Annual variation and comprehensive evaluation of seawater quality in Trachidermus fasciatus Heckel germ plasm resource protection area in Jinghai Bay

Abstract:

Based on the continuous surveys of heavy metals, nutrients and related environmental factors of surface water in Trachidermus fasciatus Heckel germ plasm resource protection area in Jinghai Bay from 2011 to 2013, the water quality was analyzed, and the nutrient level, heavy metals and organic pollution were evaluated. The heavy metal concentrations were below the limit of the first class sea water in 2011, and Pb concentrations exceeded the first class sea water limit in 2012. In 2013, the concentrations of Cu, Pb and Hg were 5.19, 2.79, 0.07 μg/L, all above the limit of the first class seawater. In 2011 and 2012, N/P values were higher than the Redfield ratio of 16, indicating that phosphate was relatively deficient compared to nitrogen. Based on the eutrophication evaluation model, the surveyed area belonged to phosphorus limiting potential eutrophication in 2011, moderate eutrophication in 2012 and eutrophication in 2013. The organic pollution index was higher than 4 in 2011 and 2013, indicating that the survey area suffered from serious organic pollution. DIN and PO4-P were the key pollutants of the surface water in Jinghai Bay. The seawater quality belonged to the permitted level in 2012, while in 2011 and 2013 the water quality belonged to the light pollution level due to pollution from terrestrial runoffs and aquaculture etc.