Method for remedying mercury-contaminated soil of farmland through crops

Abstract

The invention relates to the technical field of mercury-contaminated soil remediation, in particular to a method for remedying mercury-contaminated soil of farmland through crops. The method comprises the steps that at the end of March or the beginning of April, a plurality pieces of farmland with the mercury-contaminated soil are selected, early-rice seedlings with developed root systems are selected to be transplanted, fertilizer and water management is conducted, microbial flora liquid is sprayed in the rice seedling stage, and harvesting is conducted in late July to early August; oilseed rape seeds are sown in the farmland in early September to early October in the current year, and oilseed rapes are uprooted after being ripen; ramie seedlings are transplanted to the farmland in a sunny day in late March to middle April in the next year, and first-stage ramie, second-stage ramie and third-stage ramie are harvested; and the steps are cyclically operated till the mercury content of the farmland soil reaches the national standard. According to the method, three crops such as the rice, the oilseed rape and the ramie which have the high enrichment effect on heavy metal mercury are sequentially planted on the farmland with the mercury-contaminated soil, remediation of the crops on the mercury-contaminated soil is promoted through a chemical regulation agent, and then the annual average purifying rate of mercury in the soil reaches up to 45%.

Description

technical field [0001] The invention belongs to the technical field of mercury-contaminated soil restoration, in particular to a method for crop restoration of mercury-contaminated soil in farmland. Background technique [0002] Mercury is an element that is harmful to the environment and is not essential to the human body. Since industrialization, large-scale human activities have caused a large amount of mercury to be discharged into the environment. In my country, with the rapid economic growth and the continuous improvement of urbanization, the problem of mercury-contaminated soil is very serious nationwide, especially causing serious harm to farmland soil. The survey results show that mercury-contaminated soil has a serious impact on the water environment and the quality of agricultural products. Significant threat, because the inorganic mercury in farmland soil can be transformed into more toxic methylmercury by sulfate-reducing bacteria or chemical action, which can pr...

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Problems solved by technology

[0003] At present, there are three main treatment methods for mercury-contaminated soil farmland: (1) Heat treatment technology, that is, to use the volatility of mercury to heat the contaminated soil to volatilize the elemental mercury in the soil. Although the effect is better, the investment cost of this method is High, the cost of treatment equipment is expensive, and it is not suitable for large-scale use, and mercury volatilization into the atmosphere is also a kind of pollution; (2) in-situ solidification / stabilization technology, that is, using chemical substances to passivate mercury in the soil to reduce its Mobility in the soil, although this method is simple, the mercury in the soil has not been removed. If the conditions change, the fixed pollutants may be released again; (3) Bioremediation technology, that is, using plant absorption and enrichment Collect mercury in the soil to achieve the purpose of purifying the soil. This method is green and environmentally friendly, and it is more suitable for the requirements of environmental protection. It has been paid more and more attention by the governments of various countries.

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