Plain refers to the land area below 200 meters above sea level, and the ground is wide, flat or slightly undulating. It is different from the gentle ups and downs of hills and the small height of the plateau. China's three major plains are Northeast China, North China and the middle and lower reaches of the Yangtze River. A basin is a basin-like terrain with high periphery (mountain or plateau) and low middle (plain or hill). The four famous basins in China are Sichuan, Tarim, Junggar and Qaidam basins.
Because the plains and basins are similar in geological structure and influence on human health, this section introduces them together.
I. Environmental characteristics and living habits
Environmental characteristics
L, low terrain
The topography of the plain is relatively flat, which is generally found at the bottom of the basin, especially in the geomorphological structure of some large basins. Because of the low terrain or the surrounding mountains, the airflow moves slowly, sometimes in a static state, with low wind speed and high humidity, and fog and inversion layer often appear.
2. Enrichment of some geochemical elements
Because the terrain at the intersection of plain and mountain or hill is gently inclined, the hilly area around the basin often forms a closed and gently inclined piedmont plain, so the plain and the bottom of the basin determine many identical geographical environment configurations, which affect the distribution of geochemical elements, easily form geochemical element enrichment areas and become the onset conditions of some endemic diseases such as endemic fluorosis.
3. Developed waters
Due to the flat terrain and high groundwater level, many areas are rich in mineral springs. There are many rivers, lakes, ponds, rice fields and swamps on the ground, and many places are overgrown with weeds, which are easy to become breeding grounds for some infectious host animals.
4. High population density and developed economy and culture.
The population distribution in China is unbalanced, the mountainous areas are sparsely populated, and the plains and some great basin, such as Sichuan Basin, are densely populated. Shipping, industry, agriculture, economy and culture are all developed, and many famous historical cities are concentrated in plain areas.
(2) Examples of residents' living habits
1, residential characteristics
Take quadrangles in the North China Plain and houses in the south of the Yangtze River as examples.
The geographical position of North China Plain is south than that of Northeast China, but the temperature is still low in winter, and the average temperature in Leng Yue can be as low as minus 6℃. The extreme minimum temperature can be reduced to -20℃ ~ 30℃, and the number of cold days with daily minimum temperature below 0℃ is greater than 100 days. In addition, there are many sandstorms in the north in spring, so heat preservation and wind and sand avoidance are the key factors to be considered in housing construction. Usually, the layout of houses facing south and facing the wind and facing the sun is adopted, and the quadrangle in Beijing is an example. It is a rectangular closed courtyard surrounded by building walls, which is symmetrical in north and south and has an open atrium. Yard is the center of lighting, ventilation and family activities; Outside the courtyard, the north wind roared and the sand rolled, but there was a calm feeling in the courtyard. In addition, in order to avoid the cold wind, a warm pavilion (door bucket) is usually installed in the house facing west, so that the front direction of the door becomes east or south to prevent the cold northwest wind from blowing directly into the house. Moreover, the quadrangle in Beijing, as an orthodox, serious, calm, closed and gentle architectural image, also embodies the humanistic environment and national psychological characteristics. It follows the hierarchy of housing, and according to the etiquette tradition, the master bedroom is arranged on the central axis, and the east and west wing rooms are for the younger generation to live in, symmetrically distributed on both sides of the axis.
China Jiangnan Water Town has a flat terrain and many canals. The house is surrounded by water, and the doors, steps and corridors are all located by the water. Houses are naturally combined with water, roads and bridges. From this, a light and warm Jiangnan culture is formed, which endows local residential buildings with an exquisite architectural image of black tiles. Its residential features are ventilation, rain-proof, moisture-proof and heat insulation. First of all, the orientation of the house is not due south as in the northern region, but south to east, with an angle of about 15. This orientation can prevent too much solar radiation from entering the room. It can also benefit from the southeast wind, the dominant wind direction in summer, and realize natural ventilation. The house is tall and wide, with thin hollow walls, many windows on the north and south walls, and even long French windows. Enter slowly through the flow to eliminate the hot and humid air in the room. Heat insulation and shading, deep house, wide eaves outside the house; In order to prevent rain and moisture, the wall foundation has a moisture-proof layer, and the wall foundation and column foundation are often made of stones. The indoor ground is 0.3-0.45 m higher than the ground, and the roof is generally a sloping tile roof with a large slope, so that the rainwater falling on the house can be discharged in time. However, in many areas, such as Hubei, there is a custom of "open rooms and dark bedrooms", which makes the dormitory less ventilated and daylighting.
