classification: people's livelihood
problem description:
October 16th is World Food Day. There are four questions, please help prawns ~ ~ ~ ~
1. The origin of World Food Day
2. How do we get the food we eat
3. What are the waste phenomena in our life
4. How should we save food
Pay attention to all the above questions, and the more detailed it is. Thank you.
Analysis:
World Food Day
In November 1979, the 2th General Assembly of the Food and Agricultural Organization of the United Nations (FAO) decided that October 16th, 1981 was the first World Food Day, and this day will be regarded as "World Food Day" every year thereafter. Its purpose is to arouse the world's great attention to the development of grain and agricultural production.
First, the background of World Food Day
"Food is the most important thing for the people", and food has always played an irreplaceable basic role in the whole national economy.
in 1972, due to the worldwide grain failure caused by two consecutive years of abnormal climate, and the Soviet Union snapped up a large number of grains, a world food crisis appeared. The FAO held the first and second food conferences in 1973 and 1974, in order to arouse the attention of the world, especially the third world, to food and agricultural production. However, the problem has not been solved, and the world food situation has become more serious. It is against this background that the resolution on "World Food Day" was made.
How many people in the world are starving now? Since its establishment, FAO has conducted five "World Food Surveys" irregularly. The conclusion drawn from these surveys is that hunger has not been eliminated, but is expanding. In a report in the early 198s, the United Nations Fund for Human Resources estimated that the world's grain output could feed 6 billion people at that time. But during the same period, 45 million people around the world went hungry. There were only about 4.5 billion people in the world at that time. In 1995, the world population increased to 5.7 billion, and the number of hungry people increased to 1 billion.
since the 19th century, there have been two views on food, namely, blind optimism and pessimism. At the end of 19th century and the beginning of 2th century, pessimism was dominant. After the 194s, with the improvement of the world grain situation, pessimism was gradually replaced by blind optimism. By the early 197s, there was a worldwide drought, crop failure and a food crisis. The harsh reality has swept away the blind optimism. The birth of "World Food Day" shows that mankind has a correct understanding of food problems, and countries around the world have begun to pay enough attention to the development of food and agricultural production.
Second, the impact of food production on the environment
Since the 2th century, the speed of world population growth has been accelerating, especially since the Second World War, the world population has doubled every 37 years, and with the need of rapid economic growth, the food supply has been under unprecedented heavy pressure.
from 1955 to 1985, the world's grain output more than doubled, but the cultivated land area only increased by 15% in the same period. These data show two problems: first, the increase in grain production is not only due to the increase of cultivated land, but also through the excessive use of land; Second, due to the excessive use of cultivated land, soil erosion and desertification have been caused, and finally some cultivated land has to be abandoned.
The fertility of the land is mainly maintained by the intermittent leisure of the land to regenerate nutrients. Due to the increase of population pressure, more food must be produced, and the area of fallow farmland must be reduced, which makes the soil more and more barren and even completely lose its production capacity over time. In order to increase the fertility of land, applying a lot of little chemical fertilizer is one of the only technical means to increase grain production in the world today. However, the harm of chemical fertilizer to the environment has been ignored by people. Any kind of chemical fertilizer applied in farmland cannot be fully absorbed and utilized by plants. The average utilization rate of chemical fertilizer for various crops is: nitrogen 4% ~ 5%; 1-2% of phosphorus; 3% ~ 5% potassium. Excess chemical fertilizer poses a great threat to the living environment of human beings.
1。 Pollution of chemical fertilizer on water body < P > There are too many nutrients such as nitrogen and phosphorus, and one of the most serious consequences is eutrophication of water body. Eutrophication of water body is a natural process of water body aging, but chemical fertilizer has greatly accelerated this process.
another serious consequence is the pollution of groundwater. Nitrate and nitrite in chemical fertilizer move with the water flow in the soil or enter the groundwater through the soil layer.
2。 Pollution of chemical fertilizer on soil < P > Long-term excessive and simple application of chemical fertilizer will acidify or alkalize the soil; In addition, some of the mineral raw materials and chemical raw materials used to make chemical fertilizers contain a variety of heavy metals, radioactive substances and other harmful components, which enter the farmland with fertilization and cause soil pollution. For example, the application of phosphate fertilizer inevitably brings harmful substances such as cadmium, strontium, fluorine, uranium, radium and thorium to the soil. Excessive application of phosphate fertilizer will make the cadmium content in soil dozens or even hundreds of times higher than that in general soil. Some fertilizers also contain organic pollutants, such as ammonia water, which often contains a large amount of phenol, especially ammonia water produced from coking plant waste gas, containing more than one thousandth of phenol, which causes phenol pollution in soil after application.
3。 Pollution of chemical fertilizer to the air
The pollution of chemical fertilizer to the air is mainly caused by the decomposition of nitrogen fertilizer into ammonia gas and N2O generated during denitrification. Nitrogen oxide gas enters the atmosphere, which makes the air quality worse. In particular, nitrous oxide gas is stable in the troposphere, can rise to the stratosphere, and has a double reaction with ozone under the photochemical action: < P > N2O+O3->; NO + O2
NO + 2--> NO2+O2
This reaction consumes ozone and destroys the ozone layer. It is speculated that by the year 2, ozone will be reduced by 2% due to the application of nitrogen fertilizer.
4。 Offshore organisms are threatened by chemical fertilizers < P > The loss of a large amount of chemical fertilizers provides rich nutritional conditions for the proliferation of "red tide organisms", which has become one of the main causes of marine red tide. The occurrence of red tide has destroyed the ecosystem of the sea area, and poisoned or killed fish and shellfish.
