Impacts of haze on the photobleaching of chromophoric dissolved organic matter in surface water

Ganghui Tong; Xueling Yang; Yun Li; Meng Jin; Xubiao Yu; Ying Huang; Rongyue Zheng; Jun-Jian Wang; Huan Chen

doi:10.1016/j.envres.2022.113305

Impacts of haze on the photobleaching of chromophoric dissolved organic matter in surface water

Environ Res. 2022 Sep;212(Pt B):113305. doi: 10.1016/j.envres.2022.113305. Epub 2022 Apr 14.

Authors

Ganghui Tong¹, Xueling Yang¹, Yun Li¹, Meng Jin¹, Xubiao Yu², Ying Huang¹, Rongyue Zheng¹, Jun-Jian Wang³, Huan Chen⁴

Affiliations

¹ School of Civil and Environmental Engineering, Ningbo University, Ningbo, 315211, China.
² School of Civil and Environmental Engineering, Ningbo University, Ningbo, 315211, China. Electronic address: yuxubiao@nbu.edu.cn.
³ Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, 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.
⁴ Biogeochemistry & Environmental Quality Research Group, Clemson University, South Carolina, 29442, United States; Department of Environmental Engineering and Earth Science, Clemson University, SC, 29634, United States.

PMID: 35430280
DOI: 10.1016/j.envres.2022.113305

Abstract

Sunlight plays an important role in the photochemical processes of chromophoric dissolved organic matter (CDOM), which is closely related to water self-purification and primary productivity of healthy aquatic ecosystem health. The fine particles of haze, a widespread air pollutant, absorb natural ultraviolet (UV) irradiation and have an unknown degree of influence on the photochemical transformation of CDOM. Here, an in-situ experiment investigating how the amount and composition of CDOM changes under hazy conditions was conducted in Ningbo, southeastern China, a city that frequently suffers from seasonal haze pollution. The results indicated that haze attenuated UV light under different weather conditions. The UV intensities were reduced from 1124.90 ± 91.58 to 510.26 ± 40.26 μW cm^-2 and 748.54 ± 101.68 to 316.32 ± 40.48 μW cm^-2 on sunny and cloudy days, respectively; these values approached those on rainy days (186.97 ± 28.58 μW cm^-2). Consequently, the loss of dissolved organic carbon during the irradiation test was reduced on hazy days (e.g., from 5.63% to 2.59% on sunny/hazy days). The impact of haze on CDOM photobleaching was further assessed by an excitation-emission matrix (EEM) combined with parallel factor (PARAFAC) analysis. On hazy days, the EEM-PARAFAC components were saved from photobleaching to different degrees; and humic-like substances showed a stronger protective effect from haze than protein-like substances because of their higher photosensitivity. Consequently, haze could cause more terrestrial CDOM to remain in surface water. UV intensity played a critical role in the composition characteristics of CDOM. This study identifies the linkage between atmospheric pollution and water quality and demonstrates that long-term and large-scale haze may adversely influence aquatic ecology through pollutant/nutrient accumulation.

Keywords: Air pollution; Dissolved organic matter; Photochemistry; Water quality.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

China
Dissolved Organic Matter*
Ecosystem
Humic Substances / analysis
Photobleaching
Rivers* / chemistry
Spectrometry, Fluorescence / methods

Substances

Dissolved Organic Matter
Humic Substances