Residue, temporal trend and half-life time of selected organochlorine pesticides (OCPs) in surface soils from Bacninh, Vietnam

Selected pesticidal POPs and metabolites in the soil of five Vietnamese cities: Sources, fate, and health risk implications

Large quantities of organochlorine pesticides (OCPs) have been used in tropical regions. The fate processes and risks of these legacy contaminants in the tropics are poorly understood. Herein, we investigated the occurrence of three classes of widely used OCPs and their metabolites in surface and core soil from five cities across Vietnam with a prevalent tropical monsoon climate and a long history of OCP application. We aimed to elucidate migration potentials, degradation conditions, and transformation pathways and assess current health risks of these contaminants. Generally, the concentrations of OCPs and metabolites in the soil core were slightly lower than those in surface soil except for hexachlorocyclohexane (HCH) isomers. 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT), 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), the sum of dicofol and 4,4'-dichlorobenzophenone (p,p'-DBP), and 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) were the most abundant compounds in both surface and core soils. A uniform distribution of HCHs (the sum of α-, β-, γ-, and δ-HCH) at trace levels was found in almost all soils, serving as evidence of the lack of recent use of HCH pesticides. Higher concentrations of DDTs (the sum of DDT, DDD, and DDE) were observed in north-central Vietnamese soil, whereas appreciable concentrations of ENDs (the sum of α- and β-endosulfan and endosulfan sulfate) were only found in southern Vietnamese soils. Empirical diagnostic ratios indicated residuals of DDTs were mainly from technical DDT rather than dicofol, whereas aged HCHs could be explained by the mixture of lindane and technical HCH. Both historical applications and recent input explain DDTs and ENDs in Vietnamese soil. Total organic carbon performs well in preventing vertical migration of more hydrophobic DDTs and ENDs. The dominant transformation pathway of DDT in surface soil followed p,p'-DDE→2,2-bis(4-chlorophenyl)-1-chloroethylene or p,p'-DDMU→1,1-bis(4-chlorophenyl)ethylene or p,p'-DDNU→p,p'-DBP, whereas the amount of p,p'-DDMU converted from p,p'-DDD and p,p'-DDE is similar in soil core. Non-cancer risks of OCPs and metabolites in all soils and cancer risks of those chemicals in core soils were below the safety threshold, whereas a small proportion of surface soil exhibited potential cancer risk after considering the exposure pathway of vegetable intake. This study implied that organic matter in non-rainforest tropical deep soils still could hinder the leaching of hydrophobic organic contaminants as in subtropical and temperate soils. When lands with a history of OCP application are used for agricultural purposes, dietary-related risks need to be carefully assessed.

Mapping the Contribution of Biomass Burning to Persistent Organic Pollutants in the Air of the Indo-China Peninsula Based on a Passive Air Monitoring Network

Biomass burning (BB) is an important source of atmospheric persistent organic pollutants (POPs) across the world. However, there are few field-based regional studies regarding the POPs released from BB. Due to the current limitations of emission factors and satellites, the contribution of BB to airborne POPs is still not well understood. In this study, with the simultaneous monitoring of BB biomarkers and POPs based on polyurethane foam-based passive air sampling technique, we mapped the contribution of BB to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the Indo-China Peninsula. Spearman correlations between levoglucosan and 16 PCBs (r_s = 0.264-0.767, p < 0.05) and 2 OCPs (r_s = 0.250-0.328, p < 0.05) confirmed that BB may facilitate POP emissions. Source apportionment indicated that BB contributed 9.3% to the total PCB and OCP mass. The high contribution of positive matrix factorization-resolved BB to PCBs and OCPs was almost consistent with their concentration distributions in the open BB season but not completely consistent with those in the pre-monsoon and/or monsoon seasons. Their contribution distributions may reflect the use history and geographic distribution in secondary sources of POPs. The field-based contribution dataset of BB to POPs is significant in improving regional BB emission inventories and model prediction.

