The Everglades: Pollution's Impact On A Delicate Ecosystem

The Everglades, a unique and treasured landscape, is under threat from pollution. The ecosystem, which is the largest subtropical wilderness in the United States, is a haven for over a million visitors annually. However, it faces alarming challenges from climate change and air pollution, which originate from industrial sources and emissions that can travel hundreds of miles. The delicate balance of the Everglades' aquatic ecosystems is disrupted by the deposition of pollutants such as nitrogen compounds, and the park's wildlife is at risk.

Eutrophication and acidification

The Everglades is particularly sensitive to eutrophication due to the influx of nutrients from agricultural runoff and emissions from nearby power plants. Agricultural runoff contains high levels of phosphorus, which has led to phosphorus enrichment in the Everglades. This has disrupted the natural balance of the ecosystem, causing an increase in some species and a decrease in others. The excess phosphorus in the water comes from fertilizer applications and enters the Everglades through stormwater runoff.

In addition to agricultural runoff, water discharged from the Everglades Agricultural Area (EAA) canals is also contributing to the problem by loading the public Everglades with excess phosphorus, carbon, and sulfur. As a result, the Everglades is experiencing a decline in water quality, with high levels of phosphorus, carbon, nitrogen, and sulfur. This has negatively impacted the plant and animal life in the region, as these nutrients can cause changes to soil nutrient cycling and disrupt the delicate balance of the aquatic ecosystems.

Acidification, while not as much of a concern in the Everglades due to the buffering capacity of its freshwater and saltwater ecosystems, can still have detrimental effects. Acidification can leach important cations from soils and water bodies, reducing habitat quality. Additionally, acid rain, caused by sulfur dioxide and nitrogen oxide emissions from industrial activities, can also contribute to acidification.

The effects of eutrophication and acidification on the Everglades are complex and interconnected. The increase in nutrient levels due to eutrophication can have cascading effects on the ecosystem, impacting both plant and animal life. Acidification can further exacerbate these issues by reducing the availability of essential cations, making it more difficult for plants and animals to thrive.

Mercury contamination

Mercury enters the Everglades in several ways. Firstly, its proximity to industrial, agricultural, and residential areas means that polluted runoff can easily spread across the landscape. The burning of fuels, medical waste, and sugarcane fields can also cause mercury to become airborne and eventually reach bodies of water.

Once mercury comes into contact with water, it undergoes a series of microbial processes that turn it into methylmercury, an organic, toxic form of mercury that can be readily absorbed by living organisms. Methylmercury then accumulates in the food chain, increasing in concentration as predators consume their prey. This process, known as biomagnification, results in dangerous levels of mercury in larger animals and top predators such as the Florida panther, alligators, and birds.

The effects of mercury contamination in the Everglades have been observed in various species. For example, high levels of mercury have been found in the feathers of wading birds, leading to disoriented behaviour and reduced breeding success. In fish, mercury concentrations have exceeded the EPA threshold for human consumption, with largemouth bass in particular showing high levels of mercury. Additionally, pythons have been found to harbour excessive mercury in their muscle tissue, puzzling researchers about their survival.

The issue of mercury contamination in the Everglades is further complicated by the presence of sulfate, another common pollutant in the area due to agricultural runoff. Sulfates stimulate bacteria that reduce sulfate but also methylate inorganic mercury, increasing the production of methylmercury. Cattails, which are common in the Everglades, can also draw in airborne mercury and contribute to the methylation process.

While efforts have been made to reduce mercury water pollution in the Everglades, it is challenging to completely remove mercury and its effects from the ecosystem in the short term. The long-term presence of mercury in the environment means that methylation can continue to occur for many years.

Phosphorus contamination

The EAA, located in South Florida, has a long history of agriculture. From the 1940s to the 1980s, the region was heavily fertilized with phosphorus-rich fertilizers, leading to high amounts of phosphorus in the soil. When groundwater drains through this soil, it picks up the phosphorus and moves it into Lake Okeechobee, the "liquid heart" of the Everglades. Lake Okeechobee is a vital source of water that feeds the Everglades.

The excess phosphorus in Lake Okeechobee has caused toxic algae blooms, which kill aquatic animals and plants and further pollute the main water source for the Everglades. These algae blooms cover the lake surface, blocking sunlight from reaching the aquatic plants. As a result, the plant life dies, depriving the lake of oxygen and leading to the death of aquatic life.

The high levels of phosphorus in the Everglades have also led to excessive growth of cattails and other vegetation that was previously sparse or absent in the region. This vegetation crowds out native Everglades plants that are favored by wildlife. Additionally, the increasing phosphorus concentrations in surface waters promote the growth of organisms such as algae and duckweed, altering the habitats of aquatic and non-aquatic wildlife.

Agricultural runoff containing phosphorus has impaired water quality in large portions of the Everglades, particularly in Lake Okeechobee. The Caloosahatchee and St. Lucie estuaries, including parts of the Indian River Lagoon, have been significantly impacted by high and variable freshwater discharges carrying nitrogen, phosphorus, and other contaminants. These discharges also alter the salinities that control the abundance of estuarine organisms.

The phosphorus contamination in the Everglades is challenging to address due to its persistence in the environment. Phosphorus forms strong chemical bonds with soil, resulting in a slow release over time. There is currently no effective plan to remove or neutralize the phosphorus in Lake Okeechobee.

