Knowledge of Plastic Bags - Chapter 2.
Plastic bags have brought convenience to people's lives, but the temporary convenience has brought long-term harm.
The recycling value of plastic bags is low, and in addition to causing visual pollution in urban streets, tourist areas, water bodies, and both sides of roads and railways, there are potential hazards during use. The plastic structure is stable, not easy to be degraded by natural microorganisms, and will not be separated for a long time in the natural environment. This means that if the waste plastic waste is not recycled, it will become pollutants in the environment and accumulate for a long time, which will cause great harm to the environment.
According to statistics, 260 million tons of plastic are used in the world every year, of which 170 million tons are single-use.
Vegetables and fruits are stored in plastic bags, which is a scientific preservation method commonly used by people in winter. The principle is to reduce the concentration of oxygen and increase the concentration of carbon dioxide, so that the fruits and vegetables are in a dormant state and the storage period is prolonged. However, the storage time should not be too long.
Because vegetables and fruits are organic foods with high water content (60%~95%), and contain water-soluble nutrients and enzymes. Strong respiratory activity continued throughout storage. In general, for every 10°C rise, the breathing intensity doubles. Under aerobic conditions, sugars or other organic substances in fruits and vegetables are oxidized and decomposed, producing carbon dioxide and water, and releasing a large amount of cooked quantity; and release a small amount of heat.
However, the concentration of carbon dioxide cannot rise indefinitely, it can only increase by 10%, and the decrease of oxygen concentration cannot exceed 5%. Otherwise, in order to obtain enough energy for life activities, fruits and vegetables must decompose more nutrients during hypoxia. . At the same time, the alcohol produced by hypoxic respiration remains in the fruits and vegetables, which will cause the fruits and vegetables to rot and deteriorate, so the fruits and vegetables should not be stored in plastic bags for too long.
If you want to store fruits and vegetables in plastic bags, it is best to open the plastic bag every 2 to 3 days, release carbon dioxide and heat, and then tie the mouth, which will reduce the occurrence of decay and deterioration.
Waste plastic products continue to accumulate in the soil, which will affect the absorption of nutrients and water by crops, resulting in reduced crop yields.
Waste plastic products discarded on land or in water are swallowed by animals as food, resulting in animal death. Nearly 1,000 sheep were killed in 20 herdsmen's families by the Qinghai Lake, and the economic loss was about 300,000 yuan. Sheep like to eat the oily residue wrapped in plastic bags, but they often eat it together with the plastic bags. Because the plastic they eat stays in the stomach for a long time and it is difficult to digest, the stomachs of these sheep are full and can no longer be eaten. Things can only be starved to death in the end. Such things are common in zoos, pastoral areas, rural areas, and oceans.
Due to the inability of plastic to degrade naturally, it has led to many animal tragedies. For example, animals such as monkeys, pelicans, dolphins and other animals in the zoo will accidentally swallow the No. 1 plastic bottle thrown away by tourists, and finally die in pain due to indigestion; looking at the beautiful and pure sea, and when I get closer, it is actually full of floating All kinds of plastic waste that cannot be contained in the ocean, and all kinds of indigestible plastics were found in the intestines of many dead seabird samples.
Colorful plastic debris washed up on the beach, and the black albatross on the island mistaken Lego toys for food. Its digestive system was blocked and eventually starved to death; a seal was entangled in a blue plastic net and could not return to it. In the sea; a brown turtle begins to slowly nibble on a thin plastic bag. An environmental group has released a report saying they found at least 267 species of marine life suffering from eating or entangling marine debris. Plastic debris kills more than a million seabirds and more than 100,000 marine mammals each year, according to the United Nations Environment Programme.
Waste plastics will not only occupy a lot of land with landfill, but the occupied land will not be restored for a long time, which will affect the sustainable use of land. If the waste plastic products that enter the household waste are landfilled, it will take 200 years to degrade them. Moreover, plastic bags are made of petroleum, which not only consumes a lot of resources, but also cannot be decomposed. Burying them in the ground will pollute the land and rivers.
Plastic bags themselves will release harmful gases, especially cooked food, which often deteriorate after being packaged in plastic bags. The impact of spoiled food on children's health and development is particularly prominent.
1. When recycling waste plastics, sorting is very difficult and economically uneconomical.
2. Plastics are easy to burn and produce toxic gases when burned. For example, when polystyrene is burned, toluene is produced. A small amount of this substance can cause blindness, and symptoms such as vomiting can be caused by inhalation. The burning of PVC will also produce toxic gas of hydrogen chloride. In addition to burning, high temperature environment will cause plastic to decompose toxic components, such as benzene rings. Wait.
3. Plastics are made from petroleum refining products, and petroleum resources are limited.
4. Plastic cannot be decomposed naturally.
5. The heat resistance of plastic is poor, and it is easy to age.
According to the calculation of a female reporter from the British "Guardian", if all the discarded plastics in the world were collected, it would be enough to cover China's land, and "it is still packaged once a year". The vast majority of plastic waste cannot be degraded or recycled. People dump them together with other wastes in the depths of garbage dumps, or incinerate them on the spot, allowing toxic gases to be emitted and released.
Some discarded plastics don't even make it to the dump, and are just left on the beach or in the sewers. The garbage you push me into the ocean, and eventually gather together due to the action of ocean currents, forming a giant garbage dump on the ocean.
It's always hard to believe that a personal vice of littering with rubbish can affect the whole of nature. In 1997, oceanographer Charles Moore first discovered the marine junkyard while sailing through the North Pacific Gyre, a collection of plastic bottle caps, plastic bags, lighters, and plastic bottles that had been broken into pieces by sunlight and waves. Identify plastic waste as it is.
An American marine researcher emphasized: "In the concept of ordinary people, the concept of too much garbage is basically piled up into 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 body The amount of garbage in the North Pacific is likely to exceed human imagination, approaching 100 million tons. Due to the difficulty of degrading, even plastic toys from 50 years ago may remain today and become "antique" garbage.
And Ebbsmeier - another professional in the floating object research community - has been tracking the accumulation of plastic in the ocean for more than 15 years. In his opinion, the way the "Trash Soup" moves "is like a giant beast running away". This ferocious giant monster swims around, and when it gets close to land, it will "vomit" recklessly to the beach.
This time, humanity hangs high after being unable to politely sympathize with sea creatures. Even if the impact of plastic products on the greenhouse effect is excluded, the toxicity of plastic will move up the food chain layer by layer, and finally be brought to the table of human beings.
A few years ago, a British media named plastic as "the worst invention of mankind". So, is it time to ditch the plastic? In this regard, an environmental consulting company in Austria did not give a positive answer. In a world without plastic, farmers and retailers would use wood, clay pots or cardboard to package their items, which would increase the total amount of packaging by 3.6 times, cost twice as much energy in production, and generate more 2.7 times higher greenhouse gases in the past.
The Guardian quoted a data from the European Packaging and Films Association as saying that the rate of food spoilage in developed countries is only 3% in the process from being harvested on the farm to the table, while in developing countries it is as high as 3%. 50%. The association speculates that this is because plastic boxes and plastic films in developing countries are not widely used. Plastic packaging is naturally lighter than the clumsy and ancient packaging method of clay pots, which greatly reduces the fuel required for transportation.