温度和冻融对生物炭增强退化土壤吸附镉的影响

Effects of temperature and frozen-thawed on cadmium adsorption enhancement by adding biochar in degraded soil

以Cd为重金属代表,川西北地区退化土壤为受试土壤,研究温度和冻融2个重要环境条件对生物炭强化退化土壤吸附Cd的影响,以期为高寒地区生物炭的应用提供理论参考。结果表明,生物炭对退化土壤的增强吸附作用受温度影响较小,而受冻融的影响不可忽略,且该影响与土壤退化程度和Cd初始浓度有关。低Cd浓度时,冻融后生物炭对轻度和中度退化土壤吸附Cd的增强作用显著下降,但对重度退化土壤吸附Cd的增强作用反而略有提升。影响生物炭对退化土壤增强Cd吸附作用的关键是土壤的退化程度,土壤退化越严重吸附增强越显著。因此,在高寒地区采用生物炭作为土壤调理剂,可有效增强重金属在退化土壤中的吸附截留,降低其环境迁移能力,减少植物吸收带来的环境安全风险。

Cd and degraded soils from northwestern Sichuan province were selected to investigate the effects of temperature and frozen-thawed adsorption enhancement by adding biochar in degraded soil which is of great significance on the application of biochar in alpine regions.The adsorption enhancement by biochar adding in degraded soil was found to be less affected by temperature.However,the influence of frozen-thawed on adsorption enhancement by biochar adding in degraded soil could not be ignored,which was related to the degree of soil degradation and the initial concentration of Cd.At low Cd concentrations,the Cd adsorption enhancement of biochar on mildly and moderately degraded soils notably decreased after frozen-thawed while the Cd adsorption enhancement effect on severely degraded soils was slightly improved.The key factor affecting the Cd adsorption enhancement of biochar on degraded soil was the degree of soil degradation,the adsorption enhancement would be higher as soil degradation became more serious.In the current study,biochar was demonstated which can effectively strengthen the adsorption and sequestration of heavy metals in degraded soils in alpine regions,reducing the environmental risk in migration and plant uptake of heavy metals.