Organochlorine pesticides (OCPs) in soils and sediments, southeast China: A case study in Xinghua Bay

Temporal evolution of organochlorine and organophosphate pesticide residues in wells in the Akkar Region (Lebanon)

The Akkar plain is the second largest agricultural area in Lebanon. This region produces huge amount of regular crops such as maize, fruits, and vegetables. In order to protect the crops, farmers use large quantities of many pesticides (including authorized and prohibited molecules) without respecting the recommended doses. In this work, we wanted to study the evolution of OCP and OPP residues at 3-year intervals in water wells in the Akkar region. Twenty OCPs and 8 OPPs were monitored in eight wells in different villages in the plain and mountains of Akkar. Solid phase extraction (SPE) method was used for pesticide extraction, followed by gas chromatography-mass spectrometry (GC-MS) analysis. The results revealed an increasing concentration of OCPs and OPPs in groundwater over the last 3 years (between 2017 and 2019-2020). This increase in contamination is due to the uncontrolled and still unregulated (by the authorities) use of pesticides, and also to the introduction of new crops. The concentrations found in groundwater confirm that some banned pesticides are still widely used. The calculation of the theoretical pesticide intake suggests that pesticide concentrations in Akkar represent a greater health risk for the population consuming well water during the rainy season.

Optimization and validation of ultrasound application with a low-temperature method to analyze organochlorine pesticides in smuggled cigarette tobacco

This work presents the optimization and validation of a method to quantify organochlorine pesticides in tobacco samples from smuggled cigarettes using ultrasound application and low-temperature extraction. The combined approach was validated for 20 organochlorine pesticides, achieving recoveries between 73% and 116%, and a relative standard deviation of less than 20%. The method minimized the matrix effect in 65% of the organochlorine pesticides. The limits of detection and quantification varied from 2 to 60 ng g-1 and 120 to 190 ng g-1, respectively. The method was applied to the analysis of 18 brands of smuggled cigarettes. The organochlorine pesticides found in the samples were cis-chlordane (89%), p,p'-dichlorodiphenyldichloroethylene (DDD) and methoxychlor (78%), endosulfan sulfate (67%), heptachlor epoxide, and endosulfan II (61%). The concentrations of the organochlorine pesticides in this study were higher than those in a similar survey on cigarettes marketed in China. The ultrasound application and low-temperature extraction may be an efficient alternative to analyzing tobacco samples since it uses only one extraction solvent, requires low-cost equipment, does not require an additional clean-up step, reduces the environmental impact through minimal waste generation, and can detect low analyte concentrations.

Behaviors and trophodynamics of o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT) in the aquatic food web: Comparison with p,p'-DDT

The broad-spectrum insecticide p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) has been banned in most countries since the 1970s on account of its environmental persistence as well as the high biomagnification of its major metabolite 1,1-dichloro-2,2-bis(4-chorophenyl)ethylene (p,p'-DDE). However, the information on the bioaccumulation and behavior of p,p'-DDTs in aquatic organisms is lacking. In this study, all 6 DDT isomers were detected in biota from the food web of the Liaodong Bay, China, and the total concentrations of DDT isomers in Chinese anchovy (Thrissa kammalensis) and Japanese Spanish mackerel (Scomberomrus niphonius) were 223 ± 42 ng/g ww and 242 ± 70 ng/g ww, respectively. In biota, o,p'-DDD dominated among the o,p'-isomers (80.5 ± 17.3%), while p,p'-DDE dominated among the p,p'-isomers (61.8 ± 15.2%). Contrastingly, sediment from the Liaodong Bay contained similar proportions of o,p'-DDT and p,p'-DDTs, suggesting an isomer-specific metabolism of the compounds in biota. A well-controlled laboratory exposure experiment with Japanese medaka (Oryzias latipes) demonstrated that o,p'-DDT was more difficult to metabolize to o,p'-DDE compared with that of p,p'-DDT. Significantly positive regressions were found between trophic levels and lipid equivalent concentrations for both o,p'-DDT and o,p'-DDD, and the trophic magnification factors (TMFs) were estimated as 12.3 and 9.12 (p < 0.05), respectively. The TMFs of o,p'-DDT and o,p'-DDD in the aquatic food web were higher than p,p'-DDT (7.76), p,p'-DDD (4.17), and p,p'-DDE (3.39), which may be explained by the isomer-specific metabolism differences in biota.

First report of organochlorine pesticides (OCPs) in coral tissues and the surrounding air-seawater system from the South China Sea: Distribution, source, and environmental fate

The levels, fate, and potential sources of 22 organochlorine pesticides (OCPs) in coral tissues and the surrounding air-seawater system from the South China Sea (SCS) were elucidated for the first time. ∑₂₂OCPs (total concentration of 22 OCPs) (16.1-223 pg L^-1) was relatively higher in coastal seawater than in offshore seawater, which may be the widespread influence of coastal pollution inputs under the western boundary current. The atmospheric ∑₂₂OCPs were predominantly distributed in the gas phase (48.0-2264 pg m^-3) and were mainly influenced by continental air mass origins. The air-seawater exchange of selected OCPs showed that OCPs tended to migrate from the atmosphere to seawater. The distribution of ∑₂₂OCPs in coral tissues (0.02-52.2 ng g^-1 dw) was significantly correlated with that in air samples, suggesting that OCPs may have a migration pattern of atmosphere-ocean corals in the SCS. Corals exhibited higher bioaccumulation ability (Log BAFs: 2.42-7.41) for OCPs. Source analysis showed that the new application of technical Chlordanes (CHLs) was primarily responsible for the current levels of CHLs in the surrounding environment over the SCS, while historical residues were the primary sources of other OCPs.

