How are pollutants in the atmosphere dispersed?
Once in the environment, air pollutants may be dispersed via air, water, soil, living organisms and food. The pathways of dispersion vary greatly, depending upon both the emission source and the pollutant concerned. Rates and patterns of dispersion also depend to a large extent upon environmental conditions.
What atmospheric conditions affect dispersion of pollutants?
A principle feature of atmospheric circulation is wind speed or velocity. Air movement associated with the horizontal motion of the atmosphere is commonly called wind and significantly affects pollutant concentration. In general, the higher the wind’s velocity, the lower the pollutant concentration will be.
What are the 4 atmospheric pollutants?
Ozone (O3) Nitrogen dioxide (NO2) Carbon monoxide (CO) Sulphur dioxide (SO2)
What are factors for atmospheric dispersion?
An atmospheric dispersion factor is the effluent concentration (x) divided by the source strength (Q) at a given distance and direction from the source. Atmospheric dispersion factors are averaged and processed over different time frames, depending on the use to which they will be put.
What is atmospheric pollutant dispersion and what causes it?
The movement of pollutants in the atmosphere is caused by transport, dispersion, and deposition. Transport is movement caused by a time-averaged wind flow. Dispersion results from local turbulence, that is, motions that last less than the time used to average the transport.
How does atmospheric stability influence the accumulation of air pollutants?
The atmospheric stability plays an important role in the accumulation of air pollutants and greatly influence their degradation, dispersion and deposition. Between these two pollutants the correlation is high because their sources are the same: transport and biomass burning.
What are the various atmospheric pollutants?
Six Common Air Pollutants The most commonly found air pollutants are particulate matter, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead.
What are the assumptions made in Gaussian dispersion of air pollutants?
Gaussian models, while the most commonly used, are not without limitations. The model assumes that wind speed and direction is constant, emission rates are constant, the terrain is flat, deposition is negligible, and the shape of the plume is conical (Reed, 2005).
What are the conditions that determine atmospheric stability?
Three characteristics of the sounding then determine the stability of the atmospheric layer in which the parcel of air is embedded. These are: (1) The temperature lapse rate through the layer; (2) temperature of the parcel at its initial level; and (3) initial dew point of the parcel.
How does a pollutant disperse in the atmosphere?
As an air pollutant is transported from a source to a potential receptor the pollutant disperses into the surrounding air so that it arrives at a much lower concentration than it was on leaving the source.
How are dispersion models used in atmospheric pollution modeling?
Dispersion models usually incorporate meteorological, terrain, physical and chemical characteristics of the effluent and source design to simulate the formation and transport of pollutant plumes[7, 8].
What are two types of atmospheric dispersion conditions?
•Dispersion conditions are moderate Atmospheric Stability Subadiabatic – Weak Lapse Rate Stable Conditions •2 major types of inversion: Subsidence: descent of a layer of air within a high pressure air mass (descending air increases pressure & temp.)
How does plume rise affect dispersion and transport?
•Plume rise affects dispersion and transport –Affects maximum ground level concentrations –Affects distance to maximum ground level conc. Lapse Rates and Atmospheric Stability Weak Lapse Condition (Coning) Wind