Distribution of Phthalate Esters in the Groundwater of Jianghan Plain, Hubei, China

Front. Earth Sci. China 2009, 3(1): 73–79 DOI 10.1007/s11707-009-0017-5

RESEARCH ARTICLE

Distribution of phthalate esters in the groundwater of Jianghan plain, Hubei, China

Dan ZHANG, Hui LIU (✉), Ying LIANG, Cheng WANG, Hecheng LIANG, Hesheng CAI

Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China

Abstract Samples of groundwater were collected from developmental toxicities in animals (Agarwal et al., 1986). 17 sites in the Jianghan plain in July 2007. Sixteen Recent investigations have shown that several PAEs are phthalate esters (PAEs) were detected in samples collected environmental hormones (Kambia et al., 2001). Since they by using solid-phase extraction (SPE)-gas chromatography are not chemically but physically bound to the polymer (GC). The results show that there were one or several PAEs chains, they may be leached into the environment. The most in all the samples, and the concentrations of total PAEs commonly used PAEs (dimethyl-, diethyl-, di-n-butyl-, ranged from 80.12 to 1882.18 ng/L. Four PAEs, i.e. di-iso- butylbenzyl-, bis (2-ethylhexyl)- and di-n-octyl phthalate butyl phthalate (DIBP), di-n-butyl phthalate (DBP), bis (2- esters) and another plasticizer, the bis(2-ethylhexyl) adipate, ethoxyethyl) phthalate (BEEP) and di (2-ethylhexyl) have been included in the list of priority pollutants in phthalate DEHP) were the dominant species. Among several countries. For example, the US Environmental these, DIBP, DBP and DEHP concentrations were closely Protection Agency (EPA) has established a maximum related to the water supply from the Yangtze River, admissible concentration (MAC) in water of 6 μg/L for bis Hanjiang River and Honghu Lake. However, the distribu- (2-ethylhexyl) phthalate (DEHP) and 0.4 mg/L for bis(2- tion of BEEP was irregular, which may be due to the ethylhexyl) adipate (Fukuwatari et al., 2002; Gomez-Hens application of some kind of products containing BEEP in and Aguilar-Caballos, 2003). the related areas. PAE distribution was irrelevant to the Therefore, PAE contamination has become a hot issue. electrical conductivity and sample depth. Many researchers have paid much attention to the distribution of PAEs in the atmosphere (Wang et al., Keywords phthalate esters (PAEs), groundwater, solid- 2008b), soil (VikelsØe et al., 2002; Li et al., 2006; Cai et phase extraction (SPE), gas chromatography (GC) al., 2008; Zeng et al., 2008a), surface water and sediments (Yuan et al., 2002; Sha et al., 2007; Wang et al., 2008a; Zeng et al., 2008b), landfill (Asakura et al., 2004; Zheng et 1 Introduction al., 2007), and sewage sludges (Cai et al., 2007). However, there are very limited reports about the distribution of Phthalate esters (PAEs) are synthetic compounds which PAEs in groundwater. In many areas in China, ground- have been used as pesticide carriers or insect repellents, as water is used as drinking water. It is meaningful to study well as in cosmetics, fragrances, lubricants and defoaming the distribution and source of PAEs in groundwater so as to agents. However, by far, they are mostly utilized as provide basic knowledge for control. additives in plastic products. Several PAEs are carcino- The Jianghan plain is located in the central and southern genic in animal models (Huber et al., 1996). In addition, area of Hubei Province in the Middle Reach of the Yangtze fl some PAEs and their metabolic products act functionally as River, where oods and water-logging occur frequently. antiandrogens during the prenatal period (Mylchreest et al., This area is low-lying and is characterized by deep alluvial 1998; Moore et al., 2001) and cause reproductive and deposits, many smaller rivers and numerous larger and shallow lakes formed by the meandering of the Yangtze River. The alluvial plain is a honeycomb of waterways Received May 20, 2008; accepted November 4, 2008 bordered by natural levees, and the depressional areas E-mail: [email protected] encompassed by these waterways are dish-shaped in cross 74 Front. Earth Sci. China 2009, 3(1): 73–79 section. The Jianghan plain is one of the important bases of (DPP), diphenyl isophthalate (DPIP) and dibenzyl phtha- Chinese agricultural productivity late (DBZP), were purchased from Dr. Ehrenstorfer GmbH In the present paper, seventeen groundwater samples (Germany); they included an internal standard (benzyl were collected from the eastern part of the Jianghan plain, benzoate), three surrogate standards (500 ng/μLin Hubei, China. Concentrations of 16 PAEs were analyzed acetone) and sixteen PAEs (1000 ng/μL in n-hexane). using solid-phase extraction (SPE)-gas chromatography To avoid contamination, no plastic equipment was used (GC). The distribution of PAEs and the relationship with during sampling and processing. All the glass apparatuses surface water are discussed. were soaked in K2CrO4 sulfuric acid solution at least 12 h, rinsed with organic-free reagent water at least 10 times, and finally baked at 180°C for 4 h. 2 Experiments 2.2 Sampling 2.1 Reagents and chemicals Seventeen groundwater samples were collected in July All solvents, including methylene chloride, hexane, metha- 2007 from the Jianghan plain (Wuhan–Qianjiang section), nol and acetone were of HPLC grade and purchased from Hubei, China. The temperature, electrical conductivity, pH TEDIA (USA) and have a purity of at least 99%. and depth of the samples were recorded during sampling. AccuBOND C18 SPE sorbent was purchased from Agilent. Sampling sites and basic properties are shown in Fig. 1 and Sodium sulfate (granular, anhydrous) was purified by heating Table 1. All samples were sealed in 4 L glass containers at 450°C for 4 h in a SX2-8-13 muffle furnace (Wuhan, and carried back to the laboratory within the day and stored China) and cleaned with methylene chloride before use. at 4°C in a refrigerator before further research. Twenty PAE standard solutions used in this study, including dimethyl phthalate (DMP), diethyl phthalate 2.3 Standards preparation (DEP), diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), bis (2-methoxyethyl) phthalate (BMEP), bis(4- A stock standard solution of 100 mg/L of 20 PAEs was methyl-2-pentyl) phthalate (BMPP), diamyl phthalate prepared by diluting the original standard solution with (DAP), bis (2-ethoxyethyl) phthalate (BEEP), hexyl 2- hexane. Calibration standard solutions with concentrations ethylhexyl phthalate (HEHP), dihexyl phthalate (DHP), of 0.5, 1, 5, 10, 20, 30, 40, 50 mg/L were prepared by butyl benzyl phthalate (BBP), bis (2-n-butoxyethyl) diluting the stock standard solution with hexane. Stock and phthalate (BBEP), di (2-ethylhexyl) phthalate (DEHP), calibration standard solutions were stored at 4°C in the dicyclohexyl phthalate (DCP), di-n-octyl phthalate (DOP), refrigerator. The calibration curve was established for each dinonyl phthalate, benzyl benzoate, diphenyl phthalate PAE, and calibration solutions were replaced every month.