2. Look at these clothes
The dress characteristics of plains and basins are different due to different climatic zones. The clothing materials of Jiangnan Water Town are mostly light and breathable fabrics such as linen and silk. The color should be light and the thickness should be thin, and the body should be covered as little as possible, and the tailoring should be decent. Take more umbrellas and straw hats to keep out the sun and rain when you go out, and only need to prepare thin cotton-padded clothes in winter. In the northeast plain, clothes are required to be extremely warm. In addition to single and double clothes, stand-up clothes also need cotton, wool or fur clothes with good cold and warm performance. In order to protect the head, hands and feet from frostbite, cotton (wool) hats, shoes, gloves, scarves and masks are also essential items.
3. Physical and personality characteristics
Jiangnan residents are thin, with delicate skin and heavy humidity (including internal humidity and external humidity). For example, Wu Youke mentioned in Treatise on Epidemic Febrile Diseases: "People in the lowlands in the south are more likely to get wet when it rains for a long time, and people in the northeast are tall and straight. Of course, this is only in a broad sense. Natural conditions are only one factor that affects the formation of personality, and cannot be generalized.
4. Dietary characteristics
The plains and basins are vast, and the diet structure is complex and diverse. Among them, two customs are more distinctive, namely, instant spicy and smoked products.
Residents in plain or humid areas such as Sichuan and Hunan have a special hobby for peppers, which are indispensable for three meals a day almost all year round. Northeasters love garlic and mustard, just as people in Hunan and Sichuan love peppers. People know from long-term life practice that eating spicy food in winter can stimulate appetite and help digestion, thus increasing heat production in the body, helping to drive away cold and keep warm, and also preventing rheumatism or lumbago and leg pain; Eating spicy food in summer can accelerate human perspiration and heat dissipation, help prevent heatstroke and cool down, and help overcome the "bitter summer phenomenon" in hot and humid climate. It can be seen that eating spicy food is a dietary habit developed by local people in order to adapt to the cold and humid environment. However, all kinds of spicy and irritating, people with hemorrhoids, tuberculosis hemoptysis and gastric ulcer should use it with caution.
Sichuan pickles, Jinhua ham, northeast bacon and sauerkraut are all local delicacies. This is also a means for people to adjust their tastes and extend the supply period of vegetables and meat. However, modern research has proved that these pickled and smoked foods contain nitrosamines and other substances, which have a strong carcinogenic effect if they are ingested excessively for a long time.
Second, factors conducive to health.
Abundant mineral resources
Most of the famous mineral spring resorts in China are located in inland plains or hilly areas, such as Huaqingchi in Lintong, Shaanxi, Xiaotangshan in Beijing, Tanggangyu in Liaoning, Xingcheng and Wuliantang in Heilongjiang, Bantang in Anhui, Tangshan in Nanjing, Panzhihua in Sichuan, Jingou River in Shawan, Xinjiang, and Xing Zi Hot Springs in Lushan, Jiangxi, etc. Mineral springs contain various chemical particles, gases and radioactive substances. Such as iodine, bromine, calcium, magnesium and carbon dioxide, hydrogen sulfide, radon and so on. The temperature, pressure, buoyancy and chemical composition of mineral spring have certain physiological effects on human body, which can prevent and treat some diseases.
(2) Beautiful and pleasant lakeside scenery and climate recuperation.
The lakeside climate resorts in China are mainly distributed in the plains of the middle and lower reaches of the Yangtze River, such as Taihu Lake in Jiangsu, Donghu Lake in Wuhan, Poyang Lake in Jiangxi and Dongting Lake in Hunan. In addition, there are some resorts with riverside climate, such as Qiantang River and Songhua River, and scenic resorts, such as Suzhou and Hangzhou, which have always been yearned for by Chinese and foreign people. These resorts are characterized by fresh air and humid and pleasant climate; Beautiful scenery, trees, flowers, blue waves, lakes and mountains complement each other, and places of interest are dotted among them, which is pleasing to the eye.
