Center for Applied Geoscience, Eberhard Karls University of Tübingen, Schnarrenbergstr. 94-96, 72076 Tübingen, Germany.
Department Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany.
Environ Sci Technol. 2021 Apr 20;55(8):5106-5116. doi: 10.1021/acs.est.0c07772. Epub 2021 Mar 24.
Suspended particulate matter (SPM) plays an important role in the fate of organic micropollutants in rivers during rain events, when sediments are remobilized and turbid runoff components enter the rivers. Under baseflow conditions, the SPM concentration is low and the contribution of SPM-bound contaminants to the overall risk of organic contaminants in rivers is assumed to be negligible. To challenge this assumption, we explored if SPM may act as a source or sink for all or specific groups of organic chemicals in a small river. The concentrations of over 600 contaminants and the mixture effects stemming from all chemicals in bioassays were measured for river water, SPM, and the surface sediment after solid-phase extraction or exhaustive solvent extraction. The bioavailable fractions of chemicals and mixture effects were estimated after passive equilibrium sampling of enriched SPM slurries and sediments in the lab. Dissolved compounds dominated the total chemical burden in the water column (water plus SPM) of the river, whereas SPM-bound chemicals contributed up to 46% of the effect burden even if the SPM concentration in rivers was merely 1 mg/L. The equilibrium between water and SPM was still not reached under low-flow conditions with SPM as a source of water contamination. The ratios of SPM-associated to sediment-associated neutral and hydrophobic chemicals as well as the ratios of the mixture effects expressed as bioanalytical equivalent concentrations were close to 1, suggesting that the surface sediment can be used as a proxy for SPM under baseflow conditions when the sampling of a large amount of water to obtain sufficient SPM cannot be realized.
悬浮颗粒物 (SPM) 在雨水事件中对河流中有机微量污染物的命运起着重要作用，此时沉积物重新移动，浑浊径流成分进入河流。在基流条件下，SPM 浓度较低，并且假定 SPM 结合的污染物对河流中有机污染物的总体风险的贡献可以忽略不计。为了挑战这一假设，我们探讨了 SPM 是否可能成为小河流中所有或特定有机化学物质组的源或汇。在固相萃取或彻底溶剂萃取后，测量了河水、SPM 和表层沉积物中超过 600 种污染物的浓度以及生物测定中所有化学物质的混合物效应。在实验室中通过对富含 SPM 的泥浆和沉积物进行被动平衡采样，估算了化学物质的可利用部分和混合物效应。溶解化合物在河流水柱（水加 SPM）中占总化学负荷的主导地位，尽管河流中的 SPM 浓度仅为 1mg/L，但 SPM 结合的化学物质仍占效应负荷的 46%。在低流量条件下，即使 SPM 是水污染的来源，水和 SPM 之间仍未达到平衡。SPM 相关与沉积物相关的中性和疏水性化学物质的比例以及以生物分析等效浓度表示的混合物效应的比例接近 1，这表明在无法采集大量水以获得足够的 SPM 时，在基流条件下，可以将表层沉积物用作 SPM 的替代物。
