Chemical characteristics and estimation on the vertical flux of N, P, Si in upwelling area of Taiwan Strait

Based on the data obtained from oceanographic surveys at the central and northern parts of the Taiwan Straft during the pgriod from 1983 to 1988, it is showed that the nutrient content in the coastal and bottom waters is relatively high with an upward and offward decrease, and that the upwelling in the Fujian coastal area controls the distribution of nutrients in summer.The upwelling water is characterized by 2.29 μmol/dm³ of nitrate; 2.83 μmol/dm³ of silicate; 0.20 μmol/dm³ of dissolved inorganic phosphate, respectively.Significant rnrreJation between nutrients and dissolved oxygen content and its degree of saturation, temperature, and salinity, respectively are found in the upwelling area.Average of N/P ratio in the area (15.9) approaches to Redfield ratio.Their vertical flux is estimated to be 23.6 mg/ (m²·d) for PQ₄³-P, 223 mg/ (m²·d) for NO₃-N, 302 mg/ (m²·d) for SiO₃^2--Si, respectively, which is the main source of nutients in the areas in summer.The mean of the flux of PO₄^3--P and NO₃^--N is about 86% and 73% necessary for phytoplankton in the euphotic zone.