Heavy metals can interact strongly with proteins and various enzymes in the human body, making them inactive. They may also be enriched in some organs of the human body. If they exceed the limit that the human body can tolerate, they will cause acute poisoning, subacute poisoning, chronic poisoning, etc. The following is my introduction to the causes of heavy metal pollution. I hope it can help you.
Heavy metal pollution mainly comes from industrial pollution, followed by traffic pollution and domestic waste pollution. Industrial pollution is mostly discharged into the environment through waste residue, waste water and waste gas, which is enriched in people, animals and plants, thus causing great harm to the environment and human health. The treatment of industrial pollution can reduce its pollution through some technical methods and management measures, and beware of the emission standard of heavy metal pollution in tea; Traffic pollution is mainly the emission of automobile exhaust. The state has formulated a series of management measures, such as using ethanol gasoline, installing automobile exhaust purifier, etc; Domestic pollution is mainly the pollution of some domestic waste, such as waste batteries, broken lights, unused cosmetics, glazed dishes, etc. as long as we control the pollution of heavy metals from their sources, we can reduce the pollution of heavy metals more or less.
Lead pollution
It is a toxic metal that can be accumulated in human and animal tissues. It mainly comes from various paints, coatings, batteries, smelting, hardware, machinery, electroplating, cosmetics, hair dyes, glazed dishes, tableware, coal, puffed food, water pipes, etc. It enters the body through the skin, digestive tract and respiratory tract and is compatible with a variety of organs. The main toxic effects are anemia, neurological disorders and kidney injury. Vulnerable groups include children, the elderly and immunocompromised people. The safe concentration of lead to aquatic organisms is 0.16mg/l. When rice and wheat are irrigated with water containing 0.1 ~ 4.4mg/l lead, the content of lead in crops increases significantly. The normal lead content in the human body should be 0.1 mg / L. if the content exceeds the standard, it is easy to cause anemia and damage the nervous system. Children's brain is much more sensitive to lead damage than adults. Once the blood lead content exceeds the standard, active lead elimination measures should be taken. Children can take lead excretion oral liquid or use other products to excrete lead.
Cadmium pollution
Cadmium is not an essential element of the human body. Cadmium is very toxic and can be accumulated in the human body, mainly in the kidney, causing changes in the function of the urinary system; The main sources of cadmium are wastewater discharged from electroplating, mining, smelting, fuel, battery and chemical industry; The cadmium content in waste batteries is high, and it also exists in fruits and vegetables, especially mushrooms. There is also a small amount in dairy products and grains. Cadmium can replace calcium in bones, seriously soften bones and break bones, which will cause gastric dysfunction, interfere with the enzyme system of zinc in human body and organisms, and lead to the rise of hypertension. Vulnerable groups are mining workers and people with low immunity. When the cadmium content in the water is 0.1mg/l, it can slightly inhibit the self purification of surface water. The safe concentration of cadmium on silver carp is 0.014mg/l. When irrigated with water containing cadmium of 0.04mg/l, the soil and rice are obviously polluted. When the cadmium content in agricultural irrigation water is 0.007mg/l, it can cause pollution. The concentration of cadmium in normal people's blood is less than 5 μ g / L and that in urine is less than 1 μ g / L. Cadmium can interfere with calcium in bone. If a long-term intake of trace cadmium causes serious softening of bones, broken bones and bone pain, it will also cause gastric dysfunction, interfere with the enzyme system of zinc in human body and organisms, and lead to the rise of hypertension.
Mercury pollution
Mercury and its compounds are highly toxic substances that can accumulate in the human body. It mainly comes from instrument factory, salt electrolysis, precious metal smelting, cosmetics, lighting lamps, dental materials, coal, aquatic organisms, etc. After the metal mercury in the blood enters the brain tissue, it gradually accumulates in the brain tissue. When it reaches a certain amount, it will cause damage to the brain tissue, and another part of mercury ions will be transferred to the kidney. Inorganic mercury ions entering the water body can be transformed into more toxic organic mercury, which enters the human body from the food chain and causes systemic poisoning; Vulnerable groups include women, especially expectant mothers and seafood lovers; Natural water contains very little mercury, generally no more than 0.1 μ g/L。 In normal people, the mercury concentration in blood is less than 5-10 μ g / L, and the mercury concentration in urine is less than 20 μ g / L. If acute mercury poisoning, it will induce hepatitis and hematuria.
