What is the difference between point source and non-point source pollutants? Give examples.

• A. Non-point pollutants originate from identifiable discharges (e.g., a factory outfall); point pollutants come from diffuse sources (e.g., agricultural runoff, urban stormwater).
• B. Point sources originate from identifiable discharges (e.g., a factory outfall); non-point pollutants come from diffuse sources (e.g., agricultural runoff, urban stormwater).
• C. Point sources come from diffuse areas (e.g., farmland); non-point come from a single pipe.
• D. Point sources are natural; Non-point sources are anthropogenic.

Answer: (B)

The key idea is whether the pollutant source is identifiable and located at a single point versus dispersed over a large area. Point sources are identifiable discharges from a specific site, like a factory outfall or a wastewater treatment plant outlet. Non-point sources come from diffuse, widespread areas where pollution enters water bodies from many locations, such as agricultural runoff or urban stormwater washing over streets and yards.

This description fits the example given: pollutants from a known discharge point are point sources, while pollutants from runoff over large areas are non-point sources. The other options mix up the definitions or rely on natural vs. human origins, which isn’t how the standard distinction is made.