SYSU-HKUST Research Center for Innovative Environmental Technology (SHRCIET), School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China.
Water Res. 2013 Sep 15;47(14):5027-39. doi: 10.1016/j.watres.2013.05.043. Epub 2013 Jun 28.
Anthropogenic activities have dramatically changed the loads and compositions of dissolved organic matter (DOM) in urbanized streams. In this study, the spatial and temporal variations of DOM in the anthropogenically impacted Zhujiang River were investigated by analyzing the water samples in an upstream, urbanized area and downstream of the rivers on different days of one year. The results indicated that the levels of dissolved organic carbon (DOC) and total phosphorus (TP) were unaffected by seasonal changes, but the specific UV254 absorbance (SUVA) values and the total nitrogen (TN) content were greater in the winter than those in the summer. Parallel factor (PARAFAC) analysis of the excitation emission matrices (EEM) revealed the presence of three anthropogenically derived components [tryptophan-like (C1) and tyrosine-like proteins (C3) and anthropogenic humic substances (C5)] in the urbanized rivers, and they had greater seasonal and spatial variability than the terrestrial and microbial humic substances (C2 and C4). Cluster analysis revealed that treated wastewater was an important source of DOM in the urbanized streams. Photodegradation experiments indicated that the DOM in the populous area of the rivers had greater photodegradation potentials than that in the downstream region or in the natural waters. Interestingly, that the anthropogenic humic substances (C5) were considerably more photoreactive than the other four PARAFAC components, which exhibited a decrease of 80% after exposure to sunlight for 0.5 d. This study suggests that the treated wastewater could be an important input to the DOM in the urbanized rivers and the naturally occurring photodegradation could help in eliminating the anthropogenic DOM during their transport.
人为活动极大地改变了城市化河流中溶解有机物质（DOM）的负荷和组成。在这项研究中，通过分析一年中不同日期上游、城市化地区和下游河流的水样，研究了人为影响的珠江中 DOM 的时空变化。结果表明，溶解有机碳（DOC）和总磷（TP）水平不受季节变化的影响，但冬季的比色紫外吸光度（SUVA）值和总氮（TN）含量大于夏季。激发发射矩阵（EEM）的平行因子（PARAFAC）分析显示，城市化河流中存在三种人为衍生成分[色氨酸类似物（C1）和酪氨酸类似蛋白（C3）和人为腐殖质（C5）]，它们比陆地和微生物腐殖质（C2 和 C4）具有更大的季节性和空间变异性。聚类分析表明，处理后的废水是城市化河流 DOM 的重要来源。光降解实验表明，河流人口稠密地区的 DOM 具有比下游地区或天然水中更大的光降解潜力。有趣的是，人为腐殖质（C5）比其他四个 PARAFAC 成分具有更高的光反应性，在暴露于阳光 0.5 天后，其减少了 80%。本研究表明，处理后的废水可能是城市化河流 DOM 的重要输入，自然发生的光降解有助于在运输过程中消除人为 DOM。
