The chemical industry makes our interesting and comfortable. But there is also a flip side - the appearance in the environment of substances that are unnatural for it. Surely, everyone heard something about heavy metals. But not everyone knows the definition of this category of substances.
Heavy metals are substances that have a density greater than iron and are found in small quantities in the natural environment. But in the new, human-created environment, they have a very strong effect on plants, animals and humans. The thing is that sometimes there are too many of them for systems not adapted to such concentrations of matter, whether it is the body of a person, animal, or plant organism.
Heavy metals in water appear from time to time in different regions of the world. So it was in Japan. The condition caused by the increased concentration of mercury was called Minimat's disease. More than a hundred people died from it, and the number of sick people was estimated in thousands. The unfortunate people felt very weak, it was very difficult for them to speak, the gait became awkward, the field of vision narrowed, and his legs went numb. In severe cases, it came to complete loss of vision and death. This sad event happened in 1953.
The reason was that a river flowed into the Minamata Bay. And a chemical plant was pouring waste into it. In rotting aquatic plants, mercury was used to produce methylmercury, an extremely toxic substance. The higher it went up the food chain , the stronger the concentration increased. Most of the poison accumulated in predatory fish. When methylmercury entered the human body, it accumulated in the brain, gradually causing all the described problems with the central nervous system.
Also in Japan, a story happened in the Dzintsu River basin in the 20s of the 20th century. A terrible disease was observed there for a long time: people had bones deformed and they died with moans, translated into Russian as “it hurts!”. This horror lasted until the 70s, when patients also filed a lawsuit against the company, which poured cadmium into the rivers as part of mine wastes.
Heavy metals are less common in soil, but farmers are advised to check the soil for their presence before planting their plants. After all, if this is not done, people, animals, and plants will suffer. And this is not only morally unacceptable and punishable, but also unprofitable.
What is most often found in soils? First of all, lead. Where does he come from? From the exhaust. That is why you should not pick berries and mushrooms right next to the road. And if there is a field? In civilized countries, special fences have long stood. Sometimes lead gets into the soil with low-quality insect repellents. So when you buy pesticides for gardening, be sure to find out at least on the Internet their ins and outs.
We have already talked about cadmium. It may also be in the soil. It used to be brought into the earth along with phosphorus fertilizers. Then people became more attentive, but sometimes a high concentration of cadmium in this category of fertilizers is found now.
Arsenic is found in waste products, in which its concentration increases, so it is doubtful that waste recycling is a panacea for the ecological well-being of humans.
If earlier the main part of environmental pollution by heavy metals was useful in developed countries for emissions from the chemical industry, now the main problem is related to their increased amount in some fertilizers. Potash fertilizers do not have the ability to contain cadmium, but phosphorus fertilizers can. Therefore, it is better to prefer foreign ones, where control is much stricter.
You should not be very afraid of heavy metals, however, if elevated levels of their content have been noted in your area, you need to spend at least one month a year in a clean ecological environment.