Spatial distribution of organochlorine pesticides (OCPs) and effect of soil characters: A case study of a pesticide producing factory

The distribution and concentration of some organochlorine pesticides (OCPs) in the soil around a pesticide factory in Zibo, China, were examined, including dichlorodiphenyltrichloroethane (DDT) and its metabolites, isomers of hexachlorocyclohexane (HCH) and endosulfan (ENDO). The results showed that the OCPs concentrations were extraordinary high in this region. The concentrations of DDTs, HCHs, and ENDO were measured in the range of 0.775–226.711, 0.248–42.838, and 0.081–1.644 mg kg^?1, respectively. DDT and its isomers were identified to be the dominate contaminants in most of the sampling sites. In the vertical direction, the distribution pattern of the total OCPs was in order of DDTs, HCHs, and ENDO in the 0–20 cm, but in 20–40 and 40–60 cm the trends were unobvious. Although no recent input occurred in most areas, the residues of OCPs remained in deep soil due to their persistence. Unlike ENDO, DDTs and HCHs appeared to have the similar property in terms of not only the migration pattern in soil, but also the relationship to the same dominant impact factor (i.e. organic matter). DDTs and HCHs were affected positively by the organic matter, whereas ENDO was affected negatively. Due to the interrelationship among various impact factors, the spatial distribution of pesticides in the soil was considered to be a combined result.     

Persistent organochlorine pesticide and PCB residues in surface sediments of Lake Qarun,a protected area of Egypt

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in sediment samples collected from 34 locations in Lake Qarun, Egypt to elucidate their concentrations, distribution, possible sources and potential ecological risk. A total of 25 OCPs and 29 PCBs were identified and quantified. OCPs and PCBs were found to be ubiquitous pollutants in the aquatic environment of Lake Qarun, particular near urban areas reflecting the local usage and input of these pollutants. Total concentrations of OCPs and PCBs in sediments ranged from 1.01 to 164.8 ng g^?1 and 1.48 to 137.2 ng g^?1, respectively. Among OCPs, γ-HCH, heptachlor, aldrin, endrin, p,p′-DDE, oxy-chlordane and endosulfan I and II were the most abundant compounds. The composition of PCB congeners was dominated by the tri-, tetra-, penta- and hexa-chlorinated biphenyls. The ratios of certain metabolites (isomers) to their parent compounds (mixtures) indicated there are still new inputs of lindane, endrin, heptachlor and technical endosulfan to Qarun Lake, while the ratios of (p,p′-DDE + p,p′-DDD)/∑p,p′-DDTs indicate earlier usage of DDT. Contamination levels of PCBs and HCHs can be categorized as moderate to high compared to other urbanized regions worldwide. According to established sediment quality guidelines, γ-HCH, endrin and chlordanes would be more concerned OCP species for the ecotoxicological risk in Lake Qarun.     

Concentrations and distributions of 18 organochlorine pesticides listed in the Stockholm Convention in surface sediments from the Liaohe River basin,China

Organochlorine pesticides (OCPs) were analyzed in 26 surface sediment samples from the Liaohe River basin, and the distributions of and potential environmental risks posed by OCPs in the basin were evaluated. Eighteen OCPs listed in the Stockholm Convention were determined using isotope-dilution gas chromatography–high resolution mass spectrometry. This is the first study of hexachlorobenzene (HCB) in the Liaohe River basin sediments. The total OCP concentrations were 0.39–68.06 ng g^?1 dry weight. The total α-, β-, γ-, and δ-hexachlorocyclohexane (HCH), the total dichlorodiphenyltrichloroethane (DDT – p,p′-dichlorodiphenyldichloroethane (DDD), p,p′-dichlorodiphenyldichloroethylene (DDE), o,p^'-DDT, and p,p′-DDT), and the HCB concentrations in the sediment samples were 0.1–28.48 ng g^?1 (mean 4.01 ng g^?1), 0.08–6.52 ng g^?1 (mean 3.07 ng g^?1), and 0.18–24.8 ng g^?1 (mean 4.38 ng g^?1), respectively. The HCB concentrations were higher than the concentrations of the other OCPs, and the HCHs and HCB together were the dominant OCPs. β-HCH was the most abundant HCH isomer. The concentrations of DDTs and other OCPs were relatively low, and the (DDE+DDD)/DDT ratios (>0.5) and DDD/DDE ratios (<1) indicated that no recent DDT inputs had occurred in the Liaohe River system. The main sources of HCHs were probably the historical production and agricultural use of HCH in the study area. The DDT and HCH concentrations were generally below or similar to the concentrations that have been found in other parts of the world. An ecotoxicological evaluation indicated that HCHs in surface sediments pose slight risks to human and ecological health in the Liaohe River basin.     

