Glossary
Agriculture (source of thermal pollution)
Farming practices, particularly irrigation, where water used for crops absorbs heat from the sun and soil before returning to natural waterways at an elevated temperature.
Example:
In arid regions, irrigation water pumped from a river can absorb significant heat in fields, and its return flow contributes to thermal pollution from agriculture.
Cooling Towers
Structures used to dissipate waste heat from industrial processes, especially power generation, into the atmosphere, primarily through evaporative cooling.
Example:
Many large power plants utilize cooling towers to reduce the temperature of their discharge water, though they can still release warm water vapor into the atmosphere.
Evaporative Cooling
A cooling process that occurs when water changes from a liquid to a gas (evaporates), absorbing latent heat from the surrounding environment and lowering its temperature.
Example:
The misting fans used at outdoor events cool people down through evaporative cooling as tiny water droplets absorb heat from the air and skin.
Fish Kills
A sudden and widespread death of fish in a body of water, often resulting from environmental stressors such as critically low dissolved oxygen levels or extreme temperatures.
Example:
During a summer heatwave, a shallow pond experienced a massive fish kill as the water warmed and oxygen levels plummeted.
Harmful Algal Blooms (HABs)
Rapid increases in the population of algae that can produce toxins or deplete oxygen, often exacerbated by warmer water and nutrient pollution.
Example:
Warmer ocean temperatures combined with agricultural runoff can trigger harmful algal blooms, leading to 'red tides' that harm marine life and human health.
Industrial Facilities (source of thermal pollution)
Factories, refineries, and other manufacturing operations that release heated wastewater as a byproduct into aquatic environments.
Example:
A paper mill's discharge of warm process water into a local stream demonstrates how industrial facilities can be a source of thermal pollution.
Metabolic Rate
The rate at which an organism uses energy to carry out its life processes. In aquatic organisms, it often increases with water temperature, demanding more oxygen.
Example:
Warmer water can elevate a fish's metabolic rate, causing it to consume more oxygen, which becomes problematic if dissolved oxygen levels are low.
Oxygen Solubility
The maximum amount of oxygen that can dissolve in a given amount of water at a specific temperature and pressure. It decreases as water temperature increases.
Example:
Cold, fast-flowing rivers typically have high oxygen solubility, which supports a rich diversity of aquatic insects and fish like trout.
Power Plants (source of thermal pollution)
Industrial facilities that generate electricity, frequently using large volumes of water for cooling and then discharging it at a higher temperature into nearby waterways.
Example:
A coal-fired power plant on a river often contributes significantly to thermal pollution by returning heated cooling water.
Recreational Activities (source of thermal pollution)
Leisure activities involving watercraft that can release warm exhaust or disturb water, leading to localized temperature increases in small bodies of water.
Example:
A busy weekend of motorboating on a small, shallow lake can contribute to thermal pollution from recreational activities due to engine heat and exhaust.
Reproductive Cycles
The sequence of physiological and behavioral changes in organisms related to reproduction, which can be highly sensitive to specific environmental conditions like temperature.
Example:
Many salmon species require precise cold water temperatures for spawning, and thermal pollution can disrupt their reproductive cycles, impacting population numbers.
Susceptibility to Disease
The likelihood of an organism contracting a disease, which can be increased by environmental stressors that weaken its immune system or promote pathogen growth.
Example:
Fish living in thermally polluted waters often experience increased stress, leading to a higher susceptibility to disease and greater mortality rates.
Thermal Pollution
The degradation of water quality by any process that changes ambient water temperature, often caused by human activities like industrial discharge.
Example:
A power plant releasing heated water into a lake is a prime example of thermal pollution, stressing the local ecosystem.
Urbanization (Heat Island Effect)
The phenomenon where urban areas are significantly warmer than surrounding rural areas due to heat absorption by paved surfaces and buildings, which can warm stormwater runoff.
Example:
The extensive concrete and asphalt in a city create an urban heat island effect, causing rainwater to heat up before flowing into local rivers.