Contamination, risk and quantitative identification of nutrients and potentially toxic elements in the surface sediments of Baiyangdian Lake, North China.

Potentially toxic elements (PTEs) in lake sediments are concerning because of their toxic effects on lacustrine ecosystems and human health. Baiyangdian Lake (BYDL), the "pearl of North China", plays a vital role in maintaining the ecological health of North China. Here, risk assessment and source identification of nutrients and PTEs in sediments were performed. The results showed that the sediments were highly contaminated with total organic carbon (TOC) and total nitrogen (TN), but contamination by total phosphorus (TP) was minor, and the ecological risk associated with Cd was considerable, especially in the northern region. The average noncarcinogenic hazard quotient of PTEs increased in the order of Zn < Hg < Cd < Cu < Ni < Pb < Cr < As. Statistical analyses indicated that Al, Ti, Fe, Co, Cr, Hg, Ni, and rare earth elements were primarily from natural origins; Pb was derived from local tourism development and pollution by fishermen; and TOC, TN, TP, As, Cd, Cu, Zn, and Mn were mainly derived from industrial and agricultural activities. Additionally, the mean contribution rates of industrial wastewater and domestic sewage sources, agricultural sources, and natural sources to BYDL sediment pollution were 59.9%, 17.9%, and 22.2%, respectively. Spatially, industrial and domestic sewage sources contributed more in the northwestern region (average 79.8%) than in the southern region (average 35.5%), while agricultural sources contributed the most in the southwestern region (average 41.3%). These findings will advance our knowledge of the spatial differences, contamination risks and sources of nutrients and PTEs in BYDL and provide a scientific basis to help policy-makers establish a healthy ecological community in BYDL of the Xiong'an New Area.