Organochlorine pesticides in the atmosphere of Guangzhou and Hong Kong: Regional sources and long-range atmospheric transport

Organochlorine pesticides (OCPs) were measured in the atmosphere over the period of December 2003–December 2004 at four sampling sites in Guangzhou and Hong Kong. Gas phase and particle phase concentrations of 8 OCP species, including trans-chlordane (t-CHL), cis-chlordane (c-CHL), p,p′-DDT, p,p′-DDE, o,p′-DDT, α-endosulfan, α- and γ-hexachlorocyclohexane (HCH), were studied. OCPs were found predominantly in the gas phase in all seasons. t-CHL, c-CHL, o,p′-DDT, p,p′-DDT and α-endosulfan had significantly (p<0.001) higher concentrations than other OCPs, with mean values (gas+particle) typically ranging from 103 to 1440 pg m⁻³. In general, the concentrations of OCPs in summer were higher than that in winter, except for α-HCH which showed no clear seasonal pattern. Higher levels of γ-HCH and o,p′-DDT found in Guangzhou could be attributed to the present usage of lindane and dicofol in the Pearl River Delta (PRD) region. The very high concentrations of p,p′-DDT and α-endosulfan were observed at all sampling sites. The results of 7 days air back trajectory analysis indicated that the unusual high p,p′-DDT levels in summer in both cities could be related to the seasonal usage of DDT containing antifouling paints for fishing ships in the upwind seaports of the region. The high concentrations of α-endosulfan in winter in the study area suggested an atmospheric transport by the winter monsoon from the East China, where endosulfan is being used as insecticide in cotton fields. The consistency of the seasonal variation of concentrations and isomeric ratios of DDTs and α-endosulfan with the alternation of winter monsoon and summer monsoon suggested that the Asian monsoon plays an important role in the long-range atmospheric transport of OCPs.     

Organochlorine pesticide residues in maternal blood,cord blood,placenta, and breastmilk and their relation to birth size

There is a growing concern that persistent organic pollutants like organochlorine pesticides (OCPs) can impair fetal growth and affect birth size. However, currently available epidemiological evidence is inconclusive. In this case-control study, we examined the association between exposure to hexachlorocyclohexane (HCH) and its isomers (α-HCH, β-HCH and γ-HCH), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) and birth size. We recruited 60 infant-mother pairs, comprising of 30 term, small for gestational age babies with their mothers (Case group), and another 30 term, appropriate for gestational age babies with their mothers (Control group). This study was conducted in a tertiary hospital in Delhi, India, between March, 2009 and February 2010. Organochlorine pesticides were estimated in maternal blood, cord blood, placenta and breastmilk samples, using gas–liquid chromatography. Transplacental and transmammary transfer of OCPs was assessed by correlating the maternal blood OCP levels with those in cord blood and breastmilk by simple linear regression. The birthweight, crown heel length, head circumference, mid-arm circumference and ponderal index of the neonates was correlated with OCP levels in the maternal blood, cord blood, placenta and breastmilk. The OCP estimates were compared between samples of the case and control group. There was a significant (P < 0.001) transplacental transfer of all OCPs, however the transmammary transfer was insignificant for most OCPs except α-HCH. The OCP levels in the case group were higher than the control group; these were significantly more for t-HCH in cord blood and breastmilk; β-HCH in maternal blood, cord blood and breastmilk; DDE in placenta and DDT in breastmilk. There was a significant negative correlation between birthweight and t-HCH levels in maternal blood (P = 0.022), cord blood (P < 0.001), placenta (P = 0.008) and breastmilk (P = 0.005); β-HCH in cord blood (P < 0.001) and placenta (P = 0.020); γ-HCH in placenta (P = 0.045); and DDT (P = 0.009). Length at birth had a significant negative correlation with t-HCH in cord blood (P = 0.014) and breastmilk (P < 0.001); β-HCH in cord blood (P = 0.016) and breastmilk (P = 0.012); DDE in placenta (P = 0.016); and DDT in breastmilk (P = 0.006). Similarly, OCP levels were also found to be negatively correlated with head circumference, ponderal index and chest circumference in neonates. We conclude that prenatal exposure to some OCPs could impair the anthropometric development of the fetus, reducing the birthweight, length, head circumference, chest circumference and ponderal index.     

