Humification levels of dissolved organic matter in the eastern plain lakes of China based on long-term satellite observations

Xiaolan Cai; Shaohua Lei; Yunmei Li; Jianzhong Li; Jie Xu; Heng Lyu; Junda Li; Xianzhang Dong; Gaolun Wang; Shuai Zeng

doi:10.1016/j.watres.2023.120991

Humification levels of dissolved organic matter in the eastern plain lakes of China based on long-term satellite observations

Water Res. 2024 Feb 15:250:120991. doi: 10.1016/j.watres.2023.120991. Epub 2023 Dec 8.

Authors

Xiaolan Cai¹, Shaohua Lei², Yunmei Li³, Jianzhong Li¹, Jie Xu⁴, Heng Lyu¹, Junda Li¹, Xianzhang Dong¹, Gaolun Wang¹, Shuai Zeng⁵

Affiliations

¹ School of Geography, Key Laboratory of Virtual Geographic Environment of Education Ministry, Jiangsu Center for Collaboration Invocation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, China.
² National Key Laboratory of Water Disaster Prevention, Nanjing Hydraulic Research Institute, Nanjing 210029, China.
³ School of Geography, Key Laboratory of Virtual Geographic Environment of Education Ministry, Jiangsu Center for Collaboration Invocation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, China. Electronic address: liyunmei@njnu.edu.cn.
⁴ Yangtze River Basin Ecological Environment Monitoring and Scientific Research Center, Yangtze River Basin Ecological Environment Supervision and Administration Bureau, Ministry of Ecological Environment, Wuhan 430010, China.
⁵ Ministry of Ecology and Environment, South China Institute of Environmental Science, Guangzhou 510535, China.

PMID: 38113596
DOI: 10.1016/j.watres.2023.120991

Abstract

Under the influence of intensive human activities and global climate change, the sources and compositions of dissolved organic matter (DOM) in the eastern plain lake (EPL) region in China have fluctuated sharply. It has been successfully proven that the humification index (HIX), which can be derived from three-dimensional excitation-emission matrix fluorescence spectroscopy, can be an effective proxy for the sources and compositions of DOM. Therefore, combined with remote sensing technology, the sources and compositions of DOM can be tracked on a large scale by associating the HIX with optically active components. Here, we proposed a novel HIX remote sensing retrieval (IR_HIX) model suitable for Landsat series sensors based on the comprehensive analysis of the covariation mechanism between HIX and optically active components in different water types. The validation results showed that the model runs well on the independent validation dataset and the satellite-ground synchronous sampling dataset, with an uncertainty ranging from 30.85 % to 36.92 % (average ± standard deviation = 33.6 % ± 3.07 %). The image-derived HIX revealed substantial spatiotemporal variations in the sources and compositions of DOM in 474 lakes in the EPL during 1986-2021. Subsequently, we obtained three long-term change modes of the HIX trend, namely, significant decline, gentle change, and significant rise, accounting for 74.68 %, 17.09 %, and 8.23 % of the lake number, respectively. The driving factor analysis showed that human activities had the most extensive influence on the DOM humification level. In addition, we also found that the HIX increased slightly with increasing lake area (R² = 0.07, P < 0.05) or significantly with decreasing trophic state (R² = 0.83, P < 0.05). Our results provide a new exploration for the effective acquisition of long-term dynamic information about the sources and compositions of DOM in inland lakes and provide important support for lake water quality management and restoration.

Keywords: Dissolved organic matter; Eastern plain lake; Humification index; Landsat; Remote sensing.

MeSH terms

China
Dissolved Organic Matter*
Humans
Lakes / chemistry
Spectrometry, Fluorescence / methods
Water Quality*

Substances

Dissolved Organic Matter