Landfills: Local Environmental Pollution And Its Causes

Landfills are a necessary evil. They help us dispose of solid waste, prevent disease transmission, and keep our communities clean. However, they also have significant environmental and social impacts.

Landfills are a major contributor to the world's greenhouse gas emissions. As organic waste decomposes in landfills, methane, a greenhouse gas 84 times more effective at absorbing the sun's heat than carbon dioxide, is released into the atmosphere. This contributes to climate change. Landfills also produce carbon dioxide, water vapour, and trace amounts of other gases, which can create smog if left uncontrolled.

The creation of landfills often involves destroying natural habitats for wildlife. With over 3,000 active landfills in the US alone, as much as 1,800,000 acres of habitat have been lost.

While landfills are required to have plastic or clay lining, these liners often have leaks, resulting in leachate—a liquid produced by landfill sites—contaminating nearby water sources and further damaging ecosystems. Leachate can contain high levels of ammonia, which can cause eutrophication or dead zones in water sources, as well as toxins such as mercury.

Emissions from landfills also pose a threat to human health. Studies have found a link between living near landfills and an increased risk of congenital malformations, respiratory diseases, and other health issues. Additionally, landfills can decrease property values, create unpleasant odours, and attract vermin.

To reduce our reliance on landfills, we can recycle, avoid single-use plastics, and compost biodegradable items.

Methane emissions

Landfills are a major source of methane emissions, which contribute significantly to climate change. Methane is a greenhouse gas that is highly effective at absorbing heat in the atmosphere, with a potency 28 times higher than carbon dioxide over a 100-year period. Municipal solid waste landfills are the third-largest source of human-related methane emissions in the United States, accounting for about 14.4% of these emissions in 2022.

The release of methane from landfills occurs due to the decomposition of organic waste under anaerobic conditions. When municipal solid waste is initially deposited in a landfill, it undergoes aerobic decomposition, producing minimal methane. However, within less than a year, anaerobic conditions are established, and methane-producing bacteria start to break down the waste, leading to methane generation. Food waste, which comprises about 24% of municipal solid waste, is a significant contributor to methane emissions from landfills due to its rapid decay rate.

The Environmental Protection Agency (EPA) has estimated that landfills are the third-largest source of human-caused methane emissions in the U.S. However, a study by researchers at Harvard University found that the EPA's estimates might be underestimated. They used satellite observations and an atmospheric transport model to conclude that methane emissions from landfills were 51% higher than the EPA's estimates.

The impact of methane emissions from landfills extends beyond climate change. Methane emissions can also contribute to local air pollution and pose health risks to nearby communities. Methane is flammable and can reach explosive levels indoors. Additionally, methane and carbon dioxide from landfills can collect in nearby buildings, displacing oxygen and potentially causing health issues such as reduced coordination, fatigue, nausea, and unconsciousness.

To mitigate the environmental and health impacts of methane emissions from landfills, various control measures are implemented. These include collecting and treating landfill gas, also known as landfill gas energy projects. As of September 2024, there were 542 operational landfill gas energy projects in the United States, with 444 additional landfills identified as potential candidates for such projects. These projects not only help reduce methane emissions but also provide renewable energy, create jobs, and generate revenue for the community.

Air pollution

Landfills are a major source of air pollution, which can have detrimental effects on both the environment and human health. The air pollution caused by landfills is primarily due to the emission of gases, particularly methane, during the decomposition of organic waste.

Gases Emitted by Landfills

Landfills emit a variety of gases, including methane, carbon dioxide, ammonia, sulfides, vinyl chloride, ethyl benzene, toluene, and benzene. Methane and carbon dioxide are the most prevalent, accounting for 90-98% of landfill gas. The remaining 2-10% includes nitrogen, oxygen, ammonia, hydrogen, and trace amounts of other gases.

Effects of Landfill Gas on the Environment

The release of methane, a greenhouse gas, is a significant contributor to climate change. Methane is 84 times more effective than carbon dioxide at absorbing the sun's heat, making it highly potent in trapping heat in the atmosphere. In addition, methane and other gases emitted by landfills can contribute to smog formation if left uncontrolled.

Effects of Landfill Gas on Human Health

The gases emitted by landfills, particularly ammonia and hydrogen sulfide, are responsible for the objectionable odors associated with landfills. Short-term exposure to elevated levels of these gases can cause coughing, irritation of the eyes, nose, and throat, headaches, nausea, and breathing difficulties.

Additionally, studies have linked living near landfills with various health issues. For example, a study in New York found a 12% increased risk of congenital malformations in children born to families residing within a mile of a hazardous waste landfill.

Factors Affecting Gas Production in Landfills

The amount and rate of gas production in landfills depend on several factors, including the type of waste, the age of the landfill, oxygen content, moisture levels, and temperature. Gas production tends to increase with higher temperatures and moisture content. It typically reaches a peak after 5-7 years and can continue for more than 50 years.

