After reading this article you will learn about the meaning and sources of surface water pollution.
Meaning of Surface Water Pollution:
When toxic substances enter lakes, streams, rivers, oceans and other water bodies, they get dissolved or lie suspended in water. This results in the pollution of water. Due to pollution the quality of the water deteriorates, affecting aquatic ecosystems. These pollutants can also seep down and affect the groundwater deposits.
The most polluting source of water is the city sewage and industrial waste. Agricultural run-off, or the water from the fields that drains into rivers, is another major water pollutant as it contains fertilizers and pesticides. These pollutants enter into groundwater, rivers and other water bodies. Such water, which ultimately ends up in our households, is often highly contaminated and carries disease-causing microbes.
Sources of Surface Water Pollution:
a. Nonpoint Source Pollution:
A great deal of water pollution happens not from one single source but from many different scattered sources. This is called nonpoint source pollution. Nonpoint source (NPS) pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources.
NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even underground sources of drinking water.
These pollutants include:
i. Excess fertilizers, herbicides and insecticides from agricultural lands and residential areas
ii. Oil, grease and toxic chemicals from urban runoff and energy production
iii. Sediment from improperly managed construction sites, crop and forest lands and eroding stream banks
iv. Salt from irrigation practices and acid drainage from abandoned mines
v. Bacteria and nutrients from livestock, pet wastes and faulty septic systems
vi. Pollutants resulting from atmospheric deposition and hydro-modification.
Non-point-source pollution is the leading remaining cause of water quality problems. The effects of nonpoint source pollutants on specific waters vary and may not always be fully assessed. However, we know that these pollutants have harmful effects on drinking water supplies, recreation, fisheries and wildlife.
b. Point Source Pollution:
If pollution comes from a single location, such as a discharge pipe attached to a factory. It is known as point source pollution. The discharges that pose the most threat to public health and the Nation’s waters are: human wastes, ground-up food from sink disposals, laundry and bath waters, toxic chemical and metals.
Also, fecal coliform, oil and grease, pesticides, metals are types of pollutants that when discharged into the Nation’s waters threaten both the health of humans and life forms in the water. If such pollutants were left untreated, the Nation would be unable to enjoy its largest natural resource, water.