长江口潮滩沉积物－水界面无机氮交换通量

对长江口滨岸潮滩7个典型断面三态氮的界面交换通量进行了三年多的季节性连续观测,结果表明无机氮的界面交换行为存在复杂的空间分异和季节变化。NO^-₃-N和NH⁺₄-N的界面交换通量正负变化范围较大,分别介于-32.82~24.13 mmol.m^-2.d^-1和-18.45~10.65mmol.m^-2.d^-1之间;而NOsup>-₂-N的界面交换通量很小,仅为-1.15~2.82 mmol.m^-2.d^-1。NO^-₃-N的界面交换具有明显的上下游季节性时空分异特征,而NH⁺₄-N的界面交换则表现为南北岸季节性时空分异现象。盐度是控制长江口滨岸潮滩NH⁺₄-N界面交换行为的主要因素,而沉积物粒度、水体 NO^-₃-N浓度、沉积物有机质含量、水温和溶解氧含量则以不同的组合方式,共同制约着 NO^-₃-N在潮滩界面交换的时空分异格局。

Inorganic Nitrogen Fluxes at the Sediment-water Interface in Tidal Flats of the Yangtze Estuary

Inorganic nitrogen fluxes at the sediment-water interface of seven typical sites in tidal flats of the Yangtze estuary had been determined seasonally during more than three years. The results revealed that the sediment-water exchanges of inorganic nitrogen appeared to be of complicated spatial differences and seasonal variations. The measured fluxes of NO^-₃-N and NH⁺₄-N in the Yangtze estuary were higher than those in other estuaries, varying respectively from -32.82 to 24.13 mmol·m^-2·d^-1 and from -18.45 to 10.65 mmol·m^-2·d^-1. However, the fluxes of NO^-_{2/sub>-N were very low, and only varied from -1.15 to 2.82 mmol·m^-2·d^-1. The spatial and seasonal differences between the upper and lower estuary for the NO^-3-N fluxes were observed clearly, but the NH⁺4-N fluxes exhibited the spatial and seasonal differences between the south and north bank. It had been recognized that the NH⁺4-N exchange behavior was mainly controlled by the salinity, whereas the NO^-3-N exchange behavior was influenced by the different combinations of the sediment grain size, nitrate concentration in overlying water, sediment organic matter content, water temperature and dissolved oxygen concentration.}