As a benign stimulus, a beautiful environment can make people feel comfortable and refreshed. Therefore, recuperation in scenic spots and lake (river) waterfront environment has a good preventive and therapeutic effect on many diseases of nervous system, cardiovascular system and chronic digestive system.
Of course, plains and basins have many influences on human health. Fresh fruits and vegetables, rich aquatic food and various grain, cotton and oil crops provide a rich source of food and clothing for the human body. Open economy, developed transportation and long cultural tradition have met people's spiritual needs from different angles. Make the plains and some basins become important areas for China's economic, political, cultural and population development.
Three, the factors that endanger health and prevention
(1) endemic fluorosis
1 and the effects of fluoride on human body
Fluorine is a yellow-green gas, which is a relatively active element among nonmetallic elements. Fluorine is widely distributed on the earth. Rocks, soil, water, animals and plants all contain a certain amount of fluorine, which is also one of the essential trace elements for human life activities. In addition to drinking water and food, fluoride can also enter the human body through drinking tea, smoking and smoking food with firewood.
The influence of fluoride on human body is mainly reflected in the growth and development of bones and teeth. According to statistics, the human body's demand for fluorine is 2 mg per day for people under two years old, 3 mg per day for people between two and twelve years old and 2-4 mg per day for adults. When fluoride intake is too low, the incidence of dental caries is relatively high; However, when fluoride in the body is excessive, it will cause systemic chronic poisoning, mainly teeth and bones. Children over the age of seven can suffer from dental fluorosis, which shows that the surface of teeth is dull and rough, and then gradually turns yellow, tan or dark brown. In severe cases, the enamel is damaged and falls off, and the surface of the teeth is punctate, flaky or mottled. Finally, the teeth become brittle and even fall off prematurely. Excessive fluoride deposition in bones can lead to skeletal fluorosis. The main clinical manifestations are persistent pain in bones and joints, numbness of limbs, convulsions, chest tightness in the chest and waist, bending and deformation of limbs and spine, which can lead to disability and paralysis in severe cases, accompanied by systemic poisoning symptoms, such as headache, tinnitus, palpitation, nausea, vomiting, abdominal pain, diarrhea, memory loss and unresponsiveness.
The pathological mechanism of fluorosis is that excessive fluoride is deposited in bone tissue, which causes osteocyte malnutrition and leads to degenerative diseases of osteodystrophy. Excessive fluoride combines with calcium in bone to form calcium fluoride, which will inhibit the phosphorylase of bone, make the metabolism of calcium in bone disordered, slow down the absorption process of calcium, and dissociate from bone, leading to osteoporosis and skeletal fluorosis.
2. The regional distribution characteristics of fluorosis.
Low-lying and occluded areas, salt lakes, valleys and salt marshes, backed by high mountains, are the remarkable geomorphological features of fluorosis areas. The lower the terrain, the higher the fluorine content and the higher the prevalence of fluorosis, which has basically become a universal law of medical geography. China is one of the important endemic fluorosis areas in Asia. It is known that there are 2/kloc-0 provinces (cities) in China, and the northern plains such as Songnen Plain, Xiliaohe Plain, North China Plain, Hexi Corridor, Qaidam Basin and Lop Nur Depression are the worst epidemic areas.
3. Preventive measures for endemic fluorosis
(1) Investigate the water quality and improve the water source: The main cause of endemic fluorosis is the high fluorine content in drinking water. Therefore, investigating the fluorine content of reclaimed water in urban and rural areas and improving the water quality are the basic measures to prevent endemic fluorosis. For example, in many areas with high fluorine in shallow water and low fluorine in deep water, deep well water can be used instead of shallow well water; In areas with high fluorine content in well water, surface water can be used as drinking water source; When there is a shortage of low-fluorine water in the local area, low-fluorine water can also be introduced to drink in appropriate areas.
(2) Reduce the fluorine content of water: When drinking high fluorine water can't change the water source, fluoride removal measures can be taken. For example, the method of adding alkali and alum (adding 17g alkali and alum to 15L water can reduce fluoride in water from 7mg/ to1.2 ~1.5l); Boiling water for half an hour can reduce fluorine in water1/5-5/6; Some industrial enterprises can use electrodialysis to remove fluoride.
