Passivating agent for weakly acidic cadmium contaminated soil and application thereof

Abstract

The invention discloses a passivating agent for weakly acidic cadmium contaminated soil and application thereof. The passivating agent is compounded and mixed from modified biological carbon, and mineral materials including calcium oxide, a calcium magnesium phosphate fertilizer and a silicon fertilizer beneficial to the soil. The passivating agent is applied to the surface of the weakly acidic cadmium contaminated farmland soil, and the application amount of passivating agent is controlled at more than 1.5 wt% of the soil; and then soil and passivating agent rotary tillage is carried out on a plough layer 20cm above the land surface, and the maximum field water holding capacity is maintained at more than 70% stably for more than ten days to complete the in situ remediation of the weakly acidic cadmium contaminated soil. The passivating agent can effectively reduce the content of available cadmium in soil, restore agricultural function of the polluted land, and ensure food security; the passivating agent contains a lot of organic matters and other nutrients, can provide abundant nutrition for the growth of crops, and has the advantages of environment-friendliness, high repair rate, long-term stability, and high application value.

Description

technical field [0001] The invention relates to the field of soil heavy metal pollution control, in particular to a passivator for weakly acidic cadmium polluted soil and its application. Background technique [0002] Soil is the natural environment on which human beings depend and an important resource for agricultural production. However, environmental pollution and ecological damage are becoming more and more serious, which seriously affect human health and survival. Among them, heavy metal elements have a particularly serious effect on environmental pollution and damage. It will have toxic effects on crops, not only affect the safety of agricultural products, but also pose a serious threat to human and animal health through the food chain. It has become one of the most extensive and harmful environmental problems facing human beings and needs to be solved urgently. [0003] For large-area heavy metal-contaminated soils, especially medium-slightly polluted soils, the in-s...

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Problems solved by technology

[0004] At present, there have been a large number of research results on the fixation and stabilization of heavy metal cadmium-contaminated soil, but there is almost no long-term effective passivation method for weakly acidic heavy metal cadmium-contaminated soil.

Meng Lingyang studied the effects of three materials, peat, activated carbon and weathered coal, on the occurrence and bioavailability of heavy metal cadmium in the heavy metal cadmium-contaminated soil (pH=5.5) through greenhouse pot experiments and soil culture experiments, and explored its role as heavy metal cadmium. Feasibility of remediation agents for contaminated soil. The results of the study showed that the three organic carbon materials all reduced the soil pH value. After adding different inert organic carbon remediation agents to heavy metal cadmium contaminated soil, the content of extractable cadmium in the soil did not change significantly. Restorative agents instead increased the cadmium content in crops (“Effects of different inert organic carbon materials on soil cadmium occurrence and bioavailability”, Meng Lingyang et al., Journal of Agricultural and Environmental Sciences, 2011); Dai Yunchao studied through soil culture experiments The difference in the effect of adding different amendments on soil cadmium pollution with different properties in China shows that organic matter such as chicken manure can passivate heavy metals in the soil, and lime can improve acidic soil by increasing the pH of the soil, but it is only 55.5 % ("The effect of lime and organic matter on the availability of cadmium in cadmium-contaminated soils with different properties", Dai Yunchao et al., Journal of Agricultural and Environmental Sciences, 2014); some studies in recent years have shown that the application of livestock and poultry manure and crop straw as organic Fertilizer can adsorb heavy metals in soil and reduce the content of effective heavy metals in soil. However, due to the instability of organic matter, it is easy to be degraded by microorganisms, and the heavy metals after adsorption are easy to re-release into the environment, so the passivation effect on heavy metals is not ideal.

[0005] The core of in-situ chemical passivation remediation is the selection of passivating agent. It is particularly important to select a suitable passivating agent for different soil types and pollutant types. At present, there are a large number of passivating agents that can achieve the immobilization and stabilization of heavy metal cadmium contaminated soil. Repair, but the long-term effectiveness of the passivator is difficult to guarantee

In addition, acidic farmland polluted by heavy metals in my country occupies a very large proportion, but there has been no long-term effective passivator that can passivate heavy metals

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