Don't use lead in sea fishing, but iron in sea fishing! How much lead pollutes the sea?

As we all know, the method of free-flowing fishing is closely related to plumb. The plumb used in deep sea varies from 50g to 5kg, then hangs on the earth or meets the broken line of monsters. It is common to sacrifice the plumb fishing group in various ways, but it is estimated that few people really care about the pollution of plumb to the sea. In order to protect the marine environment, the plumb used by the Japanese is mainly made of iron, however. Almost all of our country uses lead!

Lead, a heavy metal, is toxic. Among all known toxic substances, lead is the most recorded in books. It is recorded in ancient books that it is dangerous to transport drinking water with lead pipes. However, heavy metal pollution is an unbearable burden for the oceans.

The following information comes from Baidu: Heavy Metals Pollution to the Ocean

China is a large maritime country with a coastline of 184,000 kilometers and abundant resources. In recent years, with the rapid development of economy, a series of serious marine environmental problems such as coastal pollution have emerged. Since the 1980s, China's marine pollution problem has become increasingly serious. By the 1990s, China's coastal pollution has been quite serious. The area of the coastal water quality inferior to the first class of sea water quality standards has increased from 100,000 square kilometers in 1992 to 220,000 square kilometers in 1999. By 2012, some coastal waters were still seriously polluted, with an area of 170,000 square kilometers that did not meet the first-class water quality standards, which was higher than the average level of 150,000 square kilometers from 2007 to 2011. The coastal waters with inferior water quality are about 68,000 square kilometers, an increase of 24,000 square kilometers over the previous year. The coastal waters of about 19,000 square kilometers are in a state of severe eutrophication.

Where does marine heavy metal pollution come from?

Whether you like it or not, heavy metals are everywhere. Heavy metals are a natural part of the earth. Some of them are indispensable to life, while others are totally useless. Almost all heavy metals are of great use in industrial production, which is the main source of heavy metal pollution in the environment.

Unlike degradable organic pollutants, heavy metals circulate indelibly in nature. Rock weathering, dust flying, volcanic eruption, Baichuan to the sea - heavy metals through these processes from land to the sea. Heavy metals do not stay in surface seawater for long. They adsorb on particulate matter and then sink into sediment. After a long period of time, the sediment layer is covered with rocks and heavy metals are confined to it again. However, human activities disturb the slow and orderly cycle of nature.

Ore mining, metal smelting, production, use and abandonment of metal products, human activities are releasing heavy metals into the environment. This greatly improves the circulation of heavy metals in the environment and their concentration in water, soil, air and other media. Although in the face of natural forces such as tsunamis, earthquakes and typhoons, human beings seem extremely small, but the ability of human beings to emit heavy metals has been comparable to nature, even far more than nature. To make matters worse, heavy metal pollutants are not evenly dispersed in the ocean, but concentrated in coastal waters, where humans live and produce fisheries. After the Industrial Revolution, the marine ecosystem felt the tremendous pressure caused by human pollution.

Heavy metals emitted by humans are transported into the ocean through the atmosphere. For example, coal combustion produces tiny particles that float in the air, which can carry heavy metals for long distances and eventually sink into offshore or even ocean. However, heavy metals in the offshore are mainly transported from rivers and directly discharged into the sea from domestic sewage and industrial wastewater. For a specific sea area, a factory, a sewage outlet may be the main source of heavy metals. The mercury pollution incident in Minami Bay in 1950s is a typical case.

A plastic factory called "asphyxian" in Mitsui City, Japan, uses mercury as a catalyst to produce acetaldehyde, which produces methylmercury as a by-product. Methylmercury is discharged into Minamata Bay with wastewater and then absorbed and enriched by fish, shrimp and shellfish. The contaminated seafood was put on unknown local tables, resulting in poisoning of at least 2,265 people, of whom 1,784 were killed. The world-shaking ecological disaster has made people realize that dumping heavy metals into the sea will not only destroy ecosystems, but also endanger humans themselves through the food chain.

