烟台四十里湾柱状沉积物氮形态地球化学特征

采用连续浸取法首次对烟台四十里湾柱状沉积物不同形态的氮进行分离,并对其垂直地球化学特征和影响因素进行分析研究.可转化态氮分为离子交换态氮(IEF-N)、弱酸浸取态氮(WAEF-N)、强碱浸取态氮(SAEF-N)、强氧化剂浸取态氮(SOEF-N).结果表明,在沉积物表层(0～10 cm)可转化态氮占总氮的26.14%,并随着深度的增加而含量降低.各形态氮占可转化态氮比例平均大小顺序为SOEF-N(89.7%)>IEF-N(7.97%)>WAEF-N(1.19%)>SAEF-N(1.14%),说明SOEF-N是可转化态氮中的绝对优势态.不同形态氮与沉积物地球化学参数之间的相关关系分析表明,沉积物含水率、总有机碳、pH值、氧化还原电位、粒度组成等因素在一定程度上影响各形态氮含量,但各站位柱状样因其沉积物特征不同受各参数影响程度也不同.

Geochemical Characteristics of Nitrogen in Core Sediments from Sishili Bay, China

A sequential extraction technique was applied to gain the information about the fractionation of nitrogen in four core sediments from Sishili Bay, China. Based on the binding strength of different nitrogen compounds to the sediment matrix, ranging from easy to more difficult, four forms of labile nitrogen, i. e. nitrogen in ion exchangeable form (IEF-N), nitrogen in weak acid extractable form (WAEF-N), nitrogen in strong alkali extractable form (SAEF-N) and nitrogen in strong oxidant extractable form (SOEF-N), were extracted. The results showed that the content of labile nitrogen averagely accounted for about 26.14% of total nitrogen in the surface (0-10 cm) of core sediments and decreased gradually with depth, which implied that under natural geochemical conditions only a small part of sedimentary nitrogen could participate in recycling in a short time scale. The SOEF-N was the predominant form. The average percentages of the four labile nitrogen forms were 89.7% for SOEF-N, 7.97% for IEF-N, 1.19% for WAEF-N, and 1.14% for SAEF-N, respectively. The contents of nitrogen in different labile forms at different sampling sites are influenced by the combination of environmental factors such as sediment pH, redox potential and particle size.