Distribution Characteristics of Nutrients in Wuleidao Bay and Jinghai Bay, Wendeng, China

Abstract

To investigate the distribution characteristics of nutrients in Wuleidao Bay and Jinghai Bay, a survey for COD, nutrients, Chlorophyll a (Chl a), was conducted in May, August, October of 2013. The results showed that due to the seasonal discharge of sewage into the sea and phytoplankton cyclical life activities, both the salinity and nutrient concentrations within the two bays and at bay mouth were higher than those of further off the coast. From the estuaries seaward, the proportion of DIN in TN was raising, while TON in TN was reducing. PO₄^-3-P was a limiting factor for phytoplankton growth, but had not yet become an absolute limiting factor. The monthly average of nitrogen, phosphorus molar ratio is in the following order, May>August>October. The correlation between Chl a and PO₄^-3-P was higher than the correlation between Chl a and DIN. DIN level could meet the second class standard of GB 8978-1996, while PO4^-3-P could meet fist class. Without considering COD, higher level of eutrophication was detected in August, while October was lower. When considering COD, August and October were both at a high level; however, both months did not reach the eutrophication level.