Benefits of humic acid in soil.
Humic acid in soil repairs soil contaminated with heavy metals.
The natural property of humic acid determines that it is a green power resource and an intrinsic factor of constructing “ecological civilization”. The most effective humic acid is fulvic acid.
Soil pollution status all over the world and in China
- At present, about 15000 tons of mercury, 3.4 million tons of copper, 5 million tons of lead, 15 million tons of manganese and 1 million tons of nickel are emitted in the world. According to the results of the national sewage irrigation area investigated by the Ministry of Agriculture of China. The metal contaminated land area accounted for 64.8% of the sewage irrigation area, of which 46.7% was slightly polluted land, 9.7% was moderate pollution and 8.4% was serious pollution. Among which mercury and lead accounted for the largest area.
- According to statistics, the area of cultivated land affected by varying degrees of pollution in the country is close to 20 million hectares, accounting for about 1/5 of the cultivated land area. The grain output caused by heavy metal pollution in China is reduced by more than 10 million tons every year. And the grain contaminated by heavy metals is as high as 12 million tons. With a total economic loss of at least 20 billion yuan. Soil heavy metals are adsorbed and accumulated by plants. And enriched into humans and animals through the food chain. Thus endangering human and animal health and causing cancer and other diseases, such as Minamata disease, bone pain disease and so on.
Humic acid is the “nucleus of life” of soil. The common elements of heavy metal pollution in soil are mainly from electroplating, mining, metallurgy, dyeing and leather industries. Which not only pollute agricultural cultivated land, but also threaten groundwater and water sources. At present, the main soil pollution remediation methods in China are sulfuric acid, lime, caustic soda and so on. But this method may cause secondary pollution. The effect is not lasting, and the remediation is not complete.
- Humic acid functional groups such as hydroxyl group, carbonyl group and amino group have strong complexation and chelation properties to heavy metal ions above divalent. Which reduces the content of water-soluble and exchanged heavy metals in soil.
- Humic acid and some heavy metals can form insoluble humate. Increase the content of carbonate bound heavy metal and oxide bound heavy metal. Reduce the content of organically bound heavy metal. Inhibit the migration of heavy metal. Thus reduce the activity, toxicity and bioavailability of heavy metal.
- The active groups formed by chelation can promote the formation of soil aggregate structure and enhance soil water retention.
- Humic acid quinone substances can reduce the heavy metal ions in the soil, quinone substances in the free electron energy is the soil cadmium, mercury formation of stable sulfide precipitation. So that the toxicity of higher hexavalent chromium reduced to less toxic chromium trivalent, reduce the toxicity of chromium.
- The structure of humic acid and its excellent properties in soil remediation will be more widely used in soil improvement and remedication.