Distribution, partitioning behavior, and ecological risk assessment of phthalate esters in sediment particle-pore water systems from the main stream of the Haihe River, Northern China

https://doi.org/10.1016/j.scitotenv.2020.141131Get rights and content

Highlights

  • DEHP, DBP, and DIBP were the dominant species in surface sediment and pore water.

  • Notable differences in PAEs concentrations were observed between urban reaches and nonurban reaches.

  • Partitioning of PAEs between surface sediment and pore water was not significantly affected by KOW.

  • DEHP and DIBP in surface sediment exhibited high ecological risk.

  • DEHP, DIBP, and DBP in pore water showed high ecological risk.

Abstract

The distribution, partitioning behavior and risk assessment of phthalate esters (PAEs) in the surface sediment-pore water system of the Haihe River were investigated. The total cumulative concentrations of 21 PAE species (Σ21PAEs) in the surface sediment ranged from 45.9 to 1474.1 ng·g−1 dry weight (dw) and were from 17.9 to 2628.8 ng·mL−1 in the pore water. Di (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and diisobutyl phthalate (DIBP) were the dominant components, and their sum accounted, on average, for 88.4% and 72.0% of Σ21PAEs in the surface sediment and pore water, respectively. The spatial distributions of Σ21PAEs in the surface sediment and pore water indicated that large amounts of the consumed products contained plasticizers in the urban and nearshore areas and increased the discharge of PAEs into the Haihe River. The river dam also affected PAEs distributions. The organic carbon normalized partitioning coefficient (logKOC) followed a sequence as dry season (2.47 ± 0.35 mL·g−1) > wet season (2.02 ± 0.45 mL·g−1) > normal season (1.98 ± 0.42 mL·g−1). The risk quotient (RQ) method was employed to assess the potential ecological risk from specific species. High ecological risks of DEHP to the sensitive algae, crustacean, and fish species along with high ecological risks of DIBP to sensitive fish species were found in the surface sediment and pore water for all sampling seasons. In addition, DBP in the surface sediment and pore water exhibited moderate and high ecological risks to sensitive aquatic species. The highest RQ values for PAEs were found in the surface sediment and pore water in suburban and urban areas, respectively, and indicated that anthropogenic activities may cause severe river pollution and high risk to the local aquatic ecosystem.

Capsule

High levels and ecological risks from PAEs were found in the urban river, and the partitioning behaviors of PAEs between the surface sediment and pore water were not significantly affected by their hydrophobicity, especially for species with low KOW.

Introduction

Phthalate esters (PAEs) have mainly been used as plasticizers to improve the technical properties (e.g., flexibility, durability, and workability) of polymers (Marx, 1972; Staples et al., 1997a). High molecular weight (HMW) phthalates (ester side-chain length ≤ four carbon numbers) such as di (2-ethylhexyl) phthalate (DEHP) are primarily used as plasticizers for polyvinyl chloride (PVC) and examples of products involved include wire and cable, flooring, wall coverings, self-adhesive films, synthetic leather and coated fabrics. Low molecular weight (LMW) phthalates (ester side-chain length ≥ five carbon numbers), e.g., diethyl phthalate (DEP) are commonly added as solvents, fixatives, and adhesives to cosmetics, medical devices, and personal care products (ATSDR, 1995; ATSDR, 2002; Latini, 2005; National Research Council, 2008). With the largest plasticizer market in the world, China accounted for nearly 42% of worldwide consumption in 2017 and has the highest expected growth during 2017–2022 (HIS Markit, 2018). Since PAEs are not covalently bonded to polymeric matrices, they are easily released from various products during manufacture, usage, and disposal, which cause extensive migration and transformation in nature (Staples et al., 1997b). To date, ubiquitous occurrence of PAEs has been detected in different environmental media such as rivers and lakes (Sun et al., 2013; Liu et al., 2014), oceans (Paluselli et al., 2018), sediments (Arfaeinia et al., 2019; Chakraborty et al., 2019), soils (Zhao et al., 2018), atmosphere (Kong et al., 2013), and even in remote Arctic regions (Xie et al., 2007).

Considering their persistent, bioaccumulative, and toxic (PBT) properties, PAEs have attracted extensive attention in recent years. The United States Environmental Protection Agency (USEPA) has issued an action plan for the control of di-isobutyl phthalate (DIBP), butyl benzyl phthalate (BBP), di-n-octyl phthalate (DnOP), di-n-pentyl phthalate (DnPP), di-isononyl phthalate (DINP), diisodecyl phthalate (DIDP), dibutyl phthalate (DBP), and DEHP (USEPA, 2012). In 2014, The European Union's Registration, Evaluation, Authorization & Restriction of Chemicals (REACH) program prohibited the use of four phthalates (DBP, BBP, DEHP, and DIBP) in consumer products sold in the EU (EC, 2014). China promulgated limitations on DEHP, DBP, BBP, DINP, DIDP, and DnOP in the coatings of toys in 2009 (AQSIQ, 2009). PAEs enter organisms through different pathways such as ingestion and breathing and then gradually accumulate in the tissues with increases in intake dosage and are transported via the food chain to high trophic levels, all of which may eventually threaten ecosystem safety and human health (Staples et al., 1997b; Latini, 2005). Additionally, it was reported that humans can be exposed to PAEs via daily diet, inhalation, and dermal contact (EC, 2003; Latini, 2005). Several epidemiological studies found correlations of PAEs with some adverse impacts, e.g., reproductive malformations, sperm damage, fertility impairment, early puberty in girls, asthma, and thyroid diseases (Latini, 2005; Gao et al., 2018).

