Distribution of HCHs and DDTs in Soils from Beijing City, China

Concentrations of HCH isomers, DDT, and its metabolites have been measured in 63 soil samples collected in the urban area and outskirts of Beijing City. HCHs and DDTs were observed in all samples and their geometric mean levels were 5.78 and 38.21 ng g⁻¹, respectively. The spatial distribution of OCPs in Beijing was clearly showed by the contour map, suggesting the sites with the higher level of OCPs are located in the west and the south region and urban areas within the study regions.” Furthermore, a t-test showed a significant difference of the level of some compounds between urban and outskirts areas. The temporal distribution of HCHs and DDTs suggested that the historical application of OCPs has a great effect on the residual level. The ratios of (α-/γ -HCH (p,p’-DDE+p,p’-DDD)/p,p’-DDT, and o,p’-DDT/p,p’-DDT indicated the present of lindane and impure dicofol besides technical HCHs and technical DDTs in Beijing. The potential risk of HCHs and DDTs was assessed on the basis of some current guideline values for soil. The level of OCPs in our study area was compared with other studies.     

气相色谱-串联质谱法测定滩涂生物样本中的六六六和滴滴涕

目的建立滩涂生物样本中的六六六(HCHs)和滴滴涕(DDTs)的气相色谱-串联质谱(GC-MS/MS)测定法。方法取可食部位匀浆样品加无水硫酸钠脱水、使用石油醚进行超声萃取,再加硫酸磺化后静置取有机相氮气吹干定容,取上清液经HP-5MS Ultra Inert毛细管气相色谱柱(30 m×250μm,0.25μm)分离,气相色谱-串联质谱分离检测,外标法定量。结果本法六六六和滴滴涕在0.100μg/L^10.0μg/L线性相关系数均≥0.999,方法检出限均为0.02μg/kg,平均样本加标回收率为57.6%~100%,相对标准偏差(RSD)在0.100μg/kg水平为15.1%~23.0%,1.00μg/kg水平为8.12%~17.1%,10.0μg/kg水平为3.22%~9.03%。使用本方法检测实际样品,六六六检出率为44.0%,滴滴涕检出率为99.0%,检出浓度为0.035μg/kg^8.17μg/kg。结论该方法前处理过程简便,定性及定量准确,灵敏度高,满足批量样品的检测。     

深圳市母乳中六六六和滴滴涕蓄积水平与影响因素分析

目的了解深圳市普通居民产妇母乳中六六六(HCHs)和滴滴涕(DDTs)的蓄积水平,并分析其影响因素,评估婴儿暴露风险。方法采集85位在深圳地区居住时间3年或以上、初产妇产后4～6周的母乳。样品经提取后,用凝胶渗透色谱和弗罗里硅土固相微萃取柱净化,采用气相色谱-电子俘获检测器(GC-ECD)检测母乳中六六六、滴滴涕(包括α-六六六、β-六六六、γ-六六六、δ-六六六、p,p’-滴滴涕、p,p’-滴滴滴、p,p’-滴滴异、o,p’-滴滴涕等8种同分异构体)的残留。通过问卷调查,分析母乳中六六六、滴滴涕的含量水平与产妇膳食情况、年龄、当地居住时间等因素进行相关性关系。结果所有母乳样品均检出p,p’-DDE,58份样品中检出β-HCH。母乳中∑HCHs的中位数为2.980ng/g(全重计),80.200ng/g(脂肪计)。∑DDTs的中位数为9.610ng/g(全重计),268.390ng/g(脂肪计)。统计分析发现,母乳中六六六、滴滴涕含量与产妇年龄、淡水鱼的消费量、禽肉的消费量呈正相关关系。结论深圳市居民母乳中检出了六六六、滴滴涕,其含量水平与年龄及膳食情况存在相关关系。婴儿六六六、滴滴涕的平均摄入估计值分别为0.468和1.842μg/(kg.d BW),均低于我国卫生部及FAO/WHO农药残留联席会议推荐的每日容许摄入量(ADI)。深圳市当地居民母乳中六六六和滴滴涕负荷水平低于全国平均水平。     

Dissipation and Residues of Boscalid in Strawberries and Soils

Field experiments were carried out to investigate the dissipation of boscalid in strawberries and soils and its residual levels in strawberries at two different sites. Boscalid (50% water dispersible granule) was applied at two dosages (349.5 and 525.0 g a.i./ha). Soils and strawberry samples were collected at 0, 1, 2, 3, 5, 7, 14, 21 days after application of boscalid. The results showed that boscalid dissipation pattern followed the first order kinetics with the half-lives of 4.9 and 6.4 days in strawberries and 6.1 and 8.0 days in the soils of Jinan and Beijing trail sites, respectively. The boscalid residues in strawberries were below the EU maximum residue level (5 mg/kg) after three days of application. This study suggests that boscalid is acceptable to apply for strawberries under the recommended dosage.     

