Environ Sci Pollut Res DOI 10.1007/s11356-015-4688-z
RESEARCH ARTICLE
Polychlorinated biphenyls and organochlorine pesticides in surface sediments from the sand flats of Shuangtaizi Estuary, China: levels, distribution, and possible sources Xiutang Yuan 1 & Xiaolong Yang 1 & Guangshui Na 1 & Anguo Zhang 1,2 & Yuze Mao 3 & Guize Liu 1 & Lili Wang 1 & Xiaodong Li 4
Received: 24 January 2015 / Accepted: 8 May 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in sediments from the sandy flat system of Shuangtaizi Estuary, the highest-latitude estuary in China, were investigated to identify their possible sources and potential ecological risk. The concentrations of 28 PCBs and 18 OCPs ranged from 1.83 to 36.68 ng g−1 dw (mean 10.53 ng g−1 dw) and from 0.02 to 14.57 ng g−1 dw (mean 5.65 ng g−1 dw), respectively. Generally, these organic pollutants showed an obvious spatial distribution, and relatively high levels were found at the high-tidal zone near river mouths. Compositional analyses indicated that tetra-PCBs were dominant for PCBs, whereas heptachlor was identified to be prevalent for OCPs in surficial sediment in the sand flats of Shuangtaizi Estuary. Overall, Shuangtaizi Estuary had moderate PCB and OCP levels in the sand flat sediments and posed a low ecological hazard to aquatic biota. Our results indicated that the sediment PCBs came from nonpoint Responsible editor: Ester Heath Electronic supplementary material The online version of this article (doi:10.1007/s11356-015-4688-z) contains supplementary material, which is available to authorized users. * Xiutang Yuan [email protected] 1
National Marine Environmental Monitoring Center, State Oceanic Administration, 42 Linghe Street, Dalian 116023, People’s Republic of China
2
Liaoning Medical University, Jinzhou 315211, People’s Republic of China
3
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, People’s Republic of China
4
Panjin Guanghe Crab Co. Ltd, Panjin 124200, People’s Republic of China
deposition, such as atmospheric contribution and river input, for light chlorinated congeners and point source deposition, such as the industrial sources along river flow, for highly chlorinated congeners, whereas OCPs originate mainly from old residuals and new usage of pesticides in agriculture and aquaculture. Keywords POPs . Shuangtaizi Estuary . Sandy flat system . Sediment . PCBs . OCPs
Introduction Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), have attracted much concern due to their persistence, bioaccumulation, and toxicity (Minh et al. 2007). Twelve POPs, including PCBs and OCPs (e.g., dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs)), were identified by the United Nations Environment Programme as components of the Bdirty dozen,^ proposed to be restricted and forbidden worldwide (Stockholm 2001). PCBs are man-made organic compounds that consist of a biphenyl with varying numbers of chlorine atoms substituted on the two six-carbon benzene rings (Dimou et al. 2006). PCBs could have 10 homologs and 209 distinct congeners depending on the number and position of chlorine atoms. Giving their characteristics of low electrical conductivity and high resistance to heat and thermal degradation, PCBs are used as heat exchange fluids in transformers and capacitors. In addition, PCBs were ideal additives in paints, dyed paper, and plastics (Yu et al. 2014). Approximately 10,000 t of PCBs were produced in China from 1965 to 1974, accounting for 1 % of global production (Zheng et al. 2010). OCPs, as a group of typical POPs, were the first artificial pesticides
Environ Sci Pollut Res
