It is a toxic metal that can accumulate in human and animal tissues. It mainly comes from various paints, coatings, batteries, smelting, hardware, electroplating, cosmetics, hair dyes, glazed dishes, tableware, coal burning, puffed food, water pipes and so on. It enters the human body through the skin, digestive tract and respiratory tract and is compatible with various organs. The main toxic effects are anemia, neurological dysfunction and kidney injury, and the susceptible population is children, the elderly and the immunocompromised.
The safe concentration of lead for aquatic organisms is 0.1.6 mg/L. When rice and wheat are irrigated with water with lead content of 0. 1 ~ 4.4 mg/L, the lead content in crops increases obviously.
The normal lead content of human body should be 0.1mg/L. If the lead content exceeds the standard, it will easily cause anemia and damage the nervous system. However, children's brains are much more sensitive to lead damage than adults. Once the blood lead content exceeds the standard, active measures should be taken to eliminate lead poisoning. Children can take lead-expelling oral liquid or use other products to drive lead.
cadmium contamination
Cadmium is not an essential element for human body. Cadmium is very toxic and can accumulate in human body, mainly in kidney, causing changes in urinary system function; The main sources of cadmium are wastewater from electroplating, mining, smelting, fuel, battery and chemical industry. The content of cadmium in waste batteries is high, and it also exists in fruits and vegetables, especially mushrooms, and a small amount exists in dairy products and grains.
Cadmium can replace calcium in bone, which will cause severe osteomalacia and fracture, cause gastric dysfunction, interfere with human body and zinc enzyme system, and lead to the increase of hypertension. The vulnerable groups are miners and people with low immunity. When the cadmium content in water is 0. 1mg/L, the self-purification of surface water can be slightly inhibited, and the safe concentration of cadmium for silver carp is 0.014 mg/L. When the cadmium content in water is 0.04Mg/L, the soil and rice are obviously polluted, and when the cadmium content in agricultural irrigation water is 0.007mg/L, it can cause
The concentration of cadmium in normal people's blood is less than 5 μ g/L, and the concentration of cadmium in urine is less than 65438 0 μ g/L. Cadmium will interfere with calcium in bones. If a small amount of cadmium is ingested for a long time, the bones will be severely softened and broken inch by inch, causing bone diseases. It can also cause gastrointestinal dysfunction, interfere with the zinc enzyme system in human body and organism, and lead to the aggravation of hypertension.
mercury pollution
Mercury and its compounds are highly toxic substances and can accumulate in human body. Mainly from instrument factory, salt electrolysis, precious metal smelting, cosmetics, lighting, dental materials, coal burning, aquatic organisms and so on. After entering the brain tissue, metallic mercury in blood gradually accumulates in the brain tissue, which will cause damage to the brain tissue when it reaches a certain amount, and another part of mercury ions will transfer to the kidney.
Inorganic mercury ions entering the water body can be transformed into more toxic organic mercury, which enters the human body through the food chain and causes systemic poisoning; Vulnerable groups include women, especially expectant mothers and seafood lovers; Mercury in natural water is very small, generally not more than 0. 1 μ g/l, mercury in normal blood is less than 5 5- 10/0μ g/l, and mercury concentration in urine is less than 20μ g/l. If acute mercury poisoning occurs, hepatitis and hematuria will be induced. ?
Chromium pollution
Mainly from inferior cosmetic raw materials, leather preparations, chrome-plated metal parts, industrial pigments, tanned leather, rubber and ceramic raw materials. If you eat and drink by mistake, it may cause poisoning symptoms such as abdominal discomfort and diarrhea, allergic dermatitis or eczema, inhalation, irritation and corrosion of respiratory tract, and pharyngitis and bronchitis. Residents in areas with serious water pollution are prone to rhinitis, tuberculosis, diarrhea, bronchitis and dermatitis.
Copper pollution
Refers to the pollution caused by copper (Cu) and its compounds in the environment. The main pollution sources are mining and smelting of copper-zinc ore, metal processing, machinery manufacturing and steel production. Dust from smelting is the main source of atmospheric copper pollution.
