Chemodiversity of water-extractable organic matter in sediment columns of a polluted urban river in South China

Peng Zhang; Chun Cao; Ying-Hui Wang; Kai Yu; Chongxuan Liu; Chen He; Quan Shi; Jun-Jian Wang

doi:10.1016/j.scitotenv.2021.146127

Chemodiversity of water-extractable organic matter in sediment columns of a polluted urban river in South China

Sci Total Environ. 2021 Jul 10:777:146127. doi: 10.1016/j.scitotenv.2021.146127. Epub 2021 Mar 1.

Authors

Peng Zhang¹, Chun Cao², Ying-Hui Wang³, Kai Yu³, Chongxuan Liu³, Chen He⁴, Quan Shi⁴, Jun-Jian Wang⁵

Affiliations

¹ College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China; State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
² College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China.
³ State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
⁴ State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China.
⁵ State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China. Electronic address: wangjj@sustech.edu.cn.

PMID: 33677294
DOI: 10.1016/j.scitotenv.2021.146127

Abstract

Dissolved organic matter (DOM) in sediments of polluted rivers significantly contributes to oxygen consumption and river blackening and odorization. However, the chemodiversity of DOM at different depths or river reaches is poorly known. Here, we studied the storage and molecular-level signatures of water-extractable organic matter (WEOM) in the sediment column (0-100 cm) of the upper, middle, and lower mainstream of Maozhou River (a polluted river in Shenzhen, China, with 40 years of urbanization) using optical spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. The sediment WEOM level increased from upstream to downstream. The relative abundances of sulfur-containing surfactants in all sediment WEOM were higher than those previously reported for surface water DOM. The WEOM in surface sediment had higher aromaticity, molecular size, and nominal oxidation state of carbon and greater signals from anthropogenic inputs than did deep sediment at the upper and middle mainstream sites. However, these characteristics varied little between surface and deep sediments at the lower mainstream site, probably due to intensive surface water and pore water interactions. The sediment WEOM at 0-40 cm in the middle mainstream showed a greater anthropogenic signature (e.g., more surfactant and dissolved black carbon contributions) than any other sediment. We demonstrate strong anthropogenic impacts on the surface sediment over decades of urbanization.

Keywords: Dissolved organic matter; Fourier transform ion cyclotron resonance mass spectrometry; Nominal oxidation state of carbon; Sediment; Spectroscopic characteristics; Urbanization.