Persistent organic pollutants in hospitalized individuals in the municipality of Petropolis, Brazil

Persistent organic pollutants (POPs) are highly lipophilic and can accumulate and biomagnify in food chains. Characterized as a public health problem, exposure to these compounds enables the development of diseases like cancer, cardiovascular disease, diabetes, and obesity. The objective of this study was to estimate the plasma levels of organochlorine pesticides and PCBs in 151 samples (97 women; 54 men) in hospitalized individuals in Petropolis, Brazil. Individuals over 18 years of age and residing for at least 2 years in the mountainous region of the State of Rio de Janeiro, Brazil, participated in a cross-sectional study. Interviews using a structured questionnaire and blood samples to estimate plasma levels of persistent organic pollutants provided data. Gas chromatography coupled with triple quadrupole mass spectrometry provided the levels of organochlorine pesticides and PCBs. Compared to data present in the literature, the concentration of POPs was lower, and individuals from 55 to 64 years of age (3.28 ng mL^-1) and women (2.52 ng mL^-1) presented a higher average concentration of organochlorine pesticides; men (0.05 ng mL^-1) also presented a high concentration of PCBs. This is the first Brazilian study to estimate the concentration of several POPs in a hospital-based sample that includes men and women, thus contributing to the characterization of our population regarding environmental exposures relevant to health.

Organochlorine pesticides in the urban, suburban, agricultural, and industrial soil in South Korea after three decades of ban: Spatial distribution, sources, time trend, and implicated risks

Organochlorine pesticides in soil samples across urban, suburban, agricultural, and industrial sites were analyzed every year between 2013 and 2016 in South Korea. The study aims to understand the residual status, diminution of occurrence from the South Korean environment, and its risk to humans after three decades of the ban. A general decreasing trend of OCPs has been observed over the years. The OCP concentrations were below the guideline values prescribed for soil pollution. Metabolites like p,p'-DDD and endosulfan sulfate contributed a major portion to the total OCP concentration over the years. The agricultural sites showed higher OCP levels than other site types. Compositional profile and diagnostic ratios suggested that the occurrence of DDT and endosulfan residues were due to historical inputs, but those of HCH and chlordane reflect recent usage in some pockets. The calculated incremental lifetime cancer risk was within the safety limit for all age groups across the genders in the majority of the sites. It is evident that the OCP load on soil is decreasing since the ban on usage. However, regular monitoring with a special focus on metabolites can be an effective control measure to regulate and eliminate the contamination of OCPs.

Effects of Organochlorine Pesticide Residues in Maternal Body on Infants

There are many organochlorine pollutants in the environment, which can be directly or indirectly exposed to by mothers, and as estrogen endocrine disruptors can cause damage to the lactation capacity of the mammary gland. In addition, because breast milk contains a lot of nutrients, it is the most important food source for new-born babies. If mothers are exposed to organochlorine pesticides (OCPs), the lipophilic organochlorine contaminants can accumulate in breast milk fat and be passed to the infant through breast milk. Therefore, it is necessary to investigate organochlorine contaminants in human milk to estimate the health risks of these contaminants to breastfed infants. In addition, toxic substances in the mother can also be passed to the fetus through the placenta, which is also something we need to pay attention to. This article introduces several types of OCPs, such as dichlorodiphenyltrichloroethane (DDT), methoxychlor (MXC), hexachlorocyclohexane (HCH), endosulfan, chlordane, heptachlorand and hexachlorobenzene (HCB), mainly expounds their effects on women's lactation ability and infant health, and provides reference for maternal and infant health. In addition, some measures and methods for the control of organochlorine pollutants are also described here.

Level, source, and distribution of organochlorine pesticides (OCPs) in agricultural soils of Tanzania

This study investigated the level, composition, and spatial and vertical distribution of the organochlorine pesticides (OCPs) at 0-2 cm and 2-20 cm in the agricultural surface soils from Southeastern to Central-western Tanzania. Although the most abundant OCPs were DDT with a mean concentration of 2.29 ng/g, dieldrin (1.57 ng/g), and methoxychlor (0.79 ng/g), HCH was the most dominant (with detection frequency of 88%). OCP dominance was in the Southern Highlands, which is the most productive agricultural zone. Though there were indicators of recent inputs for some sites, OCP contamination was mainly historical. DDT contamination was dominated by p,p'-DDE and resulted from both technical DDT and dicofol while HCH contamination was dominated by γ-HCH and resulted from both technical HCH and lindane. Based on depth, the OCPs dominated mainly the upper 2 cm, which was associated with soil and environmental factors rather than recent inputs since most of the detected compounds were historical. Nevertheless, some sites showed exceptional high abundance in the lower soil with more concentration of parent compounds. Therefore, this study recommends the need for further studies on the influence of soil properties on OCPs' transport in the soil, surface water, and air. Besides, detection of recent inputs at some sites calls for more mapping of the OCPs in the country to strengthen their control and prevention of future risks.

