Australian net (1950s–1990) soil organic carbon erosion: implications for CO2 emission and land–atmosphere modelling

[摘要] The debate remains unresolved about soil erosion substantially offsetting fossil fuel emissionsand acting as an important source or sink of CO₂.There is little historical land use and management context to this debate,which is central to Australia's recent past of European settlement,agricultural expansion and agriculturally-induced soil erosion. We use"catchment" scale (∼25 km²) estimates of ¹³⁷Cs-derivednet (1950s–1990) soil redistribution of all processes (wind, water andtillage) to calculate the net soil organic carbon (SOC) redistribution acrossAustralia. We approximate the selective removal of SOC at net erodinglocations and SOC enrichment of transported sediment and net depositionallocations. We map net (1950s–1990) SOC redistribution across Australia andestimate erosion by all processes to be ∼4 Tg SOC yr⁻¹, whichrepresents a loss of ∼2% of the total carbon stock (0–10 cm) ofAustralia. Assuming this net SOC loss is mineralised, the flux(∼15 Tg CO₂-equivalents yr⁻¹) represents an omitted 12% ofCO₂-equivalent emissions from all carbon pools in Australia. Although a smallsource of uncertainty in the Australian carbon budget, the mass fluxinteracts with energy and water fluxes, and its omission from land surfacemodels likely creates more uncertainty than has been previously recognised.

[学科分类] 地球化学与岩石