Coal combustion can affect aquatic (freshwater) or marine (saltwater) organisms in different ways. Describe each step involved in one such way, from combustion to the effect(s) on one or more species. Which environmental sphere(s) is involved in each step, and how?
The combustion of coal involves several steps, beginning with the extraction of coal from mines and ending with the release of combustion byproducts into the environment. This process can affect aquatic or marine organisms in various ways. Let's take a closer look at each step and its impacts on species, as well as the involvement of different environmental spheres:
1. Coal extraction: Coal is typically mined from the Earth's crust, which involves the removal of soil, rock, and vegetation. This process often leads to habitat destruction and sedimentation of nearby water bodies due to the disturbance of natural ecosystems. The environmental sphere involved is the geosphere (Earth's crust).
2. Transportation and handling: After extraction, coal is transported via trucks, trains, or ships to power plants or industrial facilities for combustion. During transportation and handling, coal dust or other particles can be released into the air or may accidentally spill into water bodies, leading to water pollution. The environmental spheres involved are the atmosphere (air) and the hydrosphere (water).
3. Combustion: At power plants, coal is burned in combustion chambers to generate heat, which is then used to produce electricity. During combustion, various pollutants are released, including sulfur dioxide (SO2), nitrogen oxides (NOx), mercury (Hg), particulate matter (PM), and carbon dioxide (CO2). These pollutants can be released into the atmosphere through smokestacks or emitted into water bodies through cooling water discharge. The environmental spheres involved are the atmosphere (air) and the hydrosphere (water).
4. Air pollution: Coal combustion releases air pollutants such as sulfur dioxide and nitrogen oxides, which can contribute to the formation of acid rain when they react with atmospheric moisture. Acid rain can directly or indirectly affect aquatic organisms by acidifying water bodies, leading to changes in pH levels, which affect the survival and reproduction of species. The environmental sphere involved is the atmosphere (air) and the hydrosphere (water).
5. Water pollution: During coal combustion, cooling water is used to regulate the temperature of power plant equipment. This water is often taken from nearby water bodies and, after use, discharged back into the water. However, the cooling water can absorb pollutants from the combustion process, such as heavy metals like mercury, as well as heat, which can raise water temperatures. These pollutants and thermal pollution can harm aquatic organisms, affecting their metabolism, reproduction, and overall health. The environmental sphere involved is the hydrosphere (water).
6. Bioaccumulation and biomagnification: Some pollutants released during coal combustion, like mercury, can accumulate in aquatic organisms through a process called bioaccumulation. This means that as organisms consume contaminated prey or absorb pollutants from the surrounding environment, the concentration of pollutants in their tissues increases over time. As a result, higher trophic level species, such as fish or marine mammals, can experience biomagnification, where the concentration of pollutants increases significantly as you move up the food chain. This can have severe effects on species' health, reproduction, and population dynamics. The environmental sphere involved is the biosphere (living organisms) and the hydrosphere (water).
In summary, the combustion of coal involves several steps, from extraction to combustion and, ultimately, the release of pollutants into the environment. Each step affects different environmental spheres, including the geosphere, atmosphere, hydrosphere, and biosphere. These impacts can lead to habitat destruction, water and air pollution, acidification of water bodies, thermal pollution, and the accumulation of toxic pollutants, ultimately negatively impacting aquatic or marine organisms.