Residues of organochlorine pesticides (OCPs) in aquatic environment and risk assessment along Shaying River, China

Organochlorine pesticides (OCPs) are pesticides with global scale ubiquity, persistence and bioaccumulation, which leave long-term residuals in the water body. OCPs' high toxicity poses significant threats to human health and aquatic biodiversity, making assessment of OCPs' impact on aquatic ecology and human health urgently necessary. In this research, the presence of 16 OCPs in surface water and groundwater along Shaying River, China, as well as OCPs concentration correlations, was investigated at 24 selected sampling sites. At the same time, the ecological risk and human carcinogenic risk were also analyzed by risk quotient method and USEPA's Risk Assessment Guidance, respectively. Results showed that the total concentration of OCPs ranged from 21.0 to 61.4 ng L^-1 in groundwater, and 12.3-77.5 ng L^-1 in surface water. Hexachlorocyclohexane (HCHs) and heptachlor were the prominent contaminants in groundwater, which indicated their use in the recent past and confirmed their persistence. The α-HCH/γ-HCH ratios in groundwater confirmed that γ-HCH (lindane) was used as main substitute of technical HCH in the study area. The correlation analysis illustrated that δ-HCH and γ-HCH played a dominant role in HCHs residue. Heptachlor and α-HCH, as well as endosulfan and heptachlor epoxide, had a strongly significant positive correlation, suggesting an associated usage of the two pair OCPs. An extremely high ecological risk for aquatic organism was observed for γ-HCH, heptachlor and dieldrin, while the carcinogenic risks posed by the selected OCPs in surface water and groundwater were all acceptable.

Equilibrium sampling informs tissue residue and sediment remediation for pyrethroid insecticides in mariculture: A laboratory demonstration

Mariculture product safety in relation to sediment quality has attracted increasing attention because of the accumulation of potentially hazardous chemicals, including pyrethroid insecticides, in sediment. Passive sampling has been widely used to assess the bioavailability of sediment-associated hydrophobic organic contaminants and predict their body residue in benthic organisms. Therefore, in this study, we introduced polydimethylsiloxane (PDMS) polymer as a biomimetic "chemometer" for freely-dissolved concentrations (C_free) to assess the efficacy of different carbon sorbents in reducing the bioavailability of pyrethroids in the process of sediment remediation. Black carbon (BC)-based materials (e.g., charcoal, biochar, and activated carbon) showed the advantageous sorption capacity over humic substance-based peat soil based on both C_free and tissue residue in exposed clams. Of the tested BC-type materials, biochar appeared to be an ideal one in the remediation of pyrethroid-contaminated sediment. The predictive value of the PDMS chemometer approach to informing tissue residue was confirmed by a good agreement between the measured lipid-normalized concentrations of pyrethroids in clams and the lipid-based equilibrium concentrations calculated from C_free via lipid-water partition coefficients. The quantitative inter-compartmental relationship underlying the laboratory system of sediment-pore water-PDMS-biota was also cross-validated by a mechanistically-based bioaccumulation model, thus confirming the validity of C_free as a predictive intermediate to alert for tissue residue and guide sediment remediation. The present study revealed a great promise of sensing C_free by polymer-based equilibrium sampling in predicting tissue residue of chemicals applied in mariculture against regulatory guidelines, and, in turn, informing remediation measures when needs arise. In situ demonstration is warranted in the future to ascertain the field applicability of this approach in real mariculture systems.

