夏冬季三沙湾海水营养盐含量的时空变化特征及与环境因子的相关性

Temporal and spatial variation characteristics of inorganic nitrogen and active phosphorus and relations with environmental factors in Sansha Bay of Fujian in summer and winter

根据2012年8月和2013年1月对三沙湾海域开展的海域水质现场连续调查数据,阐述了无机氮和活性磷酸盐含量时空变化特征及其与环境因子的相关性.结果表明,三沙湾海域夏冬季无机氮含量范围分别为0.059～1.669、0.569～0.940 mg/dm^3,均值为0.582、0.676 mg/dm^3,活性磷酸盐含量范围分别为0.036～0.071、0.050～0.070 mg/dm^3,均值为0.056、0.060 mg/dm^3.无机氮和活性磷酸盐含量的高值区出现在陆源径流入海区及大量网箱养殖区,总体呈湾顶向湾口递减趋势,氮磷含量表层高于底层,冬季高于夏季,大部分海域都超过第四类海水水质标准.根据CN/CP比值评价结果显示,三沙湾大部分海域浮游植物的生长为氮限制.相关性分析表明,三沙湾海域无机氮与硝酸盐含量相关性极显著（r=0.989）,表明硝酸盐是无机氮的主要存在形态;无机氮还与盐度（r=-0.923）和温度（r=0.939）有极显著的相关性,论证了沿岸径流对三沙湾营养盐的输入有重要影响.活性磷酸盐与铵盐、亚硝酸盐含量存在显著的正相关.本次调研结果为三沙湾海域富营养化研究提供基础数据.

Continuous field data were taken at 6 stations in August,2012 and January,2013 in Sansha Bay.Temporal and spatial variation characteristics of inorganic nitrogen and active phosphorus,as well as their correlations were presented.The results confirm that the content of inorganic nitrogen varies from 0.059 to 1.669,from 0.569 to 0.940 mg/dm^3,and the average values are 0.582 and 0.676 mg/dm^3 in summer and winter,respectively.The content of PO4-P are in ranges from 0.036 to 0.071,from 0.050 to 0.070 mg/dm^3,the mean value are 0.056 and0.060 mg/dm^3,respectively.The high values of DIN and PO4-P appeared in areas receiving the terrestrial runoff and areas of the cage culture,the value trends down from northern area to the entrance of the bay.The value is higher in surface water than the bottom and higher in winter than in summer,with most of areas exceed the fourth grade of seawater quality standard of China.The result of CN/CPratio shows that most phytoplankton growths are nitrogen limited.The correlation analysis shows that DIN is significantly correlated with NO3-N（r = 0.989）,salinity（r =-0.923） and temperature（r = 0.939）.PO4-P is also positive correlation with NH4-N and NO2-N.This study supplies basic information for the eutrophication research in Sansha Bay.