Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

Contamination levels and spatial distribution of organochlorine pesticides in soils from India

Organochlorine pesticides, dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH), are potential chemical pollutants extensively used for agriculture and vector control purposes due to low cost and high effectiveness. Concentrations of HCH and DDT were determined in 175 surface soil samples from different agricultural fields, fallow and urban lands of districts Nagaon and Dibrugarh, Assam, India. The mean concentrations of total HCH and total DDT were 825 ng/g (range: 98-1945 ng/g) and 903 ng/g (range: 166-2288 ng/g) in district Nagaon while 705 ng/g (range: 178-1701 ng/g) and 757 ng/g (range: 75-2296 ng/g) in district Dibrugarh, respectively. The soils from paddy fields contained highest amounts of HCH and DDT residues. Total organic carbon was found to be positively associated with soil HCH and DDT residues. Ratios of DDT/(DDD+DDE) were 1.25 and 1.82 while of α/γ HCH were 2.78 and 2.51 for districts Dibrugarh and Nagaon, respectively. Source identification revealed that soil residue levels have originated from long past and recent mixed source of technical HCH and Lindane for HCHs and mainly technical DDT for DDTs. Spatial distribution was also investigated to identify the areas with higher pesticide loadings in soil.

Chlorobenzenes and organochlorinated pesticides in vegetable soils from an industrial site, China

Organochlorinated compounds are ubiquitous contaminants in the environment, especially in industrial sites. The objective of the work was to investigate whether a vegetable field near an industrial site is safe for vegetable production. The residues of chlorobenzenes (CBs), hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in a vegetable field which was near a chemical plant in China were characterized. Point estimate quotient was used for ecological risk assessment of the investigated site. The results showed that all CBs except monochlorobenzene (MCB) were detected in soils. The total concentrations of sigmaCBs ranged from 71.06 to 716.57 ng/g, with a mean concentration of 434.93 ng/g. The main components of CBs in soil samples were dichlorobenzenes (DCBs), trichlorobenzenes (TCBs) and tetrachlorobenzenes (TeCBs), while for single congeners, 1,2,4-TCB had the highest concentration, which ranged from 13.21 to 210.35 ng/g with a mean concentration of 111.89 ng/g. Residues of hexachlorobenzene (HCB) in soil samples ranged from 0.9 to 11.79 ng/g, significantly lower than sigmaDCB, sigmaTCB and sigmaTeCB. Concentrations of sigmaHCHs and sigmaDDTs in soils ranged from 11.32 to 55.24 ng/g and from 195.63 to 465.58 ng/g, respectively, of which the main components were alpha-HCH and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE). Ecological risk assessment for the investigated site showed that the most potential risks were from TCBs and TeCBs, based on the hazard quotients. The higher residues of CBs and DDTs compared to the target values and the higher than 1 hazard quotients indicated that this area is not safe for vegetable production and thus soil remediation is needed.

Organochlorine pesticides in the soil of a karst cave in Guilin, China

Organochlorine pesticides (OCPs) including HCH, DDT, chlordane, endosulfan, and endosulfan sulfate were analyzed in surface soil of the Dayan Cave to investigate their source and concentration levels in September 2006. Generally, the data showed that outside soil of the cave had much higher concentrations than inside soil for the most detected OCPs in the cave and both inside soil and outside soil showed much lower concentration levels (basically, the levels of OCPs were less than 0.7 ng/g) than those observed in other regions within and outside China other than TC (ranging from 3.22 to 5.00 ng/g) and CC (ranging from 3.89 to 5.08 ng/g) in the soil outside. The ratios of α-/γ-HCH ranged from 0.88 to 1.20 in the soil of the cave, together with the averaged percentages of β-HCH and δ-HCH among the total HCH isomers (accounting for 39.0% and 14.2%, respectively), implied that a historical residue of local technical HCH contamination was likely to be dominant in the soil of the cave. Based on (1) the accordance of TC/CC ratios (ranging from 0.83 to 0.98) between the values observed in the outside soil and the potentially available chlordane products in the markets, and (2) the high concentrations of TC and CC observed in the outside soil, it appeared that the illegal usage of technical chlordane was done in Guilin. The low concentrations of TC (0.02 to 0.56 ng/g) and CC (0.10 to 1.71 ng/g) in the inside soil, together with the significant distinctions of TC/CC ratios between the inside soil (ranging from 0.03 to 0.33) and the outside soil, implied that the chlordane in the inside soil of the cave was a historical residue of local technical chlordane contamination. The similar ratios of DDT isomers (o, p (')-DDT/p, p (')-DDT and p, p (')-DDE+DDD/DDT) between the outside soil and the inside soil of the cave suggested that they may have the similar DDT source. The ratios of p, p (')-DDE+DDD/DDT (ranging from 3 to 8) indicated that DDT was relatively aged. The values of o, p (')-DDT/p, p (')-DDT ratios (ranging from 3 to 7.5 with a mean value of 5.45) were found to be much higher than that of technical DDT, and very similar to that of dicofol products, implied that the primary source of DDT in the soil of the cave was most probably from dicofol-type DDT products. The low concentration levels of endosulfan and the higher levels of metabolite endosulfan sulfate indicated that the residue from historical usage of technical endosulfan was likely to be dominant in the soil of the cave.

