Abstract:Environmental problems from heavy metals (HMs) attract global attention. Accurately identifying sources and quantitatively evaluating ecological risks are keys for HMs pollution prevention. Dongting Lake in China was investigated through integrated methods like positive matrix factorization and Nemerow integrated risk index to examine spatial distribution, contamination characteristics, pollution sources, and the contribution of each source and pollutant to the ecological risk of 14 HMs in its surface sediments. Results showed that the mean concentrations of HMs were 0.82-9.44 times greater than the corresponding background values. The spatial distribution of HMs varied significantly, with high values of As, Cd, Mn, Pb, Sn, Tl and Zn concentrated in the sediments from Xiangjiang inlet and Yangtze outlet; Co, Cr, Cu, Ni and V in the Lishui sediments; Hg and Sb in the sediments from Yuanjiang and Zishui inlets, respectively. The accumulation of HMs was affected by five sources: mercury mining and atmospheric deposition (F1) (17.99%), urban domestic sewage and industrial sewage discharge (F2) (24.44%), antimony ore mining and smelting (F3) (6.50%), non-ferrous metal mining and extended processing industrial sources (F4) (15.72%), and mixed sources mainly from natural sources and agricultural sources (F5) (35.35%). F1 and F2 were identified as priority pollution sources; Cd, Hg, Tl, Sb and As, especially Cd and Hg, posed relatively high ecological risks and were prioritized HMs for control.

Key words: Dongting Lake; surface sediments; heavy metal pollution; source apportionment; positive matrix factorization (PMF) model; risk assessment