Variations of organochlorine pesticides and polychlorinated biphenyls in atmosphere of the Tibetan Plateau: Role of the monsoon system

Monsoon transport is an important process that influences the global transport of persistent organic pollutants. Only a few studies focused on the influence of monsoon on organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) levels in the Tibetan Plateau. In this study, 19 samples were collected in Lhasa, the capital of Tibet Autonomous Region, using a high-volume air sampler. The average concentrations of α-HCH, γ-HCH, p-p′-DDT, p-p′-DDE, o-p′-DDT, α-endosulfan, β-endosulfan and PCBs (including PCB-28, 101, and 118) were 2.3, 10.3, 3.2, 2.9, 5.8, 6.3, 2.2, and 10.6 pg m^?3, respectively. The weak correlation coefficients between lnp (natural logarithm of partial pressure) and 1/T (reciprocal temperature) were obtained for DDTs and β-endosulfan (r² values ranged from 0.13 to 0.41). However, no significant correlations were obtained for HCHs and PCBs. These results suggested that both local emission and long-range atmospheric transport (monsoon) may influence the distribution of OCPs at Lhasa. In this study, peak concentrations of DDTs, endosulfans and PCBs were found in August, when Eastern Monsoon system occurred. However, the maximum concentrations of HCHs appeared in June (Indian Monsoon is the dominant air circulation pattern). Monthly variation of OCP/PCB levels was likely associated with the different air sources of monsoon system.     

Atmospheric deposition of organochlorine contaminants to Galveston Bay,Texas

Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB (tPCB) concentrations in air ranged from 0.21 to 4.78 ng m⁻³ with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l⁻¹, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4′-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m⁻² yr⁻¹) was significantly higher than that of pesticides by a factor of 5–10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m⁻² yr⁻¹). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux.     

Organochlorine pesticides and polychlorinated biphenyls in soil and water samples in the Northeastern part of São Paulo State,Brazil

Detailed analyses of persistent organic pollutants (POPs) such as organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs) and congeners of polychlorinated biphenyls (PCBs) in soil and surface water from the northeastern São Paulo, Brazil allowed the evaluation of the contamination status, distribution and possible pollution sources. The pesticides and PCBs demonstrated markedly different distributions, reflecting different agricultural, domestic and industrial usage in each region studied. The ranges of HCH, DDT, and PCBs concentrations in the soil samples were 0.05–0.92, 0.12–11.01, 0.02–0.25 ng g⁻¹ dry wt, respectively, and in the surface water samples were 0.02–0.6, 0.02–0.58 and 0.02–0.5 ng l⁻¹, respectively. Overall elevated levels of DDT and PCB were recorded in region 2, a site very close to melting, automotive batteries industries, and agricultural practice regions. High ratios of metabolites of DDT to DDT isomers revealed the recent use of DDT in this environment. The sources of contamination are closely related to human activities, such as domestic and industrial discharge, street runoff, agricultural pesticides and soil erosion, due to deforestation as well as atmospheric transport.     

