连续分级提取法研究春季巢湖沉积物中不同结合态氮的赋存特征

为研究沉积物中不同形态氮的释放能力及其生物可利用性大小，为湖泊水环境生态安全评估提供基础依据，以春季巢湖表层沉积物为例，采用连续分级提取法将氮分为游离态氮（FN）、可交换态氮（EN）、酸解态氮（HN）及残渣态氮（RN），并研究了这4种形态的赋存特征。结果表明，沉积物中总凯氏氮含量（TKN）在1004—2285mg·kg^-1之间，各形态氮含量大小为HN〉EN〉RN〉FN，占总提取态氮比例分别为78．32％、11．50％、9．76％、0．42％。酸解氨基酸态氮是可矿化态氮最有效贡献者，多元逐步回归方法得到“最优”方程为y=0．696AAN-108．918。连续提取法测得总氮值（TSEN）比用凯氏半微量法测得总氮值（TKN）偏小，但在误差允许的范围内，TSEN可替代半微量凯氏法测得的总氮。

Speciation Characteristics of Different Combined Nitrogen in the Spring Sediments of Chaohu Lake by Sequential Extraction Methods

In order to study the release capability and bioavailability of nitrogen in the surface sediments of Chaohu Lake, the concentrations of the total Kjeldhal nitrogen（TKN ） and its different nitrogen speciations were investigated by the sequential extraction method. By this se- quential extraction method, nitrogen speciation was divided as the free nitrogen （FN）, the exchangeable nitrogen （EN）, the acid hydrolysable nitrogen（ HN ）and the residual nitrogen（ RN ）. The results showed that the TKN concentrations of surface sediments ranged from 1 004 -2 285 mg· kg-1, the concentrations of nitrogen speciations followed the order of HN〉EN〉RN〉FN, their proportion to the total extractable N were 78.32%, 11.50%, 9.76% and 0.42% respectively. AAN was the most efficient contributor to the mineral N with the best regression equation of y=0.696AAN-108.918 by multiple stepwise regression method. The total sediment extractable nitrogen（ TSEN ） was a little smaller than the TKN. However, TSEN could take place of TKN within a certain confidence interval. Sequential extraction methods for nitrogen speciation in sediment provide basic data for the lake water environment ecological security assessment.