Wildlife Impacted By Mississippi River Water Pollution

Water pollution in the Mississippi River has had a detrimental impact on the region's wildlife, with stretches of the river exceeding water quality standards for mercury, bacteria, sediment, PCBs, and nutrients. These pollutants have made the water unsuitable for activities like fishing, swimming, and drinking. The river's water quality is influenced by various human activities, including intensive farming practices, industrial waste discharges, and urbanization. The accumulation of silt and sedimentation, for instance, poses a significant threat to fish and wildlife habitats, covering up spawning grounds and facilitating the transport of contaminants. Furthermore, the excessive use of fertilizers and pesticides in agriculture leads to nutrient loading and eutrophication, resulting in the depletion of dissolved oxygen and the death of marine life. The presence of toxic chemicals, such as nitrate, nitrite, and ammonium, also poses risks to both human and aquatic life, with long-term exposure potentially leading to health issues. While efforts have been made to improve water quality, the complex nature of the Mississippi River system and the interplay of various factors continue to present challenges in mitigating the negative impacts of water pollution on the region's wildlife.

Mercury and PCB contamination

Mercury, a heavy metal, is another critical contaminant in the Mississippi River. It accumulates in the muscle tissue of animals and people, primarily entering the food chain through atmospheric deposition and coal-burning power plants. Mercury concentrations in fish have led to consumption advisories for many lakes and streams. While some mercury occurs naturally, human activities have introduced additional mercury into the environment through sources such as dental amalgams, thermostats, thermometers, and batteries.

The presence of these contaminants in the Mississippi River has impacted the wildlife that relies on the river and its surrounding habitats. The accumulation of PCBs and mercury in fish and other aquatic organisms can result in bioaccumulation and biomagnification, leading to health issues in predators and humans who consume them. These contaminants can cause reproductive issues, growth problems, and increased cancer risks.

To address these issues, long-term monitoring of mercury and PCB levels has been conducted for over 20 years. Additionally, efforts have been made to control the use and release of mercury to prevent further environmental contamination. However, the cleanup process is complex and will require years of coordinated efforts to implement effective pollution-reduction plans.

Eutrophication and hypoxia

Agricultural runoff is a major contributor to eutrophication in the Mississippi River. Fertilizers, pesticides, and manure from farms are washed into the river during rainfall or snowmelt, adding high levels of nutrients such as nitrogen and phosphorus to the water. These excess nutrients act as a fertilizer for algae, causing rapid and excessive growth, known as algal blooms. As the algae die and decompose, they are consumed by bacteria, which use up the oxygen in the water, leading to hypoxia.

Hypoxia, or oxygen depletion, occurs when the concentration of dissolved oxygen falls below 2-3 milligrams of oxygen per liter of water. This creates "dead zones" where normal populations of fish, shellfish, and other aquatic life cannot survive due to lack of oxygen. The Gulf of Mexico, into which the Mississippi River flows, experiences a massive hypoxic zone every summer. This zone, located off the coast of Louisiana and Texas, is the largest in the United States and one of the largest globally.

The direct effects of eutrophication and hypoxia on wildlife are significant. Fish kills are a common occurrence in hypoxic zones, depleting fisheries and disrupting ecosystems. Less mobile or immobile animals, such as mussels and crabs, are particularly vulnerable and often succumb during hypoxic events. Additionally, eutrophication and hypoxia can cause physiological, developmental, and reproductive abnormalities in fish. The reduction in fish populations also impacts species that rely on them as a food source, further propagating the ecological damage.

The Mississippi River and its surrounding ecosystems are suffering from the cumulative effects of eutrophication and hypoxia. While efforts are being made to address these issues, such as the establishment of the Mississippi River/Gulf of Mexico Hypoxia Task Force, the challenges posed by these environmental concerns are complex and persistent.

Bioaccumulation of pollutants in the food chain

The Mississippi River is a source of drinking water for about 70 cities. However, it is contaminated with pollutants that affect wildlife and human health. These contaminants include pesticides, pharmaceuticals, personal care products, and wastewater indicators.

Bioaccumulation is a process where an organism absorbs a contaminant faster than it can excrete it, leading to a buildup of the substance in its tissues over time. This can impact the organism's ability to survive and reproduce. In the Mississippi River, bioaccumulation of pollutants in the food chain has been observed, particularly in bald eagles and fish.

One example of bioaccumulation in the Mississippi River is the presence of polychlorinated biphenyls (PCBs). PCBs are man-made chemicals that were widely used in industrial applications until the late 1970s due to their chemical and thermal stability. They were found in fluorescent light fixtures, carbonless paper, adhesives, plastics, paints, varnishes, and sealants. However, it was later discovered that prolonged exposure to even small concentrations of PCBs can cause liver damage, cancer, and growth and developmental problems. As a result, the manufacture of PCBs was banned in 1979.

