State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; School of Chemical and Environmental Sciences, Kashi University, Kashi 844000, Xinjiang, China.
Sci Total Environ. 2023 Dec 15;904:166653. doi: 10.1016/j.scitotenv.2023.166653. Epub 2023 Sep 4.
With the increased construction of dam reservoirs and the demand for water security, terrestrial dissolved organic matter (DOM) has received attention because of its role in regulating water quality, ecological functions, and the fate and transport of pollutants in dam reservoirs. This study investigated the transformations of soil DOM and vegetation DOM of dam reservoirs following photodegradation and biodegradation before conservative mixing, as well as the resultant effects on phenanthrene binding. Based on the results, terrestrial DOM could undergo transformation via photodegradation and biodegradation before conservative mixing in dam reservoirs. Although both processes resulted in substantial decreases in DOM concentrations, the changes in chromophoric DOM and fluorescent DOM depended on the original DOM sources. Furthermore, the photodegradation of terrestrial DOM resulted in more pronounced photobleaching than photomineralization. In addition, photodegradation of terrestrial DOM resulted in the generation of DOM-derived by-products with low molecular weight and low aromaticity, whereas the biodegradation of terrestrial DOM resulted in DOM-derived by-products with low molecular weight and high aromaticity. Subsequently, the photodegradation and biodegradation of terrestrial DOM substantially enhanced the binding affinity of phenanthrene. Soil DOM is prior to vegetation DOM when predicting the ecological risk of HOCs. These results indicate that the terrestrial DOM in dam reservoirs should be reconsidered before conservative mixing. Further studies on the coupling effects of both biogeochemical processes, as well as on the relative contributions of soil DOM and vegetation DOM after transformation to the aquatic DOM in dam reservoirs, are required. This study provides information on the environmental effects of dam construction from the perspective of biogeochemical processes.
随着大坝水库的建设增加和对水安全的需求，陆地溶解有机物 (DOM) 因其在调节水质、生态功能以及污染物在大坝水库中的归宿和迁移方面的作用而受到关注。本研究调查了在保守混合之前，光降解和生物降解作用下，水库中土壤 DOM 和植被 DOM 的转化，以及对菲结合的影响。结果表明，在保守混合之前，陆地 DOM 可以通过光降解和生物降解在水库中发生转化。虽然这两种过程都导致 DOM 浓度大幅下降，但发色 DOM 和荧光 DOM 的变化取决于原始 DOM 来源。此外，陆地 DOM 的光降解导致比光矿化更明显的光褪色。此外，陆地 DOM 的光降解产生了具有低分子量和低芳香性的 DOM 衍生副产物，而陆地 DOM 的生物降解产生了具有低分子量和高芳香性的 DOM 衍生副产物。随后，陆地 DOM 的光降解和生物降解极大地增强了菲的结合亲和力。在预测 HOCs 的生态风险时，土壤 DOM 优先于植被 DOM。这些结果表明，在进行保守混合之前，应该重新考虑水库中的陆地 DOM。需要进一步研究这两种生物地球化学过程的耦合效应，以及转化后土壤 DOM 和植被 DOM 对水库中水生 DOM 的相对贡献。本研究从生物地球化学过程的角度提供了大坝建设对环境的影响信息。
