钝化剂 - 有机肥联合修复作用下重金属污染土壤修复效应研究

Study on the remediation effect of heavy metal-contaminated soil under the combined action of passivation agents and organic fertilizers

关键词:  矿物质  重金属形态  污染修复  重金属转化  土壤肥力

Key words:  mineral matter  speciation of heavy metals  remediation of pollution  transformation of heavy metals  soil fertility

摘要:

为探寻坡缕石、沸石和海泡石对重金属Cu、Cd、Zn和Pb污染土壤的修复效果，采用温室盆栽试验，研究不同矿物质钝化剂与有机肥联合作用对土壤肥力与重金属指标的影响。结果表明：沸石+高有机肥（ZH）的全氮和有效磷含量最高，分别较CK提高了90%和2.08倍。3种钝化剂处理的作物根、叶中重金属含量从低到高表现为：沸石（Z）＜海泡石（S）＜坡缕石（P）＜CK。其中，Z和沸石+低有机肥（ZL）处理的根系中Cu含量显著低于其他处理。ZL处理的溶解态重金属Cu、Zn和Cd浓度最低，为128、407和0.47 mg∙kg⁻¹，而沸石+中有机肥（ZM）处理中Pb含量最低（13 mg∙kg⁻¹）。不同矿物质钝化剂处理后土壤残渣态含量表现为Z＞S＞P＞CK；Z处理的Cu、Zn、Cd和Pb分别较CK提高了1.5倍、1倍、15.25倍和1倍。综上，ZL处理能有效修复土壤重金属污染并保障作物正常健康 生长。

Abstract:

Background, aim, and scope Soil heavy metal pollution is an environmental problem that needs to be solved urgently. In-situ remediation with passivation agents is an ideal solution. In this study, organic fertilizers and mineral passivation agents were applied to remediate heavy metal-contaminated soil to find more efficient, and cheap passivation agents, problems with soil texture and nutrient deficiencies caused by passivation agents were eliminated by agronomic measures. Materials and methods The remediation effects of palygorskite, zeolite and sepiolite were tested on Cu, Cd, Zn and Pb contaminated soil, a greenhouse pot experiment was used to study the combined effect of the different mineral passivation agents and organic fertilizers on soil fertility, heavy metal content and changes in heavy metal indicators in crops. Results The texture composition of heavy metal-contaminated soil treated with zeolite and sepiolite changed significantly, and the composition of clay and powder particles was significantly higher than that of the control group; the addition of organic fertilizers to treatments with different mineral passivation agents significantly increased the soil. The content of organic matter, total nitrogen, available phosphorus and available potassium. The organic matter and available potassium were the highest in the SH treatment at 7.35 g·kg⁻¹ and 991 mg·kg⁻¹ respectively, 1.07 times and 1.45 times higher than that of CK. The total nitrogen and available phosphorus were highest in the ZH treatment at 0.611 g·kg⁻¹ and 77 mg·kg⁻¹, respectively, an increase of 90% and 208% respectively compared with CK. The heavy metal content in the roots and leaves of the crops treated with passivation agents was Z＜S＜P＜CK. The Cu content in the roots of the Z and ZL treatments was only 3.0 mg·kg⁻¹ and 3.2 mg·kg⁻¹, significantly lower than in other treatments. Different passivation agents had little effect on the total amount of heavy metals in the soil. The soluble Cu, Zn, Cd and Pb contents of CK were higher than those in other treatments. Cu, Zn, and Cd were lowest in the ZL treatment at 128, 407, and 0.47 mg·kg⁻¹, respectively, while Pb was 13 mg·kg⁻¹ in ZM. Reducible heavy metals in the soil dropped sharply compared with the soluble metals; reducible and oxidizable heavy metals in samples treated with zeolite and sepiolite were generally higher than in those treated with palygorskite. The soil residual metal content after treatment was zeolite＞sepiolite＞palygorskite＞CK; the Cu, Zn, Cd and Pb in samples with zeolite were 20, 36, 0.065 and 14 mg·kg⁻¹, respectively, increases of 1.5 times, 1 times, 15.25 times, 1 times compared with CK. Discussion Due to the complexity of organic fertilizer, there are few studies on remediation utilizing it combined with passivation agents. It is of great theoretical value and practical significance to further promote the research and application of heavy metal contaminated soil remediation in farmlands by studying the impact of organic fertilizer on the passivation agent remediation. It is important to minimize the adverse impact of organic fertilizer application on the passivation agents’ remediation efficiency, maximize the synergistic reinforcement of organic fertilizer on the passivation remediation effect, and improve passivation agents’ remediation capacity and stability. Conclusions Comprehensive analysis showed that low-concentration organic fertilizer+zeolite (ZL) treatment can effectively remove soil heavy metal pollution and ensure the normal and healthy growth of crops. Recommendations and perspectives For the combined remediation of heavy metal-contaminated soil using organic fertilizers and passivation agents, the appropriate amount of organic fertilizer should be selected according to the type of passivation agents, the type of soil in the experimental area, and the types of plants being planted to achieve the best effect. Zeolite+ sheep manure organic fertilizer (10—30 g·kg⁻¹) was demonstrated to be effective for heavy metal remediation of Cu, Cd, Zn, and Pb-contaminated soil.