长江口最大浑浊带及邻近水域营养盐的分布特征

根据2003年11月~2004年8月4个航次的调查数据,探讨了长江口最大浑浊带及邻近水域营养盐的分布特征。结果表明,营养盐浓度一般随盐度的增加而减小,不同营养盐表现出不同的平面分布和季节变化特点。最大浑浊带所处地理位置、水动力状况、高悬浮体含量以及生物活动等决定了营养盐分布不同于整个调查水域。与整个调查水域相比,最大浑浊带营养盐浓度更高;无机N的硝化作用进行得更为充分;高的DIN/PO4-P和SiO3-Si/PO4-P比(远高于Redfield比),相对低的SiO3-Si/DIN比等。透明度是最大混浊带浮游植物生长的主要限制因素。营养盐在河口的转移除了海水稀释作用外,还有部分的生物转移以及受悬浮体-沉积物系统的影响,特别是PO4-P。在最大浑浊带,富营养化现象更为严重。

Distribution features of nutrients in the maximum turbid zone of the Changjiang estuary and its adjacent sea areas

Based on the observation data during November 2003 to August 2004,the distribution features of nutrients in the maximum turbid zone and its adjacent sea areas in the Changjiang estuary were discussed.Nutrient concentrations generally decreased with the increasing of salinity and different nutrients represented different horizontal distributions and seasonal variations.Nutrients distributions of the maximum turbid zone were different from those of the whole investigation waters,due to its geographical situation,water dynamical condition,high content of suspended matter and biological activity,etc.Compared with the whole investigation waters,there were relative high nutrients concentrations and sufficient nitrification in three forms of inorganic N,high DIN/PO4-P and SiO3-Si/PO4-P ratios(far higher than the Redfield values),and relative low SiO3-Si/ DIN ratio in the maximum turbid zone.Transparency was the primary limiting factor of phytoplankton in the maximum turbid zone.The removals of nutrients in the estuary show that aside from biological removal,there is an affection possibly come from suspended matter-sediment system,especially PO4-P.There was more obvious characteristic of eutrophication in the maximum turbid zone than in the whole investigation waters.