Organochlorine pesticides and polybrominated diphenyl ethers in irrigated soils of Beijing, China: Levels, inventory and fate

Limited information on the levels, inventory and fate of Organochlorine pesticides (OCPs) and Polybrominated diphenyl ethers (PBDEs) in the soils irrigated by sewage or wastewater is available. In this study, variation in concentrations, profiles and fate of OCPs and PBDEs were investigated using soil samples collected from a region irrigated by sewage, mixed water and clean water in the east of Beijing, China. No significant variation was observed among groups, except for penta-BDEs. The measured ΣOCPs and ΣPBDEs residues ranged from 6.4 to 171.2 ng g⁻¹ (dw) and 501.9 to 3310.7 pg g⁻¹ (dw), respectively. ΣDDTs and BDE-209 were the most abundant congeners accounting for about 76% of ΣOCPs and 93% of ΣPBDEs. Concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDTs) and its major degradation products, and hexachlorobenzene (HCB) ranged from 1.2 to 11.4 ng g⁻¹ (dw), 4.0 to 155.6 ng g⁻¹ (dw) and 0.3 to 3.4 ng g⁻¹ (dw), respectively. The major DDT degradation products were p,p′-DDT and p,p′-DDE. The major hexachlorocyclohexane (HCH) isomer in irrigated soils is β-HCH, reflecting its higher affinity to solids and resistance to degradation than other isomers. Both α-HCH/β-HCH and p,p′-DDT/p,p′-DDE ratios were log-normally distributed and negatively correlated to log(ΣHCHs) and log(ΣDDTs), respectively, suggesting no significant recent application of OCPs. Individual BDE congeners, ΣPBDEs and ΣOCPs were significantly correlated with total organic carbon (TOC). Moreover, a good correlationship between ΣPBDEs and black carbon (BC) was obtained but not between ΣOCPs and BC. Sewage irrigation did not have obvious effect on their contaminant levels and inventory of OCPs and PBDEs.     

Concentrations of organochlorine pesticides (OCPs) residues in foodstuffs collected from traditional markets in Indonesia

A total 23 of organochlorine pesticides (OCPs) residues were determined in five groups of foodstuffs, i.e.: vegetables (carrot, potato, cucumber, corn, and onion), rice, pulses (green bean and soybean), nuts (peanut), and fish (milkfish), which collected from traditional markets in three big cities of Indonesia; Jakarta, Bogor, and Yogyakarta. OCPs were only detected in fatty foodstuffs, such as soybean, peanut, and milkfish. The concentration of HCB (expressed as ng g^?1 on a whole basis), ΣDrins, ΣDDTs, ΣHeptachlors, and ΣHCHs were in the range of <0.3–0.74 ng g^?1, <0.03–0.42 ng g^?1, <0.02–0.41 ng g^?1, <0.03–0.14 ng g^?1, and <0.03–0.06 ng g^?1, respectively, which were far below the maximum residue limits (MRLs) as established by FAO/WHO. These very low concentrations of OCPs residues in foodstuffs indicated that OCPs were used only in past time and no recent input into the environment. Furthermore, the estimated daily intake (EDI) of HCB, ΣDDTs, ΣDrins, ΣHeptachlors, and ΣHCHs in five group foodstuffs, which were 60% of total daily diet of Indonesian, were 0.09 ng kg^?1 bw d^?1, 0.04 ng kg^?1 bw d^?1, 0.01 ng kg^?1 bw d^?1, 0.003 ng kg^?1 bw d^?1, and 0.002 ng kg^?1 bw d^?1, respectively. These results were far below the acceptable daily intake (ADI) as established by FAO/WHO, which indicated that consumption of foodstuffs from Indonesia were at little risk to human health in term of OCPs at present.     

Distribution and change of DDT and HCH levels in oysters (Crassostrea rivularis) from coast of Guangdong,China between 2003 and 2007

This investigation was undertaken to understand the temporal trend, the spatial distribution and the residue level of dichloro-diphenyl-trichloroethanes (DDTs) and hexachlorobenzenes(HCHs) in bivalves from the coast of the South China in recent years. Jinjiang oysters (Crassostrea rivularis) were sampled from 15 bays along the coast of Guangdong province, China between 2003 and 2007. Gas chromatography with electron capture detector was used to quantify the contents of HCH isomers (α-, β-, γ-, δ-HCH), DDT isomers (p,p′-, o,p′-DDT), p,p′-DDD and p,p′-DDE in the oyster tissues. The results demonstrate that annual level of DDTs in the tissue increase throughout the study, particularly between 2004 and 2006. The DDTs content in the tissue varied significantly among sampling regions and some sampling sites (p < 0.05). On the other hand, the HCHs content was significantly lower than DDTs content in the tissue (p < 0.01), and remain constant among sampling years, sampling regions and sampling sites (p > 0.10). Predominance of isomer form of DDTs and higher ratio of γ-HCH/HCHs at some sites indicated that recent input of DDT and lindane in the coastal waters of Guangdong, which might be caused by dicofol spraying in crop planting and lacquer painting on fisher boat. In the soft tissues of the oysters, the highest content of HCHs was 1.21 ng/g (wet weight), and DDTs levels ranged from 0.11 ng/g to 76.3 ng/g (wet weight), far below the Maximum Residual Limits in China and many developed nations.     

