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近10年凋洲岛周边海域表层海水营养盐含量变化特征

Variations of nutrients concentration in surface seawater in adjacentarea of Weizhou Island in recent 10 years

  • 摘要: 根据2004~2013年间涸洲岛邻近海域共30个航次的营养盐监测结果,分析了涸洲岛邻近海域海水中营养盐的组成和变化特征.结果表明:无机氮(DIN)和活性磷酸盐(PO4--P)浓度的季节变化特征均为冬季>秋季>夏季,SiO?--Si各季节浓度差别不大.受陆源输入的影响,无机氮年际变化幅度比较大,整体上呈现上升趋势,NO7-N与DIN的变化趋势基本相似,且对无机氮的贡献最大;SiO²-Si和NH₄-N呈现出逐渐下降的趋势,其中Sio²--Si下降趋势比较明显;PO4-P则呈现先增加后下降的趋势.营养盐化学计量比以及浮游植物生长营养盐限制因素分析结果显示,涸洲岛邻近海域主要属于磷限制,整个海域处于贫营养化程度。近10年来涸洲岛邻近海域海水中的Si/N逐年降低,N/P先降低后增加,这种变化趋势可能会导致浮游植物种群的变化.

     

    Abstract: Thedistnibution of nutrients in surface seawater in adjacent area of Weizhou Island was analyzed based ondata obtained from30 surveys from 2004 to 2013.Theresult showed that the concentrationsof DIN and PO4-Pinseawater decreased gradually in onder of winter,autumn,and summer.However,the concentration of SiO³-Sishowed no obvious seasomal vanation.Becauseof the terrestrial input,the inter-aunnual DIN waried greatly andshowed anupgrade tendency.NOz-N showed thesameannual fluctuationas DIN and contributed mostlyto DIN.The annual mean concentration of NH4-N and SiO¹-Si decreased slightlywhile theannual mean concentration of PO4-P increased fistly before it decreased.Further analysis of the nutrients limitation for phytoplankton gowthimplied that theadjacent waters of Weizhou Island was in oligotmophic status of PHimitation.In recent 10 years,Si/N ratio gradually decreased and N/P ratio decreased firstly and then increased,which may change the phyto-plankton community structure.

     

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