不同施用量生物炭对绿豆镉吸收的阻控效应

Inhibited Effects of Different Application Levels of Biochar on the Cadmium Absorption in Mung Bean Plants

探究不同施用量生物炭对不同生长期绿豆(Vigna radiata(L.)R.Wilczek)镉(Cd)吸收的阻控效果.通过盆栽试验,以Cd污染旱地土壤为基质,对其进行2.5%和5.0%(质量分数)的鸡粪生物炭添加处理,同时以无生物炭添加(0%)作为对照处理,所有处理均种植绿豆(生长周期为70 d),探讨不同施用量的生物炭对结荚期和收获期的土壤pH、土壤Cd化学形态以及绿豆Cd吸收的影响.结果表明:生物炭添加降低了结荚期和收获期绿豆植株中Cd的富集,且植株地上、地下部分Cd吸收对不同剂量生物炭添加的响应存在差异.结荚期,不同施用量生物炭添加均显著降低绿豆植株根部Cd含量,添加2.5%生物炭对绿豆植株茎部Cd富集的阻控效应最强,而添加5.0%生物炭对绿豆植株叶片Cd富集的阻控效应最强;收获期,绿豆植株地上部分(叶、茎)的Cd含量表现为添加2.5%生物炭处理显著低于添加5.0%生物炭处理,植株地下部分(根)的Cd含量则表现为添加5.0%生物炭处理显著低于添加2.5%生物炭处理.生物炭添加改变了土壤中Cd化学形态的分布,显著降低了酸可提取态Cd的相对含量.在结荚期与收获期,添加5.0%生物炭的土壤其酸可提取态Cd的相对含量均最低,对同一处理不同生长期而言,添加2.5%生物炭的土壤中酸可提取态Cd占比减少的效果最显著,收获期降低幅度达26.68%.由此可见:在使用生物炭修复Cd污染土壤时,生物炭施用量、植物生长期和植物组织利用都应予以考虑.本研究结果可为农用旱地土壤污染治理与安全利用提供参考.

To investigate the effects of biochar with different application levels on cadmium(Cd)accumulation in mung bean at different growth stages,the pot experiment is undertaken in the Cd-contaminated dryland soil in this study.The chicken manure biochar with three application levels(0,2.5%and 5%,w/w)is added into the soils as the remediation materials.Six mung bean seedlings arere planted in each pot.The growth cycles of mung bean are 70 d.The effects of biochar application levels on soil pH,soil Cd chemical speciation and Cd absorption of mung bean at the pod bearing and harvesting stages are studied.Results show that biochar addition significantly reduces the Cd accumulation in mung bean plants.And the response of Cd uptake by above and below-ground parts of plants to biochar application levels are different.During the pod bearing stage,biochar with different application levels significantly decreases the Cd concentration in the mung bean roots.The 2.5%biochar addition exhibits the most significant effect on the inhibition of Cd accumulation in the mung bean stems,while the 5.0%biochar addition produces the most significant effect on the inhibition of Cd accumulation in the mung bean leaves.During the harvesting stage,the Cd concentrations in the aboveground parts(leaves and stems)of mung bean plants are significantly lower in the treatment with 2.5%biochar addition than that with 5.0%biochar addition.The Cd concentration of mung bean roots is significantly lower in the treatment with 5.0%biochar than that with 2.5%biochar addition.In addition,biochar alters the chemical speciation of soil Cd and reduces the relative proportion of the acid-soluble Cd.That is,at the pod bearing and harvesting stages,the lowest relative proportion of acid-soluble Cd is observed in the soil with 5.0%biochar addition.However,the 2.5%biochar addition significantly reduces the relative proportion of acid-soluble Cd between different growth stages in the same treatment,and the reduction percentage is over 26.68%.Therefore,the application levels of biochar,plant growth stage,and plant tissue utilization should be taken into account when evaluating the remediation of heavy metal contaminated soils.The study will provide a reference for the remediation of heavy metal polluted soil and safe utilization in agricultural dryland.