2009年夏季长江口及邻近海域硝酸盐、磷酸盐的变化规律及其行为特征

The behavior of nitrate and phosphate in Changjiang River Estuary and its adjacent East China Sea during summer of 2009

利用2009年6月份和8月份(夏季)长江口及邻近海域的调查资料,分析了该海域硝酸盐、磷酸盐的扩散和输运行为特征,结果表明:8月份冲淡水对长江口及邻近海域硝酸盐和磷酸盐的影响比6月份大,这可能与8月份时长江的径流量大有关;6月份和8月份,该海域硝酸盐、磷酸盐的转移机制主要是物理混合稀释过程,但8月份时的硝酸盐、磷酸盐转移机制稍显复杂;虽然8月份N∶P值比6月份更大,但是PO43-的绝对浓度却比6月份高,并且在这2个月期间,浮游植物的生长有明显的变化,可见P已满足了该区浮游植物的生长,区域内并不存在P限制;6月份PO43-绝对浓度由表层到底层水体呈逐渐降低的趋势,而8月份表层和底层水体中PO43-的绝对浓度明显高出10 m和30 m层,这可能是因为8月份时表层水PO43-受冲淡水作用影响明显、而底层水则受矿化作用影响明显所致。

The distribution and transportation of nitrate（NO-3） and phosphate（PO3-4） in Changjiang River Estuary and its adjacent East China Sea were studied on the basis of the Summer Cruise in 2009（in June and in August）.It is pointed out that the impact from Changjiang River diluted water in August was larger than that in June due to larger runoff of Changjiang River in August.NO-3 and PO3-4 concentrations were more significantly correlated with salinity in June than in August,suggesting these two substances behaved nearly conservatively in June,while did not behave conservatively in August.Although N∶P ratios in August were higher than those in June,PO3-4 absolute concentrations in August were also higher in June and phytoplankton growth is different in these two months,indicating that P is not a limiting factor for phytoplankton growth.PO3-4 absolute concentrations were higher on the top than those on the bottom in June,while absolute concentrations on the top and on the bottom were higher those on 10 m and on 30 m water layers,suggesting that Changjiang River diluted water makes an important contribution to PO3-4 on the top,and mineralization to PO3-4 on the bottom.