Assessment of seawater quality of Zhanjiang Mangrove Nature Reserve, Guangdong

Based on the water quality investigation data from August in 2009 to July in 2010, the water environment quality of Zhanjiang Mangrove Nature Reserve was assessed using single water quality parameter model, integrated water quality index model, organic pollution index model and eutrophication assessment model. The results showed that the key pollutants were dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), oil and Pb, with their annual average concentrations of 0.426 mg/L, 0.026mg/L, 0.052mg/L and 1.936μg/L, respectively. The averages of their single parameter pollution index were 2.13, 1.70, 1.04 and 1.94, respectively. Among the pollutants, DIN was the most important one. Only 33.33 percent station of DIN concentration reached the third standard of sea water quality. The averages of integrated water quality index, organic pollution index and eutrophication index were 1.81, 3.71 and 3.74, respectively, which indicated that, generally, the water quality of Zhanjiang Mangrove Nature Reserve were polluted lightly. The organic pollution degree remained the fourth level and the nutrient status of this area was eutrophied. Under the effects of Zhanjiang Harbor, the water quality of the Mangrove Nature Reserve in Techeng Island was worse and polluted more seriously.