Variation in quantity and chemical composition of soil dissolved organic matter in a peri-urban critical zone observatory watershed in Eastern China

Jianfeng Tang; Wendong Wang; Lei Yang; Changli Cao; Xinhu Li

doi:10.1016/j.scitotenv.2019.06.270

Variation in quantity and chemical composition of soil dissolved organic matter in a peri-urban critical zone observatory watershed in Eastern China

Sci Total Environ. 2019 Oct 20:688:622-631. doi: 10.1016/j.scitotenv.2019.06.270. Epub 2019 Jun 21.

Authors

Jianfeng Tang¹, Wendong Wang², Lei Yang³, Changli Cao⁴, Xinhu Li⁵

Affiliations

¹ Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Ningbo Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences, Ningbo 315800, China. Electronic address: jftang@iue.ac.cn.
² Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
³ State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
⁴ Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Ningbo Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences, Ningbo 315800, China.
⁵ College of Architecture and Urban Planning, Tongji University, Shanghai 200082, China. Electronic address: xhli@tongji.edu.cn.

PMID: 31254828
DOI: 10.1016/j.scitotenv.2019.06.270

Abstract

Soil organic matter plays a fundamental role in terrestrial ecosystems. However, little is known about the spectral characteristics and fluorescent components of soil dissolved organic matter (DOM) in peri-urban ecosystems and their influencing factors. In this study, we used the fluorescence excitation-emission matrix and parallel factor analysis (EEM-PARAFAC) to characterize soil DOM in a peri-urban Critical Zone Observatory watershed in Eastern China. Soil samples were collected at depths of 0-10 cm, 10-20 cm, and 20-40 cm from 82 sites (29 forest, 11 orchard, and 42 cropland). The results showed that soil organic carbon and water-soluble organic carbon content varied with land use type, and both were significantly higher in forest than cropland and orchard samples. Three fluorescent components, humic-, fulfic-, and protein-like substances, were derived from soil DOM using the PARAFAC model. All these components were distributed differently in the three land use types, as were their UV and fluorescence indices. The spatial distribution of soil DOM showed that the quantity and chemical composition of DOM were affected by environmental variables and human disturbance, among which pH and altitude significantly affected DOM content. Anthropogenic parameters such as distance to road and distance to town strongly influenced the chemical composition and characteristics of soil DOM. Negative correlations were observed between humic-like substances and distance to road or town, while positive correlations were observed between protein-like substances and these two parameters. These results demonstrate the pronounced influence of human activities on DOM composition and characteristics in the watershed area. The findings highlight the value of soil DOM characterization to better understand the origin, composition, and fate of DOM in soils in peri-urban critical zones.

Keywords: Dissolved organic matter; Excitation emission matrices; Fluorescence; Peri-urban area; Soil; UV–vis spectroscopy.