PAEs can directly enter aquatic environments from industrial wastewater discharges containing PAEs, effluents leaching from agricultural plastic films, and solid plastic wastes transported by surface runoff. In addition, the indirect input pathways of PAEs mainly refer to the entrance of atmospheric PAEs through dry and wet depositions (Gao et al., 2018; Kong et al., 2013). Due to strong their hydrophobicity, PAEs in aquatic environments are easily adsorbed on suspended particulates or phytoplankton, some of which precipitate and accumulate in sediments (Qiu et al., 2020). Therefore, sediments (including surface sediments and the sedimentary column) usually play a dominant role as accumulation sinks and release sources of PAEs and are extensively used as indicators for evaluating the pollution conditions of PAEs in various aquatic environments (Ramzi et al., 2018; Wang et al., 2014; Zhang et al., 2019). In addition, pore water in sediment is considered as another sink for organic pollutants and represents an important exposure pathway for benthos (Feng et al., 2020). Some reports have indicated that the partitioning processes of PAEs between sediment solid particles and pore water pose considerable effects on their migration and transformation in aquatic ecosystems and on the corresponding risk assessment of PAEs exposed to benthos (Feng et al., 2020; He et al., 2016). PAEs would degrade by hydrolysis and photolysis, and biodegradation under natural environment, in which microbial activity (such as methanogen, sulfate-reducing bacteria, and eubacteria etc.) is the principal mechanism for PAE degradation in both water and sediments (Staples et al., 1997b; Lu et al., 2020). Although the concentrations and distributions of PAEs in sediments collected from lakes and rivers have been reported (Arfaeinia et al., 2019; Chakraborty et al., 2019; Sun et al., 2013; Wang et al., 2014), some issues, such as impacts of urbanization and water conservancy facility (e.g., dam) on PAEs distribution, the partitioning behaviors and ecological risks of PAEs, are still needed to further explore.

As the largest coastal city in Northern China, Tianjin is located in the Haihe River Basin with a resident population of 15.57 million and a land area of 11,917 km2 (Tianjin Statistics Bureau, 2017). The Haihe River, the largest freshwater system in Northern China, located in a highly urbanized region and its main stream (total length of 73 km) flows through the suburban, urban and industrial areas of Tianjin and then eastward to the adjacent Bohai Sea. Some studies have indicated positive relationships between anthropogenic activities, land use patterns and PAEs concentrations (Gao et al., 2018; Zheng et al., 2014). Furthermore, the Haihe River Basin is located in a large region of China with a high population density and extensive industrialization which is characterized by the presence of large amounts of aquatic pollutants in the main stream of the Haihe River. For example, PAEs were detected at levels of 2147.1 ± 1199.9 ng·L−1 and 6.0 ± 3.7 mg·kg−1 in the overlying water and surface sediment of the adjacent Bohai Sea, respectively (Zhang et al., 2018). To date, only a small amount of research has focused on the occurrence of PAEs in the Haihe River (Chi, 2009) while studies on the partitioning behaviors of PAEs between sediment solid particles and pore water remain inadequate. The objectives of the current study aim to: (1) investigate the concentrations and spatial distributions of different PAE species in surface sediment and pore water collected in the main stream of the Haihe River, (2) analyze the partitioning coefficients (KP) of PAEs between sediment solid particles and pore water, and (3) estimate potential ecological risks of PAEs in surface sediment and pore water between urban reaches and nonurban reaches along the main stream of the Haihe River.

Section snippets

Material and reagent

High performance liquid chromatography (HPLC) grade methanol, n-hexane (HEX), dichloromethane (DCM), and pesticide-grade acetone (ACE) were purchased from a commercial manufacturer (Thermo Fisher Scientific, Waltham, Massachusetts, USA). Anhydrous sodium sulfate, silica, and alumina were also purchased from a commercial reagent company (Sinopharm Chemical Reagent Co., Ltd., Shanghai, China). Anhydrous sodium sulfate was baked at 650 °C for 10 h before use. Silica and alumina were roasted at

Spatial distributions and compositional profiles of PAEs in surface sediment and pore water

A total of 138 surface sediment samples and 138 pore water samples were collected in this study (the scope of the main stream of the Haihe River covers 38°50′N-39°00′N and 117°00′E-117°05′E). The statistical results for the specific PAEs (DMP, DEP, DBP, BBP, DEHP, and DnOP) which are in the priority list recommended by the USEPA (Keith and Telliard, 1979) are tabulated in Table 1. The average ± standard deviation of the individual species at each sampling site are summarized in Tables S4 and

Conclusions

DEHP, DBP, and DIBP served as the dominant components of Σ21PAEs in the pore water-surface sediment systems from the main stream of the Haihe River. Spatial differences in distribution of PAEs were found in the different functional zones and river reaches. Moreover, the Σ21PAEs in the surface sediment and pore water in the upstream section of the river dam were significantly higher (p < 0.01) than those in the downstream section of the river dam, indicating that interception by the river dam

CRediT authorship contribution statement

Yang Liu: Investigation, Formal analysis, Validation, Writing - original draft, Writing - review & editing. Yong He: Data curation, Methodology, Formal analysis, Validation, Writing - original draft. JiaoDi Zhang: Investigation, Formal analysis, Validation, Writing - original draft. ChuanYang Cai: Investigation. Florian Breider: Data curation, Methodology. Shu Tao: Conceptualization, Project administration, Resources, Funding acquisition, Supervision. WenXin Liu: Conceptualization, Project

Declaration of competing interest

None.

Acknowledgement

The present study was supported by the following projects: National Natural Science Foundation of China (No. 41991311), and National Key Research and Development Program of China (No. 2019YFC1804204). All the authors are grateful to the Elsevier Language Editing Service for polishing the English expressions in this paper.

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