Simultaneous effect of dissolved organic carbon, surfactant, and organic acid on the desorption of pesticides investigated by response surface methodology

Desorption of pesticides (fenobucarb, endosulfan, and dichlorodiphenyltrichloroethane (DDT)) from soil to aqueous solution with the simultaneous presence of dissolved organic carbon (DOC), sodium dodecyl sulfate (SDS), and sodium oxalate (Oxa) was investigated in batch test by applying a full factorial design and the Box-Behnken response surface methodology (RSM). Five concentration levels of DOC (8 to 92 mg L^-1), SDS (0 to 6.4 critical micelle concentration (CMC)), and Oxa (0 to 0.15 M) were used for the experiments with a rice field topsoil. The results of RSM analysis and analysis of variance (ANOVA) have shown that the experimental data could be well described by quadratic regression equations with determination coefficients (R ²) of 0.990, 0.976, and 0.984 for desorption of fenobucarb, endosulfan, and DDT, respectively. The individual effects and interaction of DOC, SDS, and Oxa were evaluated through quadratic regression equations. When the aqueous solution includes 50 mg L^-1 DOC, 3.75 CMC SDS, and 0.1 M Oxa, the maximum desorption concentrations of fenobucarb, endosulfan, and DDT were 96, 80, and 75 μg L^-1, respectively. The lowest concentration of SDS, DOC, and Oxa caused the minimum desorption. This point at conditions of concern for flooding water is high content of organic compounds causing potentially high contamination by desorption, and the remarkably lower desorption at organic matter-free conditions. The suspended organic matter is one of the common characteristics of flooding and irrigation water in rice fields, and surfactants from pollution increase the problem with desorption of legacy pesticides in the rice fields.

Distribution and residue profile of organochlorine pesticides and polychlorinated biphenyls in sediment and fish of Lake Manzala, Egypt

Sediment and fish (Oreochromis niloticus) samples collected from Lake Manzala were analyzed to assess the spatial distribution of OCPs and 96 PCBs. Relatively higher concentrations of chlorpyrifos, ∑DDT, and HCB were found, particularly at the Bahr Al-Baqar drain station, which has uncontrolled inputs of untreated domestic, agricultural, and industrial wastes. The concentrations of ∑PCBs ranged from 19 to 69 ng/g dw and from 7.4 to 29 ng/g dw for sediment and fish samples, respectively. Ratios of DDT to its metabolites suggest that the source of ∑DDT is from past usage of technical DDT in the regions surrounding the lake. Sediment quality guidelines were exceeded in 88, 75, and 42% of sediments for the Effects Range Low (ERL) for ∑PCBs, ∑DDT, and 4,4'-DDE, respectively. Sediment from the Bahr Al-Baqar drain exceeded the Probable Effects Level (PEL) for DDT isomers 2,4' and 4,4'. All fish samples from Lake Manzala were well below action and tolerance levels set by US EPA for ∑DDT, chlordane, dieldrin, heptachlor, mirex, and PCBs.

HIGHLIGHTS

Distributions of OCPs and PCBs in sediment and tilapia from Lake Manzala were investigated. Chlorpyrifos, ∑DDT, and HCB sediment concentrations were spatially variable and relatively elevated. ∑96PCBs, ∑DDT, and 4,4'-DDE exceeded the Effects Range Low in 88, 75, and 42% of the sediments, respectively. The major input from Cairo, the Bahr Al-Baqar drain, exceeded the Probable Effects Level for DDT isomers in sediments. OCP and PCB concentrations in tilapia were below action and tolerance levels set by the US-EPA.

Periodic monitoring of persistent organic pollutants and molecular damage in Cyprinus carpio from Büyük Menderes River

Concentrations of persistent organic pollutants (POPs) were quantified in river water and sediment, as well as in the liver and muscle tissues of Cyprinus carpio that were sampled four times in a year at three stations in the Büyük Menderes River (BMR). Potential biomarkers of possible cellular molecular damage, namely lipid peroxidation (LPO) degradation products, protein carbonyls (PCO) and DNA repair product 8-hydroxy-2'-deoxyguanosine (8-OHdG), were analysed. All the targeted pollutants were measurable both in biotic and abiotic samples. Interestingly, the results suggested that there was recent organochlorine pesticide (OCP) input into the river water in the first two sampling periods in all stations in contrast to prohibition, while input of polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs) was not detected. Liver POP concentrations were higher than in muscle, as expected, and were found to decrease from the first to the fourth sampling period in all stations, except PBDEs. Levels of LPO degradation products in the liver and in muscle tissues decreased from the first to the fourth sampling period. This suggests that these markers reflect the lipid damage in respective tissues due to the tissue burden of targeted POPs. Protein carbonyls were the highest in the first sampling period, followed by a dramatic decrease in the second, and then a gradual increase towards the fourth sampling period in all stations. 8-OHdG levels were lower in Sarayköy station in the first sampling period. Among the measured biomarkers, only several LPO degradation products were significantly correlated with OCPs and PCBs in liver tissue.

