27． Why should phosphorus-containing detergents be banned?
Answer: Cleaning agent is one of the commonly used surfactants in printing and dyeing production processes, and a certain amount of sodium tripolyphosphate is generally added as a builder during the manufacturing process of cleaning agents. Sodium tripolyphosphate has strong complexing effect and can complex multivalent heavy metal ions. Therefore, the fabric can reduce the hardness of the water when washed in hard water. Sodium tripolyphosphate also has the functions of dispersing, emulsifying, and peptizing fine inorganic particles or grease droplets, which can improve the suspension ability of dirt and prevent redeposition of dirt on fabrics, thereby greatly improving the decontamination ability of the cleaning agent.
Sodium tripolyphosphate itself is non-toxic and biodegradable, but the phosphorus in sodium tripolyphosphate is an important factor causing eutrophication of water bodies. As a large amount of phosphorus- and nitrogen-containing compounds flow into rivers and other water bodies, it will cause the rapid growth and reproduction of algae and plankton in the water. As the algae clumps and the algae layer thickens, the sun cannot shine at the bottom of the algae layer, resulting in the bottom The algae die and decompose. During the decomposition process, dissolved oxygen in the water will be consumed and the concentration of dissolved oxygen in the water will be reduced. Some algae can also produce toxins during the decomposition process, causing poisoning, disease, and death of fish, shrimp, etc. This phenomenon is called eutrophication of water bodies.
The problem of eutrophication of water bodies and environmental pollution has attracted the attention of all countries. Since the 1960s, eutrophication of water bodies has also occurred many times in various places. The phenomenon of eutrophication in rivers and lakes is called “algae bloom”, and the phenomenon of eutrophication in the ocean is called “red tide”. “Red tide” events have occurred many times in Lake Erie in North America and the Yorito Inland Sea in Japan. In particular, 133 red tides occurred in the Yorito Inland Sea of Japan in 1971. In 1973, only one red tide killed 14.28 million fish and caused a loss of about 70 million fish. billion yen. For this reason, various countries have taken measures to control it. One of the environmental protection measures is to restrict the use of phosphorus in cleaning agents. Since the 1980s, many waters in my country have experienced eutrophication. According to statistics, the current eutrophication level of lakes in my country accounts for 63.6% of all lakes. Among them, Taihu Lake, Chaohu Lake, Dianchi Lake, West Lake, etc. have been listed by the State Council as key management projects after the Huaihe River management. Since January 1, 1999, the sale and use of phosphorus-containing cleaning agents has been prohibited in the Taihu area’s secondary protection zones, and the sale and use of phosphorus-containing cleaning agents has been prohibited in the third-level protection zones. In order to ensure the water quality of rivers and lakes, prevent pollution, maintain the ecological balance of water bodies, and prevent the occurrence of eutrophication, the use of phosphorus-containing cleaning agents is prohibited.
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