不同密度沉水植物腐解过程中水体DOM变化特征

选取白洋淀淀区的泥、水以及晒干的优势沉水植物金鱼藻、轮藻为研究对象,设置6个密度梯度模拟实验,分别于实验进行的50 d和100 d采集水样,运用紫外和荧光光谱技术研究沉水植物腐解阶段水体中溶解性有机质(DOM)的变化。结果显示,同步荧光光谱中,类蛋白峰荧光强度的变化不具规律性,类腐殖质峰荧光强度随密度的增加呈上升趋势,I2/I1的值随着密度的增加或时间的推移均逐渐增大;三维荧光光谱中,随着密度的增加,类富里酸荧光峰A和C的强度逐渐增加,而类色氨酸荧光峰T1的强度变化不大,腐解植物的密度大于3 kg/m3时各组均产生了类海洋腐殖质荧光峰B且强度随密度的增加逐渐增强,C峰的强度与水样中的COD和TP呈显著正相关;紫外光谱测定中,A253/A203的值随着密度的增加或时间的推移而逐渐增大,水体中的芳香族化合物也增多。

Characteristics of water DOM change in process of decomposition of submerged plant in different densities

The primary aim of the present work is to investigate the change of dissolved organic matter (DOM) during the process of decay of submerged plants by means of ultraviolet spectra and fluorescence spectrum. Mud, water, and two dominant submerged plants, dried Ceratophyllum demersum and Chara, in Baiyangdian Lake were chosen as study objects. Six density gradients were established to simulate in-situ experiment and water samples were collected on the 50th day and the 100th day respectively during the experiment. The results showed that in synchronous fluorescence spectrum, the peak of protein-like fluorescence intensity varies irregularly and the peak of humic-like fluorescence intensity is on rise as density increases. I₂/I₁ increases gradually as density increases or as time goes by. In the three-dimensional excitation emission matrix fluorescence spectroscopy, with the increase of density, the peak of A and C increases gradually, while intensity of T1 changes little. When the density of decaying plants is above 3 kg/m³, the peak of B whose intensity increases as the density increases emerges in all groups. The intensity of the peak of C has positive relation with COD and TP; A₂₅₃/A₂₀₃ becomes larger as the density increases or as time goes by.