兴凯湖有色可溶性有机物来源与组成特征—中国境内特大型界湖

运用光谱吸收与三维荧光－平行因子分析法(EEMs-PARAFAC)分析了兴凯湖有色可溶性有机物(CDOM)吸收光谱、荧光光谱特征以及荧光组分与主要水质参数的相关性,以探究兴凯湖CDOM来源组成特征.结果表明:平行因子分析法解析CDOM三维荧光图谱,得到陆源类腐殖质C1、微生物作用类腐殖质C2、类酪氨酸C3和类色氨酸C4.兴凯湖中陆源类腐殖质C1能较好反演DOC、TN浓度变化,且在富营养化更强的小兴凯湖中反演效果更好.吸收系数a₂₅₄、荧光峰积分比值I_C:I_T、光谱斜率S_275-295、DOC与C1-C2、C4在兴凯湖中线性拟合程度均较好,与C1的相关性最好,这意味着陆源类腐殖质是兴凯湖CDOM库的主要贡献者,入湖河流输入是兴凯湖CDOM的重要来源之一.小兴凯湖DOC、a₂₅₄均极显著高于大兴凯湖,说明小兴凯湖的CDOM丰度要高于大兴凯湖.小兴凯湖CDOM的I_C:I_T、C1-C2和C4的值均极显著大于大兴凯湖(P<0.001),小兴凯湖S_275-295与光谱斜率比值S_R均极显著小于大兴凯湖,小兴凯湖PC1得分均值显著高于大兴凯湖品,意味着相较于大兴凯湖而言,小兴凯湖CDOM陆源输入信号更强烈,腐殖质化程度更高,亦即河流输入、农业面源污染导致小兴凯湖CDOM腐殖质化程度升高,且这一部分CDOM分子量较大,应加强兴凯湖流域中生态渔业、生态农业、生态旅游、农田退水等河流污染源排放的控制管理.

Characterizing sources and optical composition of chromophoric dissolved organic matter in Lake Xingkai,a large boundary lake in China

Research on the sources and optical composition of Chromophoric dissolved organic matter (CDOM) is of great significance to the water quality protection of the Lake Xingkai. CDOM absorption coupled with excitation-emission matrices and parallel factor analysis (EEMs-PARAFAC) were used to explore the sources and optical composition of DOM in Lake Xingkai. Four fluorescent components were identified using EEMs-PARAFAC, including a terrestrial humic-like C1, a microbial humic-like C2, a tyrosine-like C3, and a tryptophan-like C4. The fluorescence characteristic of C1is a potential surrogate tracing the variability of DOC and TN concentrations. DOM absorption a₂₅₄, the integration ratio of the fluorescence peak C to peak T (I_C:I_T), the spectral slope of CDOM absorption S_275-295 and DOC concentrations were associated closely with C1-C2, and C4 in Lake Xingkai. This indicates that terrestrial input is an important source of DOM to Lake Xingkai. Significantly higher mean a₂₅₄ and DOC concentrations were found in the Small Lake Xingkai than in the Great Lake Xingkai, indicating that the levels of CDOM in Small Lake Xingkai was higher than that in Great Lake Xingkai. The mean I_C:I_T and fluorescence intensities of C1, C2, and C4 were significantly higher in the Small Lake Xingkai than that in the Great Lake Xingkai, whereas S_275-295 and S_R was significantly lower in the Small Lake Xingkai. The mean score of PC1, positively associates with DOC, TN, DTN, NO- 3-N, a₂₅₄, I_C:I_T, SUVA₂₅₄, C1, C2 and C4, in Small Lake Xingkai was significantly higher than that in Great Lake Xingkai. These results indicated that substantial terrestrial DOM with enhanced aromaticity were exported to the Small Lake Xingkai, probably due to an enhanced riverine input and agricultural non-point source pollution in the Small Lake Xingkai watershed. Therefore, a better management of riverine input to the lake due to regional fishery, agricultural land use, and tourism in the upstream watershed is needed.