Chesapeake Bay Pollution: Understanding The Key Culprits

The Chesapeake Bay is affected by several types of pollution, including air pollution, nutrient pollution, and chemical contamination. Air pollution, caused by power plants, vehicle exhaust, and other human activities, contributes to the bay's poor air quality and has harmful effects on both ecosystems and human health. Nitrogen oxide pollution (NOx), sulfur dioxide pollution (SO2), and mercury pollution are the main types of air pollutants affecting the bay. Nutrient pollution, such as excess nitrogen and phosphorus, fuels the growth of algae blooms, blocking sunlight from reaching underwater grasses and creating dead zones with low oxygen levels that are detrimental to marine life. Chemical contaminants, including pesticides, pharmaceuticals, and metals, impair the bay's tidal waters, posing risks to both humans and wildlife.

Air pollution

There are four sources of air pollution in the Chesapeake Bay region: stationary and area sources, mobile sources, agricultural sources, and natural sources. Stationary sources include power plants, chemical manufacturing facilities, and manufacturing facilities. Mobile sources include cars, trucks, off-road vehicles, boats, airplanes, gas-powered lawn tools, and construction equipment. Agricultural sources include farm operations that emit gases, chemicals, or particulate matter, such as ammonia from livestock and poultry operations. Natural sources include lightning, dust storms, forest fires, and erupting volcanoes.

Nitrogen oxide pollution (NOx) is a significant issue for the Chesapeake Bay. NOx is a group of highly reactive gases that are released into the air when fuel is burned. Elevated levels of NOx are found in regions with a high density of fuel-burning vehicles and areas with power plants. NOx contributes to acid rain and deposits of excess nitrogen pollution, which harms the bay's ecosystem. It is estimated that about one-third of the bay's total yearly load of nitrogen pollution comes from the air. NOx emissions can irritate airways and pose risks to human health, particularly for children, the elderly, and those with respiratory ailments.

Sulfur dioxide (SO2) emissions occur when vehicles and heavy equipment burn fuel with a high sulfur content. SO2 contributes to damaging acid rain and can harm the growth of plants that sustain the bay's ecosystem.

Mercury pollution is another concern. Mercury is released into the air when coal, oil, natural gas, wood, or hazardous materials are burned, or when medical waste is burned. Mercury ends up in the waterways and can reach toxic levels in the tissue of fish and shellfish. A 2020 study found that the most contaminated fish in the Chesapeake Bay watershed include striped bass (rockfish), walleye, largemouth bass, and flathead catfish. Due to potentially harmful levels of mercury, anglers are warned to limit their consumption of certain fish species.

Other chemical contaminants polluting the Chesapeake Bay airshed include polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). PCBs were once used as dielectric and coolant fluids in electrical equipment, while PAHs are released into the air when coal, oil, gasoline, and other fossil fuels are burned. These chemicals can bind to sediment and enter the bodies of small, bottom-dwelling organisms, accumulating in the tissues of fish that consume them. As a result, fish consumption advisories are issued in areas where chemical contaminants are a concern.

To reduce air pollution in the Chesapeake Bay region, efforts should focus on maintaining forests that absorb airborne pollutants and enacting regulations to reduce emissions from vehicles and power plants. Alternative and renewable energy sources, low-emission vehicles, smart land-use planning, and innovative transportation methods can also help reduce air pollution.

Chemical contamination

One of the primary sources of chemical contamination in the Chesapeake Bay is atmospheric deposition, where pollutants emitted into the air eventually settle onto the land or water. This process contributes to the presence of harmful chemicals in the Bay's waters, such as nitrogen and mercury. Nitrogen oxides (NOx), produced by fuel-burning vehicles and power plants, are a significant source of nitrogen pollution in the Bay. These pollutants lead to the growth of algae blooms, which block sunlight from reaching underwater grasses and create low-oxygen "dead zones" that are detrimental to marine life.

Mercury pollution is another critical concern in the Chesapeake Bay. Mercury is released into the air when coal, oil, natural gas, and hazardous materials are burned, and it eventually finds its way into the waterways. Mercury can reach toxic levels in the tissue of fish and shellfish, leading to health risks for humans who consume these contaminated seafood sources. A 2020 study by the United States Geological Survey identified striped bass (rockfish), walleye, largemouth bass, and flathead catfish as the most contaminated fish species in the Bay watershed.

In addition to nitrogen and mercury, other chemical contaminants impacting the Chesapeake Bay include polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). PCBs were once used as dielectric and coolant fluids in electrical equipment, while PAHs are released during the burning of fossil fuels. These contaminants can bind to sediment and enter the food chain, accumulating in the tissues of fish and potentially affecting humans who consume contaminated seafood.

