Linking the electron donation capacity to the molecular composition of soil dissolved organic matter from the Three Gorges Reservoir areas, China

Tao Jiang; Joeri Kaal; Jiang Liu; Jian Liang; Yaoling Zhang; Dingyong Wang

doi:10.1016/j.jes.2019.11.007

Linking the electron donation capacity to the molecular composition of soil dissolved organic matter from the Three Gorges Reservoir areas, China

J Environ Sci (China). 2020 Apr:90:146-156. doi: 10.1016/j.jes.2019.11.007. Epub 2019 Dec 9.

Authors

Tao Jiang¹, Joeri Kaal², Jiang Liu³, Jian Liang⁴, Yaoling Zhang⁵, Dingyong Wang⁶

Affiliations

¹ State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, 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.
² Institut für Geoökologie, Abt. Umweltgeochemie, Technische Universität Braunschweig, Langer Kamp 19c, 38106, Braunschweig, Germany.
³ State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing 400716, China; Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
⁴ State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing 400716, China; College of Chemistry and Environmental Engineering, Baise University, Guangxi, 533000, China.
⁵ Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China.
⁶ State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing 400716, China. Electronic address: dywang@swu.edu.cn.

PMID: 32081311
DOI: 10.1016/j.jes.2019.11.007

Abstract

Soil dissolved organic matter (DOM) plays an essential role in the Three Gorges Reservoir (TGR) as a linkage between terrestrial and aquatic systems. In particular, the reducing capacities of soil DOM influence the geochemistry of contaminants such as mercury (Hg). However, few studies have investigated the molecular information of soil DOM and its relationship with relevant geochemical reactivities, including redox properties. We collected samples from eight sites in the TGR areas and studied the link between the molecular characteristics of DOM and their electron donation capacities (EDCs) toward Hg(II). The average kinetic rate and EDC of soil DOM in TGR areas were (0.004 ± 0.001) hr^-1 and (2.88 ± 1.39) nmol e^-/mg DOM_bulk, respectively. Results suggest that higher EDCs and relatively rapid kinetics were related to the greater electron donating components of lignin-derived and perhaps pyrogenic DOM, which are the aromatic constituents that influenced the reducing capacities of DOM in the present study. Molecular details revealed that even the typical autochthonous markers are important for the EDCs of DOM as well, in contrast to what is generally assumed. More studies identifying specific DOM molecular components involved in the abiotic reduction of Hg(II) are required to further understand the relations between DOM sources and their redox roles in the environmental fate of contaminants.

Keywords: Mercury; Natural organic matter; Pyrolysis; Reducing capacity; Soil dissolved organic matter; Three Gorges Reservoir.

MeSH terms

China
Electrons
Environmental Monitoring
Mercury*
Models, Chemical
Organic Chemicals / chemistry*
Soil*

Substances

Organic Chemicals
Soil
Mercury