Pollution's Impact On Chesapeake Bay: A Worrying Reality

The Chesapeake Bay is a large estuary located in the US state of Maryland. It is an important natural resource that supports recreation, business, tourism, and learning. Unfortunately, the bay is facing significant threats from pollution, particularly air pollution. Air pollution emitted by cars, trucks, power plants, and other sources can have detrimental effects on the health of the bay and its surrounding waterways. This pollution falls back to Earth, where it can be washed into rivers and streams that flow into the bay. In this paragraph, we will explore the impact of pollution on the Chesapeake Bay and discuss ways to mitigate its effects.

Air pollution from vehicles and power plants

Air pollution is a major threat to the Chesapeake Bay and its living communities. The air over the Chesapeake region travels from as far away as Canada in the north and Indiana and Kentucky in the west. This "airshed" is 570,000 square miles, more than nine times the watershed itself.

Vehicles and power plants are significant contributors to air pollution in the Chesapeake Bay region. Cars, trucks, and other vehicles emit harmful pollutants such as nitrogen oxides (NOx) and sulfur dioxide (SO2). NOx is released into the air when fuel is burned and is commonly found in regions with a high density of fuel-burning vehicles. It affects both humans and the environment, contributing to acid rain and excess nitrogen deposits, which harm the Bay's ecosystem. SO2 emissions occur when vehicles burn fuel with a high sulfur content, and they also damage the growth of plants that sustain the Bay's ecosystem.

Power plants are another significant source of air pollution in the region. They release nitrogen oxides and mercury into the atmosphere, which can travel long distances and fall onto the land and water. Mercury is released when coal, oil, or natural gas is burned, and it can reach toxic levels in the tissue of fish and shellfish, posing risks to human health.

The impact of air pollution on the Chesapeake Bay is significant. Airborne pollutants contribute to about one-third of the total nitrogen loads in the Bay, affecting the health of local waters. When pollutants fall onto the land or directly into the water, they fuel the growth of algae blooms, which block sunlight from reaching underwater grasses and create low-oxygen "dead zones" that suffocate marine life.

To address this issue, efforts are being made to reduce emissions from vehicles and power plants. This includes advocating for alternative and renewable energy sources, low-emission vehicles, and smart land-use planning. Additionally, maintaining forests that absorb airborne pollutants and enacting regulations to reduce emissions are crucial steps in mitigating air pollution across the watershed.

Nitrogen oxide pollution

NOx emissions contribute to acid rain, which harms the Bay's ecosystem. They also cause excess nitrogen pollution, which enters the Bay through a process called atmospheric deposition. This occurs when airborne pollutants fall onto land or water, either as dry particles or attached to rain, snow or other precipitation. The Chesapeake Bay's airshed, the area of land over which airborne pollutants can travel to enter the Bay, is approximately 570,000 square miles, stretching from Canada in the north to South Carolina in the south. This means that nitrogen oxide pollution from outside the immediate region can still impact the Bay.

Nitrogen is one of the biggest sources of pollution affecting the Chesapeake Bay. It is estimated that around one-third of the nitrogen polluting the Bay comes from the air. This excess nitrogen fuels the growth of algae blooms, which block sunlight from reaching underwater plants and create low-oxygen "dead zones" that suffocate marine life.

Sources of nitrogen oxide emissions that impact the Bay include vehicles, industries, power plants and electric utilities. To reduce nitrogen oxide pollution, individuals can take steps such as driving less, carpooling and using public transportation.

Sulphur dioxide pollution

Sulphur dioxide (SO2) is a toxic gas and part of a larger group of chemicals called sulphur oxides. Sulphur dioxide emissions occur when vehicles, heavy equipment, and power plants burn fuel with a high sulphur content. Diesel vehicles were once a major source of SO2 emissions, but federal regulations to reduce the sulphur content in diesel fuels have significantly lowered emissions.

