Traceability of heavy metal contamination in surface sediments and sourcesink patterns in waters of the Miaodao Archipelago: Combined effects of natural factors and human activities

Abstract

Archipelagos are unique marine units of ecological and economic value. Clarifying the source and sink patterns of heavy metals in archipelago sediments is crucial for pollution prevention. In this study, eight heavy metals ( As, Cd, Co, Cu, Hg, Ni, Pb and Zn) and their contamination levels were analyzed in 107 surface sediment samples from the marine waters of the Miaodao Archipelago. The sources and effects of the heavy metals were studied by integrating natural and anthropogenic factors, and their source-sink patterns were summarized. All analyzed heavy metals were present at low concentrations, with only light As contamination and a low single-factor ecological risk for Cd. Natural and anthropogenic sources accounted for 82.3 % and 17.7 % respectively. Shipping activities and aquaculture were the main anthropogenic sources of Co, Ni, Cu, Zn and Cd, and industrial and agricultural activities were the main anthropogenic sources of As and Pb. Yellow River pollutants, local aquaculture and shipping activities are the main contributors of metals in the sediments. The barrier effect of the archipelago coupled with natural factors led to the pooling of heavy metals, while human activities further enriched metal concentrations. The complex sedimentary dynamic environment and unique source-sink patterns of the archipelago greatly influence the distribution of metals. There is a need for enhanced monitoring and control of heavy metal contamination, especially As and Cd, in the region.