Contrasting carbon processing and stabilization pathways in low- and high-mercury contaminated soils
Year: 2025
Type: article
Abstract: • Accumulation and stability of SOC pools were higher in low Hg stress soils. • Plant-derived C decreased and microbial-derived C increased under high Hg stress. • Carbon degradation and accumulation prevails in high and low Hg soils, respectively. The interplay between plant-derived inputs and microbial processes govern soil organic carbon (SOC) dynamics. Environmental contamination, particularly heavy metal stress, disrupts both plant input and microbial activity, thereby altering soil carbon sources and transformation processes. However, the specific contributions of microbial- and plant-derived carbon to SOC accumulation and the underlying mechanisms of carbon sequestration under contaminant stress, such as mercury (Hg), remain unclear. In this study, we collected 19 soil samples under varying Hg stress levels and quantified microbial- and plant-derived necromasses using amino sugars and lignin phenol as biomarkers. The SOC pool size, including both mineral-associated and particulate organic C decreased under high Hg stress (HgH). Additionally, SOC stability, evaluated using a persistence index based on the Hill number multifunctionality framework, was significantly lower for HgH, indicating lower carbon persistence. Furthermore, the source composition of the SOC pool differed across Hg levels, with lower plant-derived C and higher microbial-derived C observed in HgH soil, indicating a compensatory pattern. Fourier transform ion cyclotron resonance mass spectrometry analysis revealed contrasting SOC sequestration and accumulation pathways in low- and high-Hg-contaminated soils. In HgH soils, a degradation-dominated pathway (i.e., priming effect) prevailed, whereas an accumulation-driven pathway (i.e., entombing effect) dominated in low-Hg soils. These findings underscore the importance of considering pollution-induced shifts in carbon cycling processes.
Source: Geoderma
Institutions: Southwest University, Huazhong Agricultural University, State Key Laboratory of Agricultural Microbiology, Sichuan Agricultural University, Chinese Academy of Sciences, Research Center for Eco-Environmental Sciences, State Key Laboratory of Environmental Chemistry and Ecotoxicology, Institute of Geochemistry, State Key Laboratory of Environmental Geochemistry, China University of Geosciences
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDGs: Life on land, Climate action
Open Access status: gold
Estimated APC paid: $3,320
Funders: Chongqing Postdoctoral Science Foundation, National Natural Science Foundation of China, Southwest University, Fundamental Research Funds for the Central Universities, Chongqing Graduate Student Research Innovation Project, Fundamental Research Funds for Central Universities of the Central South University
OpenAlex ID: W4415267906