Efficient adsorption of chlorpyrifos onto modified activated carbon by gamma irradiation; a plausible adsorption mechanism

Commercial Granulated Active Carbon (GAC) has been modified using 10 Gy dose Gamma irradiation (GAC10 Gy) for increasing its ability of air purification. Both, the raw and treated samples were applied for removing Chlorpyrifos pesticide (CPF) from ambient midair. Physicochemical properties of the two materials were characterized by Fourier Transform Infrared (FT-IR) and Raman spectroscopy. The phase formation and microstructure were monitored using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), supported with Energy-Dispersive X-ray (EDX). The Surface area measurement was detected using BET particle size prosometry. Obtained outcomes showed that, the maximum adsorption capacity, given by Langmuir equations, was greatly increased from 172.712 to 272.480 mg/g for GAC and GAC10 Gy, respectively, with high selectivity. The overall removal efficiency of GAC10 Gy was notably comparable to that of the original GAC-sorbent. The present study indicated that, gamma irradiation could be a promising technique for treating GAC and turned it more active in eliminating the pesticides pollutants from surrounding air. The data of equilibrium has been analyzed by Langmuir and Freundlich models, that were considerably better suited for the investigated materials than other models. The process kinetics of CPF adsorbed onto both tested carbon versions were found to obey the pseudo first order at all concentrations with an exception at 70 mg/l using GAC, where, the spontaneous exothermic adsorption of Chlorpyrifos is a strong function for the pseudo-first order (PFO) and pseudo second order (PSO) kinetics.

Sedimentary evolution of PAHs, POPs and ECs: Historical sedimentary deposition and evolution of persistent and emerging organic pollutants in sediments in a typical karstic river basin

Knowledge on the occurrence and distributions of organic compounds, especially PAHs, POPs and ECs, in karstic river basins is limited. This study aims to determine the depositional history and sources of PAHs, PCBs, OCPs, antibiotics, EDCs and phenolic compounds and the ecological risk they have in the Panyang River Basin, an area with a typical karstic landscape and a high-longevity population. Sediment core analysis was adopted, correlation and principal component analyses were conducted to analyze pollution sources, and lead isotope technology was implemented for dating analysis. The sediment core covered 108 years. PCBs were detected with concentrations ranging from 3.80 to 16.18 μg/kg in the core with two concentration peaks in 1950 and 2005 that were related to anthropogenic effects. Eight of the 20 targeted phenolic compounds were detected, with concentrations ranging from 0.42 to 1.10 mg/kg. All PAHs were detected in the cores, with concentrations from 12.91 to 37.80 μg/kg. They were mainly related to natural diagenetic processes and domestic and agricultural sources. The concentrations of different OCP compounds ranged from undetected to 213.43 μg/kg and were mainly related to agricultural activities and long-range transportation. These key findings can assist environmental planning and management in this river basin.

Persistent organic pollutants in sediments of the Wouri Estuary Mangrove, Cameroon: Levels, patterns and ecotoxicological significance

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 - 27.4, and 83 - 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

Pollution characteristics and underlying ecological risks of primary semi-volatile organic compounds (SVOCs) in urban watersheds of Shanghai, China

We investigated the pollution characteristics of ninety semi-volatile organic compounds (SVOCs) in the rivers and lakes of Shanghai. Total concentrations of Σ₉₀SVOCs in water and sediment samples from 30 sites ranged from 1.47 to 19.5 μg/L and 2.38 to 9.48 mg/kg, respectively. PAEs and PAHs were the major contaminant compounds found in all samples. OCPs accounted for less than 3% of the total concentrations of Σ₉₀SVOCs and other SVOCs were either not detected or only detected in trace amounts. Our results indicated that domestic swage, industrial wastewater, petroleum products, and other human activities were the pollutant sources to the water and sediment. It is noteworthy that products that contain the banned chemicals HCH and DDT are still under use within the studied areas. Ecological and health risk assessment results showed that dieldrin and BBP have the potential to cause adverse effects on the environment, while B(a)p and DBP have high carcinogenic risks to humans.

A national-scale characterization of organochlorine pesticides (OCPs) in intertidal sediment of China: Occurrence, fate and influential factors

Organochlorine pesticides (OCPs) have been restricted for application for about 30 years in China. Intertidal zone is a sink for anthropogenic pollutants, and to better understand the current pollution status of OCPs in China, 324 surface sediment samples collected from 14 typical intertidal zones of China were analyzed for 22 OCPs. The total concentrations of OCPs ranged from 0.051 to 4141.711 ng/g, with DDTs and HCHs being the dominant components. Seasonal variations were not significant for most intertidal zones (p > 0.05), while significant spatial variations (p < 0.05) were found among 14 intertidal zones, with the highest OCPs concentrations detected in Jiulong Jiang (JLJ). The OCPs concentrations in intertidal sediments would rarely to frequently cause adverse biological effects and DDTs were the major threat. Apart from the historical usage of technical DDT and lindane, current usage of technical DDT and HCH were also implied, especially for intertidal zones such as Beidaihe (BDH) and Yingluo Wan (YLW). PCA analysis indicated that compounds within the same type of OCPs were from similar source, while different types of OCPs were generally from different sources and not used together. Our results further indicated that OCPs together with organic particles entered into the intertidal zones mainly through river input.

Levels and distribution of polybrominated diphenyl ethers in humans and environmental compartments: a comprehensive review of the last five years of research

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs), present in the environment, animals, and humans. Their levels, distribution, and human exposure have been studied extensively, and over the last decade, various legal measures have been taken to prohibit or minimize their production and use due to the increasing amount of evidence of their harmful effects on human and animal health.Our aim here was to make a comprehensive and up-to-date review of the levels and distribution of PBDEs in the aquatic environment, air, and soil, in indoor dust, and in humans. To fulfill this, we searched through Web of Science for literature data reported in the last five years (2015-2019) on levels of at least six key PBDE congeners in abovementioned matrices. According to our summarized data, significant PBDE mass concentrations/fractions are still being detected in various sample types across the world, which implies that PBDE contamination is an ongoing problem. Secondary sources of PBDEs like contaminated soils and landfills, especially those with electronic and electrical waste (e-waste), represent a particular risk to the future and therefore require a special attention of scientists.

