Because the real quench distance is only the minimum figure @ TDC (which is not the point of maximum risk), and there is measurable pumping loss getting those few molecules in and out of that small space, and as the clearance expands the loss is reduced.
Why is nonpoint source pollution potentially more harmful than point source pollution? a. Nonpoint source pollution disrupts the water cycle. b. Nonpoint source pollution is difficult to regulate. c. Nonpoint source pollution comes from more than one source. d. Nonpoint source pollution is more damaging to living organisms than point source pollution. Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage or hydrologic modification.
Nonpoint source pollution occurs when rain runs off farmland, city streets, construction sites, and suburban lawns, roofs and driveways and enters our waterways. This runoff often contains harmful substances such as toxics, pathogens, excess nutrients and sediments. It is called nonpoint source pollution because it does not come from a single source, or point, such as a sewage treatment plant or an industrial discharge pipe. Therefore nonpoint source pollution does not meet the legal definition of point source from Section 502(14) of the Clean Water Act. There are four main forms of nonpoint source pollution: sediments, nutrients, toxic substances and pathogens.