Nonpoint source pollution (NPS) results from precipitation, land runoff, drainage, seepage, hydrologic, and atmospheric deposition. Unlike pollution from sewage treatment plants and industrial waste, NPS occurs from various diffuse sources. The NPS pollution occurs during the melting of the snow and rainfall moving over and through the ground. As the water moves, it takes and carries human-made and natural pollutants with it and deposits them in the rivers, lakes, coastal waters, groundwaters, and wetlands.
What are the nonpoint sources of water pollution?
Nonpoint source pollution (NPS) is defined as widespread pollution of different water bodies or air that is not caused by a specific single source. This form of contamination is frequently the result of small amounts of toxins accumulating over a vast area, and it differs from point source pollution, caused by a single source. Nonpoint source contamination is caused by land runoff, precipitation, drainage, air deposition, hydrological change, and seepage, and it is challenging to attribute pollution to a single source. Polluted runoff from agricultural areas flowing into a river or wind-borne garbage drifting out to sea are examples of nonpoint source pollution.
A variety of sources
Nonpoint source water contamination could come from a variety of places, and there are no precise solutions or modifications that can be made to solve the problem, making it difficult to control. Nonpoint source water contamination is difficult to prevent since it results from different people’s daily activities, such as lawn fertilisation, road construction, pesticide application, and building development. Improving the management of agricultural activities, marinas, forestry, and urban and suburban operations is required to reduce nonpoint source pollution.
Various nonpoint sources of water pollution
Sediment: Silt and suspended particles are examples of sediment, commonly known as loose soil. Sediment can enter surface waters by eroding stream banks and surface runoff from unsuitable plant cover on both urban and rural terrain. Turbidity is caused by sediment in water bodies, which reduces the quantity of light reaching deeper depths, inhibiting the growth of hidden aquatic plants and, as a result, affecting species that rely on them, such as shellfish and fish. High turbidity levels also hamper drinking water filtration systems. Sediment can also come from a variety of different places. Potential sources are construction sites, stream banks, agricultural fields, and highly disturbed environments.
Nutrients: Nutrients are the inorganic stuff from runoff, animal waste, landfills, and crop areas. Phosphorus and nitrogen are the two main nutrients that exist in our surroundings. Phosphorus is a nutrient that comes in a variety of bioavailable forms. It’s well-known for being overabundant in human sewage. It is a key component of many fertilisers used in farming or agriculture, as well as in household activities and the industries, and it has the potential to become a major limiting factor in freshwater systems & estuaries. Because numerous kinds of phosphorus are adsorbed on soil particles, phosphorus is most typically transferred to water bodies by soil erosion.
Toxic contaminants and chemicals: Heavy metals such as lead, mercury, zinc, and cadmium, as well as organics such as polychlorinated biphenyls and polycyclic aromatic hydrocarbons, fire retardants, and other chemicals, are resistant to breakdown. Some other sources of the pollutants are mining operations, fossil fuel burning, landfills etc. Organic and inorganic compounds are the most common toxic substances. Some nonpoint source pollution examples are pesticides such as acids, DDT, and other salts. These substances cause a severe impact on the water bodies and ecosystem. They can endanger human and aquatic species’ health while also resisting environmental disintegration, allowing them to survive in the environment. Croplands, orchards, construction sites, nurseries, lawns, gardens, and landfills could all be sources of harmful chemicals.
In the above chapter, we have discussed nonpoint source pollution with examples. Land runoff, precipitation, air deposition, drainage, seepage, and hydrologic alteration are all common sources of NPS pollution. Unlike pollution from factories & sewage treatment plants, NPS contamination occurs from a variety of sources. Rainfall or melting of snow moving over and through the earth causes NPS contamination. As the runoff progresses, it takes up and transports contaminants, both natural and man-made, eventually depositing them in rivers, lakes, wetlands, groundwater, and coastal waterways.