夏季高原河流CDOM光学特性、组成及来源研究

对高原河流有色溶解有机物(CDOM)光学特性、组成及来源进行研究,有利于更好的了解高原河流水体生态环境,为高原河流生态系统中溶解有机物(DOM)循环过程的研究提供数据参考.利用2017年夏季无定河和湟水流域河流的实测数据对CDOM的吸收特性、荧光特性、水质参数以及它们之间关系进行分析,进而对高原干旱地区河流CDOM光学特性及其组成与来源进行研究.研究结果表明:两流域河流中CDOM吸收系数随波长的增加呈衰减趋势,但吸收光谱曲线差别较大;两流域CDOM在440 nm处的吸收系数a(440)]与溶解有机碳(DOC)具有显著相关性(p0.01),而与叶绿素a浓度(Chla)不存在相关性.无定河a(440)与Chla浓度的相关性说明其河流现场产生(生物活动)作用较小.通过对比分析S_(275-295)、SUVA_(254)发现,无定河分子量和芳香性程度均大于湟水,且湟水与无定河CDOM的分子量变化要高于其它河流的研究.根据CDOM三维荧光光谱分析发现,类腐殖质荧光峰是两流域河流CDOM荧光的主要贡献者;通过荧光指数FI、腐殖化指数HIX、生物源指数BIX的研究发现,湟水以陆源输入为主,腐殖化程度高,无定河以陆源输入为主的同时存在一定的自生成分,人为生产活动干扰是其陆源输入的主要影响因素.通过冗余分析发现,湟水DOC、Chla、pH对类腐殖质荧光峰及荧光强度影响较大(p0.01);无定河DOC、电导率(EC)、浊度(Tur)与类腐殖质荧光峰及荧光强度显著正相关(p0.01).

Optical characteristics, composition and sources of colored dissolved organic matter in plateau rivers in summer

Studying optical characteristics, composition and source of colored dissolved organic matter (CDOM) in the plateau river will help to understand the water ecological environment of the plateau rivers and provide foundations for researching dissolved organic matter (DOM) cycling in the plateau river ecosystem. CDOM absorption characteristics, fluorescence characteristics and water quality parameters as well as the relationships among them were analyzed based on the samples collected from Wudinghe and Huangshui rivers located in plateaus in 2017 summer to study characteristics, sources and the constituent of CDOM. Results show that CDOM absorption coefficient of the two rivers decreased with the increase of wavelength and the absorption spectra curve showed great differences in different watersheds. The absorption coefficient of CDOM at 440 nma(440)] strongly correlated with dissolved organic carbon (DOC) for the samples in the two watersheds while there was no correlation between a(440) and chlorophyll a concentration (Chla). Correlation between a(440) and Chla concentration in Wudinghe river indicated that the onsite generation (biological activity) of the river affected weakly on CDOM. Comparisons S_275~295 and SUVA₂₅₄ indicated that CDOM in Wudinghe river was more molecular weight and aromatic than that in Huangshui river. Moreover, the molecular weight changes of Huangshui river and Wudinghe river CDOM was higher than that of other rivers investigated in previous studies. According to the analysis based on the three-dimensional fluorescence spectrum, the humic-like fluorescence peaks were the main fluorescence of CDOM for both Huangshui and Wudinghe river. Fluorescence index (FI), humification index (HIX) and biological source index (BIX) showed that CDOM in Huangshui river was dominated by terrestrial input and the degree of humification was high while CDOM in Wudinghe River was also dominated by terrestrial input and exhibted a certain autogenous component. Redundancy analysis (RDA) results indicate that DOC, Chla and pH of Huangshui river had a great influence on the humic-like fluorescence peak and fluorescence intensity (p<0.1). DOC, electrical conductivity (EC) and turbidity (Tur) in Wudinghe river significantly positive correlated to the humic-like fluorescence peaks and fluorescence intensity (p<0.1).