The concentration, spatial distribution characteristics, river–lake relationship analysis and source apportionment of heavy metals in the sediments of the Yangtze River, Poyang Lake and its tributaries were studied in this work. Heavy metals were detected more frequently in the sediments of the Yangtze River compared with the sediments of Poyang Lake and its tributaries. V, Cr, Pb and Ni were the dominant heavy metals in Poyang lake, with V being the most abundant in the lower Yangtze River, Poyang Lake and its tributaries. As, Cu, Ni and V showed similar distribution patterns, with a fan-shaped increasing trend in the southwestern area of Poyang Lake. The spatial distribution of Cr, Hg, Pb and Cd showed a large spatial variability with a decreasing distribution from the northwest to the southeast of the lake. The heavy metals in the sediments of Poyang Lake are related to those in its tributaries. The organic matter, oxidation-reduction potential and depth of sediments are correlated with the heavy metals in sediments. Mining, industrial and road traffic sources were the main sources of heavy metals in the study area. Except for Cd and Hg, most heavy metals in Poyang Lake exhibited a low ecological risk in an environmental evaluation. The results of this study might guide future studies on heavy metals in the sediments of Poyang Lake.

The spatial and temporal distributions, contamination evaluation, and source apportionment of Cu, Zn, As, Pb, Cd, and Cr in the sediments of Hulun Lake were explored in this work. The pollution characteristics of six heavy metals were assessed by single factor pollution index (PI) and geo-accumulation index (Igeo). The sources of heavy metals in the surface sediments were analyzed by the positive definite matrix factorization (PMF) and Pearson correlation analysis. The sedimentary records of heavy metals in core sediments were reproduced by radioisotopes. The average concentrations of 6 heavy metals except Cd were lower than the corresponding background values. The spatial distributions of Cu, Zn, Cr, Cd and As were generally similar and showed higher abundances in the southwestern part of the lake. With the use and import of heavy metals, the concentration of heavy metals in core sediments increased with the fluctuation of years. The peak of heavy metal concentration was related to the high growth rate of gross domestic product in 2003-2008. The single factor pollution index and geo accumulation index results showed that the surface sediment was mainly polluted by Cd, followed by Zn and As. Natural parent material, agricultural activities and industrial activities were the main sources of heavy metal pollution in the sediments, accounting for 17.03%, 26.34%, and 56.63% of the total heavy metal accumulation, respectively. Pb was derived mainly from natural parent material. Cd and As were closely associated with agricultural activities. Cu and Zn were mainly attributed to industrial mining activities. Source apportionment of the ecological risks of heavy metals illustrated that industrial sources were the primary ecosystem risk sources (66.1%), followed by agricultural sources (23.75%) and natural sources (10.15%). The results will also provide reference data for future studies of heavy metals pollution in sediments from Hulun Lake and other lakes.

Spatial-temporal distribution patterns, contamination assessment and source apportionment of Cd, As, Pb, Cu, Zn, and Cr in sediments of Erhai Lake, a large plateau lake in southwest China, were investigated. The results indicated that elevated concentrations of Cr, As, Cu, and Zn were primarily distributed in the eastern and central regions of Erhai Lake, whereas Cd and Pb were mainly concentrated in the west-central region. Cd exhibited the most severe pollution, with 15.4% of samples reaching extremely high single factor pollution index levels, followed by As, for which 65.8% of samples showed high contamination. Cu and Cr presented moderate pollution levels. In contrast, the geoaccumulation index indicated that 70.0% of Zn and 84.6% of Pb samples were unpolluted. Tourism, agricultural activities, and industrial activities contributed 29.90%, 15.32%, and 54.78% respectively by positive matrix factorization model. Specifically, Cu, Zn, As, and Cr originated predominantly from industrial activities, Cd showed strong associations with agricultural practices, and Pb was mainly ascribed to traffic-related pollution. Industrial sources contributed the most to ecological risk (62.50%). The temporal trend derived from the sediment cores revealed a surge in pollution levels during the early 21st century, which may be related to rapid economic growth and non-ferrous metal production. Overall, the results provide a valuable baseline for environmental monitoring and management in Erhai Lake.