模拟酸雨下生物炭添加对土壤盐基离子淋失的影响

Effects of biochar addition on soil-exchangeable base cations under simulated acid rain

通过室内土柱试验,研究模拟酸雨淋洗下添加生物炭对土壤交换性盐基离子(Ca^2+、Mg^2+、K^+、Na^+)的影响。采用双因素全面试验法,在pH值3.5、5.6和7.0的3种模拟酸雨条件下,设置0、0.5%、1%和2%的4个生物炭添加量,测定淋出液及淋洗后土壤中4种盐基离子含量。结果表明:酸雨淋洗条件下,与无生物炭处理相比,较高生物炭添加量(2%和1%)会增加盐基离子的淋失总量。同一处理淋出液中,Ca^2+的淋失总量最大,Mg2+最易淋失。相同生物炭添加量下,4种盐基离子淋出总量均随淋洗液pH值升高而降低,淋洗液pH值为3.5时各盐基离子的淋出总量均最高;相同pH值淋洗液下,Ca^2+、Mg^2+、K^+的淋出总量为2%生物炭>1%生物炭>无生物炭处理>0.5%生物炭,而Na^+的淋出总量为2%生物炭>无生物炭处理>1%生物炭>0.5%生物炭。在酸雨淋洗条件下,与无生物炭处理相比,添加生物炭的处理可提高土壤pH值及交换性盐基离子的含量,生物炭添加量为2%时对土壤交换性盐基离子的提升效果最佳。淋洗后各处理土壤中4种盐基离子含量表现为Ca^2+>K^+>Mg^2+>Na^+。研究表明,在生物炭添加下,酸沉降同样会加剧土壤盐基离子的淋洗损失。与无生物炭处理相比,模拟酸雨条件下,生物炭添加量增加提高了pH值及盐基离子含量,其中以添加2%生物炭的处理效果最佳。

The effects of biochar addition on soil-exchangeable base cations(Ca^2+,Mg^2+,K^+,and Na^+)under simulated acid rain conditions were studied via a soil column simulated experiment.A two-factor comprehensive test of three pH(3.5,5.6,and 7.0)eluents and four levels of biochar(0,0.5%,1%,and 2%)additives were used in this study;a total of 12 soil treatment tests were conducted to determine the four base ions in a leaching solution and soil after leaching.The results showed that:In comparison to the treatment without biochar,higher levels of biochar additives(i.e.,2% and 1%)increased the total amount of base ion leaching under simulated acid rain.It was also observed that,the leaching loss of Ca^2+ was the highest and Mg^2+ was the least resistant to leaching.Utilizing the same amount of biochar,the total leaching amount of the four base ions decreased with the increase in the pH value of the eluent,and the total leaching amount of each base ion was the highest when the eluent pH value was 3.5.In tests conducted using the same soil sample(pH:3.5),the order of total leaching amounts of Ca^2+,Mg^2+,and K^+ was 2% biochar treatment>1% biochar treatment>no biochar treatment>0.5% biochar treatment,whereas that of Na^+ was 2% biochar treatment>no biochar treatment>1% biochar treatment>0.5% biochar treatment.Under the influence of acid rain leaching,in comparison to the treatment without biochar,the treatment with biochar could increase the soil pH value and decrease the exchangeable base ion content.When the biochar dosage was 2%,the enhancement effect of soil-exchangeable base ions was the best.After leaching,the content of the four basic ions in soil was Ca^2+>K^+>Mg^2+>Na^+.With biochar addition,acid deposition also increased the leaching loss of soil base ions.However,compared to the treatment without biochar,adding biochar increased the pH value and content of base ions under the simulated acid rain condition,and this confirmed that the treatment with 2% biochar was the most effective.