Remediation method of heavy metal contaminated soil and organic-inorganic mixed conditioner adopted by remediation method

Abstract

The invention provides a remediation method for heavy metal contaminated soil and an organic-inorganic mixed conditioner adopted by the remediation method. The remediation method comprises the following steps of: applying an organic soil conditioner and potassium sulfate to heavy metal contaminated soil before sowing, and then applying sodium silicate and a calcium magnesium phosphate fertilizer. According to the method, the organic conditioner and the inorganic conditioner are combined, and through cooperative application of the various conditioners, synergistic interaction is achieved, so that the maximum passivation effect is achieved. Effective heavy metals in the soil are firstly converted into stable organic binding state and sulfide binding state, and then the residual effective heavy metals are converted into stable phosphate binding state and silicate binding state as well as sub-stable carbonate binding state and hydroxide binding state, so that long-term passivation of the effective heavy metals in the soil is facilitated, and the influence of cultivation and soil acid-base property change on effective heavy metals is reduced. The organic-inorganic mixed conditioner comprises 200-400 kg / mu of an organic source soil conditioner, 20-40 kg / mu of potassium sulfate, 30-50 kg / mu of calcium magnesium phosphate fertilizer and 20-40 kg / mu of sodium silicate.

Description

technical field [0001] The invention relates to the field of soil fertilizers, in particular to a repair method for heavy metal polluted soil and an organic-inorganic mixed conditioner used therefor. Background technique [0002] According to the "2014 National Land Pollution Survey Bulletin", the over-standard rate of soil pollutants in cultivated land is 19.4%, and the pollution type is dominated by inorganic models, followed by organic models. 82.8% of the bits. Inorganic pollutants are mainly cadmium, nickel, copper, arsenic, mercury, and lead. Among them, cadmium has the highest rate of exceeding the standard, reaching 7%. Farmland pollution (especially heavy metal cadmium) has caused serious obstacles to farmland production. The heavy metal cadmium in the soil exceeds the standard, which leads to serious obstacles to farmland production. On the one hand, it will lead to the accumulation of heavy metals in plants, and the excessive heavy metal cadmium in agricultural p...

AI Technical Summary

Problems solved by technology

Mineral soil conditioners have a single performance and are applied in large quantities. Although they can reduce the available cadmium in the soil, it is easy to cause the following problems:

[0004]1. Mineral source soil conditioners are generally strongly alkaline, and single and large-scale application can easily lead to soil calcification and compaction, destroy soil physical and chemical properties, and increase soil bulk density. Decreased permeability promotes the rapid decomposition of organic matter, reduces crop yield, and reduces comprehensive benefits

[0005]2. The mineral source soil conditioner itself contains relatively high heavy metals. Long-term large-scale application will easily lead to an increase in the total amount of soil cadmium. During the application of the mineral source soil conditioner, Although the available cadmium in the soil can be temporarily controlled, once the soil conditioner is no longer used, the cadmium content of agricultural products will be higher than that before the use of mineral source soil conditioning

[0006]3. The unit price of mineral source soil conditioner is high, it has no effect on improving soil organic matter and fertility, and has no potential to increase production, which is not conducive to large-scale promotion and long-term use by farmers

However, the carbonate-bound cadmium and the hydroxide-bound cadmium are unstable, and they are easy to change with the organic acid secreted by the roots of the soil tillage and the pH value of the soil. The cadmium will form a free state again, increasing the risk of agricultural products exceeding the standard.

[0008]5. Single use of mineral source soil conditioner, single weight reduction mechanism, poor weight reduction effect

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