(e.g., DDTs, HCHs, dieldrin, endrin, aldrin, etc.) and have attracted considerable interests because of their historically high production, persistence, bioaccumulation, and potentially negative effects on nontarget organisms (Zhou et al. 2014). The production and usage of these pesticides were stopped or restricted in the 1970s and 1980s in developed countries; however, most OCPs, especially DDTs and HCHs, are still used in some developing countries in agriculture due to their high efficiency, low cost, and broad-spectrum pest-killing efficacy (Zhao et al. 2009). In China, although the production and application of PCBs and OCPs have been totally banned in 1974 and 1983, respectively, high levels of these organic pollutants were still detectable in sediments and organisms (Yuan et al. 2013; Yu et al. 2014). POP behavior in marine ecosystems is affected by several factors such as sources and physicochemical properties, water and sediment movement, and size fraction (Marini and Frapiccini 2014; Mwanamoki et al. 2014). POPs are absorbed onto particulate matter and accumulate in sediments according to their high hydrophobicity and molecular mass (Medeiros et al. 2005). Sediments, the primary reservoir for hydrophobic contaminants, are generally affected by anthropogenic activities and local geology (Calmano et al. 1996; Salomons and Förstner 1984; Salomons 1995). Therefore, surface sediments, which reflect the current contamination status (Yan et al. 2009), are considered an optimal medium to evaluate the environmental quality in estuarine and coastal systems (Sprovieri et al. 2007; Mwanamoki et al. 2014). Shuangtaizi Estuary (121°30′–122°00′E, 40°50′–41°20′N), the highest-latitude estuary in China, possesses one of the few remaining intertidal sand flats, which are a significant habitat for various marine organisms, especially clams and lugworms (Zhang et al. 2013). Around the estuary, three main rivers, namely, Shuangtaizi River, Daliao River, and Daling River, flow into the sea and form the present sandy flat system, which covers a tidal flat area of 67,000 ha, accounting for 56 % of the total flat area in Liaodong Bay (the largest bay in the Bohai Sea of China). The sand flats in Shuangtaizi Estuary are divided into two parts by Shuangtaizi River (Fig. 1): one is Panshan Shore (PS), and the other with a fusiform shape named Geligang (GLG, meaning habitats for clams). These rivers continuously receive various contaminants such as PCBs and OCPs from a large number of domestic sewage inputs and industrial activities. Meanwhile, the Shuangtaizi Estuary provides excellent conditions for commercial rice planting (Lin et al. 2013) as well as crab and clam cultures (Zhang et al. 2013). However, the application of excessive pesticides in agriculture and aquaculture would have resulted in increasing residues of OCPs and PCBs in both kind and level during the past decades, which entered into rivers and at last accumulated in the estuarine sediments. The estuarine ecosystem, as one of the most important global ecosystems, provides certain key ecosystem services
such as food supply, biodiversity, recreation, and scientific research. Therefore, it is of great significance to maintain the habitat quality and ecosystem health of an estuarine system (Barbier et al. 2011). On the other hand, estuaries are strongly susceptible to pollution from anthropogenic input via rivers and industries as well as surrounding agriculture and aquaculture. Investigations on PCBs and OCPs in estuarine environments have been conducted worldwide in recent years (e.g., Gao et al. 2013; Liu et al. 2008; Fernandez et al. 1999; Tolosa et al. 1995). Although POP (e.g., PAHs and PCBs) monitoring and assessment in sediments of Daliao River and soils of the adjacent wetland have been reported (Liu et al. 2014; Ma et al. 2014; Zhang et al. 2010), no PCB and OCP investigation to date is available in the Shuangtaizi Estuary, despite its abovementioned ecological significances. Our study provides the first identification of the levels, sources, and ecological risk of PCBs and OCPs in sediments of the vast tidal flats in Shuangtaizi Estuary. Such data are hopeful to provide important baseline information for environmental monitoring and further policy making in this area.