Contamination characteristics of organochlorine pesticides in multimatrix sampling of the Hanjiang River Basin, southeast China

Hanjiang River, the second largest river in Guangdong Province, Southern China, is the primary source of drinking water for the cities of Chaozhou and Shantou. Our previous studies indicated that soils from an upstream catchment area of the Hanjiang River are moderately contaminated with organochlorine pesticides (OCPs), which can easily enter the river system via soil runoff. Therefore, OCPs, especially downstream drinking water sources, may pose harmful health and environmental risks. On the basis of this hypothesis, we measured the OCP concentrations in dissolved phase (DP), suspended particle matter (SPM), and surface sediment (SS) samples collected along the Hanjiang River Basin in Fujian and Guangdong provinces. OCP residue levels were quantified through electron capture detector gas chromatography to identify the OCP sources and deposits. The concentration ranges of OCPs in DP, SPM, and SS, respectively, were 2.11-12.04 (ng/L), 6.60-64.77 (ng/g), and 0.60-4.71 (ng/g) for hexachlorocyclohexanes (HCHs), and 2.49-4.77 (ng/L), 6.75-80.19 (ng/g), and 0.89-252.27 (ng/g) for dichloro-diphenyl-trichloroethanes (DDTs). Results revealed that DDTs represent an ecotoxicological risk to the Hanjiang River Basin, as indicated by international sediment guidelines. This study serves as a basis for the future management of OCP concentrations in the Hanjiang River Basin, and exemplifies a pattern of OCP movement (like OCP partition among multimedia) from upstream to downstream. This pattern may be observed in similar rivers in China.

Pesticides in Ichkeul Lake-Bizerta Lagoon Watershed in Tunisia: use, occurrence, and effects on bacteria and free-living marine nematodes

This study aimed to identify the most commonly used agricultural pesticides around Ichkeul Lake-Bizerta Lagoon watershed. First survey of pesticide use on agricultural watershed was performed with farmers, Regional Commissioner for Agricultural Development, and pesticide dealers. Then, sediment contamination by pesticides and response of benthic communities (bacteria and free-living marine nematode) were investigated. The analysis of 22 active organochlorine pesticides in sediments was performed according to quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, biodiversity of indigenous bacterial community sediment was determined by terminal restriction fragment length polymorphism (T-RFLP), and free-living marine nematodes were counted. The results of the field survey showed that iodosulfuron, mesosulfuron, 2,4-dichlorophenoxyacetic acid (2,4 D), glyphosate, and fenoxaprops were the most used herbicides, tebuconazole and epoxiconazole the most used fungicides, and deltamethrin the most used insecticide. Sixteen organochlorine pesticide compounds among the 22 examined were detected in sediments up to 2 ppm in Ichkeul Lake, endrin, dieldrin, and hexachlorocyclohexane being the most detected molecules. The most pesticide-contaminated site in the lake presented the higher density of nematode, but when considering all sites, no clear correlation with organochlorine pesticide (OCP) content could be established. The bacterial community structure in the most contaminated site in the lake was characterized by the terminal restriction fragments (T-RFs) 97, 146, 258, 285, and 335 while the most contaminated site in the lagoon was characterized by the T-RFs 54, 263, 315, 403, and 428. Interestingly, T-RFs 38 and 143 were found in the most contaminated sites of both lake and lagoon ecosystems, indicating that they were resistant to OCPs and able to cope with environmental fluctuation of salinity. In contrast, the T-RFs 63, 100, 118, and 381 in the lake and the T-RFs 40, 60, 80, 158, 300, 321, and 357 in the lagoon were sensitive to OCPs. This study highlighted that the intensive use of pesticides in agriculture, through transfer to aquatic ecosystem, may disturb the benthic ecosystem functioning of the protected area. The free-living marine nematodes and bacterial communities represent useful proxy to follow the ecosystem health and its capacity of resilience.

