Chesapeake Bay Pollution: Causes And Effects Explained

The Chesapeake Bay is affected by pollution from a variety of sources, including air pollution from cars, trucks, power plants, and other sources, as well as nutrient pollution from agricultural runoff, wastewater treatment plants, and septic systems. While air pollution can fall back to earth and end up in waterways, nutrient pollution can fuel the growth of harmful algae blooms, creating low-oxygen dead zones that harm marine life. Additionally, airborne nitrogen oxides can contribute to algal blooms and deplete oxygen levels in the water, posing risks to both ecosystems and human health.

Air pollution from vehicles, power plants, and industries

Vehicular emissions are a major source of nitrogen oxides (NOx), which can irritate airways and pose risks to human health. These NOx emissions, along with ammonia, are responsible for the presence of airborne nitrogen polluting the Bay. Airborne nitrogen oxides fall into the waters, triggering a chain reaction that fosters algal blooms, blocking sunlight from reaching underwater vegetation and creating "'dead zones" through oxygen depletion, ultimately leading to the suffocation of marine life.

Power plants, particularly coal-fired ones, are another significant source of air pollution affecting the Chesapeake Bay. These stationary sources continuously emit pollutants like nitrogen oxides and mercury, which can travel long distances and contaminate the Bay's waters. Mercury, a toxic metal, is released into the air when coal, oil, natural gas, and hazardous materials are burned. It eventually ends up in the Bay's waterways, reaching toxic levels in the tissue of fish and shellfish, posing risks to both ecosystems and human health.

Industries and manufacturing facilities also contribute to air pollution, discharging pollutants such as nitrogen oxide (NOx) and sulfur dioxide (SO2) into the atmosphere. These emissions mix with natural rainfall, leading to the formation of nitric and sulfuric acids, which further contaminate the land and water of the Chesapeake Bay region. Additionally, the use of mercury in industrial processes releases inorganic mercury into the air, which eventually finds its way into the Bay's ecosystem.

To address the air pollution affecting the Chesapeake Bay, efforts are being made to reduce emissions from vehicles and power plants through new regulations and improved technologies. Maintaining and expanding forests is also crucial, as trees act as "attenuation machines," absorbing and trapping airborne pollutants, including nitrogen, and helping to reduce the overall level of air pollution in the watershed.

Nitrogen oxide pollution

The impact of nitrogen oxide pollution on the Bay is significant. It is a key contributor to ground-level ozone pollution and acid rain, which harms the Bay's ecosystem, including plants that sustain it. When nitrogen oxides fall into the water, they contribute to algal blooms, which cloud the water and absorb oxygen, leading to the creation of "dead zones" where marine life, such as crabs, fish, and underwater grasses, suffocate and die due to lack of oxygen.

Efforts to reduce nitrogen oxide pollution in the Chesapeake Bay include advocacy and litigation by organisations like the Chesapeake Bay Foundation (CBF) to limit emissions travelling across state lines into the Bay watershed. The Clean Air Act has also helped decrease nitrogen oxide pollution, and there is a focus on reducing air pollution through the use of electric or manual lawn mowers and yard tools instead of gas-powered machines.

Overall, nitrogen oxide pollution is a critical issue for the Chesapeake Bay, impacting both the ecosystem and human health, and continued efforts are needed to reduce emissions and mitigate their harmful effects.

Mercury pollution

Mercury is a naturally occurring element, but its prevalence in the environment has tripled since the Industrial Revolution. Mercury pollution in the Chesapeake Bay is a pressing issue, with the toxic metal contaminating waterways and reaching dangerous levels in the tissue of fish and shellfish. The burning of coal, oil, natural gas, hazardous materials, and wood releases mercury into the air, which can then travel great distances before being deposited into the Bay through rainfall or as a gas.

Coal-fired power plants are the largest source of mercury air emissions in the United States, contributing over 40% of the pollution. When coal is burned to generate electricity, mercury is emitted from the smokestacks of power plants and other coal-burning sources, eventually making its way into the Chesapeake Bay and other bodies of water. Trash incinerators are also significant contributors to mercury pollution in the region.

