不同改良剂在石灰性潮土上对土壤小麦体系镉的吸收转运的影响

Effects of different amendments on the absorption and transport of Cd in soil-wheat system in calcareous chao soil

为筛选出适宜石灰性潮土重金属Cd污染退化土壤生态修复的钝化材料,在某石灰性潮土Cd污染农田进行大田和盆栽小麦试验,研究硅钙镁肥、羟基磷灰石和鸡粪单施及复配处理在小麦成熟期时对土壤pH、土壤Cd的生物有效性以及小麦植株各器官Cd吸收转运富集的影响。结果表明:不同钝化剂处理均可降低土壤中DTPACd和小麦各器官中Cd含量,土壤DTPACd和小麦籽粒Cd含量较对照下降幅度分别为0.60%~73.66%、8.03%~90.88%;各钝化处理可改变土壤Cd的赋存形态,降低Cd的活性;硅钙镁肥和羟基磷灰石可显著提高土壤pH,有利于降低土壤中Cd的活性和迁移;鸡粪降低土壤pH值,不利于土壤Cd的钝化作用;各处理间土壤DTPACd含量与土壤pH值呈极显著负相关,但与小麦植株各器官Cd含量为正相关,且均达到极显著水平。大田与盆栽试验结果均表明硅钙镁肥对土壤Cd修复治理效果较好,但考虑其成本、修复效果和对农田生态的影响,微碱性土壤施用硅钙镁肥还需进一步定量。

[Background]A certain area of high-yield farmland in North China has been seriously polluted due to the cadmium containing sewage irrigation for many years.Soil pollution degradation threatens grain production,and soil degradation caused by heavy metal pollution urgently needs to be rehabilitated.To find a material or compound formula that can be both low cost and remediation efficiency is very necessary for the remediation of heavy metal pollution in slightly alkaline soil in northern China.Compared with the total amount of heavy metals in soil,the bioavailability and form of heavy metals in soil have more influence on biotoxicity.Among the existing remediation technologies of heavy metal pollution in soil,the in-situ chemical fixation remediation technology can better satisfy the remediation and treatment of moderate and mild heavy metal pollution in terms of methods and time,and is especially suitable for the large-scale moderate and mild contaminated farmland in China.At present,there are no efficient,cheap and environmentally friendly remediation materials suitable for calcareous chao soils in the north of China.[Methods]In order to screen the stabilizing materials suitable for ecological restoration of degraded soil polluted by heavy metal Cd in calcareous chao soil,field and potted wheat experiments were carried out in a farmland polluted by heavy metal Cd in calcareous chao soil.The effects of single application of silicon-calcium-magnesium fertilizer(abbreviated to Si-Ca-Mg fertilizer),hydroxyapatite and chicken manure on soil pH,soil Cd bioavailability and Cd absorption,transport and enrichment in various organs of wheat plant during wheat maturity were studied.[Results]The contents of DTPA-Cd in soil and Cd in wheat organs decreased by different stabilizing agents.The contents of DTPA-Cd in soil and Cd in wheat grains decreased by 0.60%-73.66%and 8.03%-90.88%,respectively,compared with the control.Each stabilizing treatment changed the chemical form of Cd and reduced the activity of Cd in soil.Si-Ca-Mg fertilizer and hydroxyapatite significantly increased soil pH and reduced the activity and migration of Cd in the soil.Chicken manure reduced soil pH value,which was not conducive to soil Cd stabilization.Soil DTPA-Cd content was negatively correlated with soil pH value among all treatments,but positively correlated with Cd content in various organs of wheat plants,which all reached extremely significant levels.[Conclusions]Field and pot experiments showed that the Si-Ca-Mg fertilizer had better effect for Cd pollution remediation.However,considering the cost,remediation effect and the influence on farmland ecology,accurate application dosage and further quantitative research about Si-Ca-Mg fertilizer in slightly alkaline soil should be determined.