上海地区不同河道CDOM光谱吸收特征及其可能来源分析

Spectral Absorption Characteristics and Potential Source of CDOM in Rivers in Shanghai Region

于2013年8月对上海徐汇、青浦、宝山、嘉定、闵行和松江6个区14条河道水体中的有色可溶性有机物（CDOM）的光谱吸收特性、分布概况及其可能来源进行研究.结果表明,不同区域河道水体中CDOM吸收系数在紫外到可见光波段均呈指数递减趋势,波长350 nm处的吸收系数[a（355）]在2.34～4.33 m^-1之间,不同区域差别较大,城镇河道水体CDOM吸收系数总体高于城郊农业区河道.相关性分析表明,a（355）分别与水体ρ（CODMn）和浊度呈显著相关,但与ρ（Chl-a）（平均为30.59 μg·L^-1）相关性不显著,说明河道水体CDOM主要来自于陆源,如城镇生活污水、工业废水和农业面源污染等,对250和365 nm波长处吸收系数的比值M和光谱吸收斜率S值的分析也得出相同结论.对上海河道水体CDOM光学特性的研究有助于了解上海不同区县河道水体水下光场的分布概况,为上海市河道水生植被的恢复提供理论基础.

Spectral absorption characteristics,distribution and potential sources of CDOM （chromophoric dissolved organic matter） in 14 rivers running in 6 districts of Shanghai were investigated in August 2013.Results show that spectral absorption coefficients of CDOM in the rivers,regardless of districts,all displayed an exponentially decreasing trend in all bands from ultraviolet to visible light with CDOM spectral absorption coefficient a（355） varying in the range of 2.34-4.33 m^-1.Spectral absorption coefficient of CDOM in rivers varied sharply from district to district.On the whole,CDOM spectral absorption coefficient was higher in rivers running in the urban area than in rivers in the suburban area.Correlation analysis reveals that,CDOM spectral absorption coefficient a （355） was closely related to permanganate index and turbidity,separately,but not so much to concentration of chlorophyll a （average 30.59 μg · L^-1）,which suggests that the CDOM in the rivers may mainly come from the terrestrial sources,such as urban domestic sewages,industrial wastewater,agricultural non-point source pollution,etc..Analysis of M,ratio of a（250）/a（365）,and S,spectral absorption slope,brought about the same conclusion.The study of CDOM optical properties in the river water of Shanghai would help understand distribution of underwater light field in the rivers of Shanghai,and lay down some theoretical basis for restoration of aquatic vegetations in the rivers.