联合三维荧光光谱、 紫外光谱和化学还原法, 对洨河人工湿地水体DOC与COD的变化特征以及溶解性有机物(DOM)的来源、 化学结构、 腐殖化程度与氧化还原性质进行研究, 以期为深入揭示DOM在人工湿地中的地球化学行为及其生态环境效应提供科学依据。 结果显示, 河流水体COD 60%以上来自DOC的贡献, 而其经过人工湿地后含量的降低则主要是由有机物中的N, H, S, P元素更容易被去除所导致的, 其贡献率可达65%。f470/520与BIX两种指数共同指示了水体DOM主要由微生物贡献, 表明水体DOM明显受到微生物的降解作用。 三维荧光光谱PARAFAC模型分析显示, 人工湿地水体DOM包含类蛋白和类腐殖质组分, 其中类富里酸和类胡敏酸组分比类蛋白质组分更容易被降解, 类富里酸与类胡敏酸组分具有相似的分解命运。 有色溶解性有机物(CDOM)与荧光溶解有机物(FDOM)具有共源性, 均主要由类腐殖质组成, 二者进入人工湿地后没有产生选择性降解。 水体进入人工湿地后E2/E3, A240～400, r(A, C)与HIX指标没有发生显著变化, 表明人工湿地对水体DOM的腐殖化程度不会产生显著影响。 然而, 人工湿地环境不仅有利于形成还原态的DOM, 促进水体三价铁的还原, 而且可以提高DOM作为电子穿梭体的能力, 这可能与DOM的芳香性碳在人工湿地中能够得以更好保存有关。

The evolution of water DOC and COD, and the source, chemical structure, humification degree and redox of dissolved organic matter (DOM) in a constructed wetland of Xiao River, Hebei, was investigated by 3D excitation–emission matrix fluorescence spectroscopy coupled with ultraviolet spectroscopy and chemical reduction, in order to explore the geochemical processes and environmental effects of DOM. Although DOC contributes at least 60% to COD, its decrease in the constructed wetland is mainly caused by the more extensive degradation of elements N, H, S, and P than C in DOM, and 65% is contributed from the former. DOM is mainly consisted of microbial products based on proxies f470/520 and BIX, indicating that DOM in water is apparently affected by microbial degradation. The result based on PARAFAC model shows that DOM in the constructed wetland contains protein-like and humus-like components, and Fulvic- and humic-like components are relatively easier to degrade than protein-like components. Fulvic- and humic-like components undergo similar decomposition in the constructed wetland. A common source of chromophoric dissolved organic matter (CDOM) and fluorescent dissolved organic matter (FDOM) exists; both CDOM and FDOM are mainly composed of a humus-like material and do not exhibit selective degradation in the constructed wetland. The proxies E2/E3, A240～400, r(A, C) and HIX in water have no changes after flowing into the constructed wetland, implying that the humification degree of DOM in water is hardly affected by wet constructed wetland. However, the constructed wetland environment is not only beneficial in forming the reduced state of DOM, but also facilitates the reduction of ferric. It can also improve the capability of DOM to function as an electron shuttle. This result may be related to the condition that the aromatic carbon of DOM can be stabilized well in the constructed wetland.