Characterization, source identification and risk associated with polyaromatic and chlorinated organic contaminants (PAHs, PCBs, PCBzs and OCPs) in the surface sediments of Hooghly estuary, India

The spatial distribution, source identification and ecotoxicological impact of a group of persistent organic pollutants (POPs: dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexanes (HCHs), polychlorobiphenyls (PCBs), polychlorobenzenes (PCBzs)), and polyaromatic hydrocarbons (PAHs) were investigated in surface sediment samples (0-5 cm, <63 μm grain size) along the ecologically stressed Hooghly River estuary, East India. The results demonstrated a wide range of concentrations (ng/g dry weight) with the following decreasing order: ∑₁₆PAHs (3.3-630) > ∑₆DDTs (0.14-18.6) > ∑₇PCBs (0.28-7.7) > ∑₂PCBzs (0.01-1.3) > ∑₅HCH (0.10-0.6), with a dominance of p,p'-DDT and higher molecular weight PAHs. Selected diagnostic ratios indicated a mixture of both pyrolytic and petrogenic sources of PAHs, inputs of weathered DDT and their degradation in oxidizing environment, and a predominance of industrial input over the agricultural wastes. The cumulative impact of the pollutants (effective range medium quotient (ERMq): 0.01-0.16) reflected minimal to low ecotoxicological risk, with highest probability of toxic effects towards surrounding biota at Barrackpore (21%). ∑₆DDTs exceeded the effect range low value resulting occasional adverse impact to the sediment dwelling organisms. Among the PAHs, the 4-ringed compounds accounted for 68% of the PAHs. Further, carcinogenic PAHs (BaA, Chry, BbF, BkF, BaP, DahP, Inp) possessed highest cancer risk (CR = 2.09 × 10^-3) to the local population when exposed to the sediments from the studied area and ingestion was found to be the primary process of contamination. The study strongly recommends a systematic monitoring of POPs and PAHs, being the Hooghly River water used by local people for their livelihood.

Pollution levels of banned and non-banned pesticides in surface sediments from the East China Sea

In this paper, 65 pesticides, including banned ones of DDTs, etc. and non-banned ones of iprobenfos, etc. have been detected in 31 surface sediment samples from the East China Sea (ECS) to study their pollution levels, sources, and risks. There were 8 banned pesticides (90-97%) and 10 non-banned pesticides (26-100%) presenting higher detection frequencies. For the 18 pesticides detected, their total contents ranged from 183.49 to 1363.77 ng/g dry weight (d.w.) and presented a seaward decreasing trend. Higher contents of banned pesticides were concentrated in the inner shelf close to Zhoushan Island. Iprobenfos, one of non-banned pesticides, showed the highest detection frequency (100%) and pollution level (79.14-1169.18 ng/g d.w.), indicating its continuous input in recent years. The pesticides concentrations in water calculated by the equilibrium partitioning (EqP) method were lower than the toxicological endpoint for tested aquatic invertebrates and fish, indicating ecological risks of these pesticides were at low levels.

Determination of Occurrences, Distribution, Health Impacts of Organochlorine Pesticides in Soils of Central China

Organochlorine pesticides are groups of chemicals applied to prevent pest and insect infestation. This study was aimed at investigating the concentration, potential sources, cancer risk and ecological toxicity of organochlorine pesticides (OCPs) in Huangpi district, Wuhan, China. Eight OCPs in soil samples collected from four land-use types at depths of 0–10 and 10–20 cm were examined. Sample extraction was carried out by solid phase matrix extraction method and analyzed using Agilent gas chromatograph 7890B equipped with electron capture detectors (ECD). The total concentration of OCPs ranged from 0.00–32.7 ng g⁻¹ in the surface and 0.01–100.45 ng g⁻¹ in the subsurface soil layer. Beta hexachlorocyclohexanes (β-HCH) with 2.20 and 7.71 ng g⁻¹ in the surface and subsurface soil layers, respectively, was the dominant compound. The mean concentrations of OCPs in all samples were less than the threshold values for hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in China soil. Concentration of OCPs in the four land-use types were in the order of: paddy field > barren land > farmland > plastic greenhouse. Results of composition analysis revealed recent application of lindane as a major and historical use of new technical HCHs as a minor source of HCHs. On the other hand, application of new technical p,p’-DDT is the main source of DDTs in the study area. The estimated lifetime average daily dose, incremental lifetime cancer risks and hazard quotient values revealed that there is less likelihood of carcinogenic and noncarcinogenic health risks on the local residents.

Sources and transformation pathways for dichlorodiphenyltrichloroethane (DDT) and metabolites in soils from Northwest Fujian, China

Dicofol (2,2,2-trichloro-1,1-bis-(p-chlorophenyl)ethanol) found in the environment is not only a miticide originated from commercial use, but also a metabolite of dichlorodiphenyltrichloroethane (DDT), which is often overlooked. To verify the sources and transformation pathways of DDT and related metabolites in soils, we measured p,p'-(dicofol + DBP) (sum of p,p'-dicofol and 4,4'-dichlorobenzophenone), DDT and six metabolites in soils from Northwest Fujian, China. The ratios of 1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane (o,p'-DDT)/1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDT) and the mass balance demonstrated that p,p'-(dicofol + DBP) predominantly originated from p,p'-DDT transformation rather than from actual dicofol application. p,p'-(dicofol + DBP) accounted for 45.0% as the primary metabolites of DDT in this study, more than 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDE) and 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDD), which might lead to large overestimations of the fresh DDT input by using the traditional ratio of (∑₂DDD + ∑₂DDE)/∑₂DDT (with all o,p'- and p,p'- isomers included). In paddy fields where the conditions alternate between aerobic (dry period) and anaerobic (wet period), both p,p'-DDD and p,p'-DDE were likely to degrade to 1-chloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDMU), which further transformed to 2,2-bis(p-chlorophenyl)ethylene (p,p'-DDNU). Degradation of p,p'-DDMU to p,p'-DDNU mainly occurred in waterlogged paddy soils. However, p,p'-DDNU might not transform to other higher-order metabolites in aerobic surface soils. Overall, our study confirmed p,p'-(dicofol + DBP) as metabolites of p,p'-DDT, suggested DDE and DDD were parallel precursors of DDMU, and further verified the transformation pathways of DDT in surface soils.

Organic contamination and remediation in the agricultural soils of China: A critical review

Soil pollution is a global problem in both developed and developing countries. Countries with rapidly developing economies such as China are faced with significant soil pollution problems due to accelerated industrialization and urbanization over the last decades. This paper provides an overview of published scientific data on soil pollution across China with particular focus on organic contamination in agricultural soils. Based on the related peer-reviewed papers published since 2000 (n=203), we evaluated the priority organic contaminants across China, revealed their spatial and temporal distributions at the national scale, identified their possible sources and fates in soil, assessed their potential environmental risks, and presented the challenges in current remediation technologies regarding the combined organic pollution of agricultural soils. The primary pollutants in Northeast China were polycyclic aromatic hydrocarbons (PAHs) due to intensive fossil fuel combustion. The concentrations of organochlorine pesticides (OCPs) and phthalic acid esters (PAEs) were higher in North and Central China owing to concentrated agricultural activities. The levels of polychlorinated biphenyls (PCBs) were higher in East and South China primarily because of past industrial operations and improper electronic waste processing. The co-existence of organic contaminants was severe in the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei Region, which are the most populated and industrialized regions in China. Integrated biological-chemical remediation technologies, such as surfactant-enhanced bioremediation, have potential uses in the remediation of soil contaminated by multiple contaminants. This critical review highlighted several future research directions including combined pollution, interfacial interactions, food safety, bioavailability, ecological effects, and integrated remediation methods for combined organic pollution in soil.

