外源盐对盐碱土壤CO2吸收的影响

Effect of exogenous salt on carbon dioxide(CO2)absorption in saline-alkali soil

为探明盐碱土壤CO2吸收机理及影响因素,通过室内实验,利用外源盐调节土壤电导率(electrical conductivity,EC),探究盐碱土壤CO2吸收速率的变化趋势、累积吸收量和土壤EC之间的关系。结果表明:培养期间,土壤样品在36 h出现吸收现象,且EC值高的土壤达到CO2吸收速率峰值时间短。回归分析显示,土壤CO2累积吸收量随EC增加而增加(R2=0.8637)。单因素方差分析发现,不同电导率土壤,CO2累积吸收量均具有显著差异(p<0.001)。土壤EC是影响盐碱土壤CO2吸收变化的重要因素,土壤EC值升高,增加盐碱土壤对CO2的吸收速率和土壤CO2累积吸收量。

Background,aim,and scope According to previous studies,it is suggested that the carbon pool lost by atmospheric CO2 is likely to exist in widely distributed saline-alkali soils.The huge“carbon source”and“carbon sink”function of soil play an important role in the study of global carbon cycle.In order to discuss the carbon cycle process between atmosphere and soil,the variation trend of CO2 uptake rate in different electrical conductivity(EC)soils and the relationship between cumulative uptake and soil EC were studied by regulating different EC soils for culture.Materials and methods KCl solution was added to regulate soil EC,and the soil mass water content in the culture system was controlled to 25%.Silica gel plug was used to seal the soil to be placed in SP-01 biochemical incubator at(25±1)℃for 216 h.The mass concentration of CO2 was determined by meteorological chromatograph(Agilent-6820),and the working conditions of the instrument were set.Results(1)The higher the EC value of soil is,the shorter time it takes to reach the peak uptake value.After 168 h of culture,the CO2 adsorption rate curve of soil became stable,and the value was close to 0 mg∙kg−1∙h−1.(2)The higher the soil EC,the higher the cumulative uptake of soil CO2,and the stronger the soil CO2 uptake.The cumulative uptake of CO2 in soil increased linearly with the increase of EC.Discussion The experimental results of this study and the previous studies showed that the soil with high EC has potential carbon sequestration function.During the culture period,the uptake rate of CO2 in soil exhibited different degrees of uptake properties.The uptake phenomenon appeared after 36 h of culture and tended to be stable after 168 h,and the value was close to 0 mg∙kg−1∙h−1.The results also showed that high EC soil has the function of absorbing CO2.Conclusions Soil EC is an important factor to regulate the uptake rate of soil CO2.The higher the EC,the shorter time for the soil to reach the peak value of CO2 uptake.Through the study of the cumulative uptake of CO2 in soil,it was found that the higher the saline-alkali soil with EC,the higher the uptake of CO2(R2=0.8637).High EC is conductive to increasing the cumulative uptake of CO2 in soil.Recommendations and perspectives The saline-alkali soil environment is changeable and complex,so it is necessary to further find out the mechanism of CO2 uptake and the effect of soil carbon sequestration in saline-alkali soil,which also needs the comprehensive application of soil microorganism,geo-environmental chemistry and other fields.The paper is aimed to provide theoretical support for the follow-up researches.