Carbon Dioxide's Impact: Is It A Water Pollutant?

Carbon dioxide (CO2) is a greenhouse gas that is released into the atmosphere through human activities such as burning fossil fuels and land-use changes. While it is often associated with air pollution, carbon dioxide can also be a water pollutant. Water pollution by nutrients, such as fertilizer, human and animal waste, and other sources, releases carbon dioxide into the oceans. This adds to the carbon dioxide already present in the ocean due to absorption from the atmosphere, contributing to the acidification of seawater and potentially impacting marine life and ecosystems. The adverse effects of carbon dioxide water pollution on the oceans have been recognized by organizations such as the American Chemical Society.

Carbon dioxide is a major source of water pollution

Carbon dioxide (CO2) is a major source of water pollution, particularly in the oceans. While CO2 is often associated with air pollution, it is also a significant contributor to water pollution, which can have far-reaching impacts on marine ecosystems.

One of the primary ways that CO2 enters the oceans is through the absorption of atmospheric carbon dioxide. The oceans act as a natural sink for carbon dioxide, absorbing about one-third of the CO2 released into the atmosphere. This absorption leads to the formation of carbonic acid, resulting in an increase in ocean acidity or ocean acidification. Since the Industrial Revolution, the pH of the ocean's surface waters has dropped from 8.21 to 8.10, with a 30% increase in acidity. This change in pH has already had visible effects on marine life, such as the deterioration of ocean snails' shells, which become cloudy, ragged, and weakened when exposed to more acidic waters.

Human activities, such as the burning of fossil fuels and nutrient runoff from fertilizer, human and animal waste, and other sources, have significantly contributed to the increase in atmospheric CO2 levels. According to William G. Sunda and Wei-Jun Cai, atmospheric CO2 levels have risen by about 40% since the Industrial Revolution due to these human activities. This increase in atmospheric CO2 has, in turn, led to higher concentrations of CO2 in seawater, exacerbating the problem of ocean acidification.

The effects of ocean acidification can be particularly severe in certain regions, such as the "Dead Zone" in the Gulf of Mexico and the Baltic Sea. In these areas, the combination of rising atmospheric CO2 and local sources of water pollution, such as nutrient runoff and algal blooms, can create a synergistic effect, leading to substantial increases in ocean acidity. This heightened acidity can have detrimental consequences for commercial fisheries and marine ecosystems in these regions.

Additionally, while water vapor is recognized as the most abundant greenhouse gas in the Earth's atmosphere, contributing to the "greenhouse effect" that traps heat, CO2 plays a significant role in climate change and global warming. The annual rate of increase in atmospheric CO2 has been about 100 times faster than previous natural increases, and in 2023, global average atmospheric CO2 reached a record high of 419.3 parts per million. These rising levels of CO2 have far-reaching implications for the planet's climate and ecosystems, including the oceans.

Ocean acidification is caused by carbon dioxide

Carbon dioxide (CO2) is a greenhouse gas that is released into the atmosphere through human activities such as burning fossil fuels and deforestation. The ocean absorbs about one-third of the CO2 released into the atmosphere, which results in the formation of carbonic acid and leads to ocean acidification. This process has increased the acidity of ocean waters, negatively impacting marine life, especially organisms that rely on carbonate ions to build shells and skeletons.

Ocean acidification is primarily caused by the increasing concentration of carbon dioxide in the Earth's atmosphere due to human activities. The burning of fossil fuels, such as car emissions, and changing land use practices, including deforestation, have significantly contributed to the rise in atmospheric CO2 levels. As a result of these human activities, the ocean has absorbed approximately 29-30% of the additional carbon dioxide, leading to a decrease in the pH of seawater.

When carbon dioxide dissolves into the ocean, it triggers a chemical reaction that increases the concentration of hydrogen ions, making the water more acidic over time. This process is known as ocean acidification and has far-reaching implications for marine ecosystems. The increased acidity can disrupt the ecological balance of the oceans and negatively impact commercial fisheries in coastal regions.

In addition to the direct effects of carbon dioxide absorption, ocean acidification is also influenced by the biological breakdown of organic matter during algal blooms. Nutrient runoff from fertilizer, human and animal waste, and other sources contributes to the CO2 levels in the ocean, further enhancing unwanted changes in ocean acidity. These changes in ocean chemistry have already impacted commercial fish and shellfish populations, and they continue to threaten marine life and human food sources that rely on healthy ocean ecosystems.

To address the issue of ocean acidification caused by carbon dioxide, it is crucial to transition to clean energy sources and implement pollution regulations for power plants and fuel-economy standards for vehicles. Conservation efforts, such as the 30x30 pledge, aim to protect and enhance the resilience of critical carbon sinks like forests and wetlands, mitigating the impacts of increasing CO2 levels on ocean acidification.

