Distribution and sources of organochlorine pesticides in sediments of the Xiangjiang River, south-central China

The Xiangjiang River (XR), the second largest tributary of the Yangtze River, is mainly located in Hunan province in south-central China. Nineteen surface sediment samples (the top 3-cm layer) collected from XR were analyzed to determine the concentrations, distribution, sources, and ecological risk of organochlorine pesticides (OCPs). The concentrations of OCPs were 3.0–29.8 ng/g (dry weight) with a mean of 12.6?±?7.7 ng/g. The widely detected compounds included HCHs, DDTs, HCB, and dieldrin. Overall, the dominant OCPs in the sediments were mainly composed of residual and degradation products, e.g., β-HCH with a mean of 42.2 % in HCHs and p,p′-DDE with a mean of 43.5 % in DDTs, implying that OCPs in the sediments had suffered from long-term aging without fresh inputs in XR. However, there was a high proportion of p,p′-DDT to DDTs in three sites, suggesting that there was use of technical DDT from their surrounding areas at present. The ratios of α-HCH/γ-HCH and p,p′-DDD?+?p,p′-DDE/DDTs increase from the upper reaches to the lower reaches of XR, suggesting sediments enriched with α-HCH and metabolites DDD and DDE during sediment transport process and could be attributed to the transformation of γ-HCH to α-HCH and DDT to DDE or DDD. The assessment of the ecological risk indicates that the OCPs in the sediments of XR have a moderate adverse biological effect on organisms.     

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?Celectron 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 ??-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, ??-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 ??-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 ??m). The concentrations of OCPs were affected by salinity.     

Levels and source of organochlorine pesticides in surface waters of Qiantang River, China

Qiantang River is a typical river used for drinking water source, flowing through agricultural area in east China. Surface water samples at 45 sampling sites from the river were collected and analyzed for 13 organochlorine pesticides (OCPs) during six surveys in 2 years of 2005–2006. Sediments, soils, farmland runoff water and dry/wet deposition of this region were also measured for their OCPs residue in order to know possible source of OCPs contamination. The total OCPs concentrations in surface water were 7.68–615.2 ng/l. β-HCH, δ-HCH, Aldrin, Heptachlor, Heptachlor epoxide are the major OCPs in water. The maximum levels of OCPs in water were found in July, while significantly lower OCP concentrations were measured in January. Significant linear correlation was found between the concentration of HCH and that of total 13 OCPs in water. The measured OCP concentrations in sediments, soils, farmland runoff water and dry/wet deposition are discussed in relation to concentrations and patterns found in the surface water. Comparison of OCP levels in sediments and soils led to conclusion that erosion of soil contribute significantly to the contamination of water. The OCPs dry and wet deposition to water body was estimated to 0.49 and 0.86 ton/year, respectively. The ratio of α/γ-HCH and (DDE+DDD)/∑DDT in environmental matrix indicated there probably existed new OCPs input of lindane and dicofol into the river.     

Organochlorine pesticides in the dust fall around Lake Chaohu, the fifth largest lake in China

The residual levels of organochlorine pesticides (OCPs) in the dust fall around Lake Chaohu were measured using gas chromatography mass spectrometry from April 2010 to March 2011. The fluxes, components, temporal–spatial variations, and sources of OCPs were also analyzed. Twenty-one types of OCPs were detected in the dust fall samples around Lake Chaohu, with a total concentration of 51.54?±?36.31 ng/g and a total flux of 10.01?±?13.69 ng/(m² day). Aldrin (35.3 %), endosulfan (39.1 %), dichlorodiphenyltrichloroethanes (DDTs) (49.8 %), and isodrin (37.1 %) were the major OCPs in the spring, summer, autumn, and winter, respectively. Both the residual level and the flux were higher in the spring than in other seasons and higher at the outer lake sampling sites than inner lake sampling site. The potential source of the hexachlorcyclohexanes in the dust fall may be recent lindane usage. The DDTs mainly came from historical dicofol usage, and a significant input of DDT was found during April and June. The presence of endosulfan may be due to the present use of technical endosulfan. The aldrin in the dust might be due to its occasional usage, and isodrin may be a result of long-distance transport from other countries.     