Sorption of Chlorophenolates in Soils and Aquifer and Marine Sediments

This article describes the sorption behavior of 3 hydrophobic ionizable chlorophenols—2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol—in different types of natural sorbents. A series of experiments was carried out with 11 topsoil samples, 9 aquifer sediments, and 12 marine sediments differing in pH, organic-matter content, and mineral composition and presumably also in type of organic matter due to their differing origins. Ionized forms of chlorophenols dominated in almost all sorption experiments. Freundlich isotherm coefficients K_f and 1/n, as well as organic-matter sorption coefficient (log K_om) and free-energy change (G^o), were calculated for all 3 compounds in all sorbents. The sorption intensity of predominantly ionized chlorophenols increased linearly with the increase of sorbent organic-matter content and decreased with the increasing sorbent pH. Different sorption behavior of all 3 compounds in marine sediments with respect to topsoils and aquifer sediments was indicated by significant differences in K_f and 1/n coefficients as well as in log K_om and G^o values. The highest K_f and log K_om values were obtained for sorption of chlorophenolic compounds in topsoils and the lowest in marine sediments, although both groups of sorbents had similar organic-matter content. The 1/n coefficient, reflecting the isotherm nonlinearity, was considerably lower than unity for all compounds in almost all sorbents. The most significant deviation of sorption isotherms from linearity was observed in marine sediments. Only marine sediments showed a linear increase in sorption intensity of all 3 compounds with the increase in sorbent-specific surface area. These results pointed to a different mechanism of sorption in marine and terrestrial sorbents and confirmed that the capacity of sorption was related to amount as well as type and origin of organic matter.     

Multi-medium Distributions of HCHs,DDTs, and PCBs in Typical Petrochemical Industrial Area and Surrounding Regions of Jilin Province,Northeast China

The levels of DDTs, HCHs and PCBs in topsoil, cereal and irrigation water from typical industrial and agricultural areas of Jilin Province in Northeastern China were evaluated by using gas chromatography coupled with an electron capture detector. The amount of ∑OCPs and ∑⁷PCBs found in topsoils ranged from 24.7 to 98.0 and 17.2 to 98.7 ng g⁻¹, respectively. The geometric means of ∑HCHs, ∑DDTs and ∑⁷PCBs in rice stem samples were 28.9, 32.4 and 49.0 ng g⁻¹, respectively. The average level of total OCPs concentration in rice field water in Meihekou area (0.849 ng g⁻¹) is higher than that in Jilin area (0.178 ng g⁻¹) and all OCPs concentrations in rice field water met the water quality standards for Grade I regulated by China’s national environmental quality standard of surface water.     

Occurrence and Downslope Mobilization of Quaternary Herbicide Residues in Vineyard-Devoted Soils

The aim of this study was to examine the fate of quaternary herbicides in soil deposits derived from erosion of vineyard-devoted soils. Herbicide occurrence in the crop soils was due to the farmer application inputs. Special attention should be paid to the presence of paraquat (PQ) in the studied vineyard-devoted soils. The major factor governing the sorption of PQ was the solid state organic fraction with the clay mineral content also making a significant contribution. The mobilization and transport of quats-enriched soil particles may generate downslope and downstream environmental problems that mainly affect detritivore ecology.     

Residues of DDTs and their spatial distribution characteristics in soils from the Yangtze River Delta, China