Materials and methods Sample collection and preparation Four and nine sections perpendicular to the Shuangtaizi River current were set in PS and GLG, respectively (Fig. 1). A total of 60 sampling sites (30 in each region) were investigated, and 60 undisturbed samples (a 10 cm×10 cm2 of 5-cm surficial sediment) were gently collected in the lowest water level in spring tide of May 2013 using a triangular stainless steel spade and placed in pre-cleaned glass jars. The samples were initially stored in an icebox until delivery to the laboratory and kept at −20 °C for further handling. Global positioning system (GPS) was used for locating the sampling site. In the laboratory, all samples were dried under −52 °C and
RESEARCH ARTICLE
Polychlorinated biphenyls and organochlorine pesticides in surface sediments from the sand flats of Shuangtaizi Estuary, China: levels, distribution, and possible sources Xiutang Yuan 1 & Xiaolong Yang 1 & Guangshui Na 1 & Anguo Zhang 1,2 & Yuze Mao 3 & Guize Liu 1 & Lili Wang 1 & Xiaodong Li 4
Received: 24 January 2015 / Accepted: 8 May 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in sediments from the sandy flat system of Shuangtaizi Estuary, the highest-latitude estuary in China, were investigated to identify their possible sources and potential ecological risk. The concentrations of 28 PCBs and 18 OCPs ranged from 1.83 to 36.68 ng g−1 dw (mean 10.53 ng g−1 dw) and from 0.02 to 14.57 ng g−1 dw (mean 5.65 ng g−1 dw), respectively. Generally, these organic pollutants showed an obvious spatial distribution, and relatively high levels were found at the high-tidal zone near river mouths. Compositional analyses indicated that tetra-PCBs were dominant for PCBs, whereas heptachlor was identified to be prevalent for OCPs in surficial sediment in the sand flats of Shuangtaizi Estuary. Overall, Shuangtaizi Estuary had moderate PCB and OCP levels in the sand flat sediments and posed a low ecological hazard to aquatic biota. Our results indicated that the sediment PCBs came from nonpoint Responsible editor: Ester Heath Electronic supplementary material The online version of this article (doi:10.1007/s11356-015-4688-z) contains supplementary material, which is available to authorized users. * Xiutang Yuan [email protected] 1
National Marine Environmental Monitoring Center, State Oceanic Administration, 42 Linghe Street, Dalian 116023, People’s Republic of China
2
Liaoning Medical University, Jinzhou 315211, People’s Republic of China
3
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, People’s Republic of China
4
Panjin Guanghe Crab Co. Ltd, Panjin 124200, People’s Republic of China
deposition, such as atmospheric contribution and river input, for light chlorinated congeners and point source deposition, such as the industrial sources along river flow, for highly chlorinated congeners, whereas OCPs originate mainly from old residuals and new usage of pesticides in agriculture and aquaculture. Keywords POPs . Shuangtaizi Estuary . Sandy flat system . Sediment . PCBs . OCPs
Introduction Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), have attracted much concern due to their persistence, bioaccumulation, and toxicity (Minh et al. 2007). Twelve POPs, including PCBs and OCPs (e.g., dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs)), were identified by the United Nations Environment Programme as components of the Bdirty dozen,^ proposed to be restricted and forbidden worldwide (Stockholm 2001). PCBs are man-made organic compounds that consist of a biphenyl with varying numbers of chlorine atoms substituted on the two six-carbon benzene rings (Dimou et al. 2006). PCBs could have 10 homologs and 209 distinct congeners depending on the number and position of chlorine atoms. Giving their characteristics of low electrical conductivity and high resistance to heat and thermal degradation, PCBs are used as heat exchange fluids in transformers and capacitors. In addition, PCBs were ideal additives in paints, dyed paper, and plastics (Yu et al. 2014). Approximately 10,000 t of PCBs were produced in China from 1965 to 1974, accounting for 1 % of global production (Zheng et al. 2010). OCPs, as a group of typical POPs, were the first artificial pesticides
Environ Sci Pollut Res