Distribution characteristics of organochlorine pesticides in surface and vertical sediments from the Zha Long Wetland, China

Introduction

The Zha Long Wetland, the first water bird conservation area in China, lies on the northern bank of the Song Nen Plain with an area of 2,100 km². In many areas of the Zha Long Wetland, water pollution has led to a decrease in the wetland??s ecological function, vegetation degradation, a decrease in the number of bird species, and the depletion of fish resources.

Materials and methods

The sediments used in this study were collected from the surface sediment of seven sites and from different depths in three types of marshes in the Zha Long Wetland in northeast China in late October 2006. The levels and distribution patterns of 17 organochlorine pesticides (OCPs; ??-HCH, ??-HCH, ??-HCH, ??-HCH, p,p??-DDE, p,p??-DDD, p,p??-DDT, endosulfan I, endosulfan II, endosulfan sulfate, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, and methoxychlor) in surface sediments as well as hexachlorocyclohexane (HCH) and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) in vertical sediments were investigated.

Results and discussion

The concentrations of HCHs, DDTs, endosulfans, heptachlors, aldrin, and methoxychlor in surface sediments ranged from 10.44 to 41.97 ng/g, nd (undetectable levels) to 211.88 ng/g, nd to 69.89 ng/g, nd to 28.10 ng/g, 9.81 to 623.83 ng/g, and from nd to 3.99 ng/g, respectively. The highest levels of OCPs were detected in Tangtugangzi at a total concentration of 727.72 ng/g, where the dominant compound was endrin at a concentration of 483.04 ng/g. In the vertical sediments, the HCHs and DDTs were in the ranges of nd?C136.00 and nd?C214.06 ng/g, respectively.

Conclusions

Different distributions of HCHs, DDTs, and other OCPs indicated that they originated from different contamination sources. Composition analyses in surface sediments indicated recent OCP usage or discharge at some sample sites in the Zha Long Wetland.     

Sequestration of organochlorine pesticides in soils of distinct organic carbon content

In the present study, five soil samples with organic carbon contents ranging from 0.23% to 7.1% and aged with technical dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) for 15 months were incubated in a sealed chamber to investigate the dynamic changes of the OCP residues. The residues in the soils decreased over the incubation period and finally reached a plateau. Regression analysis showed that degradable fractions of OCPs were negatively correlated with soil organic carbon (SOC) except for α-HCH, while no correlation was found between degradation rate and SOC, which demonstrated that SOC content determines the OCP sequestration fraction in soil. Analysis of the ratio of DDT and its primary metabolites showed that, since it depends on differential sequestration among them, magnitude of (p,p′-DDE + p,p′-DDD)/p,p′-DDT is not a reliable criterion for the identification of new DDT sources.     

Distribution and ecological risk assessment of organochlorine pesticides in surface sediments from the East Lake,China

Organochlorine pesticides (OCPs) are ubiquitous pollutants, and their presence in urban lakes is a concern for human and ecological health. Surface sediments in the East Lake, China, were collected in winter 2012 and summer 2013 to investigate concentrations, distribution patterns, possible sources, and potential ecological risks of OCPs in this area. The total concentrations of 14 OCPs ranged from 6.3 to 400 ng g^?1 dry weight (dw) with an average concentration of 79 ng g^?1 dw. The mean values of hexachlorocyclohexanes (HCHs) (α-, β-, γ-, and δ-HCH) and dichlorodiphenyltrichloroethanes (DDTs) (p,p’-DDE, p,p’-DDD, and p,p’-DDT) were 36 and 7.6 ng g^?1 dw, accounting for 45 and 10 % of the total OCPs, respectively. The concentrations of OCPs in sediment samples collected in winter were significantly higher than those in summer, especially the HCHs, of which in winter were two times greater than summer. Composition analyses indicated that DDTs and endosulfan were mainly from historical contribution. Historical use of technical HCH and new input of lindane were probably the source of HCHs in the East Lake. Most sampling sites of HCHs and DDTs were found to have the potential ecological risk based on levels specified in the sediment quality standards.     