Monitoring and Assessment of Persistent Organochlorine Residues in Sediments from the Daliaohe River Watershed, Northeast of China

Surface sediment samples from 12 sites of the three selected rivers in Daliaohe River watershed (Hunhe River, Taizihe River and Daliaohe River) were analyzed with the objective of establishing sources and hazard of the organochlorinae pesticides (OCPs) and polychlorinated biphenyl (PCBs) in surface sediments. The total concentrations of OCPs varied from 3.06 to 23.24 ng g⁻¹. ∑HCH (α-HCH, β-HCH, δ-HCH, γ-HCH), ∑DDT (p, p′-DDE, p, p′-DDD, o, p′-DDT, p, p′-DDT) and ∑Cyclodiene (Heptachlor, Aldrin, Heptachlor epoxide, Dieldrin, Endrin) ranged from 1.86 to 21.48, 0.5 to 2.81 and 0.56 to 1.53 ng g⁻¹, respectively. Results of OCPs also illustrate that the most dominant pollutants among the OCPs was ∑HCH, and γ-HCH was the most dominant isomer in HCH, which was evidence of recent input of lindane. It possibly came from the runoff of polluted soils and long-scale transportation. Total PCB concentrations ranged between 1.88 and 16.88 ng g⁻¹. The peak concentrations of PCBs were found in sediments from station T5 and D3, which are in the vicinity of industrial areas and ferry, respectively. These data show a moderate level of OCPs and PCBs contaminations compared to that in other countries.     

Occurrence of organochlorine pesticide residues in green mussel (Perna viridis L.) and water from Ennore creek, Chennai, India

Green mussel (Perna viridis) and water samples were collected from Ennore creek, Chennai by seasonal sampling and analyzed for organochlorine pesticide residues (OCPs) like dichloro-diphenyl-trichloroethane (DDT) and its metabolites, isomers of hexachlorocyclohexane (HCH) and endosulfan. These residues were analyzed by using gas chromatograph (GC) with μECD. In the present study, mussel samples showed very low concentrations of OCPs in the statistical order of DDT (5.83 ng g^???1 wet tissue) > endosulfan (2.84 ng g^???1 wet tissue) > HCH (2.34 ng g^???1 wet tissue). Concentrations of OCPs in water samples were in the statistical order of endosulfan (29.21 ng L^???1)?> HCH (17.14 ng L^???1)?> DDT (14.63 ng L^???1). To our knowledge, this is the first report on the seasonal variation of OCPs and especially the quantification of endosulfan in Ennore Creek. The present study recommends that continuous monitoring in Ennore creek is necessary to assess possible impact on human health.     

Occurrence,sources, and ecological risks of PBDEs,PCBs, OCPs,and PAHs in surface sediments of the Yangtze River Delta city cluster,China

Polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in 25 surface sediments in three cities (Nantong, Wuxi, and Suzhou) in the Yangtze River Delta, eastern China were measured. The mean concentrations were 378, 45.8, 1.98, 4,002 ng/g for PBDEs, OCPs, PCBs, and PAHs, respectively. Their levels in the sediments in the three cities were generally consistent with the city industrialization. PBDEs and OCPs were markedly dominated by deca-BDE (>90 %) and DDTs (>70 %). A principle component analysis of the analytes identified three major factors suggesting different sources of the contaminants in the sediments. PBDEs and the organic carbon in the sediments have common sources from industrial activities; whereas OCPs and PCBs, correlated with the second factor, were mainly from historical sources. The third factor with loadings of PAHs is indicative of various combustion sources. Ecological risk assessment indicated that the potential highest risk is from DDTs, for which 22 sites exceed the effects range low (ERL) values and three sites exceed the effects range median (ERM) value.     

Selected organochlorine pesticides (OCPs) in surface soils from three major states from the northeastern part of India

Eighty-two surface soil samples were collected from forest, grassland, tea estate, wildlife sanctuary, wetland, and roadside areas from the northeastern states of India, viz., Tripura, Manipur, and Assam. Thirteen different organochlorine pesticides (OCPs) were detected from background soils using gas chromatography electron capture detector. Manipur soils were found to be with higher concentration of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), and endosulfan followed by Tripura and Assam. The spearman correlation coefficient shows significant correlation between HCHs, DDTs, and endosulfan isomers (r ²?>?0.5 and p?<?0.05). Additionally, α-HCH, δ-HCH, o,p′-DDE, and endosulfan-sulfate shows good correlation with total organic carbon in soil (r ²?=?0.5, p?=?0.05), indicating that the soil organic matter could enhance adsorption of these compounds, also demonstrating that the present OCPs in the background soil were from similar source. Further principal component analysis evaluates that most of the higher volatile compounds where clustered together in soil. However, after comparing with different states of Indian soil samples, the concentrations of OCPs in the present study areas are much lower and comparable with background soil across the globe.     

