洞庭湖典型垸内沟渠沉积物不同形态氮的赋存特征

Occurrence Characteristics of Different Forms of Nitrogen in Sediments in the Dongting Lake Typical Canal

摘要: 随着人类活动影响的加剧，洞庭湖局部区域已经出现轻中度富营养化，为了探究影响洞庭湖富营养化的因素，采用连续分级提取法针对洞庭湖垸内沟渠开展沉积物不同形态氮的赋存特征研究。结果表明研究区域沉积物总氮(TN)含量在586.82~1438.35 mg•kg−1之间，各形态氮的含量大小依次为：酸解态氮(HN) > 残渣态氮(RN) > 可交换态氮(EN) > 游离态氮(FN)，分别占沉积物总氮的69.27%、16.72%、13.32%、0.69%。可矿化程度较高的HN占比最高，总可矿化有机氮平均277.15mg/kg，沉积物向上覆水中释放氮的能力较高，存在加剧洞庭湖区水体富营养化程度的风险，本研究可为洞庭湖沟渠水体富营养化控制和治理提供一定的理论依据。

Abstract: With the influence of human activities, eutrophication has appeared in some areas of Dongting Lake. In order to study the eutrophication factors, the occurrence characteristics of different forms of Nitrogen in the typical canal of Dongting Lake were explored by sequential extraction method. The results show that the TN concentrations of surface sediments ranged from 586.82 to 1438.35 mg•kg−1, and the concentrations of nitrogen speciation follow the order of the acid hydrolysable nitrogen (HN) > the residual nitrogen (RN) > the exchangeable nitrogen (EN) > the free nitrogen (FN), and their proportions to the total extractable N are 69.27%, 16.72%, 13.32%, 0.69%. As the most efficient contributor to the mineral N, HN occupies the highest proportion so that the potential contribution of nitrogen in the sediments to overlying water is greater. This study provides an important basis for the eutrophication treatment in the Dongting Lake area.