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.     

Concentrations,distributions, sources,and risk assessment of organochlorine pesticides in surface water of the East Lake,China

East Lake resides in the urban area of Wuhan City and is the largest urban lake in China. The concentrations of 16 organochlorine pesticides (OCPs) were analyzed in 108 surface water samples collected from the East Lake. The total concentrations of OCPs ranged from not detected to 120 ng L^?1 with predominance of δ-HCH, heptachlor, and α-HCH. The mean values of HCHs and DDTs were 7.40 and 5.70 ng L^?1, respectively, accounting for 40 and 31 % of the total OCPs. For the five lakelets in East Lake, Houhu Lake exhibited the highest concentrations of HCHs, DDTs, and total OCPs, which has been used actively for fisheries and surrounded by suburban rural areas and farmlands. Historical lindane or technical HCH input was probably the source of HCH, while technical DDTs might be the source of DDT in the East Lake. The ratio between heptachlor and its metabolic products indicated recent input of heptachlor. Although the combining ecological risks for all aquatic species in the East Lake calculated by species sensitivity distribution reached approximately 10^?5, the OCPs in the East Lake had slight effects on aquatic organisms. The carcinogenic risks and non-carcinogenic hazard indices of DDTs and HCHs indicated that water in the East Lake was not suitable as water sources for human. However, the results indicated the water quality was safe for people to swim in the urban lake.     

The residues, distribution, and partition of organochlorine pesticides in the water, suspended solids, and sediments from a large Chinese lake (Lake Chaohu) during the high water level period

The levels of organochlorine pesticides (OCPs) in the water, suspended solids, and sediments from Lake Chaohu during the high water level period were measured by a solid-phase extraction gas chromatograph–electron capture detector. The spatial distributions of the three phases and the water/suspended solids and sediment/water partition coefficients were analyzed. The results showed the following: (1) The mean contents of OCPs in the water, suspended solids, and sediments were 132.4?±?432.1 ng/L, 188.1?±?286.7 ng/g dry weight (dw), and 13.7?±?9.8 ng/g dw, respectively. The dominant OCP components were isodrin (85.1 %) for the water, DDTs (64.4 %) for the suspended solids, and both isodrin (48.5 %) and DDTs (31.8 %) for the sediments. (2) β-HCH was the primary isomer of HCHs in the water and sediments, and the proportions were 61.7 and 41.3 %; γ-HCH was the primary isomer in the suspended solids, accounting for 49.3 %; p,p′-DDT was the dominant content of DDTs in the water and suspended solids, whereas p,p′-DDD was the main metabolite of DDTs in the sediments. (3) The concentrations of contaminants in the water from the western lake were greater than those from the eastern lake, but the concentrations in the suspended solids from the western lake were less than those from the eastern lake. (4) There was no significant correlation between the water–suspended solids partition coefficient K _d and the n-octanol–water partition coefficient K _ow, and between the sediment–water organic-C weighted sorption coefficients K _oc and K _ow.     

