不同污染程度湖泊沉积物中不同粒级可转化态氮分布

研究了污染程度不同的五里湖、月湖、东太湖和贡湖不同粒级沉积物中总可转化态氮以及各形态可转化态氮的含量与分布.结果表明:4个湖泊的沉积物各粒级中各形态可转化态氮的含量及其地球化学特征均不相同.强氧化剂可提取态氮(SOEF-N)是释放能力最弱的形态，为可转化态氮的主体，占总可转化态氮的66.97%～87.97%.离子交换态氮(IEF-N)结合能力最弱，是最容易被释放的形态，为可转化态无机氮的主体，占总可转化态氮的7.37%～22.25%.同一粒级中，各形态可转化态氮对氮循环的贡献为SOEF-N最大，IEF-N其次，强碱可浸取态氮(SAEF-N)与弱酸可浸取态氮(WAEF-N)最低.随着沉积物粒级的由粗到细，总可转化态氮以及各形态可转化态氮含量均呈逐渐增加趋势.沉积物细颗粒部分对氮循环的可能贡献占绝对的主体，是粗颗粒部分的几倍到几十倍.相比而言，污染程度轻的贡湖和东太湖沉积物无论总可转化态氮还是各形态可转化态氮，细颗粒部分的相对含量均低于污染程度重的五里湖和月湖沉积物. 

Distribution of Transferable Nitrogen in Different Grain Size from the Different Trophic Level Lake Sediments

Amounts and distributions of total transferable nitrogen and different transferable nitrogen forms of different grain size fraction sediments from Wuli Lake, Yue Lake, Dongtaihu Lake and Gonghu Lake that are in different trophic levels were investigated. The results show that the geochemical characteristics of transferable nitrogen in different grain size fraction from the studied 4 sediments are different. The content of SOEF-N, the weakest released form and the highest in all transferable nitrogen forms, accounts for about 66.97 % - 87.97 % of the transferable nitrogen. IEF-N is the predominant form of the transferable inorganic nitrogen, which can take part in nitrogen cycling most easily, and accounts for 7.37 % - 22.25 % of the total transferable nitrogen. Under the same gain size, among various forms of transferable nitrogen, SOEF-N contributes the most to nitrogen cycling, with IEF-N being the second, and SAEF-N and WAEF-N contribute the least. With the change of sediment grain sizes from coarse to fine, the contents of total transferable nitrogen and different transferable nitrogen forms are increasing. The relative contribution of fine grain size fraction to nitrogen cycling is absolutely the main fraction, which is several times to 10 times of that in coarse grain size fraction. In contrast, the relative contents of total transferable nitrogen and different transferable nitrogen forms of the fine grain size fraction from Gonghu Lake and Dongtaihu Lake sediments that are slightly polluted are lower than that from the Wuli Lake and Yue Lake sediments that are heavily polluted.