DDT) and Its Metabolites in Rivers in Tianjin, China

中国科技论文在线 http://www.paper.edu.cn Chemosphere 68 (2007) 10–16 www.elsevier.com/locate/chemosphere Spatial and temporal variations and possible sources of dichlorodiphenyltrichloroethane (DDT) and its metabolites in rivers in Tianjin, China S. Tao *, B.G. Li, X.C. He, W.X. Liu, Z. Shi Laboratory for Earth Surface Processes, College of Environmental Sciences, Peking University, Beijing 100871, China Received 13 July 2006; received in revised form 20 December 2006; accepted 21 December 2006 Available online 9 February 2007 Abstract Water, suspended solid (SS) and sediment samples were collected from nine water courses in Tianjin, China and analyzed for dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs, including o,p0-,p,p0-DDT, DDD and DDE). The average DDX concentrations in water, SS and sediment were 59 ± 30 ng lÀ1, 2690 ± 1940 ng gÀ1 dry wt. and 340 ± 930 ng gÀ1 dry wt., respectively. Due to the termination of the extensive agricultural application and industrial manufacture, DDXs in river sediment decreased by one order of magnitude since 1970’s and low DDT fractions in these sediments were observed. Still, DDXs in the sediments near the outlets of the major manufacturers remained relatively high attributed to the historic input. DDXs in sediment were also positively correlated with organic matter content. Spatial distributions of DDXs in SS and water was different from that in sediment. For SS, a negative correlation between DDX concentration and SS content indicated a dilution effect in many rivers. Dissolved organic carbon content was the major factor affecting DDX concentrations in water phase. Wastewater discharged from dicofol manufacturers and likely illegal agricultural application were the primary reasons causing high DDT (DDE + DDD) ratios in SS and water. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: DDT; River water; Sediment; Suspended solids; Tianjin; Dicofol 1. Introduction zenemethanol) (Qiu et al., 2005). DDT is used as an inter- mediate to produce dicofol in China and around 5–10% China was a major producer and consumer of dichloro- of DDT has been detected in the final product (Wei, diphenyltrichloroethane (DDT) in the past, and also uti- 2002). Since DDXs, especially freshly released DDT, have lized DDT for vector control, resulting in high residual been widely detected in China (Gong et al., 2004; Chen levels of DDT and its metabolites (DDXs) in various envi- et al., 2005; Wu et al., 2005; Peng et al., 2005; Hu et al., ronmental media and ecological compartments (Wong 2005) and some of these compounds were identified as et al., 2005; Sun et al., 2005; Chen et al., 2005; Liu et al., endocrine disrupters (Soto et al., 1994), public concerns 2006). Although the extensive application in agriculture over the enduring presence of DDT in the environment has been banned since 1992 (Chen, 1990), release of DDT have recently increased. into the environment is continuing, owing to possible illegal As one of the fastest growing areas in northern China, usage and occurrence of DDT as an impurity in other Tianjin, locating in the low reaches of Hai River, has suf- widely employed pesticides, such as dicofol (active ingre- fered from severe contamination of DDT from various dient: 4-chloro-a-(4-chlorophenyl)-a-(trichloromethyl)ben- sources. DDT had been extensively applied in local agriculture for several decades (Zhao and Ma, 2001). A large * Corresponding author. Tel./fax: +86 10 62751938. quantity of DDT was also produced locally in Dagu Chem- E-mail address: [email protected] (S. Tao). ical Company and Tianjin Chemical Company. Moreover, 0045-6535/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2006.12.082 转载中国科技论文在线 http://www.paper.edu.cn S. Tao et al. / Chemosphere 68 (2007) 10–16 11 Renmin Pesticide Company and a number of other manu- South Canal (S. Canal), North Canal (N. Canal), South facturers in this area have produced dicofol since 1990’s. Sewer (S. Sewer), North Sewer (N. Sewer) and Beijing Over the years, the wastewater originated from the manu- Sewer (BJ Sewer) are either artificial water courses or facturers has been discharged into the adjacent aquatic open sewers. These water bodies collect the majority of nat- environment without effective treatment. It was reported ural runoff as well as industrial and domestic effluents in recently, that the mean DDX concentration in sediment Tianjin. samples from South Sewer (Nanpaiwu River) was 29 ng The sediment samples were collected using a grab sam- gÀ1 dry wt. (Hu et al., 2005). The measured DDXs in the pler, and the water and SS were sampled using cylinder sediments from the neighboring Hai River and Dagu Sewer samplers. At least three sub-samples were collected for each ranged from 2 to 19 ng gÀ1 dry wt. and 