Profiling heavy metals distribution in surface sediments from the perspective of coastal industrial structure and their impacts on bacterial communities

Abstract

Heavy metal pollution of marine sediments along the coastal industrial parks have always received extensive attention due to their persistent hazard to local marine ecosystem. Despite this, our knowledge about the influence of geography and coastal industrial structures on heavy metal distributions remains little. In this study, surface sediment samples were collected from the coastal zone of the industrial park in Ningbo. The physicochemical properties, heavy metals with ecological risk levels and bacterial structures as well as their relationships in these sediments were comprehensively analyzed. We found that: heavy metal concentrations of surface sediment revealed wide variation between this study sea area and other coastal economic areas; increasing attention should be paid to the Cu, Hg, Cd and As pollution due to their high contamination degree and environment risk; the distribution of heavy metals is closely related to the geographic location and nearshore industrial structures; the physicochemical features (e.g., TN, PHCs and pH) of sediments could better explain the occurrence characteristics of heavy metals present; individual metals (Cu and Cr) significantly affected the bacterial α-diversity; Cr inhibits multiple functional pathways associated with energy metabolism and pollutant degradation; RDA analysis and co-occurrence network confirmed that several heavy metals (especially Zn, Cr, Cu and Cd) exhibited large effects on bacterial community structure; moreover, genera Idiomarina Sulfurovum and Sulfurimonas could be used as biological indicators for specific heavy metals contamination in our study. Our findings provide a novel insight to understand the heavy metal distribution and bacterial variation associated with industrial activities.