(e.g., DDTs, HCHs, dieldrin, endrin, aldrin, etc.) and have attracted considerable interests because of their historically high production, persistence, bioaccumulation, and potentially negative effects on nontarget organisms (Zhou et al. 2014). The production and usage of these pesticides were stopped or restricted in the 1970s and 1980s in developed countries; however, most OCPs, especially DDTs and HCHs, are still used in some developing countries in agriculture due to their high efficiency, low cost, and broad-spectrum pest-killing efficacy (Zhao et al. 2009). In China, although the production and application of PCBs and OCPs have been totally banned in 1974 and 1983, respectively, high levels of these organic pollutants were still detectable in sediments and organisms (Yuan et al. 2013; Yu et al. 2014). POP behavior in marine ecosystems is affected by several factors such as sources and physicochemical properties, water and sediment movement, and size fraction (Marini and Frapiccini 2014; Mwanamoki et al. 2014). POPs are absorbed onto particulate matter and accumulate in sediments according to their high hydrophobicity and molecular mass (Medeiros et al. 2005). Sediments, the primary reservoir for hydrophobic contaminants, are generally affected by anthropogenic activities and local geology (Calmano et al. 1996; Salomons and Förstner 1984; Salomons 1995). Therefore, surface sediments, which reflect the current contamination status (Yan et al. 2009), are considered an optimal medium to evaluate the environmental quality in estuarine and coastal systems (Sprovieri et al. 2007; Mwanamoki et al. 2014). Shuangtaizi Estuary (121°30′–122°00′E, 40°50′–41°20′N), the highest-latitude estuary in China, possesses one of the few remaining intertidal sand flats, which are a significant habitat for various marine organisms, especially clams and lugworms (Zhang et al. 2013). Around the estuary, three main rivers, namely, Shuangtaizi River, Daliao River, and Daling River, flow into the sea and form the present sandy flat system, which covers a tidal flat area of 67,000 ha, accounting for 56 % of the total flat area in Liaodong Bay (the largest bay in the Bohai Sea of China). The sand flats in Shuangtaizi Estuary are divided into two parts by Shuangtaizi River (Fig. 1): one is Panshan Shore (PS), and the other with a fusiform shape named Geligang (GLG, meaning habitats for clams). These rivers continuously receive various contaminants such as PCBs and OCPs from a large number of domestic sewage inputs and industrial activities. Meanwhile, the Shuangtaizi Estuary provides excellent conditions for commercial rice planting (Lin et al. 2013) as well as crab and clam cultures (Zhang et al. 2013). However, the application of excessive pesticides in agriculture and aquaculture would have resulted in increasing residues of OCPs and PCBs in both kind and level during the past decades, which entered into rivers and at last accumulated in the estuarine sediments. The estuarine ecosystem, as one of the most important global ecosystems, provides certain key ecosystem services
such as food supply, biodiversity, recreation, and scientific research. Therefore, it is of great significance to maintain the habitat quality and ecosystem health of an estuarine system (Barbier et al. 2011). On the other hand, estuaries are strongly susceptible to pollution from anthropogenic input via rivers and industries as well as surrounding agriculture and aquaculture. Investigations on PCBs and OCPs in estuarine environments have been conducted worldwide in recent years (e.g., Gao et al. 2013; Liu et al. 2008; Fernandez et al. 1999; Tolosa et al. 1995). Although POP (e.g., PAHs and PCBs) monitoring and assessment in sediments of Daliao River and soils of the adjacent wetland have been reported (Liu et al. 2014; Ma et al. 2014; Zhang et al. 2010), no PCB and OCP investigation to date is available in the Shuangtaizi Estuary, despite its abovementioned ecological significances. Our study provides the first identification of the levels, sources, and ecological risk of PCBs and OCPs in sediments of the vast tidal flats in Shuangtaizi Estuary. Such data are hopeful to provide important baseline information for environmental monitoring and further policy making in this area.
Materials and methods Sample collection and preparation Four and nine sections perpendicular to the Shuangtaizi River current were set in PS and GLG, respectively (Fig. 1). A total of 60 sampling sites (30 in each region) were investigated, and 60 undisturbed samples (a 10 cm×10 cm2 of 5-cm surficial sediment) were gently collected in the lowest water level in spring tide of May 2013 using a triangular stainless steel spade and placed in pre-cleaned glass jars. The samples were initially stored in an icebox until delivery to the laboratory and kept at −20 °C for further handling. Global positioning system (GPS) was used for locating the sampling site. In the laboratory, all samples were dried under −52 °C and
