Rethinking terrestrial dissolved organic matter in dam reservoirs before mixing: Linking photodegradation and biodegradation and the phenanthrene binding behavior

Yupeng Wu; Xueshuai Zhang; Rong Hao; Yaru Zhou; Guohong Qiu; Ronggui Hu; Yantun Song

doi:10.1016/j.scitotenv.2023.166653

Rethinking terrestrial dissolved organic matter in dam reservoirs before mixing: Linking photodegradation and biodegradation and the phenanthrene binding behavior

Sci Total Environ. 2023 Dec 15:904:166653. doi: 10.1016/j.scitotenv.2023.166653. Epub 2023 Sep 4.

Authors

Yupeng Wu¹, Xueshuai Zhang², Rong Hao³, Yaru Zhou¹, Guohong Qiu¹, Ronggui Hu¹, Yantun Song¹

Affiliations

¹ State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
² 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.
³ State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: haorong@mail.hzau.edu.cn.

PMID: 37673243
DOI: 10.1016/j.scitotenv.2023.166653

Abstract

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.

Keywords: Dam; Dissolved organic matter; Micropollutants; Transformation; Water security.

MeSH terms

Biodegradation, Environmental
Dissolved Organic Matter*
Photolysis
Soil / chemistry
Water Quality*

Substances

Dissolved Organic Matter
Soil