Deciphering the optical properties and molecular composition of dissolved organic matter in estuarine constructed wetlands of Erhai Lake, Southwest China
| 作者 | Lei Xu a, Jianlin Tang b, Gang Wu b, Bangyao Zhong b, Chongqing Yu b, Aiwen Zhong a,Qian Hu a, Wei Liao c, Tao Chen b,*, Yansong Peng d,* |
| 刊物 | Journal of Water Process Engineering |
| 标识符 | 10.1016/j.jwpe.2025.108946 |
| 摘要 | Estuarine constructed wetlands (ECWs) are critical ecological buffers for mitigating non-point source pollutants transported via riverine systems into downstream lakes. Dissolved organic matter (DOM), as the largest organic matter pool, has variations in quantity and quality that directly regulate pollutant treatment efficiency and processes of wastewater within these wetlands. However, the DOM chemistry and its changes as it traverses the ECWs remain poorly understood. Here, we investigated variations in DOM optical properties and molecular characteristics between influent and effluent in the six ECWs along the Yonganjiang River, located upstream of the Erhai Lake basin (Yunnan, China), using ultraviolet-visible (UV–Vis) spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that ECWs effectively reduce the DOM abundance in wastewater, with preferential removal of protein-like substances and aliphatic compounds. The DOM pool undergoes significant changes as the wastewater passes through wetlands, exhibiting pronounced terrestrial signatures characterized by higher unsaturation degree, aromaticity, humification degree, and recalcitrance. Additionally, a marked decrease in CHOS molecules within DOM was observed. The reduction in O3S and O5S classes, which are associated with linear alkylbenzene sulfonates (LAS) and sulfophenyl carboxylic acids (SPCs), respectively, demonstrates the purification capacity of ECWs against organic pollutants. The synergistic interactions among plant-derived organic matter inputs, photodegradation, and microbial degradation are likely the primary mechanisms governing the changes in DOM chemistry from influent to effluent within ECWs. Our findings offer novel insights into DOM removal and transformation during ECWs treatment, providing valuable guidance for optimizing wetland design and management strategies to strengthen the control of external pollution within large lake systems. |