(3) Reducing the fluorine content in food: In areas with high fluorine content, crops with low fluorine content should be selected; Or try to grow non-edible cash crops; It is forbidden to use phosphate fertilizer with high fluorine content (such as phosphate rock powder) and fluorine-containing pesticides (such as fluoroamide) to minimize the human body's intake of fluorine. If you don't use fluoride toothpaste, don't drink strong tea (the fluorine content in green tea is as high as 336mg/kg), and eat less smoked food such as fish floss, the research proves that the fluorine content in fish floss is amazing and the absorption rate is high. For example, if you eat 10 ~ 20g of fish floss a day, you will absorb 8 ~ 16 mg of fluorine from the fish floss, plus the intake from drinking water and other foods. The safe value of fluoride intake for human body is 3 ~ 4.5 mg. If it exceeds this value, fluoride will accumulate in the body and may lead to food poisoning.
(4) Eat more foods containing vitamin A.C.: Because in the case of similar fluorine content in water, individual malnutrition, especially vitamin A.C deficiency, can easily promote the occurrence of skeletal fluorosis. Therefore, we should eat more foods rich in vitamin A.C, such as pork liver, eggs, lean meat, carrots, fresh green leafy vegetables and fruits.
(5) Strictly implement the environmental protection law and limit the discharge of fluorine-containing "three wastes" from industrial and mining enterprises to the environment; Comprehensive recovery of waste gas and wastewater is an important measure to prevent fluorine from polluting the environment.
(2) Liver cancer and some infectious diseases
1, plain lowland liver cancer
Liver cancer is a highly malignant tumor, which has obvious correlation with plain and lowland in geographical distribution. The incidence of liver cancer in China is mainly concentrated in North China and South China, such as Hengyuan in the middle and lower reaches of the Yangtze River, the lower reaches of Huaihe River, the southeast coastal plain and the Pearl River Delta, followed by Songnen Plain, Sanjiang Plain, Ningxia Plain and the northern part of North China Plain. These areas are usually low-lying, water sources are blocked, drainage is not smooth, and pollutants or harmful substances are easy to accumulate; In some places, residents drink stagnant water in the ditch; Especially in the Yangtze River Delta, the climate is humid. The rainy season is long, and food is easy to get moldy. Local residents have the habit of storing food under the bed and eating smoked and pickled food, and ingest more aflatoxin, which induces liver cancer. A large number of epidemiological surveys of liver cancer in China show that low-lying environment does have a certain impact on the incidence of liver cancer.
2. Low-lying environment and some infectious diseases
Some infectious or parasitic diseases are mainly prevalent in low-lying environments. For example, malaria is a common parasitic disease, which is caused by plasmodium and spread by Anopheles mosquitoes. The clinical manifestations are periodic chills and fever, splenomegaly and anemia in different degrees. The general law of regional distribution is: the incidence rate in low-lying areas is higher than that in mountainous areas; The bottom of the basin is higher than the surrounding mountains. There are many paddy fields, lakes and swamps in low-lying areas, and the temperature is high, which is conducive to mosquito breeding and has become an important factor in malaria epidemic.
Schistosomiasis is an endemic parasitic disease, which is caused by Schistosoma japonicum in tropical and subtropical environments and spread through the skin. Clinically, there are fever, hepatomegaly and obvious increase of eosinophils in blood in the acute stage, and splenomegaly, diarrhea, purulent bloody stool and cirrhosis in the chronic stage. Oncomelania hupensis, the intermediate host of schistosomiasis, is mostly distributed in lakes, ponds, rice fields and ditches, so the prevalence of schistosomiasis is also strictly regional. In China, the surrounding areas of Dongting Lake, Poyang Lake, Taihu Lake and other lake basins in the middle and lower reaches of the Yangtze River are relatively serious in Central China, South China and Southwest China.
Preventive measures for liver cancer, malaria and schistosomiasis include carrying out environmental sanitation campaigns, eliminating mosquitoes and snails, and doing a good job in the management of feces and water sources; Pay attention to food hygiene and do a good job in food storage, mildew prevention and detoxification; Try to avoid contact with infected water and do a good job in general survey.
Conclusion: Through the above understanding, we realize the influence of plain and basin, plain and basin on human health. I believe that through my interpretation, everyone has a certain understanding of this. In later life, everyone should learn to use natural resources and try to choose areas rich in mineral resources for health care.