Marine heavy metal pollution can not be ignored?

Heavy metal pollution is different from that of other organic compounds. Many organic compounds can be reduced or eliminated by physical, chemical or biological purification of nature itself. Heavy metals are enriched and difficult to degrade in the environment. Heavy metals discharged with wastewater, even at very low concentrations, can accumulate in algae and sediment, be adsorbed on the surface of fish and shellfish, and aggregate in organisms through food chains, causing mutations in genetic materials of marine organisms, leading to slow growth and abnormal development of organisms, reducing the survival rate of embryos, larvae and adults, and even leading to the extinction of sensitive species. Ecological degradation.

Heavy metal pollution is a direct and indirect threat to ecosystems. Heavy metals accumulate in the human body through the enrichment and amplification of the food chain, which destroys the normal physiological and metabolic activities of the human body and damages human health.

After being eaten by aquatic organisms, mercury is converted into methylmercury in vivo, which can destroy blood vessels of brain tissue and cause a series of symptoms of central nervous system poisoning, such as hand, foot, lip numbness and red pain, speech disorder, hearing loss and other typical symptoms of cerebral arteriosclerosis patients; methylmercury can also lead to abortion, malformed fetus and congenital dementia. Er et al. is extremely toxic.

Lead ingested by organisms binds to a variety of enzymes, thus interfering with various physiological activities of organisms and causing harm to the whole body organs. The most important is the influence on nervous system, kidney, hematopoietic system and blood vessels. Lead poisoning is characterized by anemia, abdominal pain, hypertension, etc. Low-dose lead exposure can adversely affect the functions of human red blood cells, kidneys, immune system, bone marrow and central nervous system, all of which may not have obvious clinical symptoms before they occur. Lead poisoning may affect the age at which infants first stand, walk and speak, and may also cause distraction, memory loss, reduced understanding and learning difficulties. Accidental lead poisoning during pregnancy can result in miscarriage, stillbirth or birth deformity. Lead penetrates into the brain and can directly inhibit the secretion of growth hormone, resulting in short stature, precocious puberty, obesity and so on.

Cadmium is widely distributed in nature, and its harm to human health is mainly due to environmental pollution caused by industrial and agricultural production. When cadmium is absorbed by human body, it will selectively accumulate in the liver and kidney, causing pathological changes, anemia and poor metabolism. Cadmium in the environment can not be biodegraded, and its biological half-life in human body lasts for 10-30 years, which is the most easily accumulated toxic substance known in human body. The main toxic symptoms were arteriosclerosis, renal atrophy or chronic glomerulonephritis. In addition, excessive intake of cadmium can cause cadmium to enter the bone to replace part of calcium, resulting in bone softening and deformation, and serious cases of natural fracture and death. An autopsy of a Japanese dead man with osteodynia revealed 122 fractures in his whole body. The body length was shortened by 30 centimeters, and the cadmium content in the ashes was 150 times higher than that in the controls. In addition, cadmium has mutagenic, carcinogenic and teratogenic effects, and causes hypertension, emphysema and so on.

Chromium is a dangerous carcinogenic, teratogenic and mutagenic "three-cause" heavy metal substance. Because of its strong oxidation, it has severe corrosiveness to skin and mucosa. In addition, chromium in animals oxidizes orthoferric hemoglobin to methemoglobin, which makes it unable to carry oxygen normally; excessive chromium also makes nucleic acid and nucleoprotein precipitation denatured and inactivated.

Arsenic and its compounds exist widely in the environment. The main toxicity is arsenic compounds, of which arsenic trioxide is a highly toxic arsenic. The toxicity of arsenic in human body is mainly combined with enzymes in cells, which inactivates many enzymes and causes metabolic disorders. Highly pigmented skin and highly keratinized skin, the occurrence of tortoise ulcer is another characteristic of arsenic poisoning. Acute arsenic poisoning can cause death if it is not rescued in time.