Distribution and bioaccumulation of organochlorine pesticides (OCPs) in food web of Nansi Lake,China

The concentration of 12 organochlorine pesticides (OCPs) were measured in water, sediment, aquatic plant, and animal (shrimp and fish) of Nansi Lake by gas chromatography equipped with an electron capture detector. The total OCPs concentrations were 65.31–100.31 ng L^?1 in water, 2.9–6.91 ng g^?1 dry weight (dw) in sediments, 1.29–6.42 ng g^?1 dw in aquatic plants and 7.57–17.22 ng g^?1 dw in animals. The OCPs composition profiles showed that heptachlor compounds was also the predominant OCPs contaminants in addition to hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Nansi Lake. According to the source of HCHs and DDTs in sediment samples, there was no new input and the HCHs pollution mainly came from the use of Lindane in Nansi Lake. Bioaccumulation of OCPs in aquatic biota indicated that DDTs and heptachlor compounds had a strong accumulation, followed by HCHs and drins. The accumulation abilities of fish for OCPs were higher than those of plants and shrimps. The OCPs biota-sediment accumulation factor values of Channa argus was the highest in fish samples, followed by Carassius auratus, and Cyprinus caspio. Risk assessment of sediment showed that heptachlor epoxide had a higher occurrence possibility of adverse ecological effects to benthic species. Based on the calculation of acceptable daily intake and hazard ratio, HCHs in fish and shrimps from Nansi Lake had a lifetime cancer risk of greater than one per million. The risk assessment of water, sediment, and fish indicated the water environment of Nansi Lake is at a safe level at present.     

Organochlorine pesticide contamination in marine organisms of Yantai coast,northern Yellow Sea of China

To evaluate the contamination of organochlorine pesticides (OCPs) in marine organisms and their potential health risk on consumers in the northern Yellow Sea of China, mollusks, wild shrimps, and crabs were collected from the Yantai coast, and the OCP contents in the samples were analyzed and compared. The results indicate that all the samples have been contaminated by OCPs, and OCP concentrations varied in individual species and in sampling sites. Among the studied OCPs, ∑HCH and ∑DDT concentrations ranged from 0.91 to 13.92 ng g^?1 and from 10.16 to 411.19 ng g^?1, respectively. Meretrix was highly enriched with HCHs, while the highest DDT concentration was found in Crassostrea. For the OCP isomers, β-HCH was the predominant isomer of HCHs, and p,p′-DDE concentration was much higher than other isomers of DDTs. The concentrations of other OCPs (HCB, t-CHL, endrin, and mirex) were relatively low. For the shrimp and crab samples, Alpheus distinguendus samples accumulated a higher level of HCHs but lower DDTs than Oratosquilla aratoria and Carcinoplax vestitus in all sampling areas. HCHs in the samples of contrast area were not significantly lower than that of the sewage outfall area and port area, whereas DDTs in the samples of contrast area were relatively lower than that of the other two areas. Generally, all the OCP contents in the samples are in the range of the edible hygienic criteria except the total concentration of DDTs in Crassostrea.     

Spatial variation of potentially toxic elements in different grain size fractions of marine sediments from Gulf of Mannar, India

Marine sediments of the Gulf of Mannar (GoM), India are contaminated by potential toxic elements (PTEs) due to anthropogenic activities posing a risk to the existing fragile coral ecosystem and human health. The current study aimed to assess the distribution of PTEs (arsenic—As; cobalt—Co; copper—Cu, molybdenum—Mo; lead—Pb; and zinc—Zn) in marine sediments of different grain size fractions, viz., medium sand (710 μm), fine sand (250 μm), and clay (<63 μm) among the different coastal regions of Pamban, Palk Bay, and Rameswaram coasts of GoM, using grain size as one of the key factor controlling their concentrations. The concentrations of PTEs were measured in the different size fractions of sediment using inductively coupled plasma mass spectrophotometer. The order of accumulation of all PTEs in the three fractions was ranked as Zn > Cu > Pb > As > Co > Mo and in the three locations as Rameswaram > Palk Bay > Pamban. The concentration of PTEs in Palk Bay and Rameswaram coast was significantly different (P?<?0.05), when compared to Pamban coast. Measured geoaccumulation index (I _geo) and contamination factor (CF) indicated significant enrichment of Co and Pb from Rameswaram coast when compared to other two coasts. Although the concentration of Co was low but the measured I _geo and CF values indicated significant enrichment of this PTE in Rameswaram coast. The increased input of PTEs in the coastal regions of GoM signifies the need to monitor the coast regularly using suitable monitoring tools such as sediments to prevent further damage to the marine ecosystem.     