Once mercury enters the water, biological processes can transform it into methylmercury, a highly toxic form. Plankton absorb methylmercury, and fish consume the contaminated plankton and smaller fish, resulting in the accumulation of methylmercury in their tissues. This contamination poses a risk to human health, as consuming fish with high levels of mercury can lead to toxic effects on the brain, kidneys, and lungs.

According to a 2020 study, the most contaminated fish in the Chesapeake Bay watershed include striped bass (rockfish), walleye, largemouth bass, and flathead catfish. The Susquehanna basin has the highest mercury concentrations in the region, with more than half of its freshwater areas among the most toxic spots.

While there have been efforts to implement pollution controls and regulations to reduce mercury emissions, such as the Mercury and Air Toxic Standards (MATS) rule, the Trump administration has relaxed some of these measures, potentially increasing mercury pollution in the Chesapeake Bay and other affected areas.

Nutrient runoff from agriculture

Agriculture is the largest source of nutrient and sediment pollution entering the Chesapeake Bay. Farms are essential, providing food, natural areas, and environmental benefits. However, their impact on the Chesapeake Bay is detrimental. Nutrient runoff from farms carrying excess nitrogen and phosphorus is the main cause of the poor water quality in the Bay.

Nitrogen and phosphorus are essential nutrients for plants and animals to survive. However, when too much of these nutrients enter the Bay, they fuel the growth of harmful algae blooms. These blooms block sunlight from reaching underwater vegetation and create dead zones during decomposition, robbing the water of oxygen and suffocating marine life.

Fertilizers, manure, and pesticides are common sources of nutrient runoff from farms. When more fertilizer or manure is applied to the land than crops can absorb, or when they are improperly stored, the excess nutrients can be carried by runoff into rivers and streams, eventually making their way into the Bay. Chemical fertilizers have been estimated to account for 17% of the nitrogen and 19% of the phosphorus entering the Bay. Similarly, manure contributes to 19% of nitrogen and 26% of phosphorus pollution.

While well-managed agricultural lands can offer benefits to the Bay watershed, such as restored rivers and streams, the excessive use of conventional farming practices can have detrimental effects. Conservation practices, such as those suggested by the Environmental Protection Agency, can help reduce nutrient runoff while maintaining productive farming operations. These include conservation tillage, cover crops, forest buffers, streamside fencing, and proper manure storage.

There are also steps that individual landowners can take to reduce nutrient runoff from their properties. This includes installing features such as green roofs, rain gardens, or rain barrels to capture and absorb rainfall. Using porous surfaces instead of asphalt or concrete and redirecting downspouts towards grass or gravel can also help mitigate runoff. Proper fertilizer usage and adopting alternative transportation methods to reduce air pollution are other effective ways to decrease nutrient pollution in the Bay.

Natural sources of air pollution

Lightning, for example, can produce nitrogen oxides (NOx) and other pollutants that contribute to poor air quality. Dust storms can pick up large amounts of dust and particulate matter, carrying them over long distances and affecting air quality in downwind regions. Forest fires, whether started by humans or lightning, release massive amounts of smoke and pollutants, including NOx, carbon monoxide, and volatile organic compounds, into the atmosphere. Volcanic eruptions inject enormous amounts of gases, ash, and aerosols into the stratosphere, with the potential to affect global air quality and climate.

In the Chesapeake Bay region, natural sources of air pollution play a role in the overall air quality and ecological health of the area. While specific data on the contribution of natural sources to air pollution in the Chesapeake Bay is limited, it is known that these natural sources, in combination with human activities, impact the region. For instance, lightning and dust storms are mentioned as natural sources of air pollution in the Chesapeake Bay region, contributing to the overall pollution levels.

Additionally, natural sources of pollution in the Chesapeake Bay region can also include agricultural activities. While human-managed agricultural operations are considered a separate category of pollution sources, natural processes within agricultural ecosystems can also contribute to air pollution. For example, livestock manure and fertilizer use can result in ammonia emissions, a form of nitrogen pollution, impacting the air quality in the region.

It is important to note that natural sources of air pollution are distinct from human-caused or anthropogenic sources, which often have a more significant impact on the environment. However, natural sources can still contribute to overall air pollution levels and are, therefore, an essential consideration when addressing air quality issues, especially in ecologically sensitive areas like the Chesapeake Bay.

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