三沙湾海水中磷的分布和富营养化研究

摘要

Monitoring data of water quality in the Sansha Bay from 2010 to 2011 were used to analyze distribution characteristics and space-time variations of PO4-P.Based on N/P and Si/N,the limiting factors of phytoplankton growth and reproduction were determined,and the eutrophication conditions were assessed by Nutritional Status Index Method.It is shown from the analysis results that the the Huotong River is the key source of P in the Sansha Bay,P is the limit factor of plants growth and the P concentration varies significantly with seasonal change.In May,phytoplankton flourishes and reproduces,its growth is limited by P deficiency,and the concentration of P is minimum.In August,the concentration of P increases with P releasing from phytoplankton decomposition and higher temperature of seawater.From November to January,the concentration of P increases continuously.Eutrophication index is larger than 1 in the Sansha Bay,which might cause red tide.%根据2010、2011年三沙湾水质监测资料,评价了活性磷酸盐的分布及时空变化特征,根据N/P和Si/N比判断三沙湾浮游植物生长的限制因子,用营养状态指数评价该湾水体的富营养化状态.结果表明,霍童溪为三沙湾海水中磷的主要陆源输入来源,磷为三沙湾植物生长繁殖限制因子,磷含量季节周期变化特征明显,5月植物生长繁殖旺盛,由于磷的匮乏,生长受到限制,磷含量降至最低水平,8月由于植物腐败分解释放磷和海水水温较高抑制植物生长,使磷含量升高,11月至次年1月,磷含量持续升高.三沙湾内富营养化指数大于1,存在发生赤潮的风险.