To mitigate the impact of phosphorus contamination, efforts have been made to reduce phosphorus fertilizer use in the EAA through the implementation of Best Management Practices (BMPs). Additionally, Stormwater Treatment Areas, constructed wetlands designed to remove phosphorus from water before it reaches the Everglades, have been established. While these approaches have helped reduce phosphorus levels, more work is needed to achieve the water quality goals throughout the system.

Climate change

The Everglades, a unique and fragile ecosystem in South Florida, is highly susceptible to the impacts of climate change. Being a low-lying and flat wetland ecosystem, the region is extremely vulnerable to rising sea levels, changes in precipitation patterns, and increased temperatures. These factors have significant effects on the hydrology, flora, and fauna of the Everglades, as well as the wider South Florida region.

Rising Sea Levels

One of the most significant threats posed by climate change to the Everglades is the rise in sea levels. As global temperatures increase, polar ice caps and glaciers melt, causing a rise in global sea levels. For the Everglades, this means that the saltwater from the adjacent Florida Bay and the Atlantic Ocean can intrude further inland. This saltwater intrusion changes the natural balance of the Everglades' freshwater ecosystem, affecting the flora and fauna that have adapted to these specific conditions. The higher salinity levels can kill freshwater vegetation, alter soil chemistry, and reduce the availability of suitable habitats for many species, including the iconic American alligator and various bird species.

Changes in Precipitation Patterns

Increased Temperatures and Extreme Weather

The Everglades, like many other regions, is also experiencing rising average temperatures due to climate change. Warmer temperatures can directly impact the health and distribution of plant and animal species. For example, increased temperatures may favor the expansion of invasive plant species that can outcompete native vegetation, disrupting the natural balance of the ecosystem. Warmer waters can also affect the health and distribution of aquatic species, including fish and amphibians, with potential knock-on effects on the food chain. In addition, higher temperatures contribute to more frequent and intense extreme weather events, such as hurricanes and tropical storms, which can cause significant damage to the Everglades' fragile ecosystem.

Ecological Disruptions and Loss of Biodiversity

The combined effects of rising sea levels, altered precipitation patterns, and increased temperatures have far-reaching consequences for the Everglades' biodiversity. These climate change impacts interact with other stressors, such as pollution and habitat fragmentation, to further threaten the survival of many species. The loss of biodiversity in the Everglades would not only be an ecological tragedy but also a cultural and economic one, as the region is renowned for its unique flora and fauna, which attract tourists and support local communities.

Addressing the impacts of climate change on the Everglades requires a multi-faceted approach, including the implementation of adaptation strategies, the restoration of natural hydrology, and the mitigation of greenhouse gas emissions to slow down the rate of climate change. It is crucial to recognize the urgency of these actions to protect this ecologically rich and unique wetland ecosystem for future generations.

Air pollution

One of the primary concerns regarding air pollution in the Everglades is the high levels of mercury found in the park. Mercury is a toxic contaminant that can enter the food chain and pose risks to both human and wildlife health. It is introduced into the Everglades through human activities such as coal-burning power plants and agricultural practices. The agricultural industry's use of fertilizers and pesticides contributes to mercury contamination in the park. Additionally, mercury can be transported over long distances through the atmosphere, making it challenging to mitigate this issue. Mercury levels in the Everglades are among the highest in the United States, and they have not shown a significant decrease despite reductions in local emissions.

The conversion of the northern Everglades into the Everglades Agricultural Area (EAA) has had a significant impact on the ecosystem. Historically, the northern Everglades acted as a natural nutrient-removal system, but with agricultural development, it became a nutrient source. Stormwater from the EAA contains high levels of phosphorus from fertilizer applications, often exceeding 500 ppb. This excess phosphorus has led to eutrophication, causing overgrowth of certain plant species and disrupting the natural balance of the Everglades' aquatic ecosystems. Efforts have been made to address this issue, including the construction of Stormwater Treatment Areas (STAs) to remove phosphorus before water is discharged into the Everglades.

Nitrogen and sulfur compounds are also deposited in the Everglades through air pollution. These compounds contribute to eutrophication and acidification, which alter the composition of plant and animal communities. Nitrogen deposition affects wetland species adapted to the historically low-nutrient environment of the Everglades. It promotes dense blooms of phytoplankton, which deplete oxygen levels in the water and negatively impact fish and wildlife populations.

Ozone is another air pollutant that affects the Everglades. Ground-level ozone is formed when nitrogen oxides from vehicle exhaust, power plants, and other sources combine with volatile organic compounds in the presence of sunlight. It causes respiratory problems in people and injures plants, including ozone-sensitive species like the American elder and smooth cordgrass found in the park.

The air pollution in the Everglades has led to a reduction in visibility, with the actual visual range being about 40 miles, compared to the expected 100 miles without pollution. On high pollution days, the visual range can drop below 20 miles.

The complex interplay of various pollutants and their impacts on the Everglades underscores the urgency of addressing air pollution to protect this fragile ecosystem. Efforts to curb pollution sources, improve water treatment, and enhance ecosystem restoration are ongoing, but the future of the Everglades remains uncertain.

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