Water pollution and hazards

　　Below, D Xiaobian will introduce water pollution and its hazards:

　　1. What is water pollution

　　Water pollution refers to the phenomenon that pollutants discharged by human activities enter the water body, and the amount exceeds the self-purification capacity of the water body, causing the physical and chemical properties of water and water body bottom sediments and the biological characteristics and composition of the water environment to change, thereby affecting the use value of water, causing water quality deterioration, and even endangering human health or damaging the ecological environment.

　　2. What are the main sources of water pollution?

　　The main sources of water pollution are runoff and infiltration of industrial wastewater, domestic sewage, hospital sewage, and farmland water, as well as the stacking, burial and dumping of waste.

　　3. What are the hazards of water pollution to human health?

　　When a water pollution incident occurs, it may have the following effects on human health:

　　(1) It may cause an outbreak of waterborne infectious diseases in the population.

　　After the water body is polluted by biological pathogens, residents often cause outbreaks of waterborne infectious diseases through drinking, contact, etc., which harms human health. The most common diseases include cholera, thrombosis, dysentery, hepatitis and other intestinal infectious diseases.

　　(2) Potential health hazards such as teratogenicity, carcinogenicity, and mutagenicity, or acute or chronic poisoning.

　　When water bodies are polluted by industrial wastewater, various toxic chemicals in the water bodies, such as mercury, arsenic, chromium, phenol, cyanide, polychlorinated biphenyls, and pesticides, are transmitted through drinking water or the food chain, causing acute or chronic poisoning in the human body. Some algae can produce toxins, and shellfish (clams, cockles, mussels, etc.) can accumulate such toxins. People who eat poisoned shellfish may be poisoned or even die. Dominant algae in eutrophic lakes, such as certain species of cyanobacteria, can produce algal toxins.

　　(3) The sensory properties of water change, affecting people's normal drinking and water use.

　　Sensory hazards are mainly manifested in the color, turbidity, and odor of water. For example, when a faucet is turned on after being unused for a long time, slightly reddish water may flow out. In eutrophic water bodies, algae multiply in large numbers and gather into clumps, floating on the water surface, affecting the sensory properties of the water. When used as a tap water source, algae often clog the filter tank of the water plant and make the water quality have an unpleasant odor, causing panic and disgust among people and affecting their normal drinking and water use.