Improvement of Heavy Metal Soil in Farmland
Summary: Soil contaminated by heavy metals can also lead to other ecological and environmental problems. For example, polluted topsoil with high metal content is easy to enter into the atmosphere and water body under the action of wind and hydraulic force, resulting in other secondary ecological problems such as air, surface water, groundwater pollution and ecosystem degradation. Soil heavy metals are adsorbed and accumulated by plants and enriched in human and animals through food chain, thus endangering human and animal health, causing cancer and other diseases, such as Minamata disease, bone pain disease and so on, are typical examples.
1. Core Technology of Heavy Metal Soil Improvement in Farmland
Remediation of Heavy Metal Pollution in Farmland by Microorganism and Nano-Chelating Encapsulation
(1) Microbial action:
① The chemical forms of heavy metals in soil are changed by microorganisms to fix or detoxify heavy metals and reduce their mobility and bioavailability in soil environment.;
② Reduction, purification and fixation of heavy metals can be achieved through microbial absorption and metabolism.
(2) Passivation Technology
Passivation: chemical stabilization and physical adsorption, through chemical stabilization can form insoluble compounds, reduce the plant adsorption of heavy metals; porous passivator can also be used as a carrier of microbial agents, improve the utilization rate of microbial agents.
2. Specific steps of heavy metal soil improvement in farmland
① Soil nutrients were regulated by soil conditioning agent (plant ash), soil pH and organic manure (poultry manure, humus, etc.) in different experimental areas;
② Adding passivator and bacterium agent;
③Planting low-enriched rice;
④Heavy metal barrier agent was applied on the leaf surface;
⑤Managing crops in artificial fields;
⑥Sampling soil samples and crop samples for detection.
3. Contrastive Advantages of Heavy Metal Soil Improvement Techniques in Farmland
②The cost of restoration is about RMB 1000, which is lower than the state subsidy cost;
③The stable curing rate is expected to reach 98%, which will not be released for about 50 years according to expert evaluation.