4 to 84 ng gÀ1 dry sample type at each location. The sub-samples were then wt., respectively (Yang et al., 2005). mixed thoroughly into a composite sample to reduce the So far, the data available on DDT contamination in possible random variation. All the samples were frozen aquatic environment of Tianjin were based on a limited immediately after being transported to the laboratory number of sediment samples. To provide an overall under- and kept at À18 °C before analysis. The sediment samples standing of the DDT contamination in Tianjin, an exten- were centrifuged (Centrifuge TDL-5 > 3000 r mÀ1), freeze- sive survey was conducted recently, and water, suspended dried (EYELA-FDU-830) and rubbed to pass through a solid (SS) and sediment were sampled concurrently. In 70-mesh sieve. The SS samples were separated from water addition to the levels and compositions of DDXs in the by glass fiber filters (Sartorius, B = 47 mm, 0.5 lm, area, the present study particularly focused on spatial ashed at 450 °C). The separated SS samples were also and temporal variations and source identification, in hopes freeze-dried. of offering necessary information for assessing the potential risk on the regional ecosystem and public health, and for 2.2. Extraction and cleanup of sediment and SS samples formulating practical management strategy. The sediment and SS samples were extracted with an 2. Methodology accelerated solvent extractor (ASE-300, Dionex, USA), equipped with 34 ml extraction cells. Around 5 g freeze- 2.1. Sampling dried sediment or 0.5 g SS sample was analytically weighed, mixed with anhydrous sodium sulfate (1:5) and transferred Twenty nine water samples, twenty nine SS samples and into the extraction cell. For the sediment samples, activated sixty bottom sediment samples were collected from various copper powder (1:1 ratio of copper powder to sediment) locations along the nine major rivers and canals (Fig. 1)in was added to desulphurize the extract. The samples were summer 2002. Hai (Hai R.), Chaobai (Chaobai R.) and extracted using dichloromethane as the extraction solvent Yongding (Yongding R.) are natural rivers, while Ji Canal, under 10335 kP at 140 °C. The extraction was carried out in one cycle with 7 min heating followed by 5 min static extraction. The extracted solutions were concentrated to 0 20 km N near dryness on a rotary evaporator at 35 °C. The concentrated extracts were transferred with 2 ml hexane onto the top of a chromatography column (30 cm · 10 mm i.d.) Beijing filled with 6 g Florisil. The elution procedure consisted of 50 ml hexane and 50 ml 7:3 hexane/dichloromethane (v/v) Tianjin at a rate of 2 ml minÀ1. The eluate was collected and con- Chem. Co. centrated on the rotary evaporator, transferred to a Kud- N. Canal erna–Danish tube and then rinsed three times with BJ Sewer Chaobai R. hexane. The final volume was brought down to 1 ml under Ji Canal. Renmin a gentle stream of nitrogen. Pesticide Co. Tianjin Yongding R. Pesticide Co. 2.3. Extraction of water samples N. Sewer Bohai Bay Hai R. Dissolved DDXs in water samples were extracted by S. Sewer Dagu solid phase micro extraction (SPME). The fiber selected Chem. Co. was a fused-silica rod coated with 100 lm of poly- S. Canal Tianjin dimethylsiloxane (PDMS) from Supelco (Supelco Corp., China USA). The fibers were conditioned according to manufac- turer’s recommendations for 2 h at 250 °C before utiliza- Fig. 1. Water courses (thick lines), sampling locations (triangles) and tion. The fiber was exposed to the water sample in a major chemical and pesticide manufacturers (filled squares) in Tianjin. All 4.3 ml Supelco vial for 1 h and the water samples were con- rivers flow from northwest towards southeast. tinuously agitated with a magnetic stir bar on a stir plate 中国科技论文在线 http://www.paper.edu.cn 12 S. Tao et al. / Chemosphere 68 (2007) 10–16 revolving at 1000 rpm (Eyela RCH-3 D with 10 · 3 mm stir methane and hexane, 1:1 v/v) was concentrated to a total bar, Japan) during the extraction. Water that may have volume of 0.5 ml and then measured with GC-ECD to wicked into the needle was removed by vigorous shaking check the solvent background. The procedure blanks were of the fiber assembly and/or by touching the tip of the nee- run simultaneously with every set of the samples. A stan- dle with a tissue paper. The thermal desorption of the fiber dard solution was included for every 20 samples during occurred inside of the injection port at 220 °C for 4 min, GC measurements to monitor the stability of the detection. and once the desorption was complete, the split vent was All the samples were measured in two duplicates. opened for the remainder of the chromatographic sepa- Anhydrous sodium sulfate and glassware were heated at ration.

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