珠江佛山段沉积物中5类新污染物分布特征及风险评估

Distribution characteristics and risk assessment of five categories of emerging contaminants in sediments of the Foshan section of the Pearl River

  • 摘要: 新污染物(ECs)在沉积物中普遍存在,系统评估其风险对维护流域生态环境及饮用水安全具有重要意义.研究于2024年前、后汛期在珠江佛山段(西江、北江)10个关键点位采集沉积物样品,系统测定了5类52种ECs的浓度水平,采用生态风险商值(P)评价其生态风险,并基于随机森林优化的毒理学优先级指数(ToxPi)模型进行综合风险排序.结果表明:52种ECs中共检出44种,总浓度范围为未检出(ND)~60.5 ng·g−1,平均浓度0.83 ng·g−1;检出率和浓度最高的类别分别为全氟/多氟烷基化合物(PFASs,72.5%)和邻苯二甲酸酯类(PAEs,1.70 ng·g−1),双酚A(BPA,8.57 ng·g−1)为单物质浓度最高值;空间上北江ECs平均浓度(1.28 ng·g−1)高于西江(0.64 ng·g−1),时间上前汛期浓度普遍高于后汛期;2.1%的点位呈高风险(P≥1),紫外吸收剂(UVAs)和PAEs高风险占比最高(分别为5.5%、2.8%),邻苯二甲酸二(2-乙基己基)酯(DEHP)、2-(2′-羟基-5′-叔辛基苯基)苯并三唑(UV-329)等为重点高风险物质;ToxPi综合风险排序前10位ECs均为PFASs,各类别综合风险评分依次为PFASs(0.63)>激素类(HORMs,0.47)>PAEs(0.33)>酚类(PCs,0.30)>UVAs(0.24).研究初步明确了珠江佛山段ECs的污染现状及风险特征,为区域ECs精准管控提供了科学依据.

     

    Abstract: Emerging contaminants (ECs) are ubiquitous in sediments, and systematic assessment of their risks is essential for protecting aquatic ecosystems and ensuring drinking water safety. In this study, sediment samples were collected from 10 monitoring sites along the Foshan section of the Pearl River (including the Xijiang and Beijiang Rivers) during the pre- and post-flood seasons of 2024. The concentrations of 52 ECs from five categories were systematically measured. The ecological risk was evaluated using the Ecological Risk Quotient (P) method, and a comprehensive risk ranking was performed based on a Toxicological Priority Index (ToxPi) model optimized by random forest. The results indicated that 44 of the 52 target ECs were detected, with cumulative concentrations ranging from not detected (ND) to 60.5 ng·g−1, and a mean concentration of 0.83 ng·g−1. Per- and polyfluoroalkyl substances (PFASs) had the highest detection rate (72.5%), while phthalate esters (PAEs) exhibited the highest mean concentration (1.70 ng·g−1). Bisphenol A (BPA) (8.57 ng·g−1) was the substance with the highest concentration. Spatial analysis revealed that the mean EC concentration in the Beijiang River (1.28 ng·g−1) exceeded that in the Xijiang River (0.64 ng·g−1). Temporally, concentrations during the pre-flood season were generally higher than those observed in the post-flood season. High risk (P ≥ 1) was identified at 2.1 % of the monitoring sites, with ultraviolet absorbents (UVAs) and PAEs accounting for the largest shares of high-risk sites (5.5 % and 2.8 %, respectively). Phthalate di(2-ethylhexyl) ester (DEHP) and 2-(2-Hydroxy-5-tert-octylphenyl)benzotriazole (UV-329) were identified as key high-risk substances. The ToxPi model ranked the top 10 ECs in terms of overall risk, all of which were PFASs. The comprehensive risk scores for each category were as follows: PFASs (0.63) > hormones (HORMs, 0.47) > PAEs (0.33) > phenols (PCs, 0.30) > UVAs (0.24). This study presents a preliminary assessment of the occurrence and risk profiles of ECs in the Foshan section of the Pearl River, providing a scientific basis for targeted management of these contaminants in the region.

     

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