二龙湖表层水体有色溶解有机物的光学特性及来源

CDOM（colored dissolved organic material，有色溶解有机物）的光学特性可反映水体中内源物质与外源物质的比例，为了解二龙湖受到上游来水所含污染物的影响，利用荧光区域一体化技术和荧光指数分析水体中CDOM的荧光特性，进而判定水体污染状况，并结合CDOM荧光组分与水质参数之间的关系，探讨了不同季节二龙湖水体中CDOM光学特性在时空分布上的差异性以及CDOM的组成与来源.结果表明:①水相中CDOM表现出明显的季节性差异.其中，光谱斜率S_g（275~295 nm）和E_{250 nm:365 nm}〔a_CDOM（250）/a_CDOM（365）〕均表现为丰水期>平水期>枯水期，SUVA_{254 nm}表现为枯水期>平水期>丰水期.②水体中的荧光组分以外源组分R3（富里酸类物质）和R5（腐殖酸类物质）为主，在枯水期、丰水期和平水期分别占总荧光强度的70.0%、60.4%和51.3%.③在丰水期、枯水期、平水期，FI_{310 nm}平均值均大于0.8，FI_{370 nm}平均值均小于1.4，表明在3个水文期，微生物活动带来的内源CDOM在二龙湖南部较为明显.④ρ（DOC）（dissolved organic carbon，溶解性有机碳）与CDOM的荧光组分R2（色氨酸类组分）、R4（可溶性微生物副产物组分）和R5（腐殖酸类组分）均具有较好的相关性，相关系数（R）分别为0.71、0.80、0.73，表明DOC主要源于微生物代谢的可溶性副产物及浮游植物的降解.研究显示:水体中CDOM主要组成为内源的色氨酸与微生物蛋白质类副产物以及外源的富里酸类与腐殖酸类有机物；同时，由于冰冻、降水、生活污水排放、农业废水和水生植物等因素，导致湖泊中的CDOM的组分与来源十分复杂. 

Photometric Characteristics and Sources of Colored Dissolved Organic Matter in Surface Water from Erlong Lake

The optical properties of colored dissolved organic matter (CDOM) can reflect the ratio of endogenous substances to exogenous substances in its composition. In order to explore the effected of various pollutants in the upstream water, this study analyzed the fluorescence characteristics of CDOM in the water using the fluorescence regional integration technique and fluorescence index to determine the pollution status. The difference of CDOM optical properties and the composition and source of CDOM in the water body of Erlong Lake in different seasons were discussed with the combination of the relationship between CDOM fluorescence components and water quality parameters. The results showed that: (1) The absorption of CDOM in the water showed an obvious seasonal difference. Among them, the spectral slope S_g (275-295 nm) and E_{250 nm:365 nm}(a_CDOM(250)/a_CDOM(365)) showed wet water season > average water season > low water season, and SUVA_{254 nm} value showed low water season > average water season > wet water season. (2) The fluorescence components in the water were mainly exogenous R3 (fulvic-like) and R5 (humic-like), which accounted for 70.0%, 60.4% and 51.3% of the total fluorescence intensity in the low water season, wet water season and average water season, respectively. (3) The average value of FI_{310 nm} in the three water season was greater than 0.8, while the mean value of fluorescence index FI_{370 nm} in the three water season was less than 1.4. The endogenous CDOM caused by microbial activity in the three water seasons was more in the southern part of Erlong Lake. (4) The dissolved organic carbon (DOC) in water had a good correlation with the fluorescence components R2 (tryptophan-like), R4 (microbial protein-like) and R5 (humic-like) of CDOM, the Correlation coefficient were 0.71,0.80 and 0.73, respectively. Mainly due to the soluble by-products of microbial metabolism and the degradation of phytoplankton. The results showed that the main components of CDOM in water were intrinsic tryptophan and microbial protein by-products, as well as exogenous fulvic acids and humic acids organic compounds. Due to freezing, precipitation, domestic sewage discharge, agricultural wastewater and aquatic plants and other factors, the composition and source of CDOM in lakes are very complex.