A fast chemical oxidation method for predicting the long-term mineralization of biochar in soils

摘要

Biochar stability determines the effectiveness of biochar's functions such as carbon sequestration, soil structure improvement, soil fertility enhancement and soil pollution remediation. However, a fast method for accurately predicting biochar long-term stability in soil remains elusive. Here, firstly, an incubation experiment was conducted on mineralization dynamics of different ~(13)C-labelled biochars over 368 days to explore their actual mineralization in soils and establish their mineralization model. Thereafter, ten treatments of fast chemical oxidation methods using K_2Cr_2O_7 (0.1 M) with different H ~+ concentrations and oxidation times were applied to the bio-chars to reveal which method best matches the mineralization of biochar in soils. Results showed that the percentage of biochar-carbon oxidized by the solution containing 0.1 M K_2Cr_2O_7 and 0.2 M H~+ at 100 ℃ for 2 h was in accordance with the one that potentially would be mineralized in soils at a 100-year scale (R~2 > 0.99; REMS = 2.53; RD = 15.3). The results provided a chemical oxidation method that was robust, effective, low cost and highly available for measuring the long-term stability of biochar in soils.