As long as it is a pesticide , the problem of pesticides and phytotoxics is unavoidable, but the degree is different. The pesticides can be classified into organic pesticides and inorganic pesticides according to the source. So, how are their respective toxicities and whether they are easily degraded? Let us discuss them together. .
The organochlorine pesticides used in China are mainly 666 and DDT. In the western countries, there are cyclopentadiene compounds such as aldrin, dieldrin, and endrin. These compounds are stable in nature and require half or even ten years to degrade in the soil. They can enter the water body with runoff, drift with the atmosphere to the rest of the world, and then fall to the ground with rain and snow. Therefore, organochlorine pesticides can also be detected in Antarctica and Greenland. Certain organometallic pesticides, such as organic mercury bactericides , are stable in nature and the residual toxicity of the degradation products is quite severe and has been banned in most countries.
There are very few varieties of inorganic pesticides applied. Inorganic pesticides used in some areas are mainly mercury-containing fungicides and arsenic-containing pesticides. Mercury-containing fungicides such as mercuric chloride (mercury chloride) and calomel (mercury chloride), which can damage crops, are generally used only for seed disinfection and soil disinfection. Mercury preparations are generally stable in nature, highly toxic, and have serious residual problems in soil and organisms. The arsenic-containing pesticides are arsenious acid compounds such as arsenious acid (arsenic) and sodium arsenite, and arsenic acid compounds such as lead arsenate and calcium arsenate. Arsenic compounds are highly toxic to plants and have been used as baits to control underground pests. Arsenic compounds have been widely used to control chewing mouthparts pests, but they have also been replaced by organic insecticides due to narrow control surfaces and low efficacy.
All kinds of pesticides do not have residual toxicity problems (see pesticide residues), and the same type of pesticides of different types have different environmental hazards. The different processing forms of pesticides can spread and cover the pesticide on the surface of the crop, whether the sprayed liquid (or powder) can stably adhere to the surface of the crop, and whether the pesticide can penetrate the stratum corneum of the plant surface. Loss and so on will have an impact, which will make the difference in the degree of pollution of pesticides.
Pesticide pollution is mainly caused by organochlorine pesticide pollution, organophosphorus pesticide pollution and organic nitrogen pesticide pollution. People take pesticides from the environment mainly through diet. The reasons for the presence of pesticides in plant foods are the direct contamination of the medicament and the absorption of the pesticide from the surrounding environment.
Pesticides are degradable in the natural environment. Organophosphorus pesticides are easily degraded. Organochlorine pesticides that are difficult to degrade can also be slowly degraded by microorganisms, ultraviolet light and other factors. Pesticides also undergo metabolism and degradation in living organisms.
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