Thermal pollution from power plants raises the temperature of nearby aquatic environments like rivers and lakes. This warming water holds less dissolved oxygen, disrupting ecosystems. Species that require cooler, oxygen-rich water may die off or be forced to relocate. Remaining organisms face increased disease and chemical exposure as temperatures rise. Over time, these changes can damage biodiversity as some species overpopulate at the expense of others. While regulations now aim to lessen thermal impacts, monitoring and alternative energy development remain important for protecting fragile aquatic environments.

1. Aquatic Environments

2. Power Plants Power plants give us energy to run our cities, our homes, and our modern lives. But what else are they giving us? Acid rain, chemical pollutants in the air, and an excess of green house gasses. All of these things effect our world in a multitude of ways. I will be looking at the small aspect of the effects of temperature rise on aquatic environments, otherwise known as thermal pollution. How does the plant raise the water temperature? Waste heat needs to be cooled off, and is therefore dumped into a “sink.” The cheapest sink cooling unit is one that already naturally exists: a large body of water, like a river or lake. The water from this natural source is brought in to cool and condense steam from turbines (the waste heat mentioned earlier). “The water used for cooling warms 5 to 10 Celsius degrees (9 to 18 Fahrenheit degrees)” ( Thermal Pollution) . The water is then returned to the source. What does this do the water and the organisms within it?

3. Water Can be Changed? Not exactly. However, the hotter the water, the lower the oxygen content in the water. It's much like a person trying to climb Mount Everest. As you go higher, oxygen decreases. In water, as you go hotter, oxygen content decreases. Ignoring pressure and cold, would you like to breathe on Mt. Everest for the rest of your life? This is exactly what power plants are doing to many aquatic species. “ DO [Dissolved Oxygen] concentration is 14.6 ppm [parts per million] at 32 °F and 6.6ppm at 64°F. Thus, the cold water fish which requires about 6 ppm cannot tolerate the high water temperatures....they would die from oxygen starvation (Meenaskhi 186).

4. Even More Heat, Even Less Oxygen We already know the obvious way power plants raise the temperature of water. But what about other ways? Power plants and other industrial plants that contribute to thermal pollution also may add heat by reducing shade in the form of trees, cooling machinery with water and returning it, and using hot water to flush intake pipes. This is a bigger problem in the US today than dumping hot water back into a river or lake in many cases, since the EPA now requires cooling towers in most cases to serve as an intermediary step in the process of returning the water (Priest 158). Oxygen depletion is increased further because the warmer temperature causes faster decay of matter, and the decaying process utilizes oxygen.

5. The Wildlife

6. Disruptions in the Life Cycle “ [Temperature] affects every facet in the lives of fishes, including the routes of migration, the areas and timings of spawning, and rates of growth and mortality” (Merriman 289). “ The time which chum salmon spent in the surface water column decreased gradually with increasing surface temperature. This fact suggests that chum salmon faced with warm water mass have little chance of approaching the natal river because chemical cue for the navigation concentrates in the surface water” (Tanaka). Fish who don't have enough oxygen must leave their homes, make drastic changes in their way of living, or eventually die out. Some fish adapt, and make changes, such as (in the case of a fish able to take the high temperature) a longer breeding season. Others, like salmon, may not encounter their issue until they return to their birthplaces to spawn. Salmon who do make it past the high temperatures to get to their river beds have no assurances that their offspring will make it. The eggs that are laid, either by salmon or permanent residents of the area may not be able to handle the higher temperature, leading to eggs that don't hatch, babies that don't make it in the oxygen depleted environment, an increase of a species that did not used to be in that environment (like tropical fish) or a decrease in food source (because smaller fish have moved or died off). The entire balance of the ecosystem changes, and so does the life of the fish.

7. Disease Higher water temperatures increase bacteria that breed diseases. As a result, the fish population that remains is generally less healthy. In addition to that, oxygen depletion causes the level of chemicals to rise, because it is distributed through water and so many parts per million of oxygen, and there are now less parts oxygen, raising the concentration of the chemicals. These chemicals can cause fatalities, illnesses, and reproductive problems. Another contributor to chemicals is the layering affect thermal pollution can have, whereby certain layers of water have a higher temperature and less oxygen than others, letting chemicals concentrate and settle there.

8. The Strong Survive ...and over populate Plants and animals who do very well in the warmer temperatures reproduce at a faster rate. Their populations become stronger, using more of the available resources for the species that aren't doing so well. In the worst cases, they eventually choke them out too, severely lowering the species diversity in the area. This damages the ecosystem more, because it relies on diversity to keep itself running. The species that are surviving too well could eventually over populate, begin running out of food, and move into bigger areas, crushing more diversity. In many cases, these overpopulating species are considered pests to humans, and require extensive funding, time, and effort to control.

9. What's Being Done? Cooling towers are now being used to reduce the problem, in America. These towers allow the hot water to cool and evaporate back into the atmosphere so that they can safely return to the body of water via precipitation, without rising the temperature. Environmentalists now have more data on the effects of temperature rise, on invasive species, and on how to control them. Efforts are being made to worldwide to find more eco friendly energy alternatives, and to clean up the areas that have already been damaged. The most important thing any single person can do as the first step to aid in these efforts is to pay attention. Pay attention to the changes in your local environment, factory practices, power plants near you, issues on your ballot, and your own personal energy consumption. Awareness is the first step toward keeping the delicate balance that Earth needs to stay healthy.

10. Animations courtesy of: www.animationlibrary.com Works Cited &quot;Thermal Pollution,&quot; Microsoft® Encarta® Online Encyclopedia 2008 http://encarta.msn.com © 1997-2008 Microsoft Corporation. All Rights Reserved. Meenakshi, P.. Elements of Environmental Science and Engineering. Prentice Hall of India, 2005. Tanaka, Hideji. &quot;Potential environmental pollution which may disturb the homing migration of chum salmon&quot;. 20 June 2008 <http://landbase.hq.unu.edu/Workshops/IwateNov2004/abstracts/tanaka.htm>. Merriman, Daniel, and Walford, Lionel. Chesapeake Science, Vol. 10, No. 3/4, Proceedings of the 2nd Thermal Workshop of the U.S. International Biological Program (Sep. - Dec., 1969), pp. 289-291 Priest, Joseph. Energy: Principles, Problems, Alternatives. Dubuque, Iowa: Kendall/Hunt Publishing Company, 2006.