Table 1 Detailed description of sampling stations station name sampling position pH electrical conductivity/ temperature/°C sampling depth/m – (μS$cm 1) W1 Xiangpu N30°28'07.20";E113°00'06.60" 7.05 580 18.4 30 W2 Xiangpu N30°28'07.20";E113°00'06.60" 7.13 1208 21.4 6 W3 Yuekou N30°30'50.77";E113°05'41.36" 7.61 400 18.6 24 W4 Zoukou N30°19'32.98";E113°54'47.94" 6.83 674 18.8 30 W5 Xinnan N30°06'36.06";E112°56'24.30" 7.07 542 18.8 28 W6 Maoshi N29°55'59.16";E112°54'03.54" 7.05 517 19.6 35 W7 Dongsheng N30°15'13.14";E113°29'17.82" 7.00 930 18.7 5 W8 Hengji N30°11'39.33";E113°09'45.91" 6.93 791 18.8 32 W9 Xichi N30°00'38.26";E113°28'53.07" 7.22 731 19.4 25 W10 Datonghu N30°04'36.24";E113°46'39.48" 6.92 1774 19.8 5 W11 Chenhu N30°30'03.78";E113°32'35.40" 7.13 676 19.4 22 W12 Hanji N30°39'25.44";E113°35'52.20" 7.30 612 19.7 22 W13 Chenghuang N30°37'27.82";E113°46'31.59" 6.80 667 18.7 25 W14 Xinbang N30°25'33.12";E113°44'54.00" 7.02 543 25.0 6 W15 Changhu N30°25'29.11";E114°03'12.78" 7.04 512 18.1 11 W16 Jiangxia N30°17'48.18";E114°01'46.80" 7.38 580 25.3 4 W17 Wuhu N30°10'59.16";E113°45'51.84" 7.13 740 19.4 40 Dan ZHANG et al. Distribution of phthalate esters in the groundwater of Jianghan plain, Hubei, China 75

