1. Hydrologic Export of Soil Organic Carbon: Continental Variation and Implications.
- Author
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Hararuk, O., Jones, S. E., and Solomon, C. T.
- Subjects
CARBON in soils ,CARBON cycle ,WATERSHEDS ,SOILS - Abstract
Soil is the largest terrestrial carbon (C) reservoir and a large potential source or sink of atmospheric CO₂. Soil C models have usually focused on refining representations of microbe‐mediated C turnover, whereas lateral hydrologic C fluxes have largely been ignored at regional and global scales. Here, we provide large‐scale estimates of hydrologic export of soil organic carbon (SOC) and its effects on bulk soil C turnover rates. Hydrologic export of SOC ranged from nearly 0 to 12 g C m−2yr−1 amongst catchments across the conterminous United States, and total export across this region was 14 (95% CI 4‐41) Tg C/yr. The proportion of soil C turnover attributed to hydrologic export ranged from <1% to 20%, and averaged 0.97% (weighted by catchment area; 95% CI 0.3%–2.6%), with the lowest values in arid catchments. Ignoring hydrologic export in C cycle models might lead to overestimation of SOC stocks by 0.3–2.6 Pg C for the conterminous United States. High uncertainty in hydrologic C export fluxes and potentially substantial effects on soil C turnover illustrate the need for research aimed at improving our mechanistic understanding of the processes regulating hydrologic C export. Key Points: The rate of hydrologic export was estimated at 14 Tg C per yearHydrologic export can account for 0.5–20 percent of soil carbon turnover across conterminous U.S. watershedsOmitting hydrologic export from carbon cycle models can result in overestimation of soil carbon stocks by 0.3–2.6 Pg C [ABSTRACT FROM AUTHOR]
- Published
- 2022
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