骆马湖表层沉积物有机质分布特征及来源解析

为解析骆马湖富营养化沉积物的影响因素，2018年9月采集了骆马湖表层沉积物32个点位样品，分析了沉积物的总有机碳（TOC）、总氮（TN）、有机碳同位素（δ¹³C）和氮同位素（δ¹⁵N）指标，研究了沉积物中有机质分布特征及来源.研究表明：表层沉积物TOC含量在0.55%~3.76%，平均值为1.62%；TN含量在0.04%~0.46%，平均值为0.19%；δ¹³C含量在-27.32‰~-8.36‰，平均值为-14.98‰；δ¹⁵N含量在-1.92‰~10.17‰，平均值为7.72‰，TN与TOC在空间分布呈正相关，有机碳、氮同位素受不同来源有机质影响空间分布有较大差异.对δ¹⁵N、δ¹³C与C/N进行定性分析和端元混合模型定量计算，得出骆马湖表层沉积物有机质来源主要有三个：一是人类活动带来的土壤有机质贡献率最大，特别是东岸休闲旅游区贡献较高；二是围网养殖造成的源污染，加大了湖泊富营养化程度；第三是湖泊来水携带较高浓度的污水有机质，对"典型过水性"骆马湖水质影响较大.为了降低骆马湖水体富营养化程度，改善水生态环境质量，急需对湖体有机质的来源加大控制.

Distribution characteristics and source analysis of organic matter in surface sediments of Luoma Lake

In order to analyze the influencing factors of eutrophication sediment in Luoma Lake, In September 2018, samples of surface sediments at 32point positions of Luoma Lake were collected, and their biogeochemical indexes including total organic carbon (TOC), total nitrogen (TN), organic carbon isotope (δ¹³C) and nitrogen isotope (δ¹⁵N) were analyzed, with the aim to explore the distribution characteristics and sources of organic matter in the surface sediments of such area. The results showed that TOC content in surface sediments ranged from 0.55% to 3.76%, with an average value of 1.62%; TN content of the total nitrogen ranged from 0.04% to 0.46%, with an average value of 0.19%; δ¹³C content of organic carbon isotope ranged from -27.32‰ to -8.36‰, with an average value of -14.98‰; δ¹⁵N content of organic nitrogen isotope ranged from -1.92‰ to 10.17‰, with an average of (7.72±2.55)‰. The spatial distribution of TN and TOC was positively correlated, and the spatial distributions of organic carbon and nitrogen isotopes affected by different sources of organic matter were quite different. Through the qualitative analysis of δ¹⁵N and δ¹³C with C/N and the quantitative calculation of the end-member hybrid model, it is concluded that there were three main sources of organic matter in the surface sediments of Luoma Lake. The first is that the contribution rate of exogenous contamination of soil organic matter caused by human activities was generally the largest,especially in the leisure tourism areas along the east coast. The second is that the endogenous pollution caused by barrier net aquiculture had increased the degree of lake eutrophication. The third is that the organic matter of sewage with higher concentration of pollutants brought by the inflow water of the lake had a great impact on the "typical water-carrying" lake of Luoma Lake. Therefore, there is need to intensify controls over the sources of the abovementioned three kinds of organic matters, thus reducing the degree of lake eutrophication.