Sediment properties and heavy metal pollution assessment in the river, estuary and lake environments of a fluvial plain, China

• Comparisons of geochemical properties of sediments from river, estuary and lake are performed.
• Concerning on the relationships between metal contaminations and sediment properties.
• Investigating the effects of sediment sources on metal pollution in different aquatic environments.
• Risk assessment of metals in sediments of different aquatic environment is achieved.

A better understanding of the relationships between heavy metal pollution and sediment sources in different aquatic environments is needed. In this study, some geochemical properties, major elements and trace metals of sediments from a river, an estuary and a lake were researched in the Yangtze River Delta plain—a fluvial plain. NJ river sediments (sediments from the Nanjing section) showed a relatively coarse size and TL lake sediments (sediments from the Taihu Lake) showed a fine size as a whole. NJ river sediments revealed higher concentrations of TOC, CaO and MgO, while TL lake sediments revealed higher SiO2 and Al2O3. YE estuary sediments (sediments from Yangtze estuary) had medium ranges of major elements. For metal speciation, NJ river sediments had high concentrations of acid extractable Cd and Pb, YE estuary sediments showed high reducible fractions of Cu, Pb and Zn, and TL lake sediments revealed a high oxidizable fraction of Cu. YE estuary sediments showed strong correlations between trace metals and major elements, but TL lake sediments showed weak correlations. The heavy metal contamination levels were evaluated by enrichment factors. Based on existing heavy metal forms in sediments, the risk assessments were also manifested by the proportion of the first metal form (risk assessment code—RAC). The comprehensive RACs of sediments followed the order of river sediments > estuary sediments > lake sediments. Among heavy metals, Cd and Pb revealed the highest risks for sediments. The results of primary component analysis and cluster analysis showed that the metal speciation was associated with sediment sources and components. It is apparent that the metal contaminations are associated with sediment sources which significantly influence the geochemical properties of sediments in the different aquatic environments of the Yangtze River Delta plain.