1? The harm of soil pollution to soil ecology The soil pollution caused by chemical fertilizer is to worsen the physical properties of soil, disperse the soil colloid, destroy the structure, harden the soil and acidify the soil. The soil itself contains a large number of microorganisms. Under the action of sunlight, air and water, microorganisms degrade organic matter in soil and convert it into humus that can be absorbed and utilized by plants as fertilizer. If the soil is hardened, the gum is destroyed, the water-holding function of the soil is lost, the soil is desertified, the living environment of microorganisms is lost, or the soil is acidified and salinized, which will affect the survival of soil microorganisms, thus destroying the original ecological structure and balance of the soil and damaging its function.
2? Soil pollution will bring serious economic losses. Many people, including some leaders, only pay attention to the economic benefits generated by enterprises, but not to the huge economic losses caused by their environmental damage. Soil pollution destroys soil function, makes the land desert, and leads to the reduction of grain production or even no harvest. The annual grain yield reduction in China caused by soil heavy metal pollution alone is more than100000 tons, and the grain polluted by heavy metals is as high as120000 tons every year, * * * about 20 billion yuan. For example, due to the long-term introduction of industrial wastewater irrigation in Zhangshi Irrigation District of Shenyang, Liaoning, China, the cadmium content in soil and rice exceeded the standard, making it inedible for people and livestock. Soil can no longer be used as cultivated land, but can only be used for other purposes.
Soil pollution is a by-product of industrialization. It can be said that all pollution sources come from industrial production. According to reports, at present, the cultivated land polluted by heavy metals such as cadmium, arsenic and chromium in China is nearly 300 million mu, of which the cultivated land polluted by "three wastes" is 1? 500 million mu, and the area of cultivated land occupied and damaged by solid waste stacking is more than 2 million mu; More than 80 million mu of cultivated land is polluted by air; Farmland irrigated by sewage accounts for 7? 3%; The area of farmland polluted by pesticides is 1? 400 million mu, the average application of pesticides per hectare is about 14 kg, which is 1 times higher than that of developed countries, but the effective rate is only 30%. A large number of pesticides are lost to the atmosphere, water, soil and agricultural products, and pesticide residues in soil are increasing year by year.
3? Soil pollution leads to air and water pollution. Polluted topsoil will enter air and water under the action of wind or water power, which will lead to secondary ecological and environmental problems such as air, surface water and groundwater pollution. If the urban population density is high, pollutants in the topsoil can enter the human body through the respiratory system with dust, which will affect health. In addition, pollutants in soil will gradually transfer to groundwater through precipitation, resulting in groundwater pollution. Heavy metals such as fluorine, mercury, cadmium and arsenic were detected in groundwater of Chuansha sewage irrigation area in Shanghai. Some rural wells in the suburbs of Chengdu have also experienced excessive pollutants such as mercury, chromium, phenol and cyanide due to soil pollution.