Evaluation of hydrocarbons and organochlorine pesticides and their tolerant microorganisms from an agricultural soil to define its bioremediation feasibility

The concentrations of hydrocarbons and organochlorine pesticides (OCPs), nutrients and tolerant microorganisms in an agricultural soil from a locality in Tepeaca, Puebla, Mexico, were determined to define its feasibility for bioremediation. The OCPs detected were heptachlor, aldrin, trans-chlordane, endosulfán I, endosulfán II, 1,1,1-bis-(4-chlorophenyl)-2,2-trichloroethane (4,4'-DDT), 1,1-bis-(4-chlorophenyl)-2,2-dichloroethene (4,4'-DDE) and endrin aldehyde, with values of 0.69-30.81 ng g(-1). The concentration of hydrocarbons in the soil of Middle Hydrocarbons Fraction (MHF), C10 to C28, was 4608-27,748 mg kg(-1) and 1117-19,610 mg kg(-1) for Heavy Hydrocarbons Fraction (HHF), C28 to C35, due to an oil spill from the rupture of a pipeline. The soil was deficient in nitrogen (0.03-0.07%) and phosphorus (0 ppm), and therefore it was advisable to fertilize to bio-stimulate the native microorganisms of soil. In the soil samples, hydrocarbonoclast fungi 3.72 × 10(2) to 44.6 × 10(2) CFU g(-1) d.s. and hydrocarbonoclast bacteria (0.17 × 10(5) to 8.60 × 10(5) CFU g(-1) d.s.) were detected, with a tolerance of 30,000 mg kg(-1) of diesel. Moreover, pesticideclast fungi (5.13 × 10(2) to 42.2 × 10(2) CFU g(-1) d.s.) and pesticideclast bacteria (0.15 × 10(5) to 9.68 × 10(5) CFU g(-1) d.s.) were determined with tolerance to 20 mg kg(-1) of OCPs. Fungi and bacteria tolerant to both pollutants were also quantified. Therefore, native microorganisms had potential to be stimulated to degrade hydrocarbons and pesticides or both pollutants. The concentration of pollutants and the microbial activity analyzed indicated that bioremediation of the soil contaminated with hydrocarbons and pesticides using bio-stimulation of native microorganisms was feasible.

Vertical distributions of organochlorine pesticides and polychlorinated biphenyls in an agricultural soil core from the Guanzhong Basin, China

The concentrations and distributions of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and polychlorinated biphenyls (PCBs) in an agricultural soil core in the Guanzhong Basin, China were determined. Overall, p,p'-DDT and p,p'-DDE were dominant contaminants and accounted for approximately 48.4 and 23.3% of the total detected DDTs. Low chlorinated PCBs (PCB 28 and PCB 52) were generally detected at higher concentrations and more frequently than high chlorinated PCBs. The peak values of ∑DDT (12.92 ng/g), ∑HCH (2.25 ng/g), and ∑PCB (3.44 ng/g) occurred in the 10-15, 15-20, and 5-10 cm sections, respectively. The negative correlation between the organochlorine pesticide (OCP) concentrations and the soil depths and the relatively high p,p'-DDT/p,p'-DDE ratios in the surface soils indicated that these chemicals were recently used illegally, despite their official ban in 1983. The increase in the ratio of α-/γ-HCH with increasing soil depth indicated that the use of lindane decreased relative to the use of technical HCHs in recent years.

Occurrence of organochlorine pesticides in surface soils from college school yards of Xi'an, China

In this study, surface soil samples from 14 representative college school yards in Xi'an, the capital city of Shaanxi province, China, were collected and analyzed for 21 organochlorine pesticides (OCPs). The total concentrations were in the ranges of 0.2-67.0 ng/g. HCHs and DDTs were the most dominant compounds among the 21 OCPs, and their concentrations ranged from 0.1-8.5 to 0.1-56.3 ng/g, respectively. Source identification analysis indicated that the residues of HCHs and DDTs were mostly due to historical use of these chemicals or from other source regions. The quality of all the Xi'an college school yard soils except sample XAUAT was classified as low pollution by OCPs according to the National Environmental Quality Standards for Soils of China (GB15618-1995).