Agricultural sources also contribute to chemical contamination in the Chesapeake Bay. Farm operations that emit gases, chemicals, or particulate matter into the air can lead to chemical pollution in the water. Additionally, the use of pesticides and fertilizers in agriculture can result in chemical runoff into the Bay, further contributing to the problem.

To address the issue of chemical contamination in the Chesapeake Bay, efforts are being made to reduce emissions from vehicles and power plants, improve wastewater treatment processes, and promote sustainable agricultural practices that minimise the use of chemicals. By implementing regulations, utilising new technologies, and adopting more sustainable practices, it is hoped that the levels of chemical contamination in the Bay can be significantly reduced.

Nutrient runoff

The Chesapeake Bay ecosystem naturally contains nutrients; however, human activities have led to an unprecedented abundance. The removal of forest and wetland habitats to accommodate population growth has resulted in increased nutrient pollution in the Bay. Almost all industries and individuals within the watershed contribute nutrients to the Bay and its tributaries.

There are three main sources of nutrient runoff into the Chesapeake Bay: wastewater treatment plants, urban and agricultural runoff, and air pollution. Wastewater treatment plants have implemented measures to reduce nutrient discharges, and their nitrogen and phosphorus loads have significantly declined since 1985. However, urban and agricultural runoff remain significant contributors.

Lawn fertilizers, septic systems, and livestock manure are common sources of nutrient runoff from urban and suburban areas. Additionally, agricultural practices such as over-irrigation, over-tilling, and excessive use of fertilizers and pesticides can lead to nutrient pollution in rivers and streams, ultimately affecting the Bay.

Air pollution, primarily from vehicles, industries, and power plants, also plays a crucial role in nutrient runoff. Atmospheric deposition, where airborne pollutants fall onto land or water, contributes about one-third of the total nitrogen load entering the Chesapeake Bay.

The consequences of nutrient runoff in the Chesapeake Bay are severe. Excess nutrients, particularly nitrogen and phosphorus, have been identified as the main cause of the Bay's poor health. The resulting algae blooms block sunlight, and their decomposition creates low-oxygen environments, leading to the suffocation of marine life.

To address this issue, the Chesapeake Bay Program has implemented Watershed Implementation Plans aimed at reducing nutrient pollution. These plans include recommendations such as installing green roofs, rain gardens, and porous surfaces to capture and absorb rainfall, properly managing fertilizers, and reducing air pollution by encouraging walking, biking, or using public transportation.

Sediment pollution

The impact of sediment pollution is not limited to the Bay itself but also affects the species that depend on it. Oysters, for example, are sensitive to the water quality and can be severely affected by sediment pollution. Additionally, the sediment can smother underwater grasses, reducing the availability of food and habitat for many aquatic species.

Efforts to reduce sediment pollution in the Chesapeake Bay have been made, with the federal Clean Water Act (CWA) requiring states to identify polluted waterways and address the issue. However, progress has been challenging, and the Bay continues to face the adverse effects of sediment pollution, especially when combined with other types of pollution such as nutrient runoff and climate change.

The Chesapeake Bay's health is crucial for the region's ecosystem and the species that depend on it. By understanding the sources and impacts of sediment pollution, effective measures can be implemented to mitigate this issue and restore the Bay's health.

Invasive species

The Chesapeake Bay has become home to more than 200 known or possible invasive species. These nonnative species are plants, animals, or microbes that have been transported from one geographic region to an area where they did not live previously. When these species outcompete or prey upon native species, disrupt ecosystems, and reduce biodiversity, they are considered invasive.

Some of the most infamous invasive fish species in the Chesapeake Bay are the blue catfish, northern snakehead, and flathead catfish. These species were introduced to the bay without the Maryland Department of Natural Resources' authorization and have since spread throughout the bay and its tributaries. They eat native fish and other organisms, such as blue crabs and mussels, and can also spread viruses and diseases. For example, potentially fatal pathogens such as largemouth bass virus and mycobacteria are found in parts of the Chesapeake Bay and could expand their range by hitchhiking along with the highly mobile northern snakehead.

The Chesapeake Bay Program has an Invasive Catfish Workgroup that focuses on managing invasive catfish species in the bay. They have approved an Invasive Catfish Management Strategy to guide efforts to control the population of these invasive species.

One strategy to control the population of invasive fish species in the Chesapeake Bay is to encourage people to fish and eat them. Blue catfish, for example, are considered delicious and nutritious. By increasing public awareness and providing recipes, resource managers hope to increase the consumption of this invasive species.

Frequently asked questions