长江口及邻近海域表层沉积物中氮形态的研究

Nitrogen forms in surface sediment in the Yangtze River estuary and adjacent area

氮是海洋初级生产力和食物链的基础,不同形态的氮具有不同的物理化学性质和生物可利用性。对长江口及邻近海域沉积物不同形态氮的含量及其影响因素的研究可以加深该区域氮生物地球化学循环过程的认识。本研究采用改进分级浸提方法测定了2014年8月长江口及邻近海域表层沉积物中离子交换态氮(IEF-N)、碳酸盐结合态氮(CF-N)、铁锰氧化态氮(IMOF-N)以及有机态和硫化物结合态氮(OSFN),描绘出研究海域表层沉积物中不同形态氮的分布特征及其影响因素。研究海域中,不同形态氮的分布由于受到不同因素的影响,含量分布和变化特征也有着相应的不同。其中陆源物质输入、沉积物的粒径大小以及海洋生物的丰度影响着IEF-N的分布;而CF-N分布与p H的变化密切相关;IMOF-N的含量受到沉积物氧化还原环境的直接影响;OSF-N则与沉积物来源有关。

Nitrogen is the foundation of marine primary productivity as well as the food chain. Nitrogen in sediments exist in different forms,which represent different physical and chemical properties and bioavailability. Marine biogeochemistry of Nitrogen can be better understood by researching the content and influencing factors of different Nitrogen forms. In this study,an improved classification extraction method was used to measure Ion-exchangeable form（ IEFN）,Carbonate form（ CF-N）,Iron-manganese oxide form（ IMOF-N） and Organic matter-sulfide form（ OSF-N） in surface sediment of the Yangtze River estuary and adjacent area in Aug. 2014. Besides,the distribution and influencing factors of different Nitrogen forms was investigated. Results show that,distribution of the forms of Nitrogen are various differently in the study area because of different influencing factors. IEF-N is mainly affected by terrigenous input,sediment grain size and biological activity. The distribution of CF-N is mainly influenced by the p H of the seawater.IMOF-N is mainly impacted by the deposits redox environmental conditions,and OSF-N by the source of sediment.