The recycling value of plastic bags is low. Plastic bags are scattered in urban streets, tourist areas, water bodies, highways and railways during use, causing visual pollution and potential harm. Plastic has a stable structure, is not easily degraded by natural microorganisms, and does not separate in the natural environment for a long time. This means that if the waste plastic garbage is not recycled, it will become a pollutant in the environment for a long time and accumulate continuously, causing great harm to the environment.
According to statistics, 260 million tons of plastics are used worldwide every year, of which 65.438+700 million tons are used once. Storing vegetables and fruits in plastic bags is a common scientific preservation method in winter. Its principle is to reduce the oxygen concentration and increase the carbon dioxide concentration, so that fruits and vegetables are in a dormant state and the storage period is prolonged. But the storage time should not be too long.
Because vegetables and fruits are organic foods with high water content (60~95%) and water-soluble nutrients and enzymes. During the whole storage period, there is still strong breathing activity. Generally speaking, every time 10℃ is increased, the respiratory intensity will increase 1 times. Under aerobic conditions, sugars or other organic substances in fruits and vegetables are oxidized and decomposed to produce carbon dioxide and water, and a large number of mature fruits are released; In the absence of oxygen, sugar can not be oxidized, but can only be decomposed to produce alcohol and carbon dioxide, and a small amount of heat is released.
However, the concentration of carbon dioxide can't be increased indefinitely, only 10% can be increased, and the concentration of oxygen can't be reduced by more than 5%. Otherwise, in order to get enough energy for life activities, more nutrients need to be decomposed. At the same time, the alcohol produced by anoxic breathing stays in the fruit sparse, which will lead to rot and deterioration of the fruit sparse, so the storage time of fruits and vegetables in plastic bags should not be too long.
If you want to store fruits and vegetables in plastic bags, it is best to open the plastic bag mouth every 2~3 days, release carbon dioxide and heat, and then tighten the mouth, which will reduce the occurrence of rot and deterioration. Waste plastic products discarded on land or in water are swallowed by animals as food, resulting in animal death. There are 20 herders near Qinghai Lake, nearly 1,000 sheep died and the economic loss was more than 300,000 yuan. Sheep like to eat oil residue wrapped in plastic bags, but they often eat together. Because the plastic they eat is difficult to digest in the stomach for a long time, the stomach is crowded, they can't eat any more, and finally they can only starve to death. Such things are common in zoos, pastoral areas, rural areas and oceans.
The natural degradation of plastics has led to many animal tragedies. For example, monkeys, pelicans, dolphins and other animals in the zoo will accidentally swallow the 1 plastic bottle thrown by tourists, and finally die of pain because they have not digested it; Looking at the beautiful and pure sea, I took a closer look. In fact, it is full of all kinds of plastic garbage that the ocean can't accommodate. In the intestines of many dead seabirds, I found all kinds of indigestible plastics.
Colorful plastic fragments were washed up on the beach, and the black albatross on the island mistakenly regarded Lego toys as food, which blocked the digestive system and eventually starved to death. A seal was entangled in a blue plastic net and could not return to the sea; A brown turtle began to chew a thin plastic bag. An environmental protection organization once published a report saying that they found that at least 267 species of marine life suffered from eating by mistake or being entangled in marine debris. According to the data of the United Nations Environment Programme, plastic waste causes more than 1 10,000 seabirds and more than 1 10,000 marine mammals to die every year. Plastic bags themselves will release harmful gases, especially cooked food. It often goes bad after being packed in plastic bags, and the influence of spoiled food on children's healthy development is particularly prominent.
1. When recycling waste plastics, sorting is very difficult and uneconomical.
2. Plastic is easy to burn, which will produce toxic gas. For example, when polystyrene burns, it will produce toluene, and a small amount will lead to blindness, and inhalation will vomit. The combustion of PVC will also produce toxic gas hydrogen chloride. In addition to combustion, it is a high temperature environment, which will lead to the decomposition of toxic components such as benzene rings.
3. Plastics are products extracted from petroleum, and petroleum resources are limited.
4. Plastics can't decompose naturally.
5. Plastic has poor heat resistance and is easy to age.
According to the calculation of a female reporter in the British Guardian, if all the waste plastics in the world are collected, it will be enough to wrap the land in China, and it will be "wrapped once a year". Most plastic wastes cannot be degraded or recycled. People pile them in the depths of garbage dumps with other garbage, or burn them on the spot, allowing toxic gases to be emitted and released.
Some waste plastics are thrown on the beach or in sewers without even entering the garbage dump. The garbage jostled into the ocean, and was finally gathered by ocean currents, forming a huge garbage dump on the ocean.
It is always hard for people to believe that the bad habit of littering by individuals will affect the whole nature. 1997, oceanographer Charles Moore first discovered the marine garbage dump while sailing across the North Pacific circulation system, where there were a large number of plastic bottle caps, plastic bags, lighters and plastic garbage that had been broken into pieces by sunlight and waves.
An American marine researcher emphasized: "In the concept of ordinary people, the concept of too much garbage is basically a hill that can be climbed. But the garbage in the Pacific Ocean is more like a big pot of garbage soup. " Moore believes that the amount of garbage in the North Pacific has probably exceeded human imagination, approaching 654.38+billion tons. Because it is difficult to degrade, even plastic toys that were 50 years ago may remain today and become "antique" garbage.
Ebbesmeyer is another authority in the field of floating objects research. He has been tracking the plastic products accumulated in the ocean for more than 15 years. In his view, the movement of "junk soup" is "like an escaped beast". This fierce giant monster roams around, and when it approaches the land, it will "vomit" on the beach at will.
This time, human beings can't euphemistically sympathize with marine life, and then hang high. Even if the influence of plastic products on the greenhouse effect is excluded, the toxicity of plastic will move up through the food chain and eventually be served on the human table.
As early as a few years ago, a British media rated plastic as "the worst invention of mankind". So, is it time to throw away the plastic? In this regard, an Austrian environmental consulting company did not give a positive answer. If there is no plastic in the world, farmers and retailers will use wood, clay pots or cardboard to package their goods, which will increase the total amount of packaging by 3.6 times, consume twice as much energy in the production process and produce 2.7 times as much greenhouse gases as in the past.
The Guardian quoted a copy of the European Packaging and Film Association as saying that the deterioration rate of food from farm harvest to serving on the table is only 3% in developed countries, while it is as high as 50% in developing countries. The association speculates that this is because plastic boxes and plastic films are not widely used in developing countries. Compared with the clumsy and ancient packaging method of pottery pots, plastic packaging is naturally lighter, which greatly reduces the fuel needed for transportation.