Gaussian plume model for estimating pollutant concentration from a point source considers the following assumptions:
(A) Concentrations are proportional to emission rate (B) Emissions take place from a virtual point (C) Pollutant does not undergo chemical transformations (D) Three-dimensional axis system of downwind, crosswind, and vertical with origin at the ground (E) Considers variable wind speed and direction
Choose the correct answer from the options given below:

Correct option is D

The Gaussian Plume Model is a widely used air pollution dispersion model that estimates pollutant concentrations from point sources under steady-state conditions. It assumes the following:
1. Concentrations are proportional to emission rate (A):
· The model assumes a direct relationship between pollutant emission rates and concentrations.
2. Emissions take place from a virtual point (B):
· Pollutants are modeled to originate from an idealized "point source" to simplify mathematical calculations.
3. Pollutants do not undergo chemical transformations (C):
· The model assumes that pollutants remain chemically inert during dispersion for accurate predictions.
4. Three-dimensional axis system (D):
· The model uses downwind (x), crosswind (y), and vertical (z) coordinates to represent dispersion in space.
5. Variable wind speed and direction (E):
· While wind is a factor, the Gaussian plume model assumes steady-state conditions for wind speed and direction, hence rejecting variability (E is excluded).
Thus, the correct set of assumptions is (A), (B), (C), and (D).
Information Booster: 1. Key Assumptions of Gaussian Plume Model:
· Steady-state emissions from a point source.
· Pollutants are uniformly mixed in the crosswind direction.
· No consideration for chemical reactions or transformations.
2. Applications:
· Assessing air quality impacts of industrial emissions.
· Predicting pollutant dispersion for regulatory compliance.
3. Limitations:
· Does not account for atmospheric turbulence or chemical reactions.
· Assumes constant meteorological conditions, which may not always hold true.
Additional Knowledge: · Assumption (A): The concentration directly depends on the emission rate, making it proportional.
· Assumption (B): Idealized "virtual point" emission simplifies calculations.
· Assumption (C): Pollutant inertness is crucial to maintain model simplicity.
· Assumption (D): The three-dimensional framework (downwind, crosswind, and vertical) enables accurate spatial modeling.
· Assumption (E): Variable wind speed/direction is generally excluded in Gaussian models but addressed in advanced models.