Fig. 1 Sampling sites in the Jianghan plain

2.4 Sample pretreatment method based on eight-point calibration curve for individual PAEs. Benzyl benzoate was used as the internal For the water phase, samples were extracted using a 12- standard for the quantification of PAEs. port vacuum manifold solid-phase extraction (SPE) system (Supelco, USA). Sample extraction and pretreatment were 2.6 Quality assurance performed according to EPA Method 3535 and 8061a with modification, respectively. Water samples were passed For all the samples, a procedural blank and spiked sample through a 0.45 μm membrane, and 10 μL 100 mg/L surrogate consisting of all reagents was run to check for interference standards (DPP, DPIP, DBZP) were added to 1 L samples. An and cross contamination. Quantifications of PAEs were SPE cartridge (500 mgÂ6 mL) (Agilent, USA) was done with the calibration curves of which the correlation pretreated with 2 mL methylene chloride, 1 mL acetone, coefficients were all higher than 0.99. Limits of detection 2 mL methanol and 2 mL organic-free water, respectively. (LODs) of the method with standard solution were Water samples were extracted at a flow rate of 4 mL/min. 22–341 ng/L under full scan acquisition mode. The spiked After being dried for about 3 min, a drying column recoveries of PAEs were in the range of 61.7%–97.8%. All containing about 8 g of anhydrous sodium sulfate was data were blank and recovery corrected. The typical placed under the SPE cartridge, as well as a 10 mL chromatogram (Fig. 2) showed that all the peaks of the 20 collection tube below each drip tip of apparatus. Elution PAEs were separated very well. solvents were in turn passed through the cartridge. The elution was condensed to 0.2 mL in a N2 blow equipment (Shanghai, China).

2.5 Instrumental analysis

The samples were analyzed with Agilent 6890N gas chromatography (PA, USA) and a DB-5 MS capillary column (30 mÂ250 mmÂ0.25 mm, Agilent, USA) for chromatographic separation. The detector temperature was maintained at 280°C. The column temperature program was initiated at 80°C for 1.0 min, increased to 280°C at a rate of 6°C/min, and held for 10 min. The ﬂow rate of the carrier gas N2 was kept constant at 1.2 mL/min. The extracts (2.0 μL) were injected onto GC in splitless mode with an inlet temperature of 280°C. – Quantitation was performed using the internal calibration Fig. 2 GC/FID chromatogram of PAEs standard /(20 mg$L 1) 76 Front. Earth Sci. China 2009, 3(1): 73–79

3 Results and discussion Interestingly, the lowest concentration of total PAEs occurred at sites W3, W4, and W12, which were farthest 3.1 PAEs species in groundwater from the Yangtze River. It also can be seen that the total PAE concentrations followed the order W16 > W15 > Figure 3 presents the detection rate of PAEs in 17 W13 > W12, W10 > W17 > W7 > W2, W1 > W3, groundwater samples. It shows that 4 PAEs species were W16 > W14, W6 > W4. This means that in the direction detected, i.e. DIBP, DBP, BEEP and DEHP. The detection vertical to the Yangtze River, the farther from the Yangtze rate of DEHP was 100%. It was reported that DBP, DIBP River the sampling sites were, the lower the concentrations and DEHP were dominant in agricultural soils among 16 of the PAEs. So the distribution of PAEs in the ground- PAEs (Zeng et al., 2008a), and DBP and DEHP were the water of the Jianghan plain was seriously affected by the main species among 5 PAEs (DMP, DEP, DBP, DEHP, Yangtze River. In this paper, samples were collected in DOP) in the Yangtze River water and sediments (Wang et July, which belongs to the high water period when the al., 2008a). In the water and sediments of urban lakes in Yangtze River supplies water underground. Thus, the high Guangzhou, DMP, DEP, DBP, DIBP, BMPP and DEHP concentrations of PAEs in the Yangtze River entered into were present in all water and sediment samples, and DBP, groundwater along with the water supply. The decreasing DIBP and DEHP were abundant in water (Zeng et al., trend of PAE concentrations with increasing intervals from 2008b). The similarity of the PAE species in these media the Yangtze River was due to the water supply character- indicated that PAEs in groundwater may come from soil istics, adsorption and degradation in the underground and surface water. However, BEEP was not detected transportation process. frequently in the environment and its concentration was very low even though it was detected elsewhere (Zeng et al., 2008a, b). The origins of BEEP in groundwater thus merit further investigation.