Arsenic pollution
It is a non essential element of human body. The toxicity of element arsenic is very low, while arsenic compounds are highly toxic. Trivalent arsenic compounds are more toxic than other arsenic compounds. Arsenic enters the human body through respiratory tract, digestive tract and skin contact. If the intake exceeds the excretion, arsenic will accumulate in the liver, kidney, lung, uterus, placenta, bone, muscle and other parts of the human body, combine with the enzyme system in the cells, inhibit the biological action of the enzyme and lose its activity, especially in hair and nails, resulting in chronic arsenic poisoning, with an incubation period of several years or even decades, Chronic poisoning includes digestive system symptoms, nervous system symptoms and skin lesions. Arsenic also has carcinogenic effect and can cause skin cancer. In general, soil, water, air, plants and human body contain trace arsenic, which will not be harmful to human body. It mainly comes from decolorizing agents, various pesticides, rodenticides, arsenate drugs, chemical fertilizers, cemented carbide, leather, pesticides, etc. in mining, metallurgy, chemical pharmacy and glass industry; The groups harmed include farmers, housewives and special occupational workers. The arsenic content in surface water varies greatly due to different water sources and geographical conditions. The arsenic content in fresh water is 0.2 ~ 230 μ M / L, average 0.5 μ M / L, seawater is 3.7 μ m/L。 If the content of arsenic in urine is more than 100 μ g / L within 24 hours, it will disorder the central nervous system and may cause cancer. Moreover, if the arsenic in pregnant women exceeds the standard, it will also induce teratogenesis.
Chromium pollution
Mainly from inferior cosmetic raw materials, leather preparations, chrome plated parts of metal parts, industrial pigments, tanned leather, rubber and ceramic raw materials; If ingested and drunk by mistake, it can cause abdominal discomfort, diarrhea and other toxic symptoms, cause allergic dermatitis or eczema, breathe in, stimulate and corrode the respiratory tract, and cause pharyngitis, bronchitis, etc. Residents in water polluted areas often suffer from rhinitis, tuberculosis, diarrhea, bronchitis, dermatitis and so on.
Copper pollution
Refers to the pollution caused by copper (Cu) and its compounds in the environment. The main pollution sources are the mining and smelting of copper and zinc ore, metal processing, machinery manufacturing, steel production and so on. The smoke and dust from smelting is the main source of atmospheric copper pollution.
1) control and eliminate the discharge of industrial "three wastes"
Vigorously promote closed-circuit circulation and non-toxic processes to reduce or eliminate the emission of pollutants. Recycle the industrial "three wastes" to turn harm into benefit. The discharged "three wastes" shall be purified, and the emission and concentration of pollutants shall be strictly controlled to make them meet the emission standards.
2) strengthen the monitoring and management of soil sewage irrigation area
For sewage irrigation areas that irrigate sewage, it is necessary to strengthen the water quality monitoring of irrigation sewage, understand the composition, content and dynamics of pollutants in the water, and avoid entering the soil with high residual pollutants that are not easy to degrade and causing soil pollution.
3 rational application of chemical fertilizers and pesticides
Prohibit or restrict the use of highly toxic and high residue pesticides, vigorously develop high-efficiency, low toxicity and low residue pesticides, and develop biological control measures. For example, it is forbidden to use pesticides that are low residue but acute and toxic. The use of organochlorine pesticides with high residues is prohibited. According to the characteristics of pesticides, apply them reasonably and formulate the safe interval for the use of pesticides. The adoption of comprehensive control measures should not only prevent the threat of pests and diseases to crops, but also limit the harm of pesticides to the environment and human health to a minimum.
4) increase soil capacity and improve soil purification capacity
Increase the content of soil organic matter and sand mixing to improve the benign soil, so as to increase and improve the type and quantity of soil colloid, increase the adsorption capacity and adsorption capacity of soil for harmful substances, and reduce the activity of pollutants in the soil. Discovering, isolating and cultivating new microbial varieties to enhance biodegradation is a very important link to improve the ability of soil purification.