Applicability of Corbicula as a bioindicator for monitoring organochlorine pesticides in fresh and brackish waters

The applicability of Corbicula as a bioindicator for monitoring organochlorine pesticides (OCPs) in fresh and brackish waters is presented here. Differences in isomer compositions and OCP bioaccumulation levels were analyzed in western Japan and the Pearl River Delta (PRD) in China. Isomer compositions of DDTs, chlordanes, and HCHs were significantly different between the two areas because of their different historical uses and property of the chemicals. This is represented by the (DDE + DDD)/DDT ratio in Corbicula, ranging 4.9-39 in western Japan and 1.1-2.4 in the PRD. However, isomer compositions in Corbicula reflected those in water, and the different patterns in Corbicula likely reflected the usage history. Concentrations of dissolved oxygen, suspended solids, and volatile suspended solids in water, and the difference in species did not influence OCP bioaccumulative levels in Corbicula when conducting biomonitoring. These levels are likely similar to those in Mytilus galloprovincialis. Therefore, Corbicula could be an appropriate bioindicator for monitoring OCPs in fresh and brackish waters.

Organochlorine pesticides in the surface water and sediments from the Peacock River Drainage Basin in Xinjiang, China: a study of an arid zone in Central Asia

Fourteen surface water and nine surface sediment samples were collected from the Peacock River and analyzed for organochlorine pesticides (OCPs) by gas chromatograph-electron capture detector (GC-ECD). All the analyzed organochlorine pesticides, except o,p'-DDT, were detected in sediments from the Peacock River; but in the water samples, only β-HCH, HCB, p,p'-DDD, and p,p'-DDT were detected at some sites. The ranges for total OCPs in the water and sediments were from N.D. to 195 ng l( - 1) and from 1.36 to 24.60 ng g( - 1), respectively. The only existing HCH isomer in the water, β-HCH, suggested that the contamination by HCHs could be attributed to erosion of the weathered agricultural soils containing HCHs compounds. Composition analyses showed that no technical HCH, technical DDT, technical chlordanes, endosulfans, and HCB had been recently used in this region. However, there was new input of γ-HCH (lindane) into the Peacock River. The most probable source was water flowing from Bosten Lake and/or agricultural tailing water that was returned directly into the Peacock River. DDT compounds in the sediments may be derived mainly from DDT-treated aged and weathered agricultural soils, the degradation condition was aerobic and the main product was DDE. HCB in the sediment might be due to the input from Bosten Lake and the lake may act as an atmospheric deposition zone. There was no significant correlation between the concentrations of OCPs (including ∑HCH, ∑DDT, chlordanes, endosulfans, HCB and total OCPs) and the content of fine particles (<63 μm). The concentrations of OCPs were affected by salinity.

Using the o,p'-DDT/p,p'-DDT ratio to identify DDT sources in China

Dichlorodiphenyltrichloroethane (DDT) has been banned in China for decades, and yet high DDT concentrations are still being detected in the Chinese environment. This might be at least partly due to the current use of dicofol formulation, which contains DDT as an impurity. In this study, a method based on the ratios of two DDT isomers, o,p'-DDT and p,p'-DDT, was established and used to estimate the relative contributions of dicofol formulation and those of technical DDT to overall environmental DDT. Based on this method and field data from the literature, we calculated that dicofol formulation contributed >72% of atmospheric DDT in 2004 in the Taihu Lake region, China, and this value was >84% in summer when dicofol was applied for agricultural purposes. Sediment and soil, however, contained mostly residual DDT from the historical use of technical DDT. In most other regions of China, we found that dicofol contributed to a significant fraction of DDT in air samples.