Levels of persistent organic pollutants in air in China and over the Yellow Sea

The occurrence of persistent toxic substances (PTS) in China and possibly their regional transport in the Yellow and East China Seas region was studied. Organochlorines in atmospheric gas-phase and particulate matter were collected by high-volume sampling (filters and polyurethane foams) during 2 weeks in June 2003 (dry season) simultaneously at a Yellow Sea coastal site in an urban area, Qingdao, China, and a rural island site, Gosan, Jeju Island, Korea. Using GC methods, the samples were analysed for 9 persistent organic pollutants (POPs) regulated under the global POP convention, namely aldrin, chlordane (cis- and trans-isomers CC and TC), DDT and metabolites (o,p′-DDT, p,p′-DDD, and p,p′-DDE), dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex and PCB (congeners number 28, 52, 101, 153 and 180), and for hexachlorocyclohexane (α-, β- and γ-isomers), a PTS and now considered for regulation under the convention, too. At the coastal site additionally o,p′-DDE and -DDD, β-endosulfan, isodrin, heptachlorepoxide and δ-HCH, and at the island site additionally p,p′-DDT and 12 additional PCB congeners were analysed. 9 samples were collected at the coastal and 15 (for PCBs 5) at the island site. Long-range advection pathways were determined based on analysed back-trajectory calculations.The mean concentrations of DDT and its metabolites, HCB, HCH, and PCB at the coast were in the 100–1000 pg m⁻³ range. Higher concentrations prevailed during nighttime. The levels were in general lower at the island site, but not for DDT. Local sources are likely. PCBs were even 2 orders of magnitude lower, suggesting that PCBs are not subject to regional transport but elevated concentrations in air are limited to the source areas. Organochlorine pesticide levels on the other hand were seemingly determined by regional transport over Mainland China rather than by emissions in the coastal area. The currently used pesticides mirex and chlordane were found at elevated levels, i.e. 79 (6.6–255) and 36 (<6–71) pg m⁻³, respectively, at the coast but not over the island. The POPs pesticides aldrin, dieldrin and endrin, never registered in China, were mostly found at <10 pg m⁻³ except for endrin at the coastal site (up to 400 pg m⁻³) and aldrin at the island site (up to 50 pg m⁻³).     

Distribution and bioaccumulation of organochlorine pesticides in surface sediments and benthic organisms from Taihu Lake, China

The spatial distribution and bioaccumulation of organochlorine pesticides (OCPs) in surface sediments and benthic organisms from Taihu Lake were studied. OCPs were detected in all sediment samples with total concentrations ranging from 4.22 to 461 ng g⁻¹ dry weight (dw). The ratios of certain metabolites to their parent compounds indicated there are still new inputs of parent DDT (dichlorodiphenyltrichloroethane) to Taihu Lake, while the highest residues of HCHs (hexachlorocyclohexanes) mainly came from earlier usage and fresh γ-HCH (lindane). No positive correlation was found between the distribution of OCPs and organic matter contents in sediments. Concentrations of OCPs and lipids in typical large benthic organisms, Bellamya aeruginosa (B. aeruginosa) and Corbicula fluminea (C. fluminea), increased with body weight. HCHs, DDTs, chlordanes and heptachlors were the dominant compounds detected in organisms and C. fluminea accumulated much more OCP than B. aeruginosa. Higher values of biota-sediment accumulation factor (BSAF) were detected in C. fluminea, which was both affected by biological characteristics of the organisms and physicochemical properties of the compounds.     

Analysis of organochlorine pesticide residues in human and cow’s milk in the towns of Asendabo,Serbo and Jimma in South-Western Ethiopia

The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-West Ethiopia were analyzed using GC–ECD. Results of the analysis indicated that all samples contained detectable quantities of p,p′-DDT and its metabolites, p,p-DDE and p,p-DDD, but none of the other OCPs analyzed. Mean levels of total DDT in the human and cow milk samples in the three areas were 12.68 and 0.389 μg g^?1 respectively. The distributions of p,p-DDT, p,p-DDE and p,p-DDD in the human milk samples from the three locations followed the same trend in which the proportion of p,p-DDT was the highest in all the three cases, comprising 55–71% of total DDT, followed by p,p-DDE, 26–39%, and the least, p,p-DDD of 2–5%. The mean ratio of DDT/DDE concentration for the three areas was calculated to be 2.01. This value was much higher than the values reported from other countries in earlier studies and indicates the existence of a higher quantity of DDT from a fresh input in the three study areas. The mean estimated daily intake of DDT by infants from mother’s milk in the three locations was found to be 62.17 μg kg^?1 body weight, which is about three times higher than the acceptable daily intake set by WHO/FAO for total DDT, 20 μg kg^?1 of body weight. This alarmingly high daily intake value is a cause for concern, since children are highly susceptible to effects from such environmental contaminants. The study has revealed that people in the study areas are facing exposure to DDT from recent use. The observed contamination of mother’s milk and the possible transfer of the contaminant from mother to child is an obvious risk associated with breast-feeding in the study areas and possibly in other parts of the country too.