Background

Chemical quality of sediment and suspended particulate matter (SPM) is usually assessed by total chemical concentrations (C_total). However, the freely dissolved concentration (C_free) is the ecologically more relevant parameter for bioavailability, diffusion and bioaccumulation. In recent studies, equilibrium sampling has been applied to determine C_free of hydrophobic organic contaminants (HOCs) in the sediment pore water, whereas such data are missing for SPM. We applied solid-phase micro-extraction to measure and compare C_free of PAHs and PCBs in pore water of sediments and SPM sampled along the German part of the river Elbe. Moreover, site-specific distribution ratios were evaluated and C_bio,lipid was predicted using C_free.

Results

C_free of PAHs remained largely constant while C_free of PCBs varied along the Elbe River. The highest C_total of PCBs and PAHs were found at Prossen (km 13) and Meißen (km 96). PCB C_total even exceeded the environmental quality standard for sediment and SPM in Prossen. Site-specific distribution ratios (K_D) revealed a stronger sorption for PAHs compared to PCBs, indicating a higher availability of PCBs. Equilibrium partitioning concentrations in lipids (C_lip↔sed) showed a high correlation with actually measured lipid-normalised concentrations (C_bio,lipid) in bream. This indicates that PCB bioaccumulation in this benthic fish species is closely linked to the sediment contamination.

Conclusions

In rivers, SPM functions as a transportation vehicle for HOCs along the stream until it eventually deposits to the sediment. This study demonstrates that due to weaker sorption of PAHs and PCBs to the SPM this matrix poses a higher risk to the aquatic environment compared to the sediment. The prediction of C_bio,lipid of PCBs was correct and shows that solid-phase micro-extraction is highly suited to predict lipid concentration, and thus a valuable tool for risk-assessment or sediment management.

中文翻译：

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易北河沉积物和悬浮颗粒物中 HOC 的平衡采样。

背景

沉积物和悬浮颗粒物 (SPM) 的化学质量通常通过总化学浓度 ( C _total ) 来评估。然而，自由溶解浓度​​ ( C _free ) 是与生物利用度、扩散和生物累积更相关的生态参数。在最近的研究中，已应用平衡采样来确定沉积物孔隙水中_{不含疏水性有机污染物 (HOC) 的}C，而 SPM 缺少此类数据。我们应用固相微萃取来测量和比较_无C易北河德国部分的沉积物和 SPM 孔隙水中多环芳烃和多氯联苯的含量。此外，评估了特定位点的分布比率，并使用C _free预测了C _bio,lipid。

结果

_{不含PAHs 的}C基本保持不变，而_{不含PCBs 的}C沿易北河变化。在 Prossen（13 公里）和 Meißen（96 公里）发现 PCB 和 PAH 的_总碳含量最高。PCB C_总量甚至超过了 Prossen 的沉积物和 SPM 的环境质量标准。与多氯联苯相比，特定地点的分布比 ( K _D ) 显示对多环芳烃的吸附更强，表明多氯联苯的可用性更高。脂质中的平衡分配浓度 ( C _lip↔sed ) 与实际测量的脂质标准化浓度 ( C _{bio,lipid ) 显示出高度相关性}) 在鲷鱼中。这表明这种底栖鱼类中多氯联苯的生物积累与沉积物污染密切相关。

结论

在河流中，SPM 作为 HOC 沿河流的运输工具，直到最终沉积到沉积物中。该研究表明，由于多环芳烃和多氯联苯对 SPM 的吸附较​​弱，因此与沉积物相比，该基质对水生环境的风险更高。PCBs C _bio,lipid的预测是正确的，表明固相微萃取非常适合预测脂质浓度，因此是风险评估或沉积物管理的重要工具。