• 关键词：溶解性有机质  紫外-可见光吸收光谱  天然水体  川西高原河流

• 基金项目：国家自然科学基金（No.41271094）

• 刘堰杨
• 四川大学环境科学与工程系, 四川省土壤环境保护工程技术中心, 成都 610065

• 秦纪洪
• 成都大学环境工程系, 成都 610106

• 孙辉
• 四川大学环境科学与工程系, 四川省土壤环境保护工程技术中心, 成都 610065

• 摘要：溶解性有机质（DOM）对全球碳循环及气候变化具有重要意义.本文选取川西北4条高海拔河流，即杂谷脑河、抚边河及岷江（高山峡谷河流）与白河（高原河流），对其天然水体中有色溶解性有机质（CDOM）的紫外-可见光吸收光谱特征进行了研究与比较.结果表明，川西高海拔河流DOC变化范围为1.55~5.66 mg·L^-1，CDOM （以a（355）表征）变化范围为0.96~6.31 m^-1，荧光溶解性有机质（FDOM）（以lgF_n（355）表征）变化保持在2.08~2.83之间.与高山峡谷区河流比较，高原河流芳香性、疏水性特征常数SUVA₂₅₄、SUVA₂₆₀较高，吸光度之比E₂/E₃、光谱斜率S_275~295及光谱斜率之比S_R较低，揭示了高原河流CDOM芳香性较强、疏水性组分丰富、分子结构较为复杂；SUVA₂₅₄、SUVA₂₆₀分别与S_R、S_275~295呈显著负相关，表明白河由于高通量陆源腐殖质输入影响了CDOM特征.川西高原4条高海拔河流中SUVA₂₅₄、SUVA₂₆₀存在显著相关关系，表明芳香性结构普遍存在于河流CDOM疏水组分中.川西高原天然河流水体中CDOM与DOM的浓度之间总体上无直接关联，因为不同天然水体在DOM形成过程中，陆源DOC输入组分和强度及转化机制存在差异.研究结果对于揭示高海拔区域在全球变化背景下有机碳循环的区域效应等方面具有重要意义.

• Abstract：Dissolved organic matter (DOM) is an optically ubiquitous active substance which is playing an indispensable role in global biogeochemical cycling of carbon and significantly affects the fate and transport of organic pollutants. DOM sampling from four rivers, including the upper reaches of Minjiang River, Zagunao River, Fubian River in the alpine-gorge region and Bai River in the Zoige wetland region, was investigated in the western Sichuan plateau using UV-Vis and EEM fluorescence spectroscopy. The concentration of DOC, CDOM and FDOM, ranges from 1.55 to 5.66 mg·L^-1, 0.96 to 6.31 m^-1 and 2.08 to 2.83 in the four high elevation rivers, respectively. Compared with the three rivers in the alpine-gorge region, the river in the Zoige wetland region shows relatively high aromaticity (SUVA₂₅₄) and hydrophobicity (SUVA₂₆₀), as well as high molecular weight (E₂/E₃、S_275~295 and S_R). Bai River is rich in terrestrial-type DOM as evidenced by a strong correlation relationship between SUVA₂₅₄/SUVA₂₆₀ with S_R/S_275~295. Statistical analysis showed that SUVA₂₅₄ and SUVA₂₆₀ were significantly positively correlated in the four rivers, indicating the hydrophobic CDOM may possess aromatic structure. Additionally, significant correlation was not observed between DOC and CDOM in natural rivers, this is possibly due to the variations in the inputs of allochthonous DOM concentration in water. This study may provide the information on the characteristics of DOM in alpine natural waters, which is essential in realizing the cycling of carbon from terrestrial ecosystems into alpine natural waters in the face of a variable and changing climate.

• Key words：dissolved organic matter  UV-Vis spectrum  natural watersheds  alpine rivers in the western Sichuan

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