高浓度悬沙对长江河口水域初级生产力的影响

根据近期观测的数据和有关文献表明,长江径流挟带的悬沙与潮流扰动产生的再悬浮泥沙在长江口形成透明度3m和3m以下的浑浊带,浑浊带悬沙的消光作用强于营养盐释放作用,抑制了长江口门区的初级生产力,使口门区的浮游植物生物量及密度显著低于附近水域.经估算,目前长江口浮游植物对N、P的吸收、同化能力分别为6.64万t/km2·α和9220t/km2·α

Effects of high-density suspended sediments on primary production at the Yangtze Estuary

Suspended sediments from the Yangtze River and re-suspended sediments caused by tidal disturbance form a high turbidity area with a transparency of lower than 3m at the Yangtze Estuary. Light limitation resulting from suspended sediments is stronger than nutrient released to the estuarine ecosystem, which makes the primary production, biodiversity and density at a lower level at the area than adjacent sea. It is estimated that the absorption and assimilation ability of phytoplankton at the Yangtze Estuary are 66400t/km²·a for N and 9220t/km²·a for P, which are only 10.5% of other coastal areas with higher bio-productivity and photosynthesis, such as California Coast Zone. Thus, the ability of absorption and assimilation for nutrients is weakened by high-density suspended sediments, which indirectly enhance the eutrophication outside the turbidity area and become a potential factor for the red tide.