5。 Chemical fertilizers can also harm forests
Recently, many countries in Western Europe have found that a large number of trees are dying in some agricultural planting areas far away from industrial areas and traffic trunk lines. The investigation confirmed that ammonia gas released by a large amount of nitrogen fertilizer used is another "culprit" that causes forest death besides acid rain.
When ammonia gas is absorbed by plant leaves, it will form alkaline ammonia ions, which will accumulate in plants, interfere with important metabolic processes, damage plant leaf cells, and hinder plant photosynthesis and growth. In some cases, plant leaves are damaged by ammonia gas, and in others, they will suffer from "ammonia poisoning" and die in a large area. Ammonia and nitrogen oxides exist, which have synergistic effects on plant damage and are more toxic.
6。 The impact of pesticides on the environment
In order to ensure grain production and prevent the occurrence of pests and diseases, pesticides have been widely used. According to the survey of FAO, if pesticides are not used, half of the world's total grain harvest will be swallowed up by various diseases, insects and weeds. Pesticides were used, but only about 15% of the losses were recovered. Pesticides are not only beneficial to human beings, but also harmful to the environment.
At present, there are more than 5 kinds of pesticides in the world. With the extensive use of various pesticides, the result is often that pests and beneficial insects are eliminated together, and the drug resistance of pests is getting stronger and stronger, and finally the dosage has to be continuously increased. Only about 1-3% of pesticides really affect agricultural pests, about 2-3% enter the atmosphere and water, and about 5-6% remain in the soil.
Using a large amount of pesticides, or using the same kind of pesticides for a long time, can make many pests develop drug resistance, and continuous use of pesticides will also kill beneficial insects and birds. Therefore, the unreasonable use of pesticides can not only completely solve the problem of agricultural pests and diseases, but also make many pests that were not harmful or difficult to control difficult to control. In this way, it is possible to increase the dosage of pesticides, form a vicious circle, and the destruction and pollution of the ecological environment will gradually increase.
7。 The influence of agricultural irrigation on soil
The importance and necessity of agricultural irrigation are well known. Now let's look at the negative effects of irrigation. Agricultural irrigation accelerates water erosion, resulting in soil hardening and salinization.
8。 Impact of agricultural irrigation on water environment
Through erosion and leaching of farmland soil, irrigation water will carry dirt particles, minerals, alkalis and salts, bacteria, viruses, pesticides and fertilizers, and domestic sewage around irrigation areas into rivers or lakes through drainage channels, which will pollute surface water, increase the salinity and turbidity of water, and affect the contents of nutrients such as water odor, PH value, temperature, nitrogen and phosphorus. Irrigation water will also pollute groundwater after infiltration into soil.
9。 Impact of irrigation water on geological environment
Because irrigation water depends on groundwater to a great extent, and the recharge of groundwater is very slow, deep groundwater is usually considered as a non-renewable resource. Over-exploitation of groundwater causes the groundwater level to drop, forming a large funnel area, causing ground subsidence and collapse, a large number of motor wells being scrapped, and seawater intrusion in coastal areas.
.......
Humans have racked their brains to increase grain production. Since 197s, the cultivation technique of plastic film mulching has appeared in the world, which has promoted the increase of grain production. However, it has caused what is called "white pollution" of agricultural ecological environment. At present, most of the plastic films used are polymer compounds made of polyethylene or polyvinyl chloride, which are extremely difficult to decompose in nature. Fragments of residual film in soil can exist for 4 years. Too much residual film reduces the permeability and fertility of soil.
after all means have been exhausted, in order to get the food necessary for life, people keep burning forests and opening up cultivated land and pasture. About 2 million hectares of forests in the world have been reclaimed as cultivated land, and about 3 million people make a living from it. The ecological environment supported by forests is seriously threatened.
III. Reflections on Commemorating World Food Day
On the earth where we live, not only the species of animals and plants, but also the species of crops are decreasing day by day. In ancient times, ancestors planted thousands of kinds of crops, but now only about 15 kinds are widely planted and become the main food source for people. Among them, corn, wheat and rice account for about 6%, while most other crop varieties are on the verge of extinction.
with the increasing variety of crops and the explosive growth of people in the world, the world food supply is becoming increasingly fragile.
Since Malthus published "The Theory of Population" in 1798, people have different views on his prediction. In 1968, Paul Ehrlich published Population Bomb. In 1972, the Club of Rome published The Limits to Growth. Both books further expressed concern that unlimited population growth would lead to large-scale famine. Some people hold different views on this view, thinking that people can not only consume, but also produce much more things than consumption. In the late 197s, Lester Brown of the Worldwatch Institute in Washington, USA, argued that farmers and farmers all over the world had exhausted ways to increase production, but the production of rice and wheat was beginning to decline. Elsewhere in Asia, rice researchers have failed to significantly increase crop yields for more than 2 years.
At present, the population of the world is increasing at the rate of 91 million per year. How long can the earth provide people with "enough" food? Many people are studying with anxiety.
Based on people's understanding of the difficulties faced by global food production and the environmental problems caused by excessive pursuit of food production, many countries attach great importance to holding World Food Day. Some heads of state give speeches on this day, some countries hold commemorative meetings or publish commemorative articles, and some national scientific research institutions publish scientific research achievements in food and agriculture and hold scientific seminars to raise people's attention and research on food and a series of problems caused by food.
what should non-governmental environmental organizations do today? It's worth thinking about.
source-Baidu entry provides content.