Fig. 4 Concentrations of total PAEs in groundwater samples

However, sites W1 and W2 showed higher PAE Fig. 3 Detection rates of PAEs in 17 groundwater samples concentrations than W3 and W4, which was mainly because W1 and W2 were close to the Hanjiang River. 3.2 Total PAE concentrations in groundwater Thus, the water supply from the Hanjiang River also affected the occurrence of PAEs in groundwater. W8 and Concentrations of total PAEs in groundwater samples W9 are near Honghu Lake. The concentration of PAEs at ranged from 80.12 to 1882.18 ng/L (Fig. 4). It was reported W8 was higher than that at W9 even though W9 was nearer that the total concentrations of 5 PAEs (DMP, DEP, DBP, the Yangtze River, which indicated that Honghu Lake also DEHP, DOP) in the Wuhan Section of the Yangtze River had an effect on the distribution of PAEs in the ground- were 0.034–0.456 μg/L and 35.73–91.22 μg/L in the high water of the Jianghan plain. The concentrations of total and low water periods, respectively (Wang et al., 2008a), PAEs at W5 and W11 were unexpectedly high. There was a whereas in the Xiaolangdi–Dongming Bridge Section of Tianhe water plant and a construction material factory at the Yellow River, the total 5 PAE concentrations ranged site W5. A steel wire plant was near site W11; and, there from 3.99 to 45.45 μg/L in June (Sha et al., 2007). The total was no industry present in the other sites. Higher concentrations of 16 PAEs in urban lakes in Guangzhou concentrations of PAEs at W5 and W11 may come from were from 1.69 to 4.72 μg/L (Zeng et al., 2008b). Thus, the these plants. concentrations of PAEs in surface water are related to the sampling season and vary with the sampling area. If DIBP 3.3 Individual PAE concentrations in groundwater and BEEP were subtracted from the total PAEs in our results, the concentrations of the total PAEs would be Figure 5 illustrates that concentrations of DIBP, DBP, much lower than that in the surface waters. BEEP and DEHP, which were nd–558.07, nd–331.33, Dan ZHANG et al. Distribution of phthalate esters in the groundwater of Jianghan plain, Hubei, China 77 nd–785.34, and nd–56.5–1100.76 ng/L, respectively. 3.4 Relationship between PAE concentration and electrical According to the national standards of drinking water in conductivity China (GB5749-2006), the limits to concentrations of DBP and DEHP for drinking water sources are 0.003 and Electrical conductivity (EC) is an important parameter of 0.008 mg/L, respectively. PAEs in the Jianghan plain did water quality. EC mainly depends on the species and not exceed this quality standard limit. However, this should concentrations of ions, which are related to the properties be paid attention to so as to prevent further pollution. of the groundwater media and pollution from artificial Different PAEs may come from different sources. The activities. It was proved that the EC of groundwater is contents of the detected four PAEs in the different closely related to the contaminant status (Gao et al., 2006). sampling sites are illustrated in Fig. 5. The concentrations As is shown in Table 1, there was an obvious difference in of DIBP, DBP and DEHP were low at sites far from the the EC of the groundwater among the different sites, which Yangtze River, such as W1, W2, W3, W4, W12, W13, and may reflect different inorganic pollutants. However, there high at sites near the Yangtze River, such as W6, W9, W10, was no linear relationship between PAE concentration and W16. The results demonstrated that the concentrations of EC (Fig. 6), which indicates that the source and DIBP, DBP and DEHP in the groundwater of the Jianghan transportation mechanism of PAEs and inorganic com- plain were closely related to the water supply of the pounds are different. Yangtze River. One of the most efficient ways to prevent pollution from PAEs in the groundwater of the Jianghan 3.5 Relationship between PAE concentration and sample plain is to control further pollution of the surface water. depth However, the distribution of BEEP was irregular, which was very different from other PAEs. This may be due to the It is easy to think that deeper groundwater is less polluted. application of some kinds of products containing BEEP in However, PAE concentration was irrelevant to sample the related areas. depth (Fig. 7). This result indicated that there was no

Fig. 5 Concentrations of DIBP, DBP, BEEP, and DEHP in 17 sampling sites 78 Front. Earth Sci. China 2009, 3(1): 73–79

Fig. 6 Correlation between concentrations of PAEs and electrical conductivity

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