东海春季赤潮前后沉积物-海水界面营养盐交换速率的研究

Exchange Rates of Dissolved Nutrients at the Sediment-Water Interface Before and After Diatom Bloom in the East China Sea in Spring

应用实验室培养法现场研究了3~5月东海硅藻赤潮发生前后10个站位的营养盐在沉积物-海水界面的交换,并应用连续函数拟合法计算了营养盐的界面交换速率.结果显示,NO3--N在赤潮前向沉积物中汇聚[-1.33^-0.68 mmol/(m2.d)],赤潮后却基本由沉积物向海水中释放[-0.69~0.82 mmol/(m2.d)].NH4+-N在赤潮前后大都从沉积物中释放[-0.65~1.46mmol/(m2.d)],赤潮后释放速率小于赤潮前.NO2--N赤潮前后除Zc17站外都向沉积物中汇聚[-0.09~0.05 mmol/(m2.d)],赤潮后汇聚速率稍高.SiO23--Si在所有站位都由沉积物向海水释放[0.85~9.23 mmol/(m2.d)],其赤潮后速率高于赤潮前.PO34--P在赤潮前向沉积物中汇聚[-0.06^-0.01 mmol/(m2.d)],在赤潮后却由沉积物向海水中释放[0~1.26 mmol/(m2.d)].NO3--N和PO43--P向东海近海沉积物的汇聚在春季不利于硅藻赤潮的暴发,但其在硅藻赤潮暴发后从沉积物的大量释放为后面紧接的大面积甲藻赤潮的暴发提供了重要的营养物质补充.

Exchange rates of dissolved nutrients at the sediment-water interface were studied before and after diatom bloom from March to May in the East China Sea in 2005. Intact sediment cores which were sampled at 10 sites were incubated on board, and exchange rates were calculated in the function method. It was shown that sediment absorbed NO3^- -N before bloom with the exchange rate ranging from - 1.33 mmol/（m^2·d） to - 0.68 mmol/（m^2·d）. The sediment released NO3^--N after bloom with the exchange rate ranging from - 0.69 mmol/（m^2·d） to 0.82 mmol/（ m^2·d）. NH4^＋ - N was almost released from sediment with the exchange rate ranging from - 0.65 mmol/（m^2·d） to 1.46 mmol/（ m^2·d）, and the rate was higher before bloom than that after bloom. NO2^- -N moved into sediment all along except at Zcl7 with the exchange rate ranging from - 0.09 mmol/（m^2·d） to 0.05 mmol/（m^2·d）, and the rate was a little higher after bloom than that before bloom. SiO3^2- -Si was released from sediment all the time with the exchange rate ranging from 0.85 mmol/ （m2·d） to 9.23 mmol/（ m^2·d）, and the rate was higher after bloom than that before bloom. The sediment absorbed PO4^3- -P before bloom with the exchange rate ranging from -0.06 mmol/（m^2·d） to -0.01 mmol/（m^2·d）, but released PO43- -P after bloom with the exchange rate ranging from 0 mmol/（m^2·d） to 1.26 mmol/（m2·d）. PO4^3--P and NO3^--N which were absorbed by sediment in spring restricted the diatom bloom, but their release from sediment after diatom bloom may make a great contribution to subsequent dinoflagellate bloom.