山口湖沉积物中溶解性有机氮的分布特征

摘要

The contents and distribution characteristics of dissolved organic nitrogen ( DON) and free amino acids ( FAA) from the 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 with averaged value of 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 with averaged value of 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 the dominating fractions of DON and SUV254 were low molecular weight with MW <1 ku at the sampling stations, and the dominating fraction of DOC was high molecular weight with MW >30 ku.At Station 2 in the downstream of Lake Shankou, the small MW fractions ( <1 ku ) with middle-level DOC/DON ratios were derived from both internal release and exogenous sources, while the large MW fractions (>30 ku) with high DOC/DON ratios mainly from external input in water.The small MW fractions (<1 ku) and high MW fractions (>30 ku) were with much low DOC/DON ratios at Stations 8 and 13, implying that they were mainly from internal sources.%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。