Spatial and seasonal variations of pesticide contamination in agricultural soils and crops sample from an intensive horticulture area of Hohhot, North-West China

The spatial variability and temporal trend in concentrations of the organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), in soils and agricultural corps were investigated on an intensive horticulture area in Hohhot, North-West China, from 2008 to 2011. The most frequently found and abundant pesticides were the metabolites of DDT (p,p′-DDE, p,p′-DDT, o,p′-DDT and p,p′-DDD). Total DDT concentrations ranged from ND (not detectable) to 507.41 ng/g and were higher than the concentration of total HCHs measured for the range of 4.84–281.44 ng/g. There were significantly positive correlations between the ∑DDT and ∑HCH concentrations (r ²>0.74) in soils, but no significant correlation was found between the concentrations of OCPs in soils and clay content while a relatively strong correlation was found between total OCP concentrations and total organic carbon (TOC). β-HCH was the main isomer of HCHs, and was detected in all samples; the maximum proportion of β-HCH compared to ∑HCHs (mean value 54%) was found, suggesting its persistence. The α/γ-HCH ratio was between 0.89 and 5.39, which signified the combined influence of technical HCHs and lindane. Low p,p′-DDE/p,p′-DDT in N1, N3 and N9 were found, reflecting the fresh input of DDTs, while the relatively high o,p′-DDT/p,p′-DDT ratios indicated the agricultural application of dicofol. Ratios of DDT/(DDE+DDD) in soils do not indicate recent inputs of DDT into Hohhot farmland soil environment. Seasonal variations of OCPs featured higher concentrations in autumn and lower concentrations in spring. This was likely associated with their temperature-driven re-volatilization and application of dicofol in late spring.     

Origination and assessment of metal pollution in Qarechay River bed sediments

In the present investigation, bulk and chemical partitioning of elements (Cu, Mn, Ni, Zn, Fe, Ca) together with organic matter as a loss in ignition in the Qarechay River bed sediments have been studied. The concentration of metals in Qarechay River bed sediments is governed by the geological units of the study area. The study of anthropogenic portion shows that a small proportion of elemental concentration belongs to this phase. However, Mn has a large portion of anthropogenic sources (43 %). Also, Mn has a share of 13.6 % in sulfide fractions. This result indicates that Mn is a highly mobile element and can easily enter the water column. The presence of Mn in sulfide fraction might be indicative of initial stages of conversion of oxidation state into reduction in Qarechay River. Share of metals in anthropogenic portion is in the following order: Mn (43 %)?>?Cu (19 %)?>?Zn (10 %)?>?Ni (3 %)?>?Fe (0 %). Organic metallic bonds are not significantly present in the study area. Geochemical index (I _geo), pollution index (I _poll), enrichment factor (EF), and pollution load index (PLI) values are indicative of a clean environment throughout the river course. These values are in well agreement with results of chemical partitioning data. Eventually, based on the results of chemical partitioning, regional standard of elements for Qarechay River bed sediments has been established.     

