Heavy Metal Pollution in Slow-Moving River: Highlight the High Risks Posed by Suspended Particulate Matter

ABSTRACT The heavy metal risks posed by suspended particulate matter (SPM) in fluvial system have long been ignored. In this paper, we characterized the heavy metal pollution within SPM sampled from a typical slow-moving river-Ziya River Mainstream (ZRM). The concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb were determined by ICP-OES and ICP-MS. Measurements indicated that all seven heavy metal contents in SPM were higher than their contents in sediments and those from rivers and lakes elsewhere in China (except for Cd and Pb). Indices and multivariate statistics were calculated to identify sources, assess ecological risks, and to highlight the role of SPM in heavy metal transport. We found that industrial discharges were the dominant sources of heavy metals within SPM. Cd likely posed a higher risk than other heavy metals. Higher heavy metal risk within SPM was found in S5, S12, and S13, suggesting that more attention needs to be focused on these sites to protect the fluvial system. We found that the properties of SPM strongly impact the Cu, Pb, and Zn transport. Given that special characteristics and motion behavior of SPM in ZRM and higher risks of heavy metals posed by SPM than sediment, we deemed that conducting source identification and risk assessment of heavy metals in SPM in slow-moving rivers may be more accurate and reasonable. Graphical Abstract