Evaluation of pesticide contamination in Dilek National Park, Turkey

National parks are used worldwide as a means to protect the ecological integrity of unique ecosystems. Dilek National Park in western Turkey is a protected habitat for several endangered and severely threatened species. Thirty-seven water and 59 sediment samples were collected and analyzed for pesticides at two different sampling depths. The park is contaminated with 16 different organochlorine pesticides, with more pesticides detected in sediments than in water. The most prevalent pesticides in the 30-60-cm depth were DDT (69.5% of the samples), heptachlor (62.3%), a-endosulfan (55% of samples), and endrin (37%). Lindane isomers were present, but at <30% of the sediment samples. These pesticides could be a long-term contamination source that enters the food web used by the very species the park is trying to protect.

Factors affecting HCH and DDT in soils around watersheds of Beijing reservoirs, China

The factors that influence the dynamics of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) in soils around the watersheds of Beijing reservoirs were examined. Compared with other studies on HCH and DDT in soils and established reference values, the concentrations of HCH and DDT in soils around our study area were relatively low. The relationships between HCH and DDT concentrations and land use, soil texture, and soil properties were discussed. HCH and DDT concentrations were higher in arable soils than those in uncultivated fallow soils. Although land use was the most important factor affecting HCH and DDT residues, additional factors such as soil texture and soil total organic carbon were also involved in pesticide retention in soils. The results indicated that the historical agricultural applications of HCH and DDT were the major source of their residues. Atmospheric deposition, as well as long-distance transportation and inputs from surrounding weathered agricultural soils may also serve as important sources of HCH and DDT residues in the watersheds.

Hexachlorobenzene sources, levels and human exposure in the environment of China

This article summarizes the published scientific data on sources, levels and human exposure of hexachlorobenzene (HCB) in China. Potential sources of unintended HCB emission were assessed by production information, emission factors and environmental policies. HCB was observed in various environmental compartments in China. HCB levels increased from South China to North China in most of environmental compartments (air, soil and mussel). Some hotspots were identified near the factories producing and using HCB. In terms of spatial distribution, HCB concentrations in air and shellfish showed much variation, which indicated some primary emission sources in China. HCB levels in air and human milk in China were relatively higher than those in other countries, but HCB levels in other compartments were similar to those in Europe and other countries in Eastern Asia. In the limited studies on temporal trends of HCB levels in China, HCB concentrations in air, sediment, fish and human milk did not show a consistent downward trend. Although HCB levels in food and human milk does not pose a health risk in China at present, long-term exposure to HCB should not be overlooked.

Modelling historical budget of alpha-hexachlorocyclohexane in Taihu Lake, China

Historical alpha-hexachlorocyclohexane (alpha-HCH) budget in Taihu Lake (TL), China has been simulated by a Gridded Basin-based Pesticide Mass Balance Model (GB-PMBM). Using annual usage of alpha-HCH from 1952 to 1984 as input, the model outputs included annual concentrations in air, water and sediment in TL, and annual cumulative burden of alpha-HCH in the lake water and sediment from 1952 to 2008. Model results showed that the modeled alpha-HCH in the air, water and sediment matched their corresponding measured data well, and the current levels of alpha-HCH in the air, water and sediment in TL in 2008 are 11.7 (3.4-22.7) pgm(-3), 0.8 (0.3-1.5) ng L(-1) and 0.18 (0.04-0.46) ng g(-1)dw (dry weight), respectively. The alpha-HCH burden in TL water started to accumulate after 1952, reached the highest value of 11,000kg in 1972, decreased very quickly since the beginning of 1980s, reduced to 200 kg in 1984 and 3 kg in 2008. It was found that TL water played a role of "distributor" in process of transport of alpha-HCH. Before 1980, TL water took a large amount of alpha-HCH from atmosphere through a huge air-water interface and carried a major portion of it out of the lake through water current. After 1980, TL water took alpha-HCH from lake sediments and river water entering the lake, and released almost all of it to air. The lake water itself cannot hold a large portion of the chemical due to its shallow depth and short residence time.

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.

Endosulfan in China 2-emissions and residues

BACKGROUND, AIM, AND SCOPE

Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4 degrees longitude by 1/6 degrees latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan.

METHODS

Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model-SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined.

RESULTS AND DISCUSSION

Historical gridded emission and residue inventories of alpha- and beta-endosulfan in agricultural soil in China with 1/4 degrees longitude by 1/6 degrees latitude resolution have been created. Total emissions were around 10,800 t, with alpha-endosulfan at 7,400 t and beta-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for alpha-endosulfan and 390 t for beta-endosulfan, and the lowest residues were 0.7 t for alpha-endosulfan and 170 t for beta-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of alpha- and beta-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data.

CONCLUSIONS

To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general.

RECOMMENDATIONS AND PERSPECTIVES

The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.