Retrospective monitoring of persistent organic pollutants,including PCBs,PBDEs, and polycyclic musks in blue mussels (Mytilus edulis) and sediments from New Bedford Harbor,Massachusetts, USA: 1991–2005

Blue mussels (Mytilus edulis) and sediments collected from 1991 to 2005 from New Bedford Harbor (NBH), MA, were analyzed for two polycyclic musks (HHCB or Galaxolide® and AHTN or Tonalide®), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs). HHCB and AHTN were found in mussel tissues at mean concentrations of 836 and 376 ng/g lipid weight (lw), respectively, which were two- to seven-fold higher than those found at a reference site. Mean concentrations of HHCB and AHTN in NBH sediments were 12 and 6.3 ng/g dry weight (dw), respectively. Four- and five-ringed PAHs, such as phenanthrene, anthracene, fluoranthene, and pyrene, collectively accounted for 61 % of the ∑PAHs concentrations in mussels from NBH. Mean ΣPCB concentrations in mussels from upper and lower NBH were 942 and 182 μg/g lw, respectively, and were dominated by tetra- and penta-chlorobiphenyl congeners, collectively accounting for 61 % of the ΣPCB concentrations. The mean concentration of ∑PBDEs in mussels from NBH was 277 ng/g lw, and no significant difference existed in the concentrations between upper and lower NBH. DDTs were the major OCP found in mussels, found at a mean concentration of 778 ng/g lw. The concentrations of HHCB, AHTN, ΣPBDEs, ΣPAHs, and DDTs in mussels decreased significantly (r ²?≥?0.56, p?≤?0.052) from 1991 to 2005. The concentrations of PCBs and chlordanes did not exhibit a decreasing trend in mussel tissues (r ²?<?0.50; p?>?0.076) from 1991 to 2005. Based on the temporal trends in the concentrations of HHCB, AHTN, ∑PAHs, and ∑PBDEs found in mussels from NBH, it was estimated that between 5.5 and 12 years were required for the concentrations of these compounds to decrease by half (i.e., environmental halving time) of the levels found in 1991.     

Distribution of persistent organochlorine chemical residues in blood plasma of three species of vultures from India

The presence of persistent organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in blood plasma of white-backed vulture Gyps bengalensis, Egyptian vulture Neophron percnopterus, and griffon vulture Gyps fulvus collected from Ahmedabad, India. All the samples had varying levels of organochlorine pesticides and PCBs. Statistically significant (P?<?0.05) differences among species were detected for beta-hexachlorocyclohexane (??-HCH), ??HCH, and dichloro-diphenyl-trichloroethane (DDT). The mean concentration of ??HCH, ??DDT, and ??PCBs among plasma ranged from 43.7 to 136, 8.8 to 64.8, and 226 to 585 ng/ml, respectively. Among the various OCPs analyzed, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p ^??-DDE) was detected most frequently. The concentrations of cyclodiene insecticides detected were lower than the other organochlorine residues. The levels of pesticides measured in plasma samples of three species of vulture were comparable to the results documented for a number of avian species and were lower than those reported to have deleterious effects on survival or reproduction of birds. Although no threat is posed by any of the organochlorine pesticides detected, continuous monitoring of breeding colonies is recommended. This study is also the first account of a comprehensive analysis of toxicants present in blood plasma of vulture species in India. The values reported in this study can serve as guidelines for future research in general as well as control values during the analysis of samples obtained from birds in the event of suspected organochlorine poisoning.     

Metal speciation in sediment and bioaccumulation in <Emphasis Type="Italic">Meretrix lyrata</Emphasis> in the Tien Estuary in Vietnam

The concentrations of seven toxic metals (cadmium (Cd), nickel (Ni), chromium (Cr), arsenic (As), lead (Pb), copper (Cu), and zinc (Zn)) were determined in sediments and the soft tissues of a bivalve species (Meretrix lyrata) collected from the Tien Estuary in Tien Giang Province, South Vietnam. The total metal concentrations in sediments (mg/kg dry weight) increased as Cd (0.06) < Cu (5.0) < Pb (13.9) < As (16.3) < Ni (24) < Cr (50) < Zn (62). Speciation analysis revealed that these metals existed mainly in the residual fraction (43–94%), followed by the Fe-Mn oxide-bound (5–35%) and organic/sulfide-bound (0.6–9.2%) fractions. The metal concentrations in M. lyrata (mg/kg dry weight) were in the ranges of 1.3–1.9 (Cd), 1.5–2.8 (Ni), 1.8–3.4 (Cr), 11–16 (As), 0.3–0.6 (Pb), 6.9–8.7 (Cu), and 95–128 (Zn), which are safe for human consumption. The order of the mean biota-sediment accumulation factor (BSAF) of the metals in the non-residual fractions of the sediment for M. lyrata was Cd > Cu > As > Zn > Cr > Ni > Pb. The Risk Assessment Codes (RACs) suggest that the highest mobility of Cd (with RAC = 37%) poses greater environmental risk to aquatic biota. Correlation analysis results show that M. lyrata can be used as a biomonitor of Cd and Cu pollution in the exchangeable, acid-soluble, and non-residual sediment fractions.     

