Groundwater Pollution: 5 Common Contamination Sources

Groundwater is a source of drinking water for more than half of US residents, but it is vulnerable to contamination. In the 1980s, a community in New Jersey experienced the effects of groundwater pollution when chloroform, arsenic and other dangerous substances made their way into the local aquifer. There are at least five ways that groundwater can be polluted.

Agricultural pesticides and fertilisers

Groundwater can be polluted by agricultural pesticides and fertilisers in several ways. Firstly, these substances can be carried by surface water, such as rainfall, snowmelt, or irrigation runoff, and infiltrate the groundwater through the soil. This can occur when pesticides and fertilisers are applied to crops or fields and then washed away by precipitation or irrigation. Additionally, if these chemicals are not properly stored or disposed of, they can leak or be dumped onto the land, eventually making their way into the groundwater.

Another way that agricultural pesticides and fertilisers can pollute groundwater is through the use of irrigation water. If the irrigation water source is already contaminated with these chemicals, either from surface runoff or improper disposal, the water applied to crops can carry the pollutants into the soil and eventually reach the groundwater. This is especially concerning in areas with shallow water tables or permeable soils.

Furthermore, the improper disposal of agricultural pesticides and fertilisers can also lead to groundwater pollution. If these chemicals are dumped or buried in landfills that do not meet federal standards or lack proper protective measures, they can leach into the groundwater over time. Even modern landfills with protective liners and monitoring systems can sometimes fail, allowing pollutants to escape and contaminate nearby groundwater sources.

Oils and salts from roadways

Oils and salts can also enter the groundwater through corroded underground storage tanks for gasoline or oil. These tanks can leak their contents into an aquifer, which can then contaminate the groundwater.

Additionally, pollutants released into the atmosphere, such as those from vehicles, can eventually return to the earth carried by rain, snow, and other forms of precipitation. These pollutants can then make their way into the groundwater.

Furthermore, older dumps and landfills that do not have modern protective measures in place can also contribute to groundwater contamination. Runoff and leaching from these sites can carry oils and salts, among other pollutants, into streams, groundwater, springs, and wells.

Industrial effluents

Once on the ground, these chemicals can leach through the soil and contaminate groundwater. This can happen when industrial effluents are improperly discarded or dumped on the land. Groundwater is particularly vulnerable to contamination from surface water, as it can infiltrate through the soil or run off into areas where the water table is above the ground surface.

Another way in which industrial effluents can pollute groundwater is through buried or drilled sources. For example, underground storage tanks for gasoline or oil can corrode and leak their contents into an aquifer. This can have serious environmental and health impacts, as polluted groundwater can become unsafe for people to drink and can harm plants, domestic animals and wildlife.

To prevent groundwater pollution from industrial effluents, proper waste management and disposal practices are essential. Modern landfills that meet federal standards are designed to prevent runoff from leaching into groundwater. This includes careful site selection, the installation of protective landfill liners and leachate collection and treatment systems, and the use of monitoring wells to check for contamination. However, these protective measures may sometimes fail, and older dumps and landfills may not have had these protections in place.

Highway deicing

Groundwater can be polluted in several ways, one of which is highway deicing. Highway deicing involves the use of chemicals to melt ice and snow on roads and highways. While this practice is essential for ensuring safe driving conditions during winter months, it can also have negative environmental impacts, including groundwater pollution.

Deicing chemicals, such as salt and other chemical compounds, are often applied to roadways to lower the freezing point of water and prevent the formation of ice. While effective, these chemicals can be washed into nearby water bodies and eventually infiltrate groundwater supplies. As the deicing chemicals melt ice and snow, they create a brine solution that can seep into the ground and contaminate underlying aquifers.

Additionally, the use of salt for deicing can increase the salinity of groundwater, particularly in areas with high water tables or where the water table is above the ground surface. This can lead to water quality issues, as excessive salt concentrations can make water unsuitable for drinking, irrigation, or industrial use.

To mitigate the impact of highway deicing on groundwater, several measures can be implemented. One approach is to use alternative deicing agents that are less harmful to the environment. These could include organic or biodegradable compounds that are less likely to persist in the environment and have a lower potential for groundwater contamination.

Another strategy is to improve the application methods of deicing chemicals. By optimising the timing, dosage, and placement of deicing agents, it is possible to minimise their environmental impact while still achieving the desired ice-melting effect. This may involve using advanced weather forecasting and road condition monitoring systems to apply deicing chemicals only when and where they are most needed.

Furthermore, implementing proper storage and handling practices for deicing chemicals can help prevent accidental spills and leaks that could contaminate groundwater. This includes using corrosion-resistant storage tanks and implementing regular maintenance and inspection programmes to identify and repair any potential leaks promptly.

Chloroform, arsenic and other dangerous substances

Groundwater can be contaminated by chemicals, bacteria or saltwater. One way this can happen is through the improper disposal of chemical waste, which can leach through the soil and contaminate groundwater. This includes hazardous wastes such as chloroform, arsenic and other dangerous substances. These can be buried or placed in open pits, or simply dumped on the land.

Another way that groundwater can be polluted is through the use of agricultural pesticides and fertilisers, oils and salts from roadways, and industrial effluents. These pollutants can be carried by surface water into the groundwater.

Corroded underground storage tanks for gasoline or oil can also leak their contents into an aquifer, contaminating groundwater.

Finally, pollutants released into the atmosphere can eventually return to the earth, carried by rain, snow and other forms of precipitation. These pollutants can then make their way into the groundwater.

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