Nonpoint Air Pollution: Everyday Examples And Their Impact

Nonpoint source pollution is a type of pollution that is difficult to trace back to a single source or point. Nonpoint source pollution is caused by rainfall or snowmelt moving over and through the ground, picking up and carrying away natural and human-made pollutants, and depositing them into lakes, rivers, wetlands, coastal waters, and groundwater. NPS pollution affects both water and air quality. Examples of NPS air pollution include smokestacks and car tailpipes.

Agricultural activities

Pesticides, for example, can directly contaminate bodies of water used for crop irrigation or aquatic plant control. They can also indirectly pollute surface waters through air transport and subsequent deposition or runoff from fields. Additionally, pesticides can seep into the soil and contaminate groundwater. The use of fertilisers in agricultural fields can also lead to nutrient pollution, as excess nutrients can be transported by runoff into nearby water bodies, impacting aquatic ecosystems. Livestock management is another contributor, as bacteria from manure and the concentration of animals in confined spaces can result in water pollution.

To address these issues, various best management practices (BMPs) can be implemented. These practices aim to reduce the negative environmental impacts of agricultural activities. Structural BMPs involve the construction of physical structures such as contour farming, fencing, and sediment basins to prevent pollution. Non-structural BMPs focus on pollution reduction at the source through effective water management, weed management, and the use of cover crops. Adopting conservation tillage practices, such as zero tillage, can help prevent soil erosion and improve soil fertility. Proper waste management techniques, such as avoiding stubble burning, can also reduce air pollution and health risks associated with agricultural activities.

The National Water Quality Initiative (NWQI) in the United States is an example of a collaborative effort to improve water quality by implementing on-farm conservation systems that control runoff in high-priority watersheds. Water quality monitoring is a critical component of this initiative, as it helps assess the impact of agricultural activities on water bodies and guides the implementation of effective conservation practices. By adopting these practices and initiatives, the agricultural sector can play a significant role in mitigating non-point source pollution and improving overall environmental quality.

Urban stormwater runoff

Nonpoint source pollution is any pollution that cannot be traced back to a single source or point, such as a pipe. Instead, nonpoint source pollution has multiple sources within a watershed, such as urban stormwater runoff, atmospheric deposition, and hydrologic modification.

One study proposed a methodology to quantify the sources of pollutants in an urban catchment and analyze the associated uncertainties. This methodology was applied to the sources of copper (Cu), lead (Pb), zinc (Zn), and polycyclic aromatic hydrocarbons (PAH) in a residential catchment in the Paris region. The study found that roof accessories, such as gutters and downspouts, were major sources of Pb and Zn, while activity-related sources like traffic and heating dominated the presence of Cu and PAH.

Mitigating urban stormwater runoff pollution requires a comprehensive understanding of its sources and the implementation of effective source controls and pollution mitigation tools. While advancements in clean manufacturing and pollution control technologies have improved the situation, the continuous release of new chemicals and substances into the environment means that identifying and managing stormwater pollution sources is an ongoing process.

Construction activities

Demolition Dust

Demolition activities create dust that contributes to air pollution. This dust can contain fine particles and toxic gases, which, when inhaled, can lead to respiratory issues for workers and nearby residents. These include asthma, bronchitis, and other lung diseases. The dust can also have ecological consequences, disrupting the balance of nearby areas and harming local plants and animals.

Heavy Machinery

The operation of heavy machinery in construction zones generates emissions that pollute the air. This type of pollution is not limited to construction sites but also includes the movement of vehicles transporting materials to and from the sites.

Material Transport

The transportation of construction materials can also contribute to air pollution. Dust from construction sites can be carried away by road vehicles, leading to non-point source pollution as it enters the atmosphere.

Ineffective Septic Systems

Construction sites with inadequate septic systems can contribute to non-point source pollution. If wastewater is not properly treated, it can seep into the surrounding soil and eventually reach nearby water bodies, impacting their quality.

Sediment and Soil Erosion

Soil erosion from construction sites can lead to sediment reaching nearby water bodies, causing water pollution. Sediment can cloud the water, hindering aquatic organisms' ability to see and feed properly. It can also carry other pollutants, such as metals and toxic chemicals, further degrading the water quality.

Stormwater Runoff

Construction sites with disturbed soil are susceptible to erosion by precipitation, leading to stormwater runoff. This runoff can carry contaminants, such as fertilizers and pesticides, into nearby water bodies, contributing to non-point source water pollution.

To mitigate the environmental impact of construction activities, implementing proper monitoring systems and adopting sustainable practices are essential. This includes using dust suppression techniques, such as water spraying or physical barriers, to control dust dispersion and installing sediment or silt fences around construction sites to reduce sediment runoff. Additionally, employing advanced technologies, such as air quality monitors, helps assess the real-time impact of construction on air quality and enables timely decision-making to minimize pollution.

Forestry activities

Sources of nonpoint source pollution associated with forestry include:

• Removal of streamside vegetation: Forestry activities that remove streamside vegetation can affect water quality by reducing the shading that regulates water temperature and by removing vegetation that stabilizes streambanks. These changes can harm aquatic life by limiting food sources, reducing shade and shelter, and decreasing suitable areas for species intolerant of warmer temperatures.
• Road construction and use: Roads in forested areas can contribute to nonpoint source pollution through erosion, sediment, and dust pollution. Road construction and use are the primary sources of sediment from forestry operations, contributing up to 90% of the total sediment.
• Timber harvesting: Logging activities can disturb soil and contribute to erosion and runoff, which can impact water quality and aquatic life. Properly designed preharvest plans and timing of operations can help reduce these impacts.
• Mechanical preparation for planting trees: This can include activities such as land clearing and soil disturbance, which can increase the risk of erosion and sediment runoff into nearby water bodies.

To address these issues, forest owners and managers can implement best management practices (BMPs) and follow site-specific forest management plans. These plans can include measures such as establishing Streamside Management Areas (SMAs) to restrict activities in vegetated areas near streams, properly timing forestry operations to avoid rainy seasons and fish spawning seasons, and using environmentally sensitive maintenance techniques for roads.

Atmospheric deposition

The sources of atmospheric deposition can be natural or human-induced. Natural sources include volcanic eruptions, dust storms, and forest fires, which release particulate matter, gases, and ash into the atmosphere. Human activities, such as burning fossil fuels, operating industrial facilities, and agricultural practices, also contribute significantly to atmospheric deposition. These activities release pollutants like nitrogen oxides, sulfur dioxide, volatile organic compounds, and particulate matter into the air.

The impact of atmospheric deposition on water quality is particularly concerning. Pollutants deposited onto land can be washed into nearby water bodies by rainfall or snowmelt, leading to nonpoint source water pollution. This process, known as runoff, carries away pollutants such as oil, pesticides, fertilizers, and sediment, which eventually end up in rivers, lakes, wetlands, and groundwater. Atmospheric deposition can also directly affect water bodies through wet deposition, contributing to the pollution of these ecosystems.

Addressing atmospheric deposition is crucial for maintaining healthy ecosystems and ensuring clean water supplies. While it may not be possible to eliminate all sources of atmospheric deposition, implementing measures to reduce emissions from human activities can help mitigate their impact. This includes regulating industrial emissions, improving fuel efficiency, adopting sustainable agricultural practices, and preserving natural areas that act as sinks for atmospheric pollutants. By addressing atmospheric deposition, we can improve air and water quality, protect biodiversity, and safeguard the health and well-being of communities that rely on these ecosystems.

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