These pollutants may then be transported over great distances, causing adverse effects such as acid rain in areas far from the emission site. The worldwide increase in the burning of coal and oil since the late 1940s has led to increasing concentrations of carbon dioxide. The resulting greenhouse effect has reduced the escape of infrared radiation from the earth, causing a possible global warming trend . Water Pollution , contamination of water by foreign matter that deteriorates the quality of the water. The major pollutants of water are sewage, infectious agents, excessive plant nutrients, organic chemicals, industrial products, petroleum, inorganic chemicals, soil sediments, and radioactive substances.
Water pollution can affect human and environmental health.
Nitrates, cadmium, and various inorganic substances such as mercury, arsenic, and lead are particularly known as hazardous to human beings. Lakes are especially vulnerable to pollution in the form of eutrophication, which is excessive plant growth that occurs when water becomes artificially enriched with nutrients. This is sometimes caused by runoff of chemical fertilizers. Eutrophication produces bad tastes and odors and unsightly green scums of algae, as well as oxygen depletion in the deeper waters and bottom sediments of lakes. Another problem is acid rain, which has left many lakes in the northeastern United States and Canada totally devoid of life.