Nickel pollution
It is the environmental pollution caused by nickel and its compounds. When smelting nickel ore and steel, some mineral powder will enter the atmosphere with the airflow. During the roasting process, nickel and its compounds are also discharged, mainly water-insoluble nickel sulfide (N iS), nickel oxide (N iO) and metallic nickel powder. , become particulate matter in the atmosphere. When the nickel powder produced by combustion meets hot carbon monoxide, it will generate volatile and highly toxic carcinogen nickel carbonyl [N i(CO)4]. Workers who refine nickel are more likely to suffer from nasal cancer and lung cancer. The wastewater from nickel plating industry, machinery manufacturing industry and metal processing industry often contains nickel. Industrial wastewater is usually treated by alkaline method, and nickel hydroxide [N i(OH)2] is precipitated and removed. Nickel can be enriched in soil, and the deposition of atmospheric particles containing nickel, irrigation of wastewater containing nickel, decay of animal and plant residues and weathering of rocks are all sources of nickel in soil. Plant growth will absorb nickel in the soil. The plants with the highest nickel content are green vegetables and tobacco, which can reach 1.5-3ppm. The critical concentration of nickel toxicity to rice is 20ppm. In China, the maximum allowable concentration of nickel carbonyl in workshop air is 0.00 1mg/m3, and the maximum allowable concentration of nickel in surface water is 0.5 mg/L. ..
Zinc pollution refers to the environmental pollution caused by zinc and its compounds. The main pollution sources are zinc mining, smelting and processing, machinery manufacturing, and emissions from industries such as zinc plating, instrumentation, organic synthesis and paper making. Zinc and its compounds are contained in the smoke and dust produced by automobile tire wear and coal burning, and zinc in industrial wastewater often exists in the form of zinc hydroxyl complex.
environmental pollution
heavy metal contamination
In terms of environmental pollution, heavy metals refer to mercury, cadmium, lead and "metalloid"-arsenic and other heavy metals with significant biological toxicity. There are five most toxic substances to human body: lead, mercury, arsenic, cadmium and chromium. These heavy metals can't be decomposed in water, and their toxicity is amplified after drinking, and they combine with other toxins in water to produce more toxic organic substances.
Soil pollution can be repaired by heavy metal-tolerant plants and can be used as non-agricultural farmland such as amusement parks. The United States has such an example. Copper tailings in Tongling, Anhui Province cooperated with Australia.
Phytoremediation has begun to take shape.
Heavy metals generally exist widely in nature in natural concentration, but due to the increasing mining, smelting, processing and commercial manufacturing activities of heavy metals, lead, mercury, cadmium, cobalt and other heavy metals enter the atmosphere, water and soil, causing serious environmental pollution. ? [2]?
Human injury
Heavy metals in various chemical states or forms will remain, accumulate and migrate after entering the environment or ecosystem, causing harm. For example, heavy metals discharged with wastewater can accumulate in algae and sediments even if the concentration is very small, and are adsorbed by fish and shellfish, resulting in food chain concentration, thus causing public hazards. For example, Minamata disease in Japan is caused by the transformation of mercury in wastewater discharged from caustic soda manufacturing industry into organic mercury through biological action; Another example is pain, which is caused by cadmium discharged from zinc smelting industry and cadmium electroplating industry. Lead emitted by automobile exhaust enters the environment through atmospheric diffusion and other processes, which leads to a significant increase in the current surface lead concentration, which makes the absorption of lead by modern people increase by about 100 times compared with that of primitive people, which is harmful to human health. Heavy metals do great harm to human body. Common ones are:
Children injured by heavy metal pollution
Mercury: It sinks directly into the liver after ingestion, which is extremely harmful to the brain, nerves and vision. Natural water contains 0.0 1 mg per liter of water, which will cause human poisoning.
Cadmium: causes hypertension and cardiovascular and cerebrovascular diseases; Destroy bones, liver and kidneys, leading to renal failure.
Lead: It is one of the most toxic heavy metal pollution. Once in the human body, it is difficult to eliminate. It can directly harm human brain cells, especially the nervous system of the fetus, and can cause congenital mental retardation.
Cobalt: It can cause radiation damage to the skin.
Vanadium: It hurts the heart and lungs and causes abnormal cholesterol metabolism.
Antimony: With arsenic, silver jewelry will turn brick red and be radioactive to the skin.
Thallium: It can cause polyneuritis.
Manganese: Too much will make people hyperthyroidism. It can also damage vital organs.
Arsenic: As a component of arsenic, it is highly toxic and can lead to rapid death. Long-term exposure to a small amount can lead to chronic poisoning. And carcinogenicity.
Any of these heavy metals can cause headache, dizziness, insomnia, forgetfulness, mental disorders, joint pain, stones and cancer.