[Nutrient distribution and its controlling mechanism in the adjacent area of Changjiang River estuary].

In this paper, the nutrient distribution, its structural characteristic and controlling mechanism around the Changjiang River estuary during Autumn 1997 and Spring 1998 were discussed, and a clear seasonal variation of nutrient distribution and structure was observed in this area. The concentrations of NO3(-)-N, SiO3(2-)-Si, PO4(3-)-P, DOP, PP and TP in Autumn 1997 were higher than those in Spring 1998, and their average concentrations were 4.97, 11.6, 0.44, 0.26, 0.82 and 1.52 mumol.L-1, respectively. However, the concentrations of NO2(-)-N, NH4(+)-N, DON, PN and TN in Spring 1998 were higher than those in Autumn 1997, with the average concentration of 0.70, 2.26, 9.88, 7.88 and 25.3 mumol.L-1, respectively. The main form of phosphorus in Autumn 1997 was PP, with the percentage about 54%, while PO4(3-)-P was the dominant fraction, with about 51% of phosphorus in Spring 1998. Both DON and PN were the main fractions of nitrogen in Autumn 1997 and Spring 1998 as well. Due to the influences of the Changjiang dilution water, the concentrations of phosphate, nitrate and silicate along the coastal area were higher than those in the outer area, except the phosphate in Spring 1998, which mainly came from Taiwan warm current. It indicated that the distribution of the nutrients in the survey area was mainly controlled by the Changjiang dilution water and the high salinity sea-water from the Taiwan warm current, and the influence of Taiwan warm current on phosphate was larger in Spring than in Autumn.