Assessment of dissolved heavy metals in the Laoshan Bay, China

A total of 84 surface seawater samples collected from Laoshan Bay, China during the period of 2017-2018 were analysed for physiochemical parameters and dissolved heavy metal concentrations. Cr and Hg concentrations are significantly higher in May than in November, whereas As, Cd and Pb concentrations are significantly higher in November than in May. The single-contaminator factors showed that the most and least dominant elements were Pb and As in both seasons, respectively. And the contamination degree of Laoshan Bay is low. Cr and Hg concentrations are significantly correlated with the physiochemical parameters except chemical oxygen demand (COD). Cu and Pb concentrations are not correlated with the physiochemical parameters. Principal component analysis is conducted to investigate the traces of the dissolved heavy metals. Ship repair activities during summer fishing moratorium and coal combustion have been identified as the major sources of the traces in the studied area in different seasons.