A point source of emissions is a source in the form of a pipe or a ventilation shaft with cross-sectional dimensions close to each other (round, square, rectangular, etc.). A linear source is a source in the form of a channel (gap) for the passage of a gas with a cross-section having a considerable length (length) several times greater than the width, for example, a series of open, closely spaced window trims, or aeration lanterns. The degree of atmospheric pollution depends on the amount of emissions of harmful substances and their chemical composition, and also largely on the characteristics of the source of emissions – the height of the source above ground level, the speed, volume and temperature of the gas discharge from the mouth of the pipe, the size of the unorganized source, the location of the source at the site etc. In accordance with this, the sources of air pollution differ in the power of the outburst (powerful, large, small), the height of the ejecta (low, medium and high), the temperature exiting gas (hot and cold).
There are also mobile and stationary, organized and unorganized, point and area sources of pollution. The peculiarity of the enterprise as an object of nature protection measures is the heterogeneity and dispersal of emission sources.The main contribution to the pollution of the atmosphere is made by cars running on gasoline (in the US they account for about 75%), then planes (about 5%), cars with diesel engines (about 4%), tractors and other agricultural machines (about 4% ), rail and water transport (about 2%). The main pollutants emitted by mobile sources (the total number of such substances exceeds 40) include carbon monoxide (in the United States its share in the total mass is about 70%), hydrocarbons (about 19%) and nitrogen oxides (about 9% ). Carbon monoxide (CO) and nitrogen oxides (N0x) enter the atmosphere only with exhaust gases, while incompletely combusted hydrocarbons (HnCm) are supplied both with exhaust gases (about 60% of the total mass of hydrocarbons emitted), and from the crankcase (about 20%), the fuel tank (about 10%) and the carburetor (about 10%); Solid impurities come mainly with exhaust gases (90%) and from the crankcase (10%).
The source of water pollution refers to the source of pollution caused by water in the form of dots. Industrial wastewaterand urban domestic sewage generated by general industrial pollution sources and domestic pollution sources are transported to the water discharge outlets by urban sewage treatment plants or through pipelines, and are discharged as important pollution point sources to water bodies. This point source contains many pollutants and complex components.
The change rule is based on the discharge law of industrial wastewater and domestic sewage, that is, seasonal and random .To control point source discharges, the Clean Water Act established the National Pollutant Discharge Elimination System (NPDES). Under the NPDES program, factories, sewage treatment plants, and other point sources must obtain a permit from the state and EPA before they can discharge their waste or effluents into any body of water. Prior to discharge, the point source must use the latest technologies available to treat its effluents and reduce the level of pollutants.
If necessary, a second, more stringent set of controls can be placed on a point source to protect a specific waterbody.