Anthropogenic nexus on organochlorine pesticide pollution: a case study with Tamiraparani river basin,South India

The levels of 17 organochlorine pesticides residues (OCPs) in surface water and sediments from Tamiraparani river basin, South India were investigated to evaluate their potential pollution and risk impacts. A total of 96 surface water and sediment samples at 12 sampling stations were collected along the river in four seasons during 2008–2009. The ΣOCP concentrations in surface water and sediments were in the range of 0.1 to 79.9 ng l⁻¹ and 0.12 to 3,938.7 ng g⁻¹ dry weight (dw), respectively. Among the OCPs, the levels of dichlorodiphenyltrichloroethanes (DDTs), aldrin, dieldrin, cis-chlordane, trans-chlordane, and mirex were dominant in the sediments. The dominant OCPs in water samples are heptachlor, o,p′-DDE, dieldrin, o,p′-DDD, and mirex, which show different source of contamination pattern among sampling seasons. The distribution pattern of DDTs, hexachlorocyclohexane, and other OCPs in the present study shows heterogenic nature of nonpoint source of pollution. Notable contamination of water and sediment sample that was observed in upstream (S2) 58 ng l⁻¹ and downstream (S11) 1,693 ng g⁻¹ dw explains agricultural and municipal outfalls, whereas frequent damming effect reduces the concentration level in the midstream. The overall spatial–temporal distribution pattern of ΣOCP residues are illustrated by GIS package.     

Development and application of microwave assisted extraction (MAE) for the extraction of five polycyclic aromatic hydrocarbons in sediment samples in Johannesburg area, South Africa

A microwave-assisted extraction (MAE) method was verified and applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) in sediment samples. Soxhlet extraction was used as the reference method. The optimum MAE was carried out with 20 mL of hexane/acetone (1:1, v/v) mixture in a 1-g sample at 250 W for 20 min. Soxhlet extraction was carried out with 250 mL of dichloromethane:hexane (1:1, v/v) mixture in a 15-g sample for 24 h in a water bath maintained at 60 °C. The collected extracts were both cleaned up, reduced to 1 mL under nitrogen and then injected into an HPLC fluorescence. To increase the sample throughput, simultaneous MAE was performed. The obtained percentage recoveries ranged from 61 to 93 and 88–98 for MAE and SE, respectively. The optimised MAE method was validated using certified reference material. It was then applied to real sediment samples from in and around the greater Johannesburg area. The sediments from Jukskei River were found to be the most polluted while Hartbeespoort Dam sediments were found to be least polluted. The overall order of concentrations for the studied PAHs per site was as follows: Jukskei River?>?Kempton Park?>?Centurion Dams?>?Natalspruit River (PIT)?>?Hartbeespoort Dam.     

Residue levels of hexachlorocyclohexane and dichlorodiphenyltrichloroethane in human milk collected from Beijing

Forty-eight human breast milk samples were collected from mothers in Beijing. The hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) (including α-HCH, β-HCH, γ-HCH, δ-HCH, p,p′-DDE, p,p′-DDD, o,p′-DDT, and p,p′-DDT) contents of the samples were determined by gas chromatography/electron capture detection and gas chromatography/mass spectrometry. α-HCH, β-HCH, γ-HCH, p,p′-DDE, p,p′-DDD, and p,p′-DDT were detected at rates of 20, 100, 10, 100, 10, and 22 %, respectively. The average residue levels in the samples were 174.6 ng/g fat for β-HCH, 333.8 ng/g fat for p,p′-DDE, 6.57 ng/g fat for α-HCH, 7.67 ng/g fat for γ-HCH, 4.18 ng/g fat for p,p′-DDD, and 11.4 ng/g fat for p,p′-DDT. The results showed that the infants’ daily intake levels of HCH and DDT were 0.95 and 1.76 μg/kg body weight/day, respectively. Our result suggested that the total residue level of these organochlorine pesticides in breast milk from Beijing decreased and was lower than that from other coastal and heavy industrial cities in China. On the other hand, the levels of HCH and DDT were higher than those from some developed countries, but lower than those from other developing countries such as India.