Sulphur dioxide is a contributor to damaging acid rain, which can harm trees and plants, inhibit plant growth, and damage sensitive ecosystems and waterways. In the Chesapeake Bay region, SO2 emissions can damage the growth of plants that sustain the Bay's ecosystem.

Sulphur dioxide also poses risks to human health. It can contribute to respiratory illness and aggravate existing heart and lung conditions. Sulphur dioxide emissions can create secondary pollutants such as sulphate aerosols, particulate matter, and acid rain, which can have further environmental and health impacts.

To reduce sulphur dioxide pollution in the Chesapeake Bay region, regulations and efforts to reduce emissions from vehicles, power plants, and other sources are necessary. This includes the implementation of alternative and renewable energy sources, low-emission vehicles, and smart land-use planning.

Mercury pollution

Mercury is a highly toxic chemical that is particularly harmful to the developing nervous system, and can cause IQ deficits in children. Fetuses, infants, children, and women of childbearing age are at the greatest risk of harm from mercury. Mercury is a natural element, but two-thirds of the mercury moving through the environment is a product of human activities.

Coal-fired power plants are the largest source of mercury air emissions in the US, accounting for more than 40% of the pollution. When coal is burned to generate electricity, mercury is released from smokestacks and washed into the Chesapeake Bay by rain.

Once mercury is in the water, biological processes can turn it into a highly toxic form called methylmercury. Plankton absorb methylmercury from the water and sediment, and fish eat the contaminated plankton and smaller fish. The methylmercury accumulates in their tissues. Humans then consume the contaminated fish, accumulating mercury in their bodies.

The amount of mercury in fish tissue can be more than a million times higher than in the surrounding water. According to a 2020 study by the United States Geological Survey, the most contaminated fish in the Chesapeake Bay watershed include striped bass (rockfish), walleye, largemouth bass, and flathead catfish.

To protect public health and the natural resources of the Chesapeake Bay, the EPA proposed the Mercury and Air Toxic Standards (MATS) rule, which would have required power plants to cut mercury emissions by at least 90%. However, after pushback from the coal industry, EPA published proposed revisions in February 2019, and in April 2020, determined that it was no longer “appropriate and necessary” to limit toxic air emissions of mercury from coal- and oil-fired power plants. This decision will increase mercury emissions within the Chesapeake Bay airshed, posing a health risk to individuals who consume contaminated fish.

Phosphorus pollution

Phosphorus is one of the three major pollutants affecting the health of the Chesapeake Bay. Phosphorus is a vital nutrient for plant life, but human activities—such as applying fertilizers or using household cleaners—contribute more phosphorus than the Bay can handle. Elevated phosphorus levels cause an increase in algae growth, which blocks sunlight and reduces oxygen levels in the water, harming fish, crabs, and other marine life.

The amount of phosphorus that enters the Chesapeake Bay varies from year to year and is strongly correlated with rainfall levels. Spikes in phosphorus runoff, such as those observed in 2011 and 2019, are typically due to above-average rainfall. The primary sources of phosphorus pollution are wastewater treatment plants, urban and agricultural runoff, and air pollution.

Agricultural runoff is a significant contributor to phosphorus pollution in the Bay, accounting for about 45% of the total phosphorus entering the waterway. Manure is one of the largest sources of phosphorus, and the use of phosphorus-rich poultry litter as fertilizer is a particular concern in Maryland's Eastern Shore region, where the Choptank River is the only major river experiencing rising phosphorus pollution levels.

Maryland has implemented the Phosphorus Management Tool (PMT), a science-based method to identify fields with high phosphorus levels and a high risk of phosphorus runoff. The PMT helps to limit manure applications in these areas and encourages farmers to adopt techniques that reduce or slowly draw down excess phosphorus. As a result of these efforts, Maryland is on track to meet its statewide phosphorus reduction goals.

By 2023, practices put in place to reduce phosphorus pollution in the Chesapeake Bay were estimated to have achieved 67% of the necessary reductions to meet applicable water quality standards by 2025.

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