents (TOC). The chiral compounds were generally nonracemic in the soils and showed preferential degradation of (−) o,p′- dichlorodiphenyltrichloroethane, (+) trans-chlordane, and (−) cis-chlordane in both the O- and A-horizons. The enantiomeric fraction (EF) distributions of chiral OCPs displayed no differences across the forest sites in the O-horizon or the A-horizon. Comparing the deviation of EFs from racemic (DEVrac = absolute value of 0.500 - EF) with environmental parameters, we found that DEVrac of cis-chlordane demonstrated a strong positive correlation with TOC (p < 0.05) and the C/N ratio (p < 0.01). This relationship suggests that these factors could affect the microbial activity and significantly impact the extent of enantioselective degradation of chiral compounds in the soils. Fresh and historical applications of DDT and historical chlordane and endosulfan uses may be prominent sources of OCP accumulation in Chinese forest soils.

Organochlorine pesticides in the soils of Cardamom Hill Reserve (CHR), Kerala, India: Geo spatial distribution, ecological and human health risk assessment

The present study assessed the organochlorine pesticides (OCPs) residues in the soils of Cardamom Hill Reserve (CHR), a tropical humid forest landscape of Idukki District of Kerala, India. The concentrations, spatial distribution, health risk for human (both adults and children) due to individual OCPs and ecological risks were estimated. Soil samples were collected randomly from 22 different sampling locations during May 2017 and 2018. The sample preparation was done by QuEChERS method. A total of 17 persistent Organochlorine pesticides (OCPs) were determined by Gas chromatography in split less mode using Electron Capture Detector (ECD). The limit of detection and quantification for OCPs in the soils ranged from 1.57 to 3.74 ng/g and 4.78 to11.33 ng/g respectively. Spatial distributions of OCPs were evaluated using Arc GIS10.5.1 software. The most frequently found OCPs in the soils of the study area were endrin, β-endosulfan, the isomers of HCH, 4, 4′-DDD, dieldrin and endrin aldehyde. The concentration of ∑OCPs were ranged from 6.35 to 118.29 ng/g. Occurrence of pesticides residues in the soils of CHR is due to both ongoing and past usage. Human health risk assessment parameters like Lifetime average daily dose (LADD), incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) for human adults and children due to individual OCPs were also estimated. Estimated LADD were lower than the reference dose and acceptable daily intake. The estimated human health risks were lower than safe limit of non- cancer risk (HQ ≤ 1.0) and low carcinogenic risks (ILCR below 10–6) in these soils. Finding from the present study provided an overview of the current status of OCPs contamination in the soils for the exposed populations are essentially negligible.

Assessment of the spatial distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in urban soil of China.

Long-term (2004-2018) persistent organic pollutants (POPs) data were collected for urban soils of China. The dataset included concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in soils, comprising a range of different compounds. Understanding the source of OCP and PCB pollution is an important step in controlling and reducing pollution levels in the environment. This study aimed to analyze the spatio-temporal distribution, pollution sources, and potential health risks of OCPs and PCBs in urban soils in different regions of China. It was found that the total OCP concentrations ranged from 7.6 to 37331μg/kg with a mean value of 2861μg/kg, and PCBs concentrations ranged from 0.3 to 123467μg/kg with a mean value of 4984μg/kg. The highest OCP concentrations were observed in Beijing and Hebei, whereas the highest PCB concentrations were found in the Zhejiang province. The geographical distribution showed that the total mean concentration of POPs of urban soil was much higher in East China than in West China. According to the isomer ratios, about 64% of provinces and cities showed new sources of dichlorodiphenyltrichloroethane (DDT) input and dicofol input was found in 30% of China. Hexachlorocyclohexane (HCH) in urban soils was mainly derived from fresh usage of lindane (γ-HCH) in most regions of China. Lifetime carcinogenic and non-carcinogenic risks of OCPs and PCBs through ingestion, inhalation, and dermal contact indicated that PCBs in urban soils of China often exceeded safe levels. The total lifetime carcinogenic risk values of PCBs were higher than the individual lifetime acceptable risk level (10-4) in 64% of the studied regions and the non-carcinogenic risk values exceeded the target risk level (10-1) in 53% of the regions. The improved knowledge of the distribution and main pollution sources of POPs in urban soil of China as a result of this study can contribute to better decision-making support for soil pollution control and monitoring.

The decomposition and ecological risk of DDTs and HCHs in the soil-water system of the Meijiang River

This research project was designed to study the residues of OCPs (organochlorine pesticides) in the sediments of the Meijiang River Basin. Samples from the Meijiang River Basin were analyzed by gas chromatography-mass spectrometry after being pretreated by Soxhlet extraction, and their compositions, distributions and sources were evaluated. The current study presents the distribution of OCPs in the soils and sediments of the Meijiang River Basin. The results demonstrate that OCPs contamination is an important environmental concern due to the excessive use of these compounds in the agricultural and industrial sectors. The ratios of α-HCH/γ-HCH, (DDE + DDD)/∑DDTs, p,p-DDT/o,p-DDT, and DDD/DDE were used as indices for identifying the possible pollution sources and assessing the decomposition of the parent compounds and the recent γ-HCH and DDT inputs. At the XY (Xiyang) and DSGYY (Dongshenggongyeyan) sites, the pollutants had industrial origins. At other sites (QTH (Qutianhu), LXC (Longxichun), ZJC (Zhenjiaochun), HKC (Hekouchun), GS (Guangshan) and RGQ (Raogongqiao)), the pollution was caused by dissolved organic matter. The SHB site was polluted by transportation and upstream pollutants. At the SXC (Shixichun), YZX (Youzhihe), DSH (Dongshihe) and ZGG (Zhegupai) sites, the metabolite was p,p'-DDD and was produced in an environment with anaerobic conditions. At the FJC (Fujiangkou), QTH (Qiutianhu), GS (Guangshang) and MX (Meixi) sites, the metabolite was DDE and was produced under aerobic conditions. In view of the health risks, the risk quotients for these contaminants were evaluated, and all risk quotients were less than 1 under the best-case scenario. This result suggests that the investigated pollutants may pose little hazard to the local ecosystem. The sediments containing toxic pesticides had a less than 55% ecological risk, indicating that the ecological risk of HCHs in the soils from the Meijiang River Basin is low.