Pollution levels of DDTs and their spatiotemporal trend from sediment records in the Southern Yellow Sea, China

In order to study the pollution levels and spatiotemporal trend of Dichlorodiphenyltrichloroethanes (DDTs) in the Southern Yellow Sea (SYS), thirty-two surface sediment samples and a sediment core have been analyzed, and our results have been compared with previous reports. DDTs contents in our samples ranged from below detection limit to 5.1ng/gdry weight (d.w.), which presented lower ecological risks in the SYS. Surface sediment results show a seaward increasing trend with high values in the northern region of the central basin of the SYS. Our reconstructed core record and historical data from previous reports reveal an increasing trend from 1905 to 1955 but a decline trend since 1985 for DDTs, which is consistent of the production, usage and banning of DDTs in China. The source identification, based on (DDE+DDD)/DDTs, suggested that aged DDTs were the major contributor, though there were some inputs of fresh DDTs from the usage of 1,1-bis(p-Chlorophenyl)-2,2,2-trichloroethanol (dicofol).

Depth-distribution, possible sources, and toxic risk assessment of organochlorine pesticides (OCPs) in different river sediment cores affected by urbanization and reclamation in a Chinese delta

Sediment cores were collected in urban (0-50 cm), rural (0-40 cm) and reclamation-affected river (0-40 cm) environments in the Pearl River Delta. Concentrations of 16 organochlorine pesticides (OCPs) were determined in all collected samples to identify the depth-distribution, possible sources and ecotoxicological risks of OCPs in river sediments affected by urbanization and reclamation in a Chinese delta. The results showed that the top 10 cm of rural river sediments had slightly lower concentrations of the 16 OCPs compared to urban and reclamation-affected rivers, whereas the 30-40 cm sediment layers in the rural river showed higher levels of the 16 OCPs. However, higher OCPs levels were observed in the 20-30 cm sediment layers in the urban river than in the rural and reclamation-affected rivers. The principal OCPs in most deeper sediment layers were hexachlorobezene (HCB), the combination of aldrin, endrin and dieldrin (ΣDRINs) and the combination of α-HCH, β-HCH and γ-HCH (ΣHCHs). The predominant OCPs in surface sediments were HCB, ΣDRINs and the combination of p,p'-DDD, o,p'-DDT, p,p'-DDT and p,p'-DDE (ΣDDTs). Generally, OCP concentrations decreased with depth along sediment profiles at most sampling sites in the three types of rivers. The source analyses indicated that some sampling sites were still suffering from the recent use of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and aldrin. According to the soil quality thresholds of China, the levels of HCHs and DDTs at most sampling sites were below class Ⅰ criteria. Based on the sediment quality guideline quotient (SQGQ), the combined ecotoxicological risk of OCPs (γ-HCH, dieldrin, p,p'-DDD, p,p'-DDE and p,p'-DDT) in surface sediments (0-10 cm) was higher than deeper sediments, and the rural river sediments exhibited a higher combined ecotoxicological risk than the sediments in urban and reclamation-affected rivers.

Evaluation of Bayesian approaches to identify DDT source contributions to soils in Southeast China

Dicofol application may be an important source to elevate the dichlorodiphenyltrichloroethane (DDT) residues to soils in Fujian, Southeast China, after the technical DDT was banned, which left DDT residues from the historical application. The DDT residues varied geographically, corresponding to the varied potential sources of DDT. In this study, a novel approach based on the Bayesian method (BM) was developed to identify the source contributions of DDT to soils, composed with both historical DDT and dicofol. The Naive Bayesian classifier was used basing on the subset of the samples, which were determined by chemical analysis independent of the Bayesian approach. The results show that BM (95%) was higher than that using the ratio of o, p'-/p, p'-DDT (84%) to identify DDT source contributions. High detection rate (97%) of dicofol (p, p'-OH-DDT) was observed in the subset, showing dicofol application influenced the DDX levels in soils in Fujian. However, the contribution from historical technical DDT source was greater than that from dicofol in Fujian, indicating historical technical DDT was still an important pollution source to soils. In addition, both the DDX (DDT isomers and derivatives) level and dicofol contribution in non-agricultural soils were higher than other agricultural land uses, especially in hilly regions, the potential cause may be the atmospheric transport of dicofol type DDT, after spraying during daytime, or regional difference on production and application.

Historical records and sources of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in sediment from a representative plateau lake, China

The PAH and OCP concentrations in sediment cores collected from a deep lake were measured and evaluated chronologically. The results indicated that the PAH and OCP concentrations significantly increased from the 1950s to the 1990s and subsequently decreased to recent years. Integrated molecular diagnostic ratios indicated that the predominant petrogenic sources occurred from the 1950s-1980s. Petroleum and fuel combustion dominated the source of contamination more recently as a result of energy structure changes in this region. Additionally, HCHs and DDTs were the dominant OCP compounds, making up a majority of the total OCPs present (>85%). HCHs accounted for a larger ratio of the OCPs between the 1950s and 1980s, suggesting that HCHs were the dominant POPs in this period. DDTs then became dominant in the 1980s and later. High α/γ-HCH ratios suggested that the emission and conversion of local technical HCHs were the predominant HCHs source. The ratios of (DDE + p,p'-DDD)/DDTs and p,p'-DDT/DDTs indicated that the DDTs mainly originated from historical input. In addition, the dramatic decrease since the 1980s may be the result of China's banning of DDTs. However, DDTs were still present in the 1990s, suggesting DDTs were still used in this region and beyond.

