The outbreak of cyanobacteria in Taihu Lake triggered the water crisis in Wuxi City. What are the human factors that cause this situation? What does it give us?

1. Loss of chemical fertilizer, which is the main source of nutrition in many eutrophic areas. For example, in the Mississippi River basin, 67% of nitrogen flows into the water body and then into the Gulf of Mexico, and more than 50% of nitrogen in the Baltic Sea and Taihu Lake also comes from the loss of chemical fertilizers.

2. Domestic sewage, including human domestic wastewater and phosphorus-containing detergents.

3. Livestock and poultry breeding, livestock and poultry manure contains a lot of nutrient wastes such as nitrogen and phosphorus, which can lead to eutrophication of water bodies.

4. Industrial pollution, including fertilizer plants and wastewater discharge.

5. Burning fossil fuels.