Area sources are sources of pollution which emit a substance or radiation from a specified area.
Area source (pollution) Wikipedia
For example, area sources of air pollution are air pollutant emission sources which operate within a certain locale. The U.S. Environmental Protection Agency has categorized 70 different categories of air pollution area source. Locomotives operating on certain linear tracks are examples of a line source, whereas locomotives operating within a railyard are an example of an area source of pollution. Other area sources of air pollution are:Multiple flue gas stacks within a single industrial plant
Open burning and forest fires
Evaporation losses from large spills of volatile liquids
Water pollution manifestations of an area source include:Surface runoff of fertilizer or pesticide from rainfall or irrigation water
Widespread failure of septic fields
Dispersal of an oil spill in a major water body
In the 1950s or earlier hydrology transport models appeared to calculate surface runoff, primarily for flood forecasting. Beginning in the early 1970s computer models were developed to analyze the transport of runoff carrying water pollutants, which considered dissolution rates of various chemicals, infiltration into soils and ultimate pollutant load delivered to receiving waters. One of the earliest models addressing chemical dissolution in runoff and resulting transport was developed in the early 1970s by the United States Environmental Protection Agency. This computer model formed the basis of much of the regulatory framework that led to strategies for water pollution control via land use and chemical handling techniques. People produce so much trash that half of it goes in water sources.