Controlling Landfill Gas Migration

To mitigate the impact of landfill gases, modern landfills employ various control measures. Once a landfill reaches its maximum capacity, it is capped with several feet of cover material. Gas collection wells made of perforated pipes are installed to direct gases vertically towards the surface, where they are vented, burned, filtered, or used for energy recovery. Older landfills and smaller dumps may lack such control measures, increasing the risk of gas migration into nearby buildings and the surrounding environment.

Groundwater contamination

Landfills are a common method of waste management, but they pose a significant risk of groundwater contamination. This is due to the leachate produced by landfill sites, which can leak through the plastic or clay liners meant to contain waste, and contaminate nearby water sources.

Leachate is a liquid produced by the decomposition of waste in landfills. It contains high levels of ammonia, which, when nitrified, produces nitrate. Nitrate causes eutrophication, or a lack of oxygen, in nearby water sources, creating "dead zones" where animals cannot survive. Leachate also contains toxins such as mercury due to the presence of hazardous materials in landfills.

The impact of leachate on groundwater was studied in Erode, India, where three non-engineered landfill sites were found to be contaminating groundwater with high levels of Cl-, NO3-, SO42-, and NH4+. These contaminants were particularly elevated near the landfill sites, indicating that leachate percolation was significantly affecting groundwater quality. The contamination was also found to decrease with distance from the landfill sites, suggesting that the leachate was the source of the pollution.

Another study monitored a polluted aquifer for twenty-four years and found that the age of the waste was the most determining factor in the degree of groundwater pollution. Closing the landfill led to improved water quality, but the season had the least influence. The results showed that the aquifer could act as a natural treatment plant for the pollutants, but the groundwater could not be used for human consumption due to potential health risks.

Overall, landfills pose a significant risk of groundwater contamination due to leachate, which can leak through liners and contaminate nearby water sources. The impact of leachate on groundwater quality depends on various factors, including the chemical composition of the leachate, rainfall, and the distance of the contamination source.

Biodiversity loss

Landfills have a significant impact on biodiversity loss. Firstly, the creation of landfills involves clearing wild areas, which leads to habitat loss and degradation. This destruction of natural habitats for wildlife can affect thousands of species, with the average landfill size in the US being 600 acres.

Secondly, landfills release pollutants into the soil, water, and air, even after site closure. Leachate, a liquid produced by landfill sites, can contaminate nearby water sources. This can cause eutrophication, creating "dead zones" where animals cannot survive due to a lack of oxygen. Additionally, toxins such as mercury, pesticides, and solvents found in leachate can poison drinking groundwater for human use.

Furthermore, the gases emitted from landfills, such as methane, carbon dioxide, ammonia, and hydrogen sulfide, can have indirect effects on biodiversity. These gases contribute to climate change and can displace oxygen in enclosed spaces, leading to potential health risks for humans and other organisms.

Finally, landfills can directly affect bird species that feed on waste from landfills. For example, the white stork population in Central and Eastern Europe has shown a trend of nesting closer to landfills, although this has not been found to affect their breeding success. However, the ingestion of waste from landfills by birds can lead to choking, injury, or poisoning.

Overall, the environmental damage caused by landfills results in a loss of biodiversity, both directly and indirectly, through habitat destruction and pollution.

Health risks

Landfills pose a variety of health risks to nearby residents, including air pollution, water contamination, and exposure to heavy metals, all of which can lead to a range of illnesses.

Air Pollution

Air pollution caused by landfill operations and emissions can cause respiratory ailments like coughing, wheezing, shortness of breath, and eye and throat irritation. Pollutants such as dust, methane, and various volatile organic compounds are released into the air, which can be harmful to human health. The emissions from vehicles and machinery used in landfill operations can further exacerbate these issues.

Water Contamination

Landfills produce a toxic liquid called leachate as waste decomposes. Leachate can contaminate neighbouring soil and water sources, impacting the quality of drinking water and the health of aquatic species. It contains a variety of harmful substances, including heavy metals and organic compounds. If leachate-contaminated water is consumed by humans, it can cause sweating, general health issues, and the potential for disease transmission.

Heavy Metals Exposure

Heavy metals released from landfills, such as lead and mercury, can enter the environment through leachate and contaminate nearby soil and water sources. These substances can accumulate in the food chain, posing health risks to humans and wildlife. Exposure to heavy metals can lead to organ damage, reproductive issues, and even death.

Other Health Hazards

The unpleasant odours and visual pollution emanating from landfills can affect the quality of life for residents, and the sight of waste can alter the habitat and behaviour of wildlife. Landfills are also often constructed near low-income neighbourhoods and communities of colour, which means these communities are more likely to experience the health risks associated with landfills.

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