多方法研究呼伦湖表层沉积物有机质的赋存特征及来源

湖泊沉积物有机质是全球碳循环的重要组成部分之一.寒旱区湖泊由于地理位置和气候条件的特殊性，其沉积物有机质的赋存和迁移转化特征更容易受到气候变化的影响.以我国寒旱区典型代表湖泊——呼伦湖为例，采用连续提取法、C/N（碳氮比值）、δ13C（碳稳定同位素）、三维荧光光谱技术对呼伦湖表层沉积物有机质的含量和组分的时空分布特征、污染来源及稳定性进行了研究.结果表明:①2018年10月（秋季）、2019年3月（冬季）、2019年5月（春季）、2019年7月（夏季），呼伦湖表层沉积物中w（TOC）的平均值分别为（25.05±9.73）（26.92±11.60）（24.68±10.19）（24.36±10.01）g/kg，呈冬季高、夏季低，由西北部向东南部递减的时空分布趋势.②w（WEOM）（WEOM为水提态有机质）、w（FA）（FA为富里酸）、w（HA）（HA为胡敏酸）和w（HM）（HM为胡敏素）的年均值分别为（0.63±0.33）（2.31±1.26）（3.42±1.49）（19.21±7.83）g/kg，w（WEOM）:w（FA）:w（HA）:w（HM）为1.0:3.7:5.5:30.7，其中HM为有机质的优势组分.③WEOM包括类富里酸组分C1，类腐殖酸组分C2和C3，以及类色氨酸组分C4共4个荧光组分，其中，类腐殖质组分（C1+C2+C3）贡献了总荧光强度的79.2%，为优势荧光组分.④沉积物有机质主要来自于陆源，陆源有机质的平均贡献率在80%左右.⑤沉积物PQ值（胡敏酸占腐殖酸的比例）和WEOM的HIX（腐殖化指数）年均值分别为0.55和6.39，表明现阶段呼伦湖表层沉积物有机质腐殖化程度较高且相对稳定.研究显示:呼伦湖表层沉积物有机质含量较高，表现出季节和空间分布差异性；有机质主要来自陆源，以类腐殖质为主，具有腐殖化程度高和相对稳定的特点. 

Occurrence Characteristics and Sources Analysis of Sediment Organic Matter of Lake Hulun by Multiple Methods

The organic matter in lake sediments is one of the important components of global carbon cycle. The occurrence, migration and transformation of organic matter of lake sediments in cold and dry regions are more susceptible to climate change due to the special geographical location and climate conditions. The spatial and temporal distribution characteristics, pollution sources and stability of organic matter in surface sediment of Lake Hulun, a typical lake in cold and arid region, were studied by sequential extraction, C/N, δ13C and three-dimensional fluorescence spectrum techniques. The results showed that the average content of total organic carbon (TOC) in the surface sediments of Lake Hulun in October 2018, March 2019, May 2019 and July 2019 was (25.05±9.73), (26.92±11.60), (24.68±10.19) and (24.36±10.01)g/kg, respectively, showing a trend of high in winter and low in summer, and decreasing from northwest to southeast. The average annual contents of water extractable organic matter (WEOM), fulvic acid (FA), humic acid (HA) and humin (HM) were (0.63±0.33), (2.31±1.26), (3.42±1.49) and (19.21±7.83)g/kg, respectively, with a relative ratio of 1.0:3.7:5.5:30.7. HM was the dominant component of organic matter. WEOM consisted of four fluorescence components, namely fulvic acid component C1, humic acid components C2 and C3, and tryptophan component C4. Humus-like component (C1+C2+C3) accounted for 79.2% of the total fluorescence intensity and was the dominant fluorescence component. The sediment organic matter was mainly derived from terrestrial sources, whith an average contribution rate of about 80%. The annual mean values of PQ and HIX of WEOM were 0.55 and 6.39 respectively, indicating that the sediment organic matter was highly humified and relatively stable. In general, the organic matter content in the surface sediments of Lake Hulun was relatively high, showing seasonal and spatial distribution differences. The organic matter mainly came from terrestrial sources and was dominated by humus-like components. The organic matters in sediments of Lake Hulun were highly humified and relatively stable.