Environmental quality assessment and source analysis of heavy metals in coastal surface sediment of Weihai City

In order to understand the characteristics of heavy metal content in the surface sediments of the coastal waters of Weihai, this study determined the contents of Cr, Cu, Zn, As, Cd, Hg and Pb in the surface sediments of 15 stations in the coastal waters of Weihai by using inductively coupled plasma mass spectrometry (ICP-MS) and catalytic hot injection cold atomic absorption spectrometry. The environmental quality was evaluated by using the geoaccumulation index method, potential ecological risk method and toxicity effect prediction method. The average mass fraction of Cr, Cu, Zn, As, Pb in the surface sediments of the coastal waters of Weihai were 64.1, 26.4, 81.2, 8.1 and 26.2 mg/kg, Cd and Hg were 124.0 and 20.7 μg/kg, respectively. The average pollution degree of heavy metals from high to low was Zn, Cu, Pb, Cr, Hg, As, Cd, but the overall pollution level was slight and the ecological environment was good. The order of ecological risk of single heavy metals was Hg, Cd, As, Cu, Pb, Cr, Zn. Except for station 15 which was of medium ecological risk, the other stations were of low ecological risk. The probability of heavy metal biological toxicity hazard in the coastal sediments of Weihai was low. Apart from natural sources, the Cu, Zn, Cd, and Pb present in the surface sediments of the coastal waters may derived from direct discharge of sewage, ship emissions and offshore aquaculture activities, while As mainly comes from nearby industrial production activities, and some of it also comes from the discharge of treated sewage.