Causes of contamination of vegetable production processes
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Factors that cause pollution in vegetables 1 Highly toxic and high residual pesticides Vegetables are used in the production of vegetables for annual production, and there are many pests and diseases. Some pests occur over generations. When a single pesticide is used alone, pests are susceptible to resistance. For example, the diamondback moth (Diptera spp.) occurs 20 generations a year, and the thrips occur 22 generations per year, making it difficult to control. Some people spray once every 2-3 days for pest control. Some even use flavanol to dilute spray melons against thrips, (the toxicity of carbofuran is 6 times stronger after water release), and some use methamidophos. Although pest control has taken place, it is humanity that we suffer. In addition, some vegetable farmers have a good market price. Regardless of the period of vegetable spraying, the vegetable is harvested and marketed. This kind of behavior that makes people forget about justice is also a factor that causes poisoning accidents. 2 Improper Use of Fertilizer Fertilizer is the food of vegetables. Without fertilizer, vegetables are difficult to grow. Applying organic fertilizer can not only ensure the growth of vegetables, but also improve the quality of vegetables. However, with the acceleration of industrialization, organic fertilizers have gradually shown limitations. Nutrients are low and non-valued, and decomposition is slow. When the crops grow in large quantities, the supply of fertility is insufficient, and the growing season will be missed. The labor intensity of handling organic fertilizers will be high. When the fertilizer is time-saving, special leaf vegetables are rapidly applied to the nitrogen fertilizer during the large growth period, which has a significant effect on yield increase. However, due to the single element contained in the fertilizer, excessive application of nitrogen fertilizer exceeds the demand for vegetable growth, which will reduce the quality of the vegetables and reduce the disease resistance. , taste worse (as the saying goes, there is slag). More serious is the excessive application of nitrogen fertilizer so that the body contains nitrate content is too large, the formation of pollution. Why nitrates become pollutants? The reason is that nitrates or nitrites combine with secondary amines in the human body to form ammonium nitrite, which is carcinogenic. China's vegetable hygiene standards stipulate that the nitrate content of vegetables shall not exceed 432PPM. According to Guangzhou, Shanghai, Beijing and other large and medium-sized cities, the nitrate content of vegetables exceeded the standard by 2-3 times. Guangzhou City measured 340 vegetable samples from 1984 to 1985. Cabbage and cabbage exceeded 89.2%, 52%, and 80% of the human body. Nitrate comes from vegetables, so excessive nitrate in vegetables is a serious pollution. At present, many people think that eating bean sprouts is safe, but many producers now promote nitrogen growth, and the growth of bean sprouts is shielded from light. Nitrogen can not accumulate in the body due to photosynthesis. 3 Environmental pollution Vegetable production is mainly caused by industrial “three wastes†and pathogenic microorganisms. Industrial "three wastes" directly affect the growth of vegetable crops and cause loss of yield. In addition, harmful substances are left on vegetables, and humans cause poisoning after eating. Such poisoning is chronic, and is often not perceived and easily overlooked. The "three wastes" mainly include sulfur dioxide, hydrogen fluoride, chlorine, toxic films, and cyanide. Heavy metals include arsenic, cadmium, mercury, and chromium. According to "Yangcheng Evening News", vegetables in Guangzhou have excessive levels of heavy metals. The typical example of heavy metal impact on human beings is Japan. In the 1960s, the state-owned Yokaichi City built an electroplating factory on its upper stream. Later, the city’s citizens continued to suffer from bone pain. It was determined by relevant experts that the electroplating factory discharged cadmium elements. Crops, human food vegetables, and rice were accumulated in the body and there was a medical name called "bone pain." The pathogenic microorganisms mainly have domestic garbage, and improper treatment of hospital pollutants invades the vegetable field to form a cross infection.