Copper is an essential trace element in organism, and its content in human body is second only to that of iron and zinc. Excess copper has obvious toxic effect on organisms and can lead to copper poisoning. Recent studies have shown that the mortality rate of hepatocellular carcinoma is positively correlated with copper content in the environment. In addition, the disorder of copper metabolism can cause brain and brain lesions.

In addition, the beneficial or harmful effects of heavy metals in water depend not only on the type and physical and chemical properties of the metal, but also on the concentration of the metal and its valence and form. Even if the concentration of beneficial heavy metals exceeds a certain value, it will be severely toxic, causing animal and plant poisoning or even death. Organic compounds of metals (such as organic mercury, organic lead, organic arsenic, organotin, etc.) are much more toxic than corresponding inorganic metal compounds, and soluble metals are more toxic than particulate metals.

Is Heavy Metal Pollution in the Ocean Increasing?

Nowadays, news of seafood heavy metals exceeding the standard is often reported in newspapers, which makes people feel that marine heavy metal pollution seems to be becoming more and more serious. Compared with thirty or forty years ago, heavy metal pollution is undoubtedly serious now; however, whether pollution is still increasing in recent years, according to public monitoring data, it is difficult to get a clear answer.

A seemingly reasonable reasoning is that China's total economic output is steadily increasing, the use and emissions of heavy metals are increasing accordingly, and heavy metal pollution will certainly become more and more serious. However, this reasoning is not necessarily true. Pollutant emissions do not always increase with economic growth. Technological progress and scientific management can cut off the link between economic development and pollution emissions. Not long ago, scholars from the University of Michigan and Tsinghua University in the United States published an article in the Journal Environmental Science and Technology, pointing out that from 1992 to 2007, the unit growth of China's GDP brought about a gradual reduction in the discharge of heavy metals from water. From 2007 to 2012, heavy metal emissions have not increased but decreased with the growth of GDP. Data from the National Bureau of Statistics also show that the total amount of lead, mercury, cadmium, hexavalent chromium and arsenic in industrial wastewater discharged from 2003 to 2011 shows a decreasing trend.

What about the oceans? Some of the heavy metal pollution in the ocean comes from the direct discharge of industrial wastewater and domestic wastewater into the sea, and more from the indirect transport of rivers. In recent years, the direct discharge of heavy metals has been effectively controlled, and the discharge shows a downward trend, while the amount of heavy metals transported by rivers is still not decreasing.

According to the Environmental Quality Bulletin issued by the Ministry of Environmental Protection in recent years, all kinds of heavy metals discharged directly into the sea with industrial wastewater and comprehensive wastewater are generally decreasing. After 2007, emissions of mercury, hexavalent chromium, lead and cadmium remained at about 1 ton or less. In addition to industrial wastewater, the contribution of domestic sewage directly discharged into the sea to heavy metal pollution should not be neglected. However, until 2011, there were no public monitoring data: mercury 19 kg, chromium 113 kg, lead 1276 kg, cadmium 46 kg. Lead emission from domestic sewage is the most serious, which is comparable to industrial sewage and comprehensive sewage.

The amount of heavy metals that enter the ocean indirectly through rivers is much larger than the direct discharge mentioned above - hundreds or even thousands of times more (Table 1). In addition, the emission of lead and copper monitored in recent years has an upward trend.

In addition to analyzing and comparing monitoring data over the years, there are some more "ingenious" methods to understand the trend of marine heavy metal pollution. As mentioned earlier, heavy metals in water will sink into sediment with particulate matter. Each layer of sediment records the pollution of the water like a Book page. If we drill a mud column and analyze the heavy metal content in each layer, we can clearly understand the history of heavy metal pollution, and even go back hundreds of thousands of years. In 2000, researchers collected columnar sediment samples from several sampling sites in the Pearl River Estuary for analysis. The results show that although the specific data of each sampling site are different, the general trend is similar: the concentration of lead and zinc in sediment has increased significantly in the past 100 years, especially in the last 20 or 30 years; copper and nickel have not increased this trend and have been fluctuating in a narrow range.

