Quantifying pH buffering capacity in acidic, organic-rich Arctic soils: Measurable proxies and implications for soil carbon degradation
Dynamic pH change promoted by biogeochemical reactions in Arctic tundra soils can be a major control on the production and release of CO2 and CH4, which contribute to rising global temperatures. Large quantities of soil organic matter (SOM) in these soils are susceptible to microbial decomposition d...
| Published in: | Geoderma |
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| Main Authors: | , , , , |
| Language: | unknown |
| Published: |
2023
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| Subjects: | |
| Online Access: | http://www.osti.gov/servlets/purl/1886317 https://www.osti.gov/biblio/1886317 https://doi.org/10.1016/j.geoderma.2022.116003 |
| Summary: | Dynamic pH change promoted by biogeochemical reactions in Arctic tundra soils can be a major control on the production and release of CO2 and CH4, which contribute to rising global temperatures. Large quantities of soil organic matter (SOM) in these soils are susceptible to microbial decomposition during permafrost thaw, with pH changes observed during anaerobic decomposition. Soil pH buffering capacity (ß) modulates the extent of pH change, but has not been thoroughly studied in Arctic tundra soils and is not represented in predictive ecosystem scale biogeochemical models. In this study, we generated titration curves for 21 acidic tundra soils from three Arctic sites across northern Alaska, United States. Geochemical and hydrological soil properties were evaluated, and correlations with ß were developed. Strong correlations between ß and both gravimetric water content (?g) (R2 = 0.847, p <0.001) and soil water retention (SWR) (R2 = 0.849, p = 0.001) indicate that a soil’s ability to retain water could be associated with its buffering properties. While relatively weaker, expected correlations with ß and soil organic carbon and cation exchange capacity were also observed. We further demonstrated the quantitative relationships between ß and the rates of biogeochemical reactions. Simulations showed that lower ß leads to higher soil pH and more CH4 production, highlighting the importance and potential implications of representing soil buffering in predictive models. Our study provides simple proxies for ß in Arctic soils, which can enable quantitative coupling between pH dynamics associated with biogeochemical reactions. Integrating ß into predictive models of Arctic biogeochemical cycling may reduce model uncertainty and further our understanding of SOM degradation to warming. |
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