巢湖沉积物不同形态氮季节性赋存特征

采用连续分级提取法研究了巢湖表层沉积物中游离态氮(FN)、可交换态氮(EN)、酸解态氮(HN)及残渣态氮(RN)的季节性赋存特征,同时结合表层沉积物中总氮(TN)及可矿化态氮(MN)含量的季节性变化,探讨各组分氮之间及其与TN﹑MN的相关关系.结果表明,除RN含量的季节性变化不明显外,TN及其他各组分N都存在季节性变化,表现为夏季低而冬季高的分布趋势.NH4+-N是FN、EN的主要组成部分.TN平均含量呈西高东低的分布特点,最大值出现在西半湖湖心,平均含量为2280.47mg/kg;有效氮的形态在不同季节表现不同,春季为酸解氨基酸态氮(AAN),夏季、秋季为可交换态氮(EN),冬季为游离态氮(FN).沉积物氮形态季节变化特征的研究为湖泊水环境生态安全评估及氮营养盐释放评价提供基础数据.

Seasonal Occurrence Characteristics of Different Forms of Nitrogen in the Sediments of Chaohu Lake

Seasonal characteristics of the free nitrogen (FN), the exchangeable nitrogen (EN), the acid hydrolysable nitrogen (HN) and the residual nitrogen (RN) in the surface sediment of Chaohu Lake were analyzed by sequential extraction method. The correlations among the nitrogen fractions with the total nitrogen (TN) and the mineralizable nitrogen (MN) were discussed considering the seasonal variations of the TN and MN. The results show that the concentrations of FN, EN and TN are lower in summer and higher in autumn and winter, NH⁺₄-N is the main fraction of FN and EN. TN concentrations are much higher in West Chaohu Lake with the maximum concentration of 2280.47 mg/kg in the west lake center than in the East Chaohu Lake. The seasonal order of mineralizable nitrogen (MN) content is winter> spring> autumn> summer. The bio-available nitrogen fraction varies with different seasons, which is the amino acid nitrogen (AAN) in spring, EN in summer and autumn, FN in winter. The study about seasonal occurrence characteristics of nitrogen fractions in sediment provided foundational data for lake ecological security evaluation and nitrogen release evaluation.