贵州草海水体溶解性有机质光谱特征及来源分析OA

Dissolved organic matter(DOM)is one of the primary driving factors of biogeochemical reac-tions,and it is important to analyze DOM composition and sources in lake water to control and prevent pollution.In this study,the composition and sources of DOM in Caohai Lake(Guizhou Province)were an-alyzed using ultraviolet-visible absorption spectroscopy and three-dimensional fluorescence spectroscopy.The relative contribution of each component of DOM was then quantitatively evaluated by parallel factor analysis.The DOM level in Caohai Lake was 11.08 mg/L in the wet season,significantly higher than in the dry season(6.40 mg/L).Caohai Lake DOM was mainly composed of humic-like substances(C1,C2,C4)and protein-like substances(C3),and humic-like substances dominated,with fluorescence intensity accounting for over 85％of the total.The protein-like components were affected by the distribution of sub-merged macrophytes and human activities in both seasons,and the relative concentrations peaked near the county town and the southeast submerged macrophyte area.The humic-like components were affected by exogenous inputs in the wet season,and the peak concentrations were at the center of the lake and the lake outlet,while peak concentrations in the dry season were near the county town.The average molecular weight of DOM in Caohai Lake was significantly higher during the wet season than during the dry season,while aromaticity was more obvious in the dry season.The DOM of Caohai Lake was influenced by both endogenous and exogenous factors,with endogenous sources more significant in dry season,showing stronger autogenetic characteristics and lower humification.The spatial distribution and seasonal variation of DOM in Caohai Lake were clear.Furthermore,there was a significant correlation among the composi-tion,source and relative molecular size of DOM.The source of DOM in the water body of Caohai Lake is significantly related to endogenous release and we therefore recommend restoration of submerged macro-phytes in Caohai Lake as soon as possible and that steps be taken to control internal pollution.