PCBs are highly persistent in the environment due to their stable nature, which prevents them from breaking down into less toxic chemicals. They can be transported over long distances and are often found in rivers through atmospheric deposition or runoff from agricultural lands. Once PCBs enter the aquatic environment, they are incorporated into the food chain and undergo biomagnification, becoming progressively more concentrated in the upper levels of the food web. This means that top predators, such as bald eagles, are at risk of accumulating high levels of PCBs, which can have detrimental effects on their health and population.

Another contaminant that bioaccumulates in the Mississippi River is mercury. Mercury is a heavy metal that accumulates in the muscle tissue of animals and humans. It can also undergo biomagnification in the food chain. Sources of mercury include coal-burning power plants, dental amalgams, thermostats, thermometers, and batteries. Efforts have been made to control mercury releases into the environment due to health concerns. However, mercury concentrations in fish tissue have led to fish consumption advisories for many lakes and streams, primarily due to atmospheric deposition.

Agricultural runoff is a significant contributor to water pollution in the Mississippi River. Excess fertilizers and pesticides used in farming can be carried by rainwater or melting snow into the river, leading to nutrient loading and eutrophication. Eutrophication is the process by which a body of water becomes enriched with nutrients, stimulating excessive growth of aquatic plant life, which can deplete oxygen levels and lead to the death of marine life.

In summary, bioaccumulation of pollutants in the food chain is a significant issue in the Mississippi River. Contaminants such as PCBs and mercury accumulate in the tissues of organisms and undergo biomagnification, posing risks to the health and survival of top predators. Agricultural practices and industrial activities contribute to the presence of these pollutants in the river, highlighting the need for effective pollution reduction strategies to protect the ecosystem and human health.

Industrial and municipal wastewater

Sources of Industrial and Municipal Wastewater Pollution

• Urban Areas: Cities and towns along the Mississippi River contribute organic compounds, synthetic chemicals, and untreated sewage to the river. While pollution from these sources has been reduced, it still poses a problem.
• Farms: Agricultural practices, including the use of pesticides and fertilizers, result in nutrient loading and eutrophication. This type of non-point source pollution is challenging to regulate.
• Factories: Industrial facilities discharge a range of organic wastes and synthetic chemicals into the river. Some specific examples include pulp mills releasing organic chemicals and power plants using chemicals in their cooling water.
• Individual Households: Residential areas contribute organic compounds and synthetic chemicals to the river through everyday activities.

Contaminants and Their Effects

• Organic Compounds: Organic wastes from various sources can be detrimental to human and aquatic health. These include surfactants, caffeine, and EDTA (a complexing agent).
• Synthetic Chemicals: Thousands of new synthetic chemicals have entered the river since World War II, and their environmental impact is still being understood.
• Untreated Sewage: Fecal coliform bacteria, resulting from untreated sewage, can reach concentrations of up to millions of bacteria per liter, posing a significant health risk.
• Heavy Metals: Mercury, PCBs, and other heavy metals accumulate in the river sediment and the food chain, leading to potential health issues such as liver damage and cancer.
• Nutrients: Excess nutrients, particularly nitrogen and phosphorus, from agricultural runoff, contribute to eutrophication and the formation of hypoxic "dead zones" in the Gulf of Mexico.

Impact on Wildlife

The release of industrial and municipal wastewater into the Mississippi River has severe ecological consequences. The introduction of contaminants and excess nutrients leads to the degradation of aquatic habitats and the decline of fish populations. Hypoxia, or low oxygen levels, in the Gulf of Mexico caused by nutrient runoff results in fish kills and a decrease in overall biodiversity in the affected areas. Additionally, the accumulation of pollutants in the river sediment and the food chain poses risks to both aquatic organisms and humans who consume fish from the river.

Agricultural runoff

Agricultural practices such as intensive farming strip nutrients from the soil. Farmers then need to add fertilizers to the soil to replace these nutrients and boost crop yields. Corn (maize), the number one crop in the United States, is very sensitive to nutrient-poor soil. As a result, farmers tend to over-fertilize their crops to avoid lower yields and poor-quality produce. This excess fertilizer becomes a problem when it is carried into a body of water through runoff or leaching. Runoff occurs when water from rainfall or melting snow moves over the ground, picking up excess nutrients and other sediments as it flows towards bodies of water.

In addition to the environmental impact, agricultural runoff can also have public health consequences. High levels of nitrate in drinking water, which can come from fertilizer use, have been linked to various health issues such as kidney dysfunction and blue baby syndrome. There is also growing attention to the potential link between consuming water with high nitrate levels and other health conditions such as colorectal cancer, thyroid disease, and birth defects.

While there have been efforts to address agricultural runoff, such as the Clean Water Act and incentive programs, it remains a significant challenge to effectively regulate and reduce this type of pollution.

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