Over 100-year sedimentary record of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) in the continental shelf of the East China Sea

Historical records of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were analyzed in two dated sediment cores (DH05 and DH11) collected from the continental shelf of the East China Sea (ECS) to investigate the influence of anthropogenic activities on marine sediment over the past century. The concentrations and fluxes of 15 PAHs were in the range of 28.6-96.5 ng g^-1 and 7.6-35.2 ng cm^-2 yr^-1 in DH05 (1920s-2009), 18.8-76.4 ng g^-1 and 13.9-30.9 ng cm^-2 yr^-1 in DH11 (1860s-2009). The sedimentary records of PAHs in the two cores generally reflected the economic development and energy consumption change in China. Identification of sources suggested that PAHs in ECS were predominantly from petrogenic origin and various combustion sources. A change of source from low- and moderate-temperature combustion to high-temperature combustion process was observed. Although a production ban of technical HCH and DDT was imposed in China in 1983, their sedimentary fluxes display increasing trends or strong rebounds from 1980s to 1990s as recorded in the core profiles. High proportions of DDD + DDE and γ-HCH suggested those OCPs mainly derived from early residuals. Temporal trends of PCBs presented relative high levels from 1970s to 1980s and high proportions of PCB congeners with 3-6 chlorines atoms indicated industrial sources.

Characteristics of residual organochlorine pesticides in soils under different land-use types on a coastal plain of the Yellow River Delta

The residual levels of organochlorine pesticides (OCPs) were examined in soils covering five types of land use along a salinity gradient on the Yellow River Delta. The most prominent OCPs were dichlorodiphenyltrichloroethane (∑DDT, arithmetic mean = 5.11 μg kg(-1)), hexachlorocyclohexane (∑HCH, 1.69 μg kg(-1)) and ∑endosulfan (10.4 μg kg(-1)). The spatial variability of OCPs composition shifted from γ-HCH and o,p'-DDT dominated pesticides in coastal soils to p,p'-DDE dominated pesticides in inland soils. In different land-use types, the percentages of β-HCH and p,p'-DDE are characterized by more recalcitrant components in decreasing order of vegetable fields, cereal fields, cotton fields, wetlands and tidal flats with increasing soil salinity. However, the less recalcitrant components, γ-HCH and o,p'-DDT, showed an opposite trend. Endosulfan sulfate predominated in all land-use types. Residual levels of β-HCH were affected by soil organic matter. The correlations between γ-HCH and clay content and between p,p'-DDE, o,p'-DDT and salinity might associate with the influence of sediment cotransport by the Yellow River and the density of anthropogenic activities in coastal region. Depth distribution of the OCPs in typical soil profiles also implied that local historical usage and sediment transport by the Yellow River both affected the OCPs residual in this region.

The legacy of organochlorine pesticide usage in a tropical semi-arid region (Jaguaribe River, Ceará, Brazil): Implications of the influence of sediment parameters on occurrence, distribution and fate

Between the 1940s and 1990s, immeasurable amounts of organochlorine pesticides (OCPs) were used in endemic disease control campaigns and agriculture in the tropical semi-arid regions of Brazil. The present study evaluated the legacy of banned OCP usage, considering the levels, ecological risk and dependence on sediment physicochemical properties for the fate and distribution in the Jaguaribe River. The sum concentration of OCPs (ΣOCPs) ranged from 5.09 to 154.43 ng·g(-1), comparable to the levels found in other tropical and subtropical regions that have traditionally used OCPs. The environmental and geographical distribution pattern of p,p-DDT, p,p-DDD and p,p-DDE shows that the estuarine zone contained more than 3.5 times the levels observed in the fluvial region, indicating that the estuary of the Jaguaribe River is a sink. The temporal pattern indicates application of dichloro-diphenyl-trichloroethanes (DDTs) in the past; however, there is evidence of recent input of these pesticides. High ecological risk was observed for levels of γ-hexachlorocyclohexanes (γ-HCH) and heptachlor, and moderate ecological risk was observed for levels of DDTs in sediments from the Jaguaribe River. The heptachlor, γ-HCH and hexachlorobenzene (HCB) concentrations depend on the organic and inorganic fractions of sediment from the Jaguaribe River, whereas the p,p-DDE, p,p-DDD, p,p-DDT and α-endosulfan concentrations depend solely on the organic fraction of the sediment.

Distribution and risk assessment of suspected endocrine-disrupting pesticides in creek water of Mumbai, India

The present study deals with the investigation of existing pollution levels and potential ecological risk assessment of endocrine-disrupting organochlorine and organophosphorous pesticide residues in the Vasai Creek water near Mumbai. The average concentration of α- and β-endosulfan (137.75 ng·L(-1)) exceeds the chronic criteria level of α- and β-endosulfan (6.5 ng·L(-1)) set by US EPA for freshwater aquatic organisms. The concentration levels of aldrin (75.31 ng·L(-1)), dieldrin (71.19 ng·L(-1)) and endrin (76.60 ng·L(-1)) was found to exceed the respective criteria levels of <0.13, 65.1, and 61 ng·L(-1) as set by US EPA for protection of freshwater aquatic organisms. In addition, the level of chlorpyrifos (208.77 ng·L(-1)) exceeds the recommended concentration value of <35 ng·L(-1) set by Ministry of Environment of British Colombia. The results of our study give an indication of probable ecotoxicological risk to the marine breeding organisms of creek.

Influence of feeding and earthworm density on compound bioaccumulation in earthworms Eisenia andrei

Earthworm density and feeding during exposure to contaminated soil have been used inconsistently in bioaccumulation studies, which may lead to possible errors in risk assessment and modeling. Hydrophobic organic pollutants with a wide range of environmental properties (phenanthrene, pyrene, lindane, p,p'-DDT, and PCB 153) were used to study the effect of different earthworm densities in combination with the presence or absence of feeding on bioaccumulation factors (BAFs). Similar BAFs were found at various soil-to-worm ratios, with the exception of phenanthrene. We recommend using at least 15 gsoil dw per earthworm. The absence of feeding doubled the BAFs and, thus, using no food ration can be considered as "the worst case scenario". Whenever food is to be applied (i.e. to ensure the validity of the test in earthworm mass loss), we suggest feeding depending on the organic carbon content of the studied soil.

