Influences of the alternation of wet-dry periods on the variability of chromophoric dissolved organic matter in the water level fluctuation zone of the Three Gorges Reservoir area, China

Tao Jiang; Dingyong Wang; Shiqiang Wei; Jinlong Yan; Jian Liang; Xueshuang Chen; Jiang Liu; Qilei Wang; Song Lu; Jie Gao; Lulu Li; Nian Guo; Zheng Zhao

doi:10.1016/j.scitotenv.2018.04.262

Influences of the alternation of wet-dry periods on the variability of chromophoric dissolved organic matter in the water level fluctuation zone of the Three Gorges Reservoir area, China

Sci Total Environ. 2018 Sep 15:636:249-259. doi: 10.1016/j.scitotenv.2018.04.262. Epub 2018 Apr 26.

Authors

Tao Jiang¹, Dingyong Wang², Shiqiang Wei², Jinlong Yan², Jian Liang², Xueshuang Chen², Jiang Liu², Qilei Wang², Song Lu², Jie Gao², Lulu Li², Nian Guo², Zheng Zhao²

Affiliations

¹ Department of Environmental Science and Engineering, College of Resources and Environment, Southwest University, Chongqing 400716, China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden. Electronic address: jiangtower666@163.com.
² Department of Environmental Science and Engineering, College of Resources and Environment, Southwest University, Chongqing 400716, China.

PMID: 29705437
DOI: 10.1016/j.scitotenv.2018.04.262

Abstract

Dissolved organic matter (DOM) is a crucial driver of various biogeochemical processes in aquatic systems. Thus, many lakes and streams have been investigated in the past several decades. However, fewer studies have sought to understand the changes in DOM characteristics in the waters of the Three Gorges Reservoir (TGR) areas, which are the largest artificial reservoir areas in the world. Thus, a field investigation of dissolved organic carbon (DOC) concentrations and of chromophoric dissolved organic matter (CDOM) properties was conducted from 2013 to 2015 to track the spatial-temporal variability of DOM properties in the TGR areas. The results showed that the alternations of wet and dry periods due to hydrological management have a substantial effect on the quantity and quality of aquatic DOM in TGR areas. Increases in DOC concentrations in the wet period show an apparent "dilution effect" that decreases CDOM compounds with relatively lower aromaticity (i.e., SUVA₂₅₄) and molecular weight (i.e., S_R). In contrast to the obvious temporal variations of DOM, significant spatial variability was not observed in this study. Additionally, DOM showed more terrigenous characteristics in the dry period but weak terrigenous characteristics in the wet period. Furthermore, the positive correlation between SUVA₂₅₄ and CDOM suggests that the aromatic component controls the CDOM dynamics in TGR areas. The first attempt to investigate the DOM dynamics in TGR areas since the Three Gorges Dam was conducted in 2012, and the unique patterns of spatial-temporal variations in DOM that are highlighted in this study might provide a new insight for understanding the role of DOM in the fates of contaminants and may help in the further management of flow loads and water quality in the TGR area.

Keywords: Chromophoric dissolved organic matter; Dissolved organic matter; Three Gorges reservoir; UV–VIS absorption; Water level fluctuation zone; Wet-dry alternation.