Assessment of the genotoxicity of endosulfan in earthworm and white clover plants using the comet assay

Endosulfan, as one of the most widely used organochlorine pesticides in the world, has increased the public concern about genotoxicity in soil ecosystems. The comet assay has been widely used in the fields of genetic toxicology and environmental biomonitoring. In the present study we conducted comet assay of endosulfan in earthworm (Eisenia foetida) and white clover (Trifolium repens L.), which are sensitive organisms suitable for acting as a bioindicator for agricultural ecosystems. Earthworms were exposed to endosulfan concentrations of 0.1, 1.0, and 10.0 mg/kg in the soil. White clover roots were immersed in hydroponic pots containing nutrient solutions of different endosulfan concentrations: 0.1, 1.0, and 10.0 mg/L. Tissues from each treatment were collected on the 7th, 14th, 21st, and 28th days of treatment process. Significant effects (p < 0.01) of both concentrations and times of exposure were observed. And endosulfan induced DNA damage in earthworm and white clover nuclei. The comet assay can be used as a reliable tool for early detection of endosulfan.

Levels, distributions, and source identification of organochlorine pesticides in the topsoils in Northeastern China

Seventeen topsoil samples (9 urban, 4 suburban, 3 rural and 1 background) were collected in/around Harbin, a typical city in northeast of China, to measure concentration levels of organocholrine pesticides (OCPs) in topsoil of Northeastern China in 2006. Hexachlorohexanes (HCH), dichlorodiphenyltrichloroethane (DDT), and hexachlorobenzene (HCB) were detected in soil samples with mean concentrations (in pg/g dry weight (dw)) of 7120, 5425, and 1039, respectively. The mean concentrations for other OCPs were very low, 4.8 pg/g dw for chlordane and 3.3 pg/g dw for endosulfan. Source identification analysis reveals that all OCPs found in soil samples were due to historical use of these chemicals or from other source regions through long- and short-range atmospheric transport. DDT was mainly used in the rural sites, whereas the sources of HCB, chlordane and endosulfan were mainly in the urban area. HCH was found almost equally in both urban and rural area. Soil concentrations of all detected OCPs, except HCHs, in and around Harbin were much lower than those in the southeast of China, which is expected since the use of these OCPs in the former was much lower than that in the latter, however higher HCH concentrations in and around Harbin than those found in most places of the Southeast China is not expected. It is suggested that high HCH concentration in soil of Northeast China was most likely due to long-range atmospheric transport (LRAT) from Southeast China and the cold condensation process.

Effect of land use change from paddy to vegetable field on the residues of organochlorine pesticides in soils

The effect of land use change from paddy to vegetable field on the residues of organochlorine pesticides (OCPs) was investigated. Soil residues of OCPs were analyzed in vegetable fields which had been converted from paddy fields for 0, 5, 10, 15, 20, 30, 50 year in Yixing, China in 2003. The mean concentrations of OCPs followed a sequence of: SigmaDDTs (13.7 microg kg(-1))> SigmaHCHs (8.6 microg kg(-1)) >>HCB (2.09 microg kg(-1))>alpha-endosulfan (1.30 microg kg(-1))>endrin (1.08 microg kg(-1))>PCNB (0.76 microg kg(-1))>dieldrin (0.58 microg kg(-1)). The mean residues of OCPs especially DDTs increased significantly with vegetable planting time after land use change in the first 15 years, then decreased from 20 to 30 years and increased a little afterward. The time under anaerobic and aerobic conditions was suggested to control mainly the change of the residues of OCPs.

Residues of organochlorine pesticides in surface soils from college school yards in Beijing, China

Organochlorine pesticides (OCPs) have been a major environmental issue, attracting much scientific concern because of their nature of toxicity, persistence, and endocrine disrupting effects. Soil samples were collected from ten college school yards in Beijing in 2006 and analyzed to determine fifteen OCPs. Dichlorodiphenyltrichloroethanes (DDTs) were found to be the main pollutants, accounting for 93.70% of total OCPs, followed by hexachlorohexanes (HCHs) (2.25%) and hexachlorobenzene (HCB) (1.82%). Content of chlordanes (CHLs), heptachlors (HEPTs), and endosulfans comprised 0.51%, 1.05%, and 0.79% of fifteen OCPs, respectively. The preliminary pollution assessment indicated that DDTs have caused high OCPs levels in some schools. Source identification showed that HCHs in soils were originated from an old mixed source of technical HCHs and lindane. And DDTs were mainly from mixed use of technical DDTs and dicofol containing DDT impurities. According to GB15618-1995 (guidelines of Chinese environmental quality standards for soils), HCHs and DDTs levels might be categorized as little and low polluting pesticides. This study indicated that the environmental quality of college school yards with large green land were not as good as was expected and there existed potential exposure risk of college population to OCPs.