Emerging investigator series: effects of sediment particle size on the spatial distributions of contaminants and bacterial communities in the reservoir sediments

Abstract

Natural sediment deposition can affect the storage capacity and water supply reliability of the reservoir, which could be resolved effectively by desilting. The successful implementation of partial desilting requires a thorough understanding of the spatial distribution of the contaminants and bacterial communities in the reservoir sediments. In this study, the effects of sediment particle size on the spatial distribution of contaminants and bacterial communities in the reservoir sediments were investigated. It was identified that the surface sediment particle size of the Linghe Reservoir firstly reduced from the reservoir head to center of the reservoir and then increased to the highest value at the backwater area. The contents of total nitrogen (TN), total phosphorus (TP), organic matter (OM) and soluble organic carbon in sediments were negatively correlated with the sediment particle size. It was found that moderate Cd contamination existed in the Linghe Reservoir, however, no other heavy metal (Pb, Cu, Zn, Cr, Mn, and Ni) contamination was identified. There was also no significant correlation between spatial distribution of heavy metals and the sediment particle size. The horizontal difference in sediment particle size also indirectly affected the bacterial community structure and the dissolved organic matter (DOM) content released by the bacteria. This study clearly shows that the horizontal difference in flow velocity led to the natural horizontal distribution of sediment particle size, which further directly affected the horizontal distributions of organic carbon, nitrogen and phosphorus and indirectly affected bacterial community structure and the DOM content released by the bacteria in the sediments.