Linking Ah receptor mediated effects of sediments and impacts on fish to key pollutants in the Yangtze Three Gorges Reservoir, China — A comprehensive perspective

Effect-Directed Analysis of Aryl Hydrocarbon Receptor Agonists in Sediments from the Three Gorges Reservoir, China

“…Thus, higher levels of contamination in the upstream of Yangtze river at Chongqing area may be diluted by sediments of the less contaminated tributary, the Jialing River. This results in lower concentrations of contaminants downstream of Chongqing, which is in agreement with previous findings. , The artificial Hanfeng Lake at Kaixian exhibited the highest AhR-mediated activity, which could be attributed to a lower dilution of discharged contamination compared to the Chongqing area, and a potential accumulation of contamination in the lake …”

“…In order to avoid cytotoxic effects in the EROD assay, the neutral red retention assay (NR) was carried out with RTL-W1 cells according to the method described by Babich and Borenfreund . The AhR-mediated activity was determined by the EROD induction assay using rainbow trout ( Oncorhynchus mykiss ) liver cells (RTL-W1) according to previously described methods by Gustavsson et al with slight modifications . Samples were analyzed in three replicates, each with three internal replicates serially diluted with medium in seven 1:2 steps.…”

“…The Three Gorges Reservoir (TGR), created in consequence of the Yangtze River’s impoundment by the Three Gorges Dam (TGD), spreads over a distance of 663 km between the town of Sandouping, Hubei Province, and the Jiangjin district of Chongqing Municipality. Besides the obvious benefits of the TGD, such as hydroelectricity, navigation, and flood control, construction of the TGD also poses great challenges to the unique ecosystem, particularly when facing numerous anthropogenic impacts, e.g., overpopulation, industrialization, and intensified shipping activities . Furthermore, construction of the dam reduced the river’s flow velocity , and consequently increased the sedimentation rate of suspend particles and adhering contaminants …”

“…As recently shown in a review, only limited research was done on bioassays to determine AhR-mediated activity in this area. Moreover, chemical analysis of target compounds provides only limited information on adverse biological effects of the complex mixture. , The concept of effect-directed analysis (EDA), featuring a combination of fractionation, chemical analysis, and bioassays, has been demonstrated to be a suitable tool for the identification of causative toxicants in complex environmental samples. This approach is directed by the biotests ( in vitro or in vivo assays), through the assignment of toxicity to several groups of toxicants by separation steps including extraction, clean up, and fractionation.…”

“…In our previous studies, sampling sites along the TGR were screened according to the triad approach to achieve a comprehensive perspective on ecotoxicological status of this area. , Two sites – close to the cities of Chongqing and Kaixian – were identified as regional “hot-spots” with respect to dioxin-like activity and mutagenicity. The present study aimed to characterize and identify individual AhR agonist in the sediments extracts in support of the prioritization and regulation of environmental contaminants present in sediments of the TGR.…”