Risks from sediments contaminated with organochlorine pesticides in Hangzhou, China

In September 2009, we investigated the residues, enantiomer fractions (EFs) and biological risks of organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs), in three different depth ranges (0-5 cm, 5-10 cm and 10-15 cm) of sediments from 15 sites in Hangzhou, China. The concentration (ng g(-1) dryweight) ranges of HCHs and DDTs in surface sediments were 0.74-5.8 and 0.76-17, respectively. The vertical distribution of mean OCP concentrations was in the order of 10-15 cm>5-10 cm>0-5 cm and implied that the residues of HCHs and DDTs gradually decreased after they were banned. The residues of OCPs in the study area mainly originated from the historical OCP use. The isomer ratios of <alpha>-HCH (α-HCH)/<gamma>-HCH (γ-HCH) (0.10-7.6) implied that HCH residues were derived not only from historical technical HCH use but also from additional use of lindane in this area. The isomer ratios of o,p'-DDT/p,p'-DDT (51% of samples were in the range of 0.3-1.3) suggested that both dicofol-type DDT and technical DDT applications may be present in most study areas. The (+)-enantiomers of α-HCH and o,p'-DDT were more prevalent than (-)-enantiomer in most samples with the fractions contain different enantiomers greater than 0.5. DDTs, especially p,p'-DDE, are the main OCP species of more ecotoxicological concern in Hangzhou.

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.

Distribution and sources of organochlorinated contaminants in sediments from Izmir Bay (Eastern Aegean Sea)

Eighteen surface sediment samples representative of the entire Izmir Bay were analyzed for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). This was in order to provide extensive information concerning the recent deposition of these compounds in this area, together with levels, distribution, possible sources and potential biological risk. Sites that were contaminated by high concentrations of organochlorine compounds were associated with dense population, such as the harbour and the Gediz River estuary. Relatively higher ΣDDT concentrations and high DDT/DDE+DDD ratios in the Gediz River estuary indicated DDT usage, probably linked to public health emergencies. According to the established guidelines for sediment quality, the risk of adverse biological effects from such levels of OCPs and PCBs as recorded at most of the study sites was insignificant. But the higher concentrations in Inner bay and in the Gediz River estuary could cause biological damage.

Organochlorine contamination (PCBs, DDTs, HCB, HCHs) in sediments from Cienfuegos bay, Cuba

The spatial distribution of various organochlorinated compounds, e.g. PCBs, DDTs, HCB and HCHs, were investigated in sediments from Cienfuegos bay, Cuba. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the residual waters of the city and thermoelectrical power approached the sediment quality guidelines for PCBs and DDTs. Relatively higher SigmaDDT concentrations and high DDT/DDE+DDD ratios in two sites near the outfalls of the city indicated a current DDT usage, probably linked to public health emergencies. These results contribute to the sparse regional database for organochlorinated compounds in the Caribbean marine environment.

Organochlorine pesticides contamination in surface soils from two pesticide factories in Southeast China

The present article attempts to investigate organochlorine pesticides' (OCPs) contamination in soils from polluted sites and to assess the soil quality in the study area. HCHs and eight other persistent organic pollutants (POPs) pesticides were studied in surface soil samples collected from a new (F) and an old (G) pesticide factory in Southeast China. According to the measured results, surface soils from F and G were contaminated with HCHs, DDTs, HCB, and chlordane, with beta-HCH and p,p'-DDT being the two dominant substances. The total OCPs concentrations of surface soils from F and G were 0.84 and 166mgkg(-1) respectively. Cluster analysis was performed to group the soil sites in terms of their total OCPs contamination levels. The ratios of alpha-HCH/gamma-HCH, o,p'-DDT/p,p'-DDT, and trans-/cis- chlordane in some of the soil samples are similar to their technical products in the study area which indicates the lack of hazardous waste management practices of the pesticide production and transportation. According to GB 15618-1995, the HCHs could be classified as light pollution and little pollution for F and G, whereas DDTs levels of F and G could be defined as little pollution and heavy pollution, respectively. This study indicates that surface soils, especially residential area soils from F and G were facing varying degrees of pollutions. The situation is more hazardous due to the continuous exposure of the population that lives in the surroundings. Therefore, on-site remediation technologies and the best available techniques/best environmental practices (BAT/BEP) should be carried out on these factories with the national implementation of the Stockholm Convention.