深圳湾海域氮磷营养盐变化及富营养化特征

Characteristics of Eutrophication and Variation Trend of Nitrogen and Phosphorus Nutrient in Shenzhen Bay

根据1986—2007年深圳湾海水水质监测资料,阐述了氮磷营养盐的变化趋势及其相互关系,并探讨了深圳湾海域富营养化程度。结果表明,深圳湾海域水体溶解态无机氮含量年际变化幅度较大,但总体呈上升趋势。氨氮是溶解态无机氮的主要组成形态,表明深圳湾无机氮处于热力学不平衡状态。深圳湾海域水体中活性磷酸盐值含量变化幅度比较小,总体呈下降趋势。深圳湾水体DIN/P值在1998年以前呈不断上升趋势,1998—2002年之间呈现波动变化,从2002年开始降低,营养盐含量和组成的改变导致浮游植物群落结构的改变,深圳湾海域发生的赤潮生物种类有从硅藻向甲藻过渡,然后从甲藻向硅藻过渡的趋势;相关分析表明,溶解态无机氮以及氮磷营养盐之间的相关关系显著(r=0.769,p<0.01),说明氮磷营养盐间有一定程度相似的生物地球化学过程;水体营养状态质量指数显示深圳湾海水富营养化程度很高,高度富营养化的水体使得深圳湾海域的赤潮日趋频繁,控制入湾水体污染刻不容缓。

Based on the field data in 1986--2007 in Shenzhen bay, annual changes characteristics of nitrogen and phosphate concentrations, as well as their correlations with each other are presented. Furthermore, the Nutrition Quality Index （NQI） is employed to assess the eutrophication degree of Shenzhen bay. The dissolved inorganic nitrogen（DIN） concentration shows an increasing trend, while phosphate （PO4^3- -P） concentrations decrease gradually. Ammonia nitrogen （NH4^＋ -N） is the primary form of inorganic nitrogen in Shenzhen bay indicating that inorganic nitrogen is in unstable thermodynamic equilibrium. The ratio of DIN/P increased gradually before 1998, and decreased after 2002. The variation and components of nutrients could influence the community structure of phytoplankton, and the dominant red tide speeies have been transformed from diatom to dinoflagellate. Nutrient correlation is significant at the 0.01 level, which shows that the nutrient undergo similar biogeochemistry processes. The NQI shows that Shenzhen bay is in high eutrophic status, and it is urgent resort to effective plan for controlling water pollution in the inflow river.