Contamination, distribution, and sources of heavy metals in the sediments of Andong tidal flat, Hangzhou bay, China

In this study, we collected sediment samples from three transects along Andong tidal flat, Hangzhou Bay, and studied the concentrations and sources of heavy metals. Enrichment factors (EF), contamination factors (CF), and geoaccumulation indexes (I-geo) showed that transect A was a polluted area while transect B and C were relatively unpolluted. The elevated heavy metal concentrations along transect A may be attributed to the human pollutions along the tidal creeks and passageway. Principal component analyses indicated that Cr, Ni, Cd, Hg, Pb, and Cu were originated from the same sources, and most of the heavy metals presented elevated concentrations near shore, suggesting the near shore pollution by anthropogenic activities. Chondrite-normalized REE patterns of sediment samples were similar to that of Upper Continental Crust, Yangtze River, and East China Sea with enrichment of LREEs, fairly flat patterns of HREEs, and significantly negative Eu anomaly and positive Ce anomaly. It is suggested that the main sources of sediments were terrigenous materials but also influenced by the sediments from East China Sea. This work provided essential information on the pollution status of sediments in the Hangzhou Bay and assessed the possible sources of heavy metals, which will be useful for the environmental protection of Hangzhou Bay. (C) 2015 Elsevier Ltd. All rights reserved.