山口湖沉积物中溶解性有机氮的分布特征

以东北典型山地湖泊山口湖为研究对象，研究了沉积物中溶解性有机氮(DON)和氨基酸的浓度及分布特征。结果表明，山口湖沉积物DON浓度为124.41~560.17 mg/kg，平均值为304.78 mg/kg，占沉积物溶解性总氮(TDN)的45.25%，占沉积物总氮(TN)的5.27%；氨基酸浓度为9.21~18.53 mg/kg，平均值为12.19 mg/kg，占DON、TDN、TN的比例分别为4.35%、1.91%和0.22%。沉积物DON分子量分级结果表明，DON和SUV254分子量分布主要是小分子量(<1 ku)为主；而大分子量(>30 ku)的DOC占主要部分。下游2号采样点沉积物在分子量<1 ku时DOC/DON处于中等水平，这部分有机质既有内源释放也有外源输入，而分子量>30 ku的DOC/DON较高，说明这部分有机质主要来自外源；上游8号、13号采样点，分子量<1 ku和>30 ku的DOC/DON很小，说明其有机质主要来自内源。

A Study on Distribution Characteristics of Dissolved Organic Nitrogen (DON) in the Sediments of Lake Shankou

The contents and distribution characteristics of dissolved organic nitrogen (DON) and free amino acids (FAA) from the 14 sediments of Lake Shankou, a typical mountain lake in northeast region were studied. The results indicated that the DON contents ranged from 124.41 to 560.17 mg/kg, averaged 304.78 mg/kg, comprising 45.25% of total dissolved nitrogen (TDN) and 5.27% of total nitrogen (TN) in Lake Shankou. The contents of FAA varied from 9.21 to 18.53 mg/kg (mean content, 12.19 mg/kg), comprising 4.35% of DON, 1.91% of TDN and 0.22% of TN, respectively. The DON molecular fraction results indicated that and low molecular weight DON and SUV254 with MW <1 ku about was the dominating fraction at the sampling stations, and high molecular weight DOC with MW >30 ku was the dominating fraction. The DOC/DON ratio results indicated that the small MW fractions(<1 ku) at station 2 which located at downstream of Lake Shankou derived from natural organic matters in sediments and allochthonous sources in water column, and the high MW fractions(>30 ku) at station 2 were mainly from external input in water. The DOC/DON ratios of the small MW fractions(<1 ku) and high MW fractions(>30 ku) at stations 8 and 13 were much low, implying their sources mainly from autochthonous contribution.