生物炭添加对土壤冻融过程中温室气体排放的影响

【目的】研究模拟生物炭添加对土壤冻融过程中二氧化碳(CO_2)、甲烷(CH_4)和氧化亚氮(N_2O)排放的影响,为冻融期土壤温室气体的减排提供参考。【方法】以伊犁河谷典型农田为研究对象,野外采集原状土柱,并在室内模拟不同幅度的冻融过程(+5℃、-5℃~+5℃和-10℃~+10℃),探求冻融过程中土壤CO_2、CH_4和N_2O排放对生物炭添加(0、20和40 t/hm~2)的响应特征。【结果】与不添加生物炭的处理相比,添加生物炭会使冻融过程中的土壤CO_2排放量提高1.1~1.4倍,但该影响远小于冻融作用对土壤CO_2排放的促进作用(为CK的1.5~3.2倍);虽然冻融作用未显著(P0.05)影响土壤CH_4的累积排放量,但生物炭的添加显著(P0.05)促进了45.5%~81.8%的CH_4吸收量;冻融作用使土壤N_2O的累积排放量提高了1.3~3.0倍,生物炭降低了冻融过程中10.2%~30.9%的土壤N_2O排放量,但在多数情况下这种减小并不显著(P0.05)。【结论】模拟生物炭添加会增加土壤冻融过程中CO_2的排放,也会促进CH_4的吸收和N_2O的减排。

Impacts of biochar addition on greenhouse gas fluxes from soils subjected to freeze-thaw process

Objective] Investigating the impacts of biochar addition on carbon dioxide (CO2),methane (CH4 and nitrous oxide (N2O) fluxes from soils subjected to freeze-thaw process could provide basis for the mitigation of soil greenhouse gas emissions during freeze-thaw period.Method] Intact soil cores were collected from a cropland in the Ili River Valley and then subjected to freeze-thaw processes with different freeze-thaw amplitudes (+5 ℃,-5 ℃-+5 ℃ and -10 ℃-+10 ℃) in the laboratory,to explore the responses of soil CO2,CH4 and N2O fluxes to biochar addition (0,20 and 40 t/hm2) during freeze-thaw process.Result] CO2 fluxes from soils with biochar additions were 1.1-1.4 times higher than those from soils without adding biochar.However,such increases were lower compared to the promoting effects of freeze-thaw on soil CO2 flux (1.5-3.2 times).Although freeze-thaw process did not significantly (P ＞ 0.05) affect the cumulative flux of soil CH4,biochar additions significantly (P ＜ 0.05) increased soil CH4 flux by approximately 45.5％-81.8％.Biochar decreased soil N2O flux by 10.2％-30.9％ during freeze-thaw process,but such decreases were not significant (P ＞ 0.05) in most cases.Conclusion] Biochar addition may increase the emission of soil CO2,while promote the uptake of soil CH4 and the mitigation of soil N2O during freeze-thaw process.