Spatiotemporal Distribution of Eutrophication and Its Relationship with Environmental Factors in Zhanjiang Sea Bay Area

Space distribution characteristics of eutrophication were analyzed based on water quality analysis of 28 sampling stations from 9 sampling sections of Zhanjiang Bay in Jan.,Apr.,Jul. and Oct.,2011. The effects of environmental factors on the eutrophication of the Bay area were investigated with principal component analysis. In addition,two evaluation methods,eutrophication index and potential eutrophication method,were also utilized and compared. The results revealed that the average value of E(eutrophication index) in Zhanjiang Bay area were 0.18,1.90,0.83 and 2.12 in winter,spring,summer and autumn respectively. These results demonstrated a consistent space distribution between the bay top and bay entrance areas amongst the varying seasons resulting in autumn spring summer winter. Eutrophication index was positively correlated to the presence of inorganic nitrogen but was negatively correlated with salinity and pH of the water,suggesting that inorganic nitrogen content played a leading role in the process of eutrophication and that estuary pollution was the largest contributor to the eutrophication of Zhangjiang Bay. The results obtained from eutrophication index method were in agreement with that of potential eutrophication method when nutritive salt composition of sea area was considered.