Persistent organic pesticide residues in sediments of Vasai Creek near Mumbai: Assessment of sources and potential ecological risk

Thirteen persistent organic pesticides were investigated in the sediments of Vasai Creek near Mumbai to evaluate their pollution levels and potential risks. It was observed that ΣOCPs level was in the range of 597-1538ng/g dw, with an average value of 1115.25ng/g dw. The level of ΣOPPs was in the range of 492-1034ng/g dw, with an average value of 798.15ng/g dw. The values o,p'-DDT/p,p'-DDT ratio gives an indication of use of technical DDT as the prime source of DDT, while the α/γ-BHC ratio indicate that BHCs in study area might have been received from fresh lindane. The results of an ecological risk assessment showed that sediment bound organic pesticides are of more ecotoxicological concern as they might create adverse ecological risk to the marine breeding habitats. These pesticides residues may get remobilize and released to overlying waters creating adverse effects on terrestrial and aquatic organisms.

Residues, Sources and Potential Biological Risk of Organochlorine Pesticides in Surface Sediments of Qiandao Lake, China

Sediment samples were analyzed to comprehensively characterize the concentrations, distribution, possible sources and potential biological risk of organochlorine pesticides in Qiandao Lake, China. Concentrations of sumHCH and sumDDT in sediments ranged from 0.03 to 5.75 ng/g dry weight and not detected to 14.39 ng/g dry weight. The predominant β-HCH and the α-HCH/γ-HCH ratios indicated that the residues of HCHs were derived not only from historical technical HCH use but also from additional usage of lindane. Ratios of o,p'-DDT/p,p'-DDT and DDD/DDE suggested that both dicofol-type DDT and technical DDT applications may be present in most study areas. Additionally, based on two sediment quality guidelines, γ-HCH, o,p'-DDT and p,p'-DDT could be the main organochlorine pesticides species of ecotoxicological concern in Qiandao Lake.

Farmer and retailer knowledge and awareness of the risks from pesticide use: a case study in the Wei River catchment, China

Monitoring the educational level of farmers and retailers on pesticide use would be useful to assess the appropriateness of information for reducing or/and avoiding the risks from pesticides in rural regions. The levels of knowledge and awareness of the dangers to the environment and human health were investigated by questionnaires for farmers (209) and retailers (20) in two rural regions (Qianyang County (S1) and Chencang County (S2)) of the Wei River catchment in China where the modes of farming and the state of erosion are very different. The results showed that farmers learned the use and dangers of pesticides mainly by oral communication (p<0.01). Protective measures were inadequate; 65% (S1) and 55% (S2) of farmers never used any protective measures during spraying (p<0.05). Washing hands (>70%) was the most common mode of personal hygiene, relative to wearing masks, showering, and changing clothes, but no significant differences were observed between the selected regions. Most pesticide wastes were dumped directly onto the land or into water, suggesting that educational measures should be taken to address the potential risks from the residues in the wastes. Over 85% of farmers (S1 and S2) claimed to use illegal pesticides, but the reasons for their use varied (p<0.01). Retailers were well-informed and highly conscious of their responsibility for the safe use of pesticides, especially in S2 (p<0.01). A canonical correspondence analysis indicated that educational level and age differed between the two regions and contributed greatly to the risks from pesticide use (p<0.01). Educational programmes targeted to age groups, proper disposal of pesticide waste, and sufficient supervision from authorities should consequently be considered for improving the levels of knowledge and awareness of the dangers of pesticides to human health and environmental pollution in the Wei River catchment, China.

Occurrence and possible sources of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) along the Chao River, China

To analyze the possible influence of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) on Miyun Reservoir, 14 soil samples and 1 water sample were collected along the Chao River, which is the main upstream source of the reservoir. A total of 24 kinds of OCPs and 12 kinds of dioxin-like PCBs were measured. Results showed that the ∑OCPs concentration ranged from 0.8145 to 16.8524 ng g(-1), and the ∑PCBs ranged from 0.0039 to 0.0365 ng g(-1). Dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were the three dominant kinds of OCPs in this region, and the majority component of the PCBs was PCB-118 in both water and soil samples. The OCP ratios suggest that new inputs of lindane exist. DDTs mainly come from old technical inputs. HCHs might come from a new application of lindane, which highlights the importance of prohibited pesticide control. OCP concentrations were higher in corn fields and orchards and lower in forest lands and grasslands, which indicated that OCPs were very much influenced by human activities. The proportion of PCB components in this study area suggested that they mainly came from atmospheric deposition.

Organo-halogenated contaminants (OHCs) in the sediments from the Soan River, Pakistan: OHCs(adsorbed TOC) burial flux, status and risk assessment

In this study, regression analysis revealed that TOC is the principal factor in controlling the fate of organo-halogenated contaminants (OHCs: PCBs, PBDEs, OCPs) in Soan River, Pakistan. The OHCs(adsorbed TOC) burial flux (OHCs(adsorbed TOC)Bf; mg/cm(2)·yr) was calculated in the following ranges: ∑PCBs (0.07-0.31), ∑PBDEs (0.005-0.029), ∑HCHs (0.015-0.046) and ∑DDTs (0.007-0.039). Apart from OHCs(adsorbed TOC)Bf, the levels of OHCs were in the following order: PCBs>DDTs>PBDEs>HCH>Chlordane>HCB. PBDEs and PCB congener patterns showed following order respectively: BDE-149>-153>-18>-138>-44 and PCB-149>-153>-18>-138>-44. DDT isomers and metabolites' pattern were p,p'-DDT>p,p'-DDD>p,p'-DDE>o,p'-DDT>o,p'-DDD>o,p'-DDE and HCHs were β-HCH>α-HCH>γ-HCH>δ-HCH. PBDE composition had similarities to penta-BDE and DE-71 mixtures and PCBs with commercial products Aroclor-1254 and -1260. (DDE+DDD)/∑DDTs and p,p'-DDT/p,p'-DDE suggested the recent input of DDTs in sediments while α/γ-HCH indicated past usage of lindane and technical mixtures. Risk assessment suggested that Soan River and its tributaries are potentially at risk against most of the OHCs.

