Environmental pollution is not limited to land, but also includes the sea. Since the beginning of the new century, the number of red tides along the coast of China is three times that of 1980s. The ensuing red tides have brought harm to the marine environment, marine fisheries, mariculture and even human health and life. However, the consequences of using lime to control red tide are worrying.

The so-called "red tide" is actually the product of abnormal proliferation of phytoplankton, protozoa or bacteria floating on the sea surface. It's not just red. Besides red, sometimes it may be blue or black, that is, "Lan Chao" or "Kuroshio", but people usually call it "red tide". Red tide can harm marine life in three ways: first, the spread of virus, which, like the spread of "avian influenza" virus, can cause marine life to be invaded and die in a large area, and if human beings eat these marine life that has ingested the virus again, it will also lead to poisoning and even death; Second, red tide absorbs a lot of oxygen in seawater during its formation and proliferation, which makes seawater anoxic and leads to the death of other marine life; Third, rapid and large-scale red tide will block the respiratory tract of some marine organisms and suffocate them. Therefore, the occurrence of red tide will inevitably bring serious harm to marine fishery and mariculture, especially those enterprises or professional households engaged in mariculture. Once the red tide strikes, their years of capital investment and hard work will go up in smoke in a short time.

Faced with this helplessness, some people have finally found a way to prevent it after painstaking exploration, that is, using lime to deal with the red tide that may strike at any time. Its operation is also very simple. As long as a red tide is found on the sea surface and attacks the aquaculture area, a ship carrying lime will be dispatched immediately to sprinkle lime on the sea surface between the red tide and the aquaculture area. Lime becomes calcium hydroxide when it meets water, which is a strong alkaline substance. Don't say red tide, many lives will die when they meet. In this way, an isolation belt is formed between the red tide and the aquaculture area, and aquatic products in the aquaculture area can also escape.

However, this method reminds me of the lessons learned by Britain in controlling sulfur dioxide pollution in the air of the Thames River basin in the 1960s. At that time, in order to eliminate sulfur dioxide pollution in industrial dust in Thames Valley, Britain adopted the method of absorbing sulfur dioxide with lime water, namely calcium hydroxide. After the chemical reaction between sulfur dioxide and calcium hydroxide, calcium sulfate and water are generated, so the sulfur dioxide in the air naturally decreases, but those calcium sulfates are discharged into the Thames, and as a result, air pollution becomes river pollution and water pollution. Later, Britain solved the problem of sulfur dioxide pollution through system engineering.

Therefore, in the face of environmental problems, we can't simply take a piecemeal approach. Sprinkling lime on the sea surface can kill all kinds of products that cause red tide and maintain aquaculture, but it also pollutes the sea water and kills other marine life. If lime is often sprinkled into the sea, it will accumulate on the seabed, which may bring us another disastrous consequence in the future. We should still establish the concept of harmonious coexistence between man and nature, prevent and reduce pollutants from entering the sea, and thus reduce or even avoid the occurrence of red tides. This is the fundamental policy.