Extensive study of potential harmful elements (Ag, As, Hg, Sb, and Se) in surface sediments of the Bohai Sea, China: Sources and environmental risks

• Published in: Environmental pollution (1987) 2016-12, Vol.219, p.432-439
• Main Authors: Li, Li, Cui, Jingjing, Liu, Jihua, Gao, Jingjing, Bai, Yazhi, Shi, Xuefa
• Format: Article
• Language: English
• Subjects: Antimony; Arsenic; Arsenic - analysis; Bohai sea; China; Environmental Monitoring; Geologic Sediments - analysis; Mercury; Metals - analysis; Oceans and Seas; Risk Assessment; Silver; Water Pollutants, Chemical - analysis
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2016.05.034

This study analyzed 405 surface sediment samples, obtained from across the Bohai Sea, for concentrations of five potentially harmful elements (Ag, As, Hg, Sb, and Se) and several ancillary parameters (Al, Fe, Mn, total organic carbon (TOC), and grain size). Statistically, the spatial distributions of these elements were correlated positively with Al, Fe, TOC, and grain size, indicating natural sources for these elements or common accumulation mechanisms. The assessment of potential environmental risk with empirical sediment quality guidelines showed that a significant proportion of the samples had As and Sb concentrations that exceeded the effects range low (ERL) or T20 values in the Bohai Sea, indicating the potential for adverse biological effects. However, the assessment results differed when using evaluation methods that considered background values. Based on the geoaccumulation index (Igeo), Hg and Ag were found to have the highest percentages (35% and 60%, respectively) in samples that were moderately contaminated. The estimated contamination degree (Cd) suggested higher contamination levels for the entire area, with 69% of the samples being moderately contaminated. Generally, except for some local hotspots, such as Jinzhou Bay, the contamination levels of these elements in the Bohai Sea were established as slight to moderate. Samples from the Jinzhou Bay area had concentrations that were 10–100 times higher than in the rest of the Bohai Sea, indicating severe contamination. •Extensive study of Ag, As, Hg, Sb, and Se in the Bohai Sea, China was performed.•Contamination hotspots were identified based on spatial distributions of elements.•Assessment methods considering background values yielded more appropriate results.•Ag and Hg had the highest anthropogenic influence and ecological risk.•About 70% of the Bohai Sea is subject to slight to moderate contamination.