nts and algae in the water grow, but when they die and settle underwater, microorganisms decompose them, while decomposing them the microorganisms take in oxygen that is dissolved in the water. The oxygen levels in the water may drop so low that fish and other oxygen-dependent animals in the water suffocate, and die. p> 6. Sediment - soil particles carried to a stream bed, lake, or ocean, if in large amounts, can also be a pollutant. Soil erosion can damage a stream or lake by adding too much nutrient matter. Sedimentation can also cover stream bed gravel where many fish lay their eggs. p> 7. Infectious Organisms - many disease causing organisms that are present in small numbers in most natural waters are considered pollutants when found in drinking water. These parasites can cause illness, especially in people who are very young or very old, and in people who are already suffering from other diseases.
8. Thermal Pollution - water is often taken from rivers, lakes, or the ocean to be used in factories and power plants. The water is usually returned to the source warmer than when it was taken. Even a small temperature change in a body of water can drive away the fish and other species that were originally there, and attract other species in place of them. Thermal pollution can speed up the biological processes in plants and animals or lower the oxygen level in the water. Fish and other wildlife near the discharge source, may die. p> Another cause of pollution, pathogens (bacteria, viruses, and protozoan) can cause many illnesses from typhoid and dysentery to minor repiratory and skin diseases. They enter waterways through untreated sewage, storm drains, septic tanks, runoff from farms, and boats that dump sewage. p> To help, we need to learn about ways for disposing harmful household wastes so they don't end up in sewage treatment plants or landfills. In our yards, we should determine whether or not we need to add nutrients before fertilizers are applied, and look for alternatives where fertilizers may run off into surface waters. We need to preserve existing trees and plant new trees and shrubs to help prevent soil erosion. Around the house we should we need to keep litter, pet waste, leaves, and grass clippings out of gutters and storm drains, and buy as many heavily packaged foods, certain boxes, cartons, bottles, etc that are made with polluting dyes. br/>
Toxic waste pollution
Another type of pollution that is definitely a threat to human safety is toxic waste pollution . This type of contamination is caused when the byproducts of chemical reactions are basically just dumped anywhere the company that produced them so pleases. Although there are supposedly safe ways of disposing of these wastes, there is no natural way of ridding the planet of them. Therefore, most toxic waste is just left out to seep into water sources and into areas of human development. Usually, the outco...