Eutrophication is a second environmental problem

Eutrophication is caused by excessive concentrations of nutrients, most commonly phosphates and nitrates, although this varies with location. Phosphorus is the limiting factor for plant growth in most freshwater ecosystems, and because phosphate adheres tightly to soil particles, more and more phosphorus is accumulating inside freshwater bodies. In marine ecosystems, nitrogen is the primary limiting nutrient. Nitrous oxide, created by the combustion of fossil fuels, has led to heightened levels of eutrophication in the ocean.

Eutrophication may occur naturally or as a result of human actions. Man-made, or cultural, eutrophication occurs when sewage, industrial wastewater, fertilizer runoff, and other nutrient sources are released into the environment. Such nutrient pollution usually causes algal blooms and bacterial growth, resulting in the depletion of dissolved oxygen in the water and causing substantial environmental degradation.

The most conspicuous effect of cultural eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Algal blooms limit light penetration, reducing growth and causing die-offs of plants in littoral zones while also lowering the success of predators that need light to pursue and catch prey. When these dense algal blooms eventually die, microbial decomposition severely depletes dissolved oxygen, creating a hypoxic or anoxic "dead zone" lacking sufficient oxygen to support most organisms.

Algal blooms release carbon dioxide

Carbon dioxide (CO2) is a greenhouse gas that is released into the oceans as a result of water pollution by nutrients. This is a major source of CO2 that often goes unnoticed by the public. The oceans absorb about a third of atmospheric CO2, which results in the formation of carbonic acid and leads to ocean acidification. Water pollution, including nutrient runoff from fertilizers, human and animal waste, and other organic matter formed during algal blooms, contributes to this process.

Algal blooms play a significant role in the release of CO2, particularly in aquatic ecosystems such as lakes and oceans. When algal blooms occur, they can decrease the CO2 concentration in the water through intensive photosynthesis. This process increases dissolved oxygen and pH levels, leading to a reduction in CO2 levels. However, it is important to note that algal blooms also contribute to the release of other greenhouse gases, such as methane (CH4) and inorganic nitrogen.

The impact of algal blooms on CO2 levels is particularly notable in shallow lake bays. Studies have shown that frequent algal blooms in these environments can lead to a dramatic increase in methane emissions while decreasing CO2 concentrations. This dynamic is influenced by the high productivity of algae, which takes in CO2 and releases oxygen during photosynthesis. As a result, the water body acts as a sink for CO2, absorbing it from the atmosphere.

While algal blooms can temporarily reduce CO2 levels in water, their decomposition can release CO2 back into the environment. When algal blooms die off and break down, they can emit CO2, methane, and inorganic nitrogen, contributing to future climate warming. This release of greenhouse gases during the decomposition process can have significant ecological and economic impacts, as seen with toxic blooms of the microalga Karenia brevis along the west coast of Florida.

In summary, algal blooms can influence the release of CO2 and other greenhouse gases in aquatic ecosystems. While they may initially decrease CO2 concentrations through intensive photosynthesis, their decomposition can result in the release of CO2 and other gases, contributing to climate change. Understanding the complex relationship between algal blooms and greenhouse gas emissions is crucial for developing strategies to mitigate their adverse effects and protect commercial fisheries and coastal regions.

Commercial fisheries are impacted by carbon dioxide

Carbon dioxide is a greenhouse gas that is enhancing unwanted changes in ocean acidity. The oceans absorb about one-third of the CO2 in the atmosphere, which results in acidification from the formation of carbonic acid. This process of ocean acidification is particularly exacerbated by water pollution, which introduces additional CO2 into the ocean through the biological breakdown of organic matter formed during algal blooms.

Secondly, carbon dioxide emissions from fuel combustion in the marine fishing sector contribute significantly to global CO2 levels. The industrial and small-scale fishing sectors have seen fluctuations in their emissions intensity over the years, with the small-scale fishing sector emitting 2.3 times more in 2016 compared to 1950. The combustion of fuel for fishing activities releases additional carbon dioxide into the atmosphere, contributing to the overall increase in greenhouse gases.

Moreover, the physical disturbance caused by bottom trawling in commercial fisheries erodes and degrades the seabed. This disturbance disrupts the natural functioning of the biological pump, affecting the ocean's ability to sequester carbon and mitigate the impacts of climate change. By disturbing the carbon-rich seabed, commercial fishing practices can release stored carbon back into the ocean and the atmosphere, further exacerbating the problem of carbon dioxide-induced ocean acidification.

Finally, the extraction of commercially important fish species by fisheries reduces their natural carbon sequestration potential. Fish play a crucial role in the ocean carbon cycle, as their bodies contain 10-15% carbon. When a fish dies, it sinks to the deep seafloor, where the carbon is sequestered for decades to centuries. By catching and removing these fish from the ocean, commercial fisheries disrupt this natural process and contribute to the carbon dioxide levels in the atmosphere.

Frequently asked questions