Thermal pollution refers to an increase of temperature in a body of water due to human or environmental causes. While a degree or two of difference may sound minor, warming of an aquatic or marine environment even by a small amount can result in devastating alterations to the habitats of fish, insects, plants, and animals. There are several main causes of thermal pollution, each contributing to what some environmental experts call a possible environmental catastrophe.
One of the major causes of thermal pollution is industrial use of water as a coolant. Factories and power plants typically use nearby sources of water to keep machinery cool and functional. While inexpensive and effective, this form of cooling process can wreak havoc on aquatic ecosystems. Water is typically siphoned away from a source, run through cooling systems at a factory or plant, then returned to the original source.
Unfortunately, in the process of cooling machinery, the water temperature rises, sometimes by several degrees. The influx of warm or hot water back into a natural source can destroy food sources or kill off species that require a certain temperature to survive. Many environmental scientists consider the industrial heating of water to be the largest factor in localized thermal pollution.
Soil erosion and deforestation are two other major factors that can lead to unnatural increases in temperature. Shore plants and trees help shade water, keeping temperatures in check by providing protection from sunlight. When plants are removed, not only does a body of water absorb more sunlight, soil held in place by root structures falls into the water. Soil erosion can cause river and lake beds to rise, creating shallower pools of water which heat more quickly.
One of the primary causes for concern with thermal pollution is the depletion of oxygen in the water. Fish rely on a certain amount of oxygen to survive underwater; they do not easily adapt to oxygen level shifts. The warmer water is, the less oxygen it can hold, making a flourishing ecosystem turn deadly for inhabitants in a short time. Additionally, shallow and warmer waters increase the production of oxygen consuming plants such as algae, which decrease oxygen levels even farther as they decompose.
There are several ways to help mitigate the effects of thermal pollution in order to stabilize and sustain aquatic environments. Factories that use water as coolant can install cooling towers and ponds which return water to original temperature before releasing it back into the natural source. Ensuring that banks and shorelines have adequate vegetation to provide shade and retain soil can also help prevent thermal pollution.