基于UV-Vis辽河保护区地表水DOM的时空分布特征

Spatiotemporal Distribution of DOM in Surface Water of Liaohe Reservation Zone Based on UV-Vis Absorption Spectra

为探讨辽河保护区地表水中DOM(dissolved organic matter,溶解性有机质)组成、腐殖化程度及时空变化,采集辽河保护区上游至下游及主要支流入辽河干流河口处丰水期和枯水期地表水样品,基于UV-Vis(紫外-可见吸收光谱)揭示地表水中DOM结构组成的时空变化特征.结果表明:①从季节上看,辽河保护区地表水丰水期DOC(dissolved organic carbon,溶解性有机碳)浓度(11.73 mg/L)高于枯水期(6.76 mg/L),且丰水期DOM中类蛋白质组分相对浓度高于枯水期,而类腐殖质组分的相对浓度较低;从空间上看,辽河保护区支流DOC平均浓度高于干流浓度,且丰水期地表水DOM中类蛋白物质与类腐殖质浓度增加.②基于UV-Vis特征参数可知,辽河保护区地表水中DOM主要以内源释放为主;从季节上看,丰水期降水量和地表径流增加,DOM的芳香性、分子量、腐殖化水平降低;从空间上看,辽河保护区地表水DOM的腐殖化程度沿河流上游至下游呈现逐渐递减趋势,且支流DOM腐殖化程度较高,具有较高的芳香性及疏水性.研究显示,河流地表水中DOM的芳香性与分子量大小受周边沿岸生态环境系统、生物条件、土地利用类型等因素影响,不同类型地表水中DOM具有显著差异.

In order to investigate the composition,degree of humification and spatiotemporal variation of DOM in the surface water of the Liaohe Reservation Zone,surface water samples were collected from the upstream to the downstream and from the main stream to the tributaries of the Liaohe Reservation Zone in dry and wet season respectively.UV-Vis was used to study the spatiotemporal variation of DOM structure in the surface water.The results showed that:(1)The concentration of DOC(11.73 mg/L)was higher than that in the dry season(6.76 mg/L),the relative concentration of DOM in the wet season was higher than that in the dry season,and the relative concentration of humus was lower.The average DOC concentration was higher than that of the main stream,and the concentrations of protein-like substances and humus in the DOM of surface water increased in the wet season.(2)Based on the UV-Vis characteristic parameters,the source of DOM in the surface water of the Liaohe Reservation Zone was mainly from the biological source.The aromaticity,molecular weight and humification level of the DOM decreased with the increase of precipitation and surface runoff.The degree of humification of DOM in the Liaohe Reservation Zone gradually decreased along the upstream and downstream,and the degree of humification,aromaticity and hydrophobicity of DOM in the tributaries was high.The aromaticity and molecular weight of DOM in surface water were affected by the ecological environment system,biological conditions and land use types,and there were significant differences between DOM in different types of surface water.