Occurrence, source apportionment and risk assessment of perfluorinated compounds in sediments from the longest river in Asia.

This study investigated the pollution of perfluorinated compounds (PFCs) in sediments from the main stream of the Yangtze River, the longest river in Asia. Totally, 13 of 15 PFASs were detected in the sediments and the total concentrations ranged from 0.058 ng/g to 0.89 ng/g dry weight (dw), with dominant contaminants by perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Concentrations of PFASs in the downstream were higher than those of upstream and midstream. Four main sources were analysed using the Unmix model, textile treatments and food packaging dominantly accounted for approximately half of the total sources, followed by metal electroplating (26.8%), fluoropolymer products (16.3%) and fluororesin coatings (7.4%). Total organic carbon (TOC), total nitrogen (TN) and grain size had significant correlation with the concentration of PFASs in sediments, indicating that the physical and chemical parameters could directly affect the adsorption process of PFASs. In addition, anthropogenic factors such as urbanization rate and per capita GDP also had a direct impact on the distribution of PFASs. Environmental risk assessment showed that PFOS posed low to medium risks to the Yangtze River, indicating that sustained attentions were needed.

Distribution and assessment of cadmium contamination in sediments from the Four River inlets to Dongting Lake, China.

The total concentrations of Cd in bulk sediments and those of the BCR sequential extraction fractions of sediments from inlets of the Four Rivers that feed Dongting Lake were determined using ICP-MS techniques. The results suggested that Cd was heterogeneously distributed in the inlet sediments of the rivers, with the highest degree of enrichment in sediments from the Xiangjiang River. The Cd anomaly was defined as Cd enrichment in sediments with an EF (enrichment factor) > 10.0, and it was identified in the inlet sediments of the Xiangjiang River. Cd in the sediments was dominated by acid-soluble Cd at a proportion of 23.9-69.8 (%) compared to its total concentrations in the sediments. The inlet sediments of the Four Rivers were contaminated with Cd, with the highest degree of contamination in the inlet sediments of the Xiangjiang River. The Cd contamination as well as the Cd anomaly in the sediments were closely related to the industrial activities (e.g. smelting and refining for ore minerals) in the areas, and Cd contamination at high levels may represent an ecological risk for the lake watershed. Cd contamination of the inlet sediments may also impact the lake basin sediments and is harmful to the lake ecological system, particularly for sediments of the Xiangjiang River. Therefore, it is essential to control and treat Cd contamination in the inlet sediments for ecological environmental protection of lake watersheds.