Another ingenious method is to use the growth characteristics of corals: the calcareous layer secreted by corals accumulates to form a skeleton, leaving behind traces of time like tree rings. The content of heavy metals in coral skeleton was positively correlated with the concentration of heavy metals in water at the time of skeleton formation. Some researchers have analyzed coral samples from Daya Bay, Guangdong Province. These samples have kept records for about 30 years. The relative concentration of zinc in the coral skeleton has steadily increased, which has accelerated in the last 10-20 years and increased by 3-5 times.

What is the status quo of pollution?

The above research methods only give us a possible way to understand the pollution of heavy metals in the ocean. So, are there any more targeted research results? What are their conclusions? What is the pollution of heavy metals in our oceans?

In order to have a comprehensive and comprehensive assessment and understanding of China's marine situation, at the beginning of the 21st century, China launched another large-scale, long-term, multi-project and rich-content offshore marine comprehensive investigation and evaluation special work - "China's offshore marine comprehensive investigation and evaluation special project" (referred to as "908 special project"). This project covers about 20% of China's total marine area. The project is considered to be the most objective and accurate survey of China's marine situation so far, and there will be no large-scale marine environment research of similar scale and intensity for quite a long time thereafter. Therefore, the data of this project is of great value and significance for understanding China's marine situation. In this project, there are quite a lot of research contents aiming at the status of heavy metals in China's oceans, especially offshore. Through the relevant research results, people can have a comprehensive and preliminary understanding of the status of heavy metals in China's oceans.

The "908 Project" investigates and evaluates the pollution status of copper, lead, zinc, cadmium, chromium, mercury and arsenic in surface seawater, organisms and sediments. The survey was conducted in spring, summer, autumn and winter from 2006 to 2007. The sampling layers were surface water samples, seabed sediments and marine organisms.

The results show that the contents of heavy metals in China's offshore seawater are as follows: the average values of seven heavy metals in each season are in line with the national seawater quality standards. However, copper, lead, zinc, chromium and mercury in some observation and research stations exceed the national seawater quality standards of the first class, but most of them meet the national seawater quality standards of the second class. Only some observation and research stations exceed the national seawater quality standards of the third class, while cadmium and arsenic in all observation and research stations meet the national seawater quality standards of the first class.

Compared with the four seas of the Bohai Sea, the Yellow Sea, the East China Sea and the South China Sea, copper and lead contents are the highest, followed by the South China Sea and the lowest in the Yellow Sea; zinc content is Bohai Sea > South China Sea > Yellow Sea > East China Sea; cadmium and chromium are Bohai Sea > Yellow Sea > South China Sea > East China Sea; mercury is Bohai Sea > East China Sea > Yellow Sea > South China Sea; arsenic is East China Sea > Yellow Sea > Bohai > South China Sea.

Overall, the heavy metal content in the Bohai Sea ranks first among the four sea areas.

At present, the amount of heavy metals entering the sea every year in China is still quite large, and the pollution situation of heavy metals in the sea is still grim. If we take timely scientific management to reduce pollution from the source, control the spread of pollution, and give the marine ecological environment time to self-repair, the situation will be recoverable. It should be pointed out that the spatial distribution of marine heavy metal pollution in China is extremely uneven, even in the context of overall deterioration, there are still many clean sea areas. According to the data of the National Bureau of Statistics, in 2010, the area of the coastal waters polluted by various degrees was 107,000 square kilometers, of which 47,800 square kilometers were seriously polluted, while 42,400 square kilometers remained relatively clean.

Maintaining the marine environment will also help our future generations catch and eat fish. We can do more.