Assessing spatial distribution, sources, and human health risk of organochlorine pesticide residues in the soils of arid and semiarid areas of northwest China

Thirty-two topsoil samples were collected to analyze the residue levels of organochlorine pesticides (OCPs) in topsoil of arid and semiarid areas of northwest China in 2011. Results showed that DDTs were the dominant contaminants with a mean concentration of 12.52 ng/g. The spatial distribution characteristics indicated that α-hexachlorocyclohexanes (HCHs) were mainly used in rural sites, whereas hexachlorobenzene (HCB) and endosulfan were detected mostly in urban areas. DDTs, heptachlor, and chlordane were found almost equally in both urban and rural areas. Source identification revealed that the current levels of HCHs in soils were attributable to the residues from their historical use and fresh usage of lindane (γ-HCH). DDTs were mainly from historical use and fresh usage of dicofol, and HCB was emitted from the chemical industry. It was also found that the current soil levels of heptachlor were mainly from its historical usage, endosulfan from fresh input, and chlordane from long-range atmospheric transport, respectively. The noncarcinogenic health risk assessment with a model was also conducted using USEPA standards for adults and children. Results indicated that health risk under nondietary exposure to OCPs decreased in the sequence of ΣDDT > ΣHCH > HCB > Σheptachlor > Σendosulfan > Σchlordane. According to the reference dose from the USEPA, the health risk under nondietary exposure to OCPs in the soil samples was at a relatively safe level.

Analysis of HCHs and DDTs in a sediment core from the Old Yellow River Estuary, China

The present study analyzed the distribution of HCHs and DDTs in a sediment core from the Old Yellow River Estuary, China. The OCP levels were detected by Soxhlet extraction followed by gas chromatography (GC) using a mass-selective detector. Sediment age was analyzed for (210)Pb using an Ortec GWL HPGe gamma spectrometer. The results indicated that the concentrations of ∑DDT in the sediment core were much lower than those of ∑HCH. Compared with the other estuarine and coastal regions in Chinese rivers, HCHs levels in this area were higher or similar, while DDTs levels were lower. The compositional analysis indicated that β-HCH and p, p'-DDD were the predominant species. The temporal trends indicated that levels of HCHs and DDTs were related with their historical usage, emission and soil residues. According to the analysis of the ratio, HCHs in this area was mainly due to the technical historical residue and recent lindane. DDTs was mainly due to historical residue. The biodegradation conditions for DDTs were anaerobic. The dicofol-type DDTs application occurred in this area.

Solid phase microextraction of organic pollutants from natural and artificial soils and comparison with bioaccumulation in earthworms

The presented study investigates the use of passive sampling, i.e. solid phase microextraction with polydimethylsiloxane fibers (PDMS-SPME), to assess the bioavailability of fiver neutral organic chemicals (phenanthrene, pyrene, lindane, p,p'-DDT, and PCB 153) spiked to natural and artificial soils after different aging times. Contaminant bioavailability was assessed by comparing PDMS concentrations with results from a 10 day bioaccumulation test with earthworms (Eisenia fetida). The hypotheses tested were (i) organic carbon (OC) normalization, which is commonly used to account for sorption and bioavailability of hydrophobic organic chemicals in soil risk assessment, has limitations due to differences in sorptive properties of OC and aging processes (i.e. sequestration and biodegradation) and (ii) PDMS-SPME provides a more reliable measure of soil contaminant bioavailability than OC normalized soil concentrations. The above stated hypotheses were confirmed since the results showed that: (i) the PDMS/soil organic carbon partition ratio (R) accounting for the role that OC plays in partitioning significantly differed between soils and aging times and (ii) the correlation with earthworm concentrations was better using porewater concentrations derived from PDMS concentrations than when organic normalized soil concentrations were used. Capsule: Sorption of organic compounds measured by SPME method and their bioavailability to earthworms cannot be reliably predicted using OC content.

Historical records of organic pollutants in sediment cores

Analyses of sediment core samples are primary sources of historical pollution trends in aquatic systems. Determining organic compounds, such as POPs, in the dated sediments enables the estimation of their temporal concentration changes and the identification of the contaminant origin in local regions. Wars, large-scale fires, economical transitions, and bans on certain chemicals are reflected in the sediment organic compound concentrations. The high POP concentrations in surficial sediments suggest that these chemicals, even after being banned, remain in the environment. Furthermore, vertical profiles can help in understanding the sedimentation process and in estimating effective countermeasures against pollution. Moreover, studies published during the period 1991-2013 on PAHs, PCBs, OCPs, dioxins and dioxin-like compound concentrations in sediment core samples are reviewed.

Residues and enantiomeric profiling of organochlorine pesticides in sediments from Xinghua Bay, southern East China Sea

The spatial distribution and chiral signatures of organochlorine pesticides (OCPs) in the surface sediments of Xinghua Bay, southern East China Sea, were investigated. The total OCP concentrations ranged from 9.15 to 40.5 ng/g dry weight, with a predominance of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs). The isomer ratios of α-HCH/γ-HCH (less than 1.0) and the predominant β-HCH implied that HCH residues were derived not only from historical technical HCH use but also from the additional use of lindane in this area. The isomer ratios of p,p'-DDT/(p,p'-DDD + p,p'-DDE) and o,p'-DDT/p,p''-DDT, and a strong correlation (R = 0.83, P < 0.001) between p,p'-DDE and o,p'-DDT depicted a cocktail input pattern of dicofol-type DDT and technical DDT. Moreover, the fact that only cis-chlordane was detectable for all sampling stations suggested the past application of technical chlordane. Based on the sediment quality guidelines (SQG), γ-HCH is the main OCP species of ecotoxicological concern in Xinghua Bay. Enantiomeric analysis showed that the (+)-enantiomers of α-HCH and o,p'-DDT were more prevalent than the (-)-enantiomers in most samples, whereas both racemic and nonracemic residues existed for o,p'-DDD. These results implied that the SQG of chiral OCPs should be reassessed using concentrations of their individual enantiomers.

Sixty-year sedimentary record of DDTs, HCHs, CHLs and endosulfan from emerging development gulfs: a case study in the Beibu Gulf, South China Sea

The temporal distribution of organochlorine pesticides (OCPs) was examined in the (210)Pb dated sediment core from the Beibu Gulf, South China Sea. The total OCPs concentrations were in the range of 0.93-26.6 ng g(-1) dry weight. Dichlorodiphenyltrichloroethanes (DDTs) (0.17-24.8 ng g(-1)), Hexachlorocyclohexanes (HCHs) (0.04-0.51 ng g(-1)), Chlordane related compounds (CHLs) (0.22-1.72 ng g(-1)) and endosulfan (n.d.-0.91 ng g(-1)) were the predominant compounds. Similar to most Chinese coastal areas, the levels of DDTs in the Beibu Gulf became elevated since the early 1990s, especially since 2000 despite the ban in 1983 in China. This suggests that the concentrations of DDTs were controlled by several processes, such as land reclamation and soil runoff. The isomer ratios of (p,p'-DDE + p,p'-DDD)/p,p'-DDT, p,p'-DDT/DDTs along with construction land expansion indicated that economic activities, land reclamation, soil runoff and the use of DDT-containing antifouling paints might be responsible for the input of DDT. The ratios of α-HCH/γ-HCH (and γ-HCH/HCHs) and trans-chlordane/cis-chlordane (TC/CC) indicated fresh inputs of lindane and chlordane, respectively. In addition, CC was found to be degraded faster than TC under anaerobic conditions in sediments from the Beibu Gulf.

