山口湖沉积物中溶解性有机氮的分布特征

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

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〈1ku和〉30 ku的DOC/DON很小,说明其有机质主要来自内源。

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.