Transformative characteristics of aquatic and soil organic matter in a constructed wetland consisting of Acorus, Nuphar, and Typha ponds

Abstract

This study investigated the transformative characteristics of dissolved organic matter (DOM) within constructed wetlands (CWs) and elucidated the distinct interplay between aquatic DOM and soil organic matter (SOM) during different treatment stages. Through comprehensive analyses, including water quality assessments, molecular weight distribution, fluorescence spectrometry, and molecular structure analysis, our investigation revealed profound transformations in aquatic DOM characteristics facilitated by CWs. Notably, the significant increase in dissolved organic carbon (DOC) concentrations within the Typha pond underscored the pivotal role of anaerobic decomposition in organic matter accumulation. Structural analysis indicated a transition toward lipid- and protein-based substances, suggesting robust microbial degradation of aromatic DOMs. Considerable differences between aquatic DOM and SOM were observed, with SOM exhibiting a lower molecular weight and a richer array of oxygen-containing functional groups of organic substances, indicative of soil adsorption processes. This study highlights the transformation of DOM in CWs as a complex interaction between autochthonous and allochthonous sources, in which the soil adsorption of specific organic fractions notably influences the CW ecosystem. Our findings emphasize the capacity of CW to enhance water quality through natural remediation processes and provide valuable insights into optimizing CW design and management for improved wastewater treatment and ecological sustainability. © 2024 Elsevier B.V.