人类活动影响下唐山湾近岸海域营养盐及其结构变化

Nutrient composition changes in coastal waters of Tangshan Bay,Hebei,China under anthropogenic influence

根据获取的唐山湾海域1995-2012年25个站位现场观测数据和资料,基于主成分分析(PCA)对人类活动影响下唐山湾海域营养盐及其结构变化进行研究.结果表明:在人类活动影响下,近20年唐山湾海域无机氮(DIN)呈现明显的增长趋势,磷酸盐(PO_4^(3-)-P)、硅酸盐(SiO_3^(2-)-Si)则呈下降趋势;平均N:P由1995年的3.0增长到2012年的26.0,而Si:N则呈下降趋势,海水营养盐结构发生了明显的变化.据此利用主成分分析识别水质变化,共提取了2个主成分,第1主成分以DIN、NO_3^--N、NH_4^+-N、PO_4^(3-)-P和NO_2^--N为代表,解释了71.5%的方差;第2主成分以叶绿素(Chl a)和SiO_3^(2-)-Si为代表,解释了21.8%的方差,说明唐山湾水质变化主要与DIN、PO_4^(3-)-P因子变化关系密切.2个主成分得分揭示了人类活动影响下唐山湾水质年际变化趋势,即由1995-2005年开发前及开发初期的N限制向2007年开发后的P限制转变.人类活动影响下唐山湾海域营养盐及其结构已经发生了明显变化,这种变化尤其是无机氮含量的增加,需要引起高度关注.

Based on the principal component analysis（PCA）,data from 25 marine monitoring stations in Tangshan Bay from 1995 to 2012 were collected to study the change of nutrient composition in Tangshan Bay under anthropogenic influence.Results showed that the inorganic nitrogen（DIN）presented an obvious increase trend in the near 20 years,while the PO4^3--P and SiO3^2--Si presented a decrease trend.The average N：P ratio increased from 3.0 in 1995 to 26.0 in 2012,but the average Si：N ratio decreased,indicating the nutrient structure in seawater had substantially changed in the near 20 years.According to the results of PCA,the change of water quality was identified.The analysis extracted the first two principal components（PC）.PC1 was associated with DIN,NO3^--N,NH4^＋-N,PO4^3--P and NO2^--N,which explained 71.5%of the variance.PC2 was characterized by Chl a and SiO3^2--Si,which explained 21.8%of the variance.It indicated that the water quality of Tangshan bay was closely related to DIN and PO4^3--P.The two principal component scores revealed the interannual change trend of water quality in the Tangshan Bay under anthropogenic influence,which changed from the N limitation before development and at early stage of development（1995-2005） to the P limitation after development（since 2007）.The nutrient composition in Tangshan Bay had changed significantly under anthropogenic influence,therefore,special attention is needed on the the change of nutrients in seawater of Tangshan Bay,especially the increase of inorganic nitrogen content.