Organochlorine pesticides were used extensively in the Yangtze River Delta, China. However, knowledge about their residual levels and environmental fates in soils of this area is limited. This paper presents the residue isomers and spatial pattern of dichlorodiphenyltrichloroethane (DDT) in soils across 17 main cities in the Yangtze River Delta. Forty-three soil surface (0-15 cm) samples were collected during a field campaign conducted in October 2003 in the Delta. Six DDT isomers (1-[2-chlorophenyl]-1-[4-chlorophenyl]-2,2-dichloroethane [o,p'-DDD], 1-[2-chlorophenyl]-1-[4-chlorophenyl]-2,2-dichloroethylene [o,p-'DDE], 1,1,1-trichloro-2-[p-chlorophenyl]-2-[o-chlorophenyl]ethane [o,p'-DDT], p,p'-dichlorodiphenyldichloroethane [p,p'-DDD], p,p'-dichlorodiphenyldichloroethylene [p,p'-DDE], p,p'-dichlorodiphenyltrichloroethane [p,p'-DDT]) were detected using gas chromatography. The results show that p,p'-DDE was the dominant isomer in the soil samples. The levels of DDT are generally low in soils of this area and are comparable to DDT levels in other cities in China and in soils from developed countries such as the United States and Germany. The isomer ratios of o,p'-DDT to p,p'-DDT and DDT to (DDD + DDE) were employed to identify the source of DDT. The computed ratios implied that the source of DDT might be related to the application of dicofol, an acaricide manufactured from technical DDTs and mainly used on cotton fields to treat mites.     

Residues of Organic Chlorinated Pesticides in Agricultural Soils of Beijing, China

Concentration of organic chlorinated pesticides (OCPs) were measured in topsoils of a selected farm (NK farm) in Beijing in 1993 and 2003. The results indicated that OCPs, mainly 1,2,3,4,5,6-hexachlorocyclohexane (HCH) and 1,1,1,-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT), degraded greatly in the 20 years after the prohibition of their use. DDT was the major contributors of pollution on the farm with 92.23% and 81.28% contributions of total OCP load in soils in 2003 and 1993 respectively. The levels of total DDT and HCH in the old orchard group, in which cultivation began in 1962, were significantly higher (p < 0.05) than those in the new orchard group in which cultivation began in 1991, and all data were higher than the level of barren land (p < 0.05). Studying the isomeric and parent substance metabolite ratios indicated there was more application and accumulation of DDT in the old orchard and that DDT in the new orchard had undergone a different degradation time period or perhaps had been applied more recently, but no new input of HCH was detected. Pollution potential was assessed on the basis of China Soil Environmental Quality Standard.     

Residues of Organochlorines in Sediments and Tilapia Collected from Inland Water Systems of Hong Kong

The levels and patterns of organochlorines including DDTs, HCHs, and PCBs were investigated in sediments and tilapia (Tilapia mossambica) collected from inland water systems [Tai Wai (S1), Fo Tan (S2), Siu Lek Yuen (S3), Tai Po (S4), and Tai Wo (S5)] in the New Territories of Hong Kong. Sediment and tilapia samples were also collected from two fish ponds for comparison. The ranges of DDTs, HCHs, and PCBs in river sediments were 2.82–8.63 ng/g (DW), 0.05–2.07 ng/g (DW), and 43–461 ng/g (DW), respectively. All these values were significantly higher (p < 0.05) than the pond sediments. Low chlorinated congeners (especially mono-, tri-, and tetrachlorobiphenyls) were enriched in sediment samples accounting for 70–80% of total PCBs.  The ranges of DDTs, HCHs, and PCBs in tilapia muscle collected from Fo Tan and Tai Wai were 28.2–40.1 ng/g (DW), 2.04–3.76 ng/g (DW) and 267–310 ng/g (DW), respectively. These values were also significantly higher (p < 0.05) than those collected from the fish ponds. Higher chlorinated PCBs (tetra-, penta-, hexa-, and heptachlorobiphenyls) were commonly found in tilapia accounting for almost 60% of the total PCBs. The effect of lipid contents in organochlorines accumulation was not significant (p < 0.05) in general. Received: 24 July 1998/Accepted: 18 November 1998     

Residues of Organochlorine Pesticides in Soils from the Southern Sonora,Mexico

Although, the Yaqui and Mayo valleys are the most important agricultural areas in Sonora, there is only limited data of the pesticides residue in soils in these valleys. This study measured the organochlorine pesticides (OCPs) in 234 soil samples (residential and agricultural) from 24 communities. The global results (mean, range) indicated that benzene hexachloride (19.2, ND-938.5 μg g⁻¹), endrin (6.6, ND-377.3 μg g⁻¹) and DDTs (36.45, ND-679.7 μg g⁻¹) were the dominant contaminants. Soil is one of the most important routes of exposure to OCPs in the population of southern Sonora and this study can be used to establish background levels of OCPs.     

