赤泥对重金属污染红壤修复效果及其评价

以赤泥作为原位固定剂,采用盆栽试验从土壤重金属Cd、Pb、Cu、Zn有效态含量,菜心(Brassicaparachinensis)生长及吸收积累Cd、Pb、Cu、Zn含量3个方面探讨不同赤泥用量对重金属污染红壤的固定修复效果,并用毒性淋出试验TCLP法对其生态风险进行评价。结果表明:菜心在未加赤泥的重金属污染土壤中生长受到严重抑制,在加入赤泥的土壤下生长良好,生物产量显著提高,茎叶干重与赤泥量呈二次相关,5.0mg/kg赤泥处理下菜心产量最大。土壤pH值随赤泥用量的增加而升高,二者呈显著正相关。土壤Cd、Pb、Cu、Zn有效态含量均与赤泥用量呈显著负相关关系;与未加赤泥相比,土壤Cd、Pb、Cu、Zn有效态含量降低范围分别为0.9%～34.2%,29.8%～96.8%,59.9%～96.4%,41.1%～92.7%。加入赤泥显著降低菜心茎叶重金属含量,其重金属含量随赤泥用量的增加而降低;与未加赤泥处理相比,茎叶Cd、Pb、Cu、Zn含量降低分别为68.6%～88.6%,87.3%～96.1%,76.6%～80.3%,79.1%～93.3%。2.5mg/kg赤泥处理下土壤生态风险最小。

Remediation Effects and Their Evaluation of Red Mud Amendment in Heavy Metal Polluted Red Soil

Red mud was chosen as the amendment in a pot experiment.Studying the available contents of Cd,Pb,Cu,Zn in soil,the growth of Brassica parachinensis and the absorbed and accumulated contents of Cd,Pb,Cu,Zn in Brassica parachinensis,this article discussed immobilization and remediation of heavy metals polluted red soil under different amounts of red mud,and assessed immobilization effect by using TCLP(toxicity characteristic leaching procedure).The main results are as follows:Brassica parachinensis could hardly grow in the polluted soil without red mud treatment,while those grown in the red mud treated soil were better.The yield of Brassica parachinensis was significantly increased in the polluted soil with red mud than that without red mud.The shoot dry weight of Brassica parachinensis was second-order correlated to the amount of red mud.The shoot yield reached the highest as the application of red mud up to 5.0 mg/kg.Soil pH value significantly increased with the increase of application rate,and there was significant positive correlation between them.The contents of available Cd,Pb,Cu and Zn were significantly negatively correlated with the amount of red mud.Compared with the treatment without red mud,the decreasing rate of concentration of available Cd,Pb,Cu,Zn ranged from 0.9% to 34.2%,29.8% to 96.8 %,59.9% to 96.4% and 41.1% to 92.7%,respectively.Application of red mud can significantly decrease the heavy metal(Cd,Pb,Cu and Zn) content in the shoot of Brassica parachinensis,and its heavy metals content decreased gradually as red mud application rate increased.Compared with the treatment without red mud,the decreasing rate of Cd,Pb,Cu and Zn content in the shoot of Brassica parachinensis ranged from 68.6% to 88.6%,87.3% to 96.1%,76.6% to 80.3%,79.1% to 93.3%,respectively.The ecological risk was the lowest at the amount of red mud 2.5 mg/kg in soil.