| 三峡库区消落带水体CDOM中电荷转移配合物对其紫外-可见吸收光谱的影响 |
| 摘要点击 2067 全文点击 925 投稿时间：2015-08-26 修订日期：2015-09-24 |
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| 中文关键词 三峡库区 消落带 溶解性有机质 电荷转移配合物 紫外-可见光谱 吸收光谱 |
| 英文关键词 Three Gorges Reservoir areas water-level fluctuation zones dissovled organic matter charge-transfer complex ultraviolet-visible (UV-Vis) spectrum absorption spectrum |
| 作者 | 单位 | E-mail | | 江韬 | 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆市农业资源与环境研究重点实验室, 重庆 400716
Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Ume SE-90183, Sweden | jiangtower666@163.com | | 梁俭 | 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆市农业资源与环境研究重点实验室, 重庆 400716 | | | 张慕雪 | 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆市农业资源与环境研究重点实验室, 重庆 400716
Department of Civil and Environmental Engineering, Michigan Technological University, Houghton, Michigan 49931, US | | | 王定勇 | 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆市农业资源与环境研究重点实验室, 重庆 400716 | | | 魏世强 | 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆市农业资源与环境研究重点实验室, 重庆 400716 | | | 卢松 | 西南大学资源环境学院, 三峡库区生态环境教育部重点实验室, 重庆市农业资源与环境研究重点实验室, 重庆 400716 | |
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| 中文摘要 |
| 以三峡库区消落带水体CDOM为研究对象,基于"双生色系统"模型,采用NaBH4还原法,研究了DOM还原前后光谱曲线及特征参数变化,探究了电荷转移配合物对DOM吸收光谱的影响. 结果表明,NaBH4还原处理后,可以将原来无特征峰的指数型吸光曲线分为两套具有特征吸收带的吸光曲线. 4个采样点中,超过35%的DOM吸光度来自于电荷转移(charge-transfer, CT)配合物,忠县石宝寨和涪陵珍溪DOM中CT配合物作所占比例最高( > 50%). 因此不能忽略CT配合物对CDOM吸光能力的贡献. 经NaBH4还原去除CT结构后,吸光曲线出现蓝移,CDOM浓度[a(355)]降低; 而断键导致DOM结构分散,分子尺寸减小, 光谱斜率(S)值降低. 同时,由于疏水性组分减少,表观芳香程度降低. 另外,特征参数SUVA、 CDOM和SR在不同DOM样本间对比时,较为稳定,而S275-295受CT影响较明显. 同时,在利用短波处CDOM对DOC浓度进行反演时,CT配合物对模型建立影响不大. |
| 英文摘要 |
| As an important fraction of dissolved organic matter (DOM), chromophoric dissolved organic matter (CDOM) plays a key role in decision of the optical properties and photogeochemistry of DOM, and further affects pollutant fate and global carbon cycle. These optical properties are ascribed to two chromophoric systems including superposition of individual chromophores and charge-transfer (CT) complexation between electron donor (e.g., phenols and indoles) and acceptor (e.g., quinones and other oxidized aromatics) in DOM structures. Thus in this study, based on the "double-chromophoric system" model, DOM samples from four typical water-level fluctuation zones of Three Gorges Reservoir (TGR) areas were selected, to investigate the effect and contribution of charge-transfer complex to ultraviolet-visible (UV-Vis) absorption property of CDOM. Using NaBH4 reduction method, original featureless absorption curve was classified into two independent curves caused by individual chromophoric group, which were derived from a simple superposition of independent chromophore and charge-transfer complex, respectively. Also, the changes in curve properties and specific parameters before and after NaBH4 reduction were compared. The results showed that in all DOM samples from the four sites of TGR, more than 35% of absorption was attributed from CT complex. Shibaozhai of Zhongxian and Zhenxi of Fuling showed the highest proportion ( > 50%). It suggested that the role of CT complex in CDOM property could not be neglected. After removal of CT complex, absorption curve showed blue-shift and CDOM concentration [a(355)] decreased significantly. Meanwhile, because of deforming of bonds by reduction, DOM structures became more dispersive and the molecular size was decreased, resulting in the lower spectral slope (S) observed, which evidentially supported that the supermolecular association structure of DOM was self-assembled through CT complex. Meanwhile, deceasing hydrophobic components led to decreased apparent aromaticity (lower SUVA values), whereas specific parameters including SUVA, CDOM and SR still were applicable for comparison among different DOM samples instead of the same sample without consideration of "double-chromophoric system" model involving the role of CT complex. Comparatively, S275-295 was dynamic due to the impact of CT effect. Furthermore, establishing DOC estimation model by short-wavelength range of CDOM was recommended because of its stability despite of CT complex. |
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