Chlorinated pesticides in stream sediments from organic, integrated and conventional farms

To determine if current sheep/beef farming practices affect pesticide residues in streams, current-use and legacy chlorinated pesticides were quantified in 100 sediment samples from 15 streams on the South Island of New Zealand. The study involved five blocks of three neighboring farms, with each block containing farms managed by organic, integrated and conventional farming practices. Significantly higher concentrations of dieldrin, ∑ endosulfans, ∑ current-use pesticides, and ∑ chlorinated pesticides were measured in sediments from conventional farms compared to organic and integrated farms. However, streams in the latter two farming categories were not pesticide-free and sometimes contained relatively high concentrations of legacy pesticides. Comparison of measured pesticide concentrations with sediment quality guidelines showed that, regardless of farming practice, mean pesticide concentrations were below the recommended toxicity thresholds. However, up to 23% of individual samples contained chlorpyrifos, endosulfan sulfate, ∑ DDT, dieldrin, or ∑ chlordane concentrations above these thresholds.

Contamination profile of DDT and HCH in surface sediments and their spatial distribution from North-East India

Contamination status and spatial distribution of DDTs and HCHs were investigated in sediments collected from ponds and riverine system from districts Nagaon and Dibrugarh, North East India. A total of 113 surface sediment samples were collected from both the districts including 43 from ponds/wetlands and 70 from rivers/streams. Based on dry weight (dw), the mean concentration of ∑HCH and ∑DDT in sediments were found to be 287 ng/g (71.2-834 ng/g) and 321 ng/g (30.1-918 ng/g) for district Dibrugarh while 330 ng/g (39.2-743 ng/g) and 378 ng/g (72.5-932 ng/g) for district Nagaon, respectively. DDTs and HCHs in sediments were well influenced by total organic carbon, clay and silt content of sediments. Source identification revealed that sediment residue levels have originated from long and recent mixed source of technical HCH and Lindane for HCHs and mainly technical DDT for DDTs. Majority of samples exceeded the sediment quality guidelines (SQG) for γ-HCH, p,p'-DDT and ∑DDT indicating potential environmental risk. This baseline data can be used as reference for regular ecological and future POPs monitoring program.

Historical contamination and ecological risk of organochlorine pesticides in sediment core in northeastern Chinese river

Twenty-eight surface sediment samples and one sediment core were analyzed for 21 organochlorine pesticides (OCPs), in order to provide extensive information of distribution, sources, pollution history and ecological risk of these OCP compounds in Daling River area, China. The results showed that hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were the most frequently detected contaminants in the surface sediment samples with concentrations (in ngg(-1) dry weight (dw)) from 1.1 to 30 and from 2.2 to 45, respectively. Analysis of variance showed significant (P<0.05) differences between HCHs and DDTs residues in surface sediment sampled from the various locations. Residues of HCHs and DDTs in sediment core (in ngg(-1)dw) ranged from 2.1 to 18 and 9.1 to 53, respectively. The temporal trends of HCHs and DDTs concentrations in the sediment core were affected by application history, emission and soil residues. Compositional analysis of HCHs and DDTs indicated that new sources were lindane and dicofol mainly due to agricultural activities. Additionally, based on the available sediment quality guidelines, slight potential health risks of DDTs may exist to benthic organisms in Daling River and Bohai Sea.

Organochlorine pesticides in soil, water and sediment along the Jinjiang River mainstream to Quanzhou Bay, southeast China

Residue levels of organochlorine pesticides (OCPs) in multiple compartments (water, soil and sediment) along the Jinjiang River mainstream to Quanzhou Bay were monitored to elucidate sources and fate. The concentrations of OCPs in surface soil of the watershed of the Jinjiang River (2.44 ± 1.97 ng/g for hexachlorocyclohexanes (HCHs) and 11.4 ± 8.46 ng/g for dichlorodiphenyltrichloroethanes (DDTs)) and the Quanzhou Bay (1.81 ± 2.15 ng/g for HCHs and 9.72 ± 14.66 ng/g for DDTs) were comparable. The concentrations of HCHs and DDTs in dissolved phase were 55-94% for the total HCHs and ten to sixteen percent for the total DDTs in the Jinjiang River. High correlations of OCPs between suspended particulate matter (SPM) and sediment (p<0.01) were found in this study, which demonstrated that OCPs absorbed onto SPM was the major source in the sediment of Quanzhou Bay. The use of lindane was the major source of HCHs in the study region. Dicofol pollution was found in water of the Jinjiang River and sediment of Quanzhou Bay. Based on the sediment quality guidelines, DDTs pose more ecotoxicological risk in environment of the Jinjiang River and Quanzhou Bay.

Organochlorine pesticides in the lower reaches of Yangtze River: occurrence, ecological risk and temporal trends

Residues of 24 organochlorine pesticides (OCPs) including DDT metabolites were investigated in the water and surface sediments from the lower reaches of the Yangtze River to evaluate their pollution and potential risks. Concentrations of OCP residues (ΣOCP₂₄ ranged from 3.07 to 23.70 ng/L in water and 0.67 to 58.80 ng/g dw in sediments) were generally within safe levels, while adverse biological effects are likely from DDT pollution in the lower reaches. HCH and DDT residues dominated the OCPs. High detection rates but low concentrations of some other OCPs, such as chlordane and endosulfan, were detected in both water and sediments. The HCH and DDT residues in the lower reaches primarily originated from historical use of technical HCH and DDT, although additional sources of lindane and dicofol existed in the region. Temporal trends of pesticide contamination levels indicated that HCH concentrations have decreased over the past decades. However, there was no obvious trend of declining DDT concentrations in the sediments from the Yangtze River. The DDT metabolites, DDMU (bis (chlorophenyl)-1-chloroethylene), DBP (dichlorobenzophenone) and DDM (bis (chlorophenyl) methane), were also investigated for the first time in water and sediments from the Yangtze River.