改性生物炭对土壤铜、锌污染的钝化及其作物积累阻控作用

Passivation of modified biochar on copper and zinc in contaminated soil and its control of crop accumulation

为探究添加改性生物炭对长期沼肥灌施土壤中铜、锌迁移转化的影响,制备稻壳生物炭(BC),并对其进行功能化改性(BC-Mn和BC-Na);以小白菜为供试材料,通过盆栽试验,研究生物炭不同添加量(0、1%、3%、5%和7%)对土壤pH值、铜锌赋存形态以及小白菜铜锌富集和转移情况。结果表明:改性生物炭具有更高的比表面积和孔容,更加丰富的活性位点和表面官能团;DTPA提取态铜、锌浓度随生物炭添加量的增加而降低,生物活性较强的酸溶态和可还原态等向稳定形式的可氧化态和残渣态转化;当BC、BC-Mn和BC-Na添加量为5%时,土壤中铜、锌的DTPA提取率分别下降34.67%、42.16%、34.72%和28.94%、36.73%、32.92%;小白菜地上部铜、锌含量分别下降30.08%、41.55%、35.65%和30.08%、27.02%、33.31%。这一研究说明,改性生物炭对土壤中重金属的钝化更加有效,对植株体内铜锌的富集、转化有显著的阻控作用。

In order to explore the effect of modified biochar addition on the migration and transformation of copper and zinc in soil with long-term biogas fertilizer irrigation, rice husk biochar(BC) was prepared and its functional modification(BC-Mn and BC-Na) was carried out. Using Pakchoi as the test material, the pot experiment method was used to study the soil pH, copper and zinc occurrence forms and accumulation and transferring in Pakchoi treated with different amounts of biochar(0, 1%, 3%, 5% and 7%). The results showed that the modified biochar had higher specific surface area and pore volume, and more active sites and surface functional groups. The concentration of DTPA-extractable copper and zinc decreased with the increase of biochar content. After adding biochar, the acid-soluble state and reducible state with strong biological activity were transformed into oxidizable state and residual state in stable form. When adding 5% BC, BC-Mn and BC-Na, the DTPA-extraction rates of copper and zinc in soil decreased by 34.67%, 42.16%, 34.72% and 28.94%, 36.73% and 32.92%, respectively. The contents of copper and zinc in the shoots of Pakchoi decreased by 30.08%, 41.55%, 35.65% and 30.08%, 27.02% and 33.31% respectively. The research results indicated that the modified biochar was more effective for the passivation of heavy metals in the soil, and had a significant effect on the control and enrichment of copper and zinc in plants.