| 天然日光辐照下两江交汇处溶解性有机质(DOM)光漂白过程：以涪江-嘉陵江为例 |
| 摘要点击 4025 全文点击 1889 投稿时间：2014-02-26 修订日期：2014-03-29 |
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| 中文关键词 溶解性有机质(DOM) 三维荧光光谱 紫外-可见吸收光谱 光漂白 光降解 天然有机物(NOM) |
| 英文关键词 dissolved organic matter (DOM) three-dimensional fluorescence spectroscopy ultraviolet-visible spectra photobleaching photodegradation natural organic matter (NOM) |
| 作者 | 单位 | E-mail | | 高洁 | 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 400716 | ajjyzhe1208@126.com | | 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 400716
重庆市农业资源与环境研究重点实验室, 重庆 400716 | Jiangtower666@163.com | | 闫金龙 | 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 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 400716
重庆市农业资源与环境研究重点实验室, 重庆 400716 | | | 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 400716
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 400716 | | | 李璐璐 | 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 400716 | |
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| 中文摘要 |
| 利用三维荧光光谱手段，结合紫外-可见吸收光谱，分析了涪江（FJ）、嘉陵江（JLJ）及两江交汇处（FJ-JLJ）溶解性有机质（DOM）在太阳辐照下的光漂白过程. 结果表明，在夏季短期太阳辐射作用下，所有样品的有色溶解性有机质（CDOM）浓度[a（280）]和荧光峰A、C、M、T均发生了较明显光漂白，降解程度大小顺序为JLJ>FJ-JLJ>FJ. 3个采样河段DOM光漂白性质因采样水域周边土地利用类型不同、江水汇合的稀释作用等影响而存在一定差异. 以森林系统为陆源输入的JLJ样本光漂白活性最高，城市输入占主导的FJ最低，两江汇合样本居中. DOM经日光辐照后，光谱斜率S和吸光度比值A250/A350增大，腐殖化指数HIX减小，它们可作为光漂白过程中DOM性质变化指标. 光漂白过程中，几乎所有样本呈现出陆源特征向自生源特征转化的趋势，尤其IT/IC先降低后显著增加，因此光漂白过程可能会夸大DOM的内源贡献，同时对利用IT/IC评估水体人为影响程度时产生干扰. 另外，吸收和荧光光谱参数在评估DOM光漂白过程中结构组分变化的一致性，进一步证明了采用两种互补的光谱手段对DOM地化特征进行辨析的可行性. |
| 英文摘要 |
| Three-dimensional fluorescence spectroscopy combined with ultraviolet-visible absorption spectra was used to investigate the photobleaching process of dissolved organic matter (DOM) sampled from Fujiang River (FJ), Jialingjiang River (JLJ) and the confluence (FJ-JLJ) under natural solar radiation. The results indicated that obvious photochemical degradation of colored dissolved organic matter (CDOM) concentration [a(280)] and all fluorescence peaks intensity (A,C,M and T) occurred under natural solar radiation, and the degradation degree was in order of JLJ>FJ-JLJ>FJ. Photobleaching properties of DOM samples from different locations showed significant differences, which could be partially explained by the sampling sites surroundings including various landuse types, and dilution effect of river confluence. Light-induced bleaching activity of JLJ samples, which was mainly terrestrial input from forest system, was the highest as compared to the lowest activity of FJ samples, which was predominated by urban inputs. Samples from confluence were in the middle. Additionally, the spectrum slope(S) and absorbance ratio (A250/A350) were increased, while the humification index(HIX) was decreased with increasing irradiation time, which can be used as important indicators for photobleaching properties changes during the process. More importantly, the predominantly allochthonous (terrigenous) characteristics of DOM almost showed a tendency of transferring to autochthonous (authigenic) characteristics due to photobleaching. Especially, IT/IC firstly decreased and then increased significantly in the process. Thus the photodegradation process may exaggerate DOM autochthonous contribution, and further interfere with the assessment of anthropogenic impacted-water quality by using IT/IC. In addition, mechanisms of light-induced DOM degradation process consistently showed by absorption and fluorescence spectrum parameters suggested the validation of analyzing DOM geochemical characteristics by the two important spectra tools. |
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