Direct and Indirect Exogenous Contamination by Pesticides of Rice-Farming Soils in a Mediterranean Wetland

It is known that the sources of soil contamination can be endogenous or exogenous and that exogenous contamination may be direct or indirect. In this work, an environmental pesticide fate study was conducted in soil profiles collected from 23 rice field sites in an important Mediterranean wetland (Albufera Natural Park, Valencia, Spain) from April 1996 to November 1997. Temporal and spatial distribution of 44 pesticide residues in an alluvial Mediterranean soil (gleyic-calcaric Fluvisol, Fluvaquent) were monitored. During this period, the levels of pesticide residues in different soil horizons (Ap1 0–12 cm, Ap2 12–30 cm, ApCg 30–50 cm, C1gr 50–76 cm, and C2r 76–100 cm) were investigated. In addition, information was collected on agricultural pesticide application practices and soil characteristics. Distribution throughout the soil profile showed that pesticide concentrations were always higher in the topsoil (Ap1 horizon), in the autumn season, and in the border with citrus-vegetable orchard soils (calcaric Fluvisol, Xerofluvent). Chlorpyrifos (organophosphorus), endosulfan (organochlorine), and pyridaphenthion (organophosphorus) insecticides were, respectively, the most detected of all the pesticides investigated. These results were associated with processes, such as nonleaching, transport by movement into surface waters, retention, volatilization, and chemical and biological degradation in the topsoil, as well as with direct and indirect exogenous contamination sources. Received: 29 January 2002/Accepted: 24 July 2002     

Sixty-Year Sedimentary Record of DDTs, HCHs, CHLs and Endosulfan from Emerging Development Gulfs: A Case Study in the Beibu Gulf, South China Sea

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

Distribution of Organochlorine Pesticides in Intertidal and Subtidal Sediments in Coastal Wetland with High Tidal Ranges

The present study aimed to understand the distribution characteristics of organochlorine pesticides (OCPs) in wetlands experiencing high tides and the manner in which these characteristics are affected by various factors, in particular, two distinct physical and topographical features (i.e., sub- and intertidal zones). For all OCPs except HCHs, the distribution levels were higher in the intertidal zone than in the subtidal zone. The spatial heterogeneity in the isomer compositional pattern, distribution levels, and correlation among individual OCPs were pronounced in the intertidal zone. Spatial homogeneity was observed within the subtidal zone, indicating that the effect of flushing and mixing was strong enough to diminish the potential local concentration peaks and unique composition pattern. It was evident that input paths and their strength impact the horizontal and transversal distribution of OCPs. The OCP group-specific discrepancy in spatial distribution suggested that (1) chlordane and chlorobenzenes were from a single dominant innermost terrestrial input path, (2) DDTs were from multiple terrestrial input paths, and (3) HCH was likely to be from the outer sea. The observations in this study imply that (1) benthic organisms could experience greater exposure in the intertidal basin than in the subtidal zone and (2) management measures of OCPs should be set after considering the tidal effect and the OCP-specific input paths.     

Application of Different Extraction Methods for the Determination of Selected Pesticide Residues in Sediments

Using several extraction methods including the QuEChERS approach, samples of both model and natural sediments were prepared. For the isolation of the target group of pesticides, two variants of two complementary extractions had to be used. Resulting extracts were analysed with LC/MS/MS. Selected methods furnishing the best results were validated in the terms of linearity and repeatability. Their limits of detection ranged from 0.1 to 2 ng/g, their limits of quantification from 1 to 6 ng/g and their recovery percentage varied between 46 % and 102 %.     

Residues of Hexachlorocyclohexane Isomers and Their Distribution Characteristics in Soils in the Tianjin Area, China

Hexachlorocyclohexane (HCH) has a history of use in China. This paper presents the results of an investigation of HCH residue isomers and their distribution characteristics in soils near Tianjin, China. One hundred eighty-eight soil samples were collected from the Tianjin area. Four HCH isomers—-HCH, -HCH, -HCH, and -HCH—were detected using gas chromatography for all samples. Concentrations of the HCH ranged from 1.3 to 1095 ng g^–1, among which -HCH accounted for 52.5%. In addition, residues of HCH within Tianjins urban areas were found to be higher. No significant differences were found between the residues of HCH in soils from waste irrigation areas and those in other areas. Total organic carbon content was determined to impact the residue levels of HCH in soils, while pH value and clay content were not related to concentrations of HCH. In general, all HCH isomers in soil samples had abnormally high residue levels, possibly the result of continuous use of HCH in this area.