Question

Stubble burning results in release of particulate matter, volatile organic compounds, oxides of nitrogen and sulfur, to name a few. A researcher is planning to use a conventional Gaussian dispersion model to estimate the contribution of stubble burning in a nearby state to air pollution in New Delhi. Choose the option(s) which could explain the possible limitations in this approach.

• A. assumption of steady state conditions e.g. constant wind speed, wind direction, and emission, etc. in conventional Gaussian dispersion models.
• B. non-accounting of wet and dry deposition in conventional Gaussian dispersion models.
• C. non-handling of chemical transformation of pollutants in conventional Gaussian dispersion models.
• D. requirement of more computational resources by conventional Gaussian dispersion models compared to chemical transport models.

Hint:

Gaussian dispersion models work well under steady-state conditions but may not be suitable for dynamic systems involving chemical transformations, deposition, or fluctuating emissions.

Answer 1

The Correct Option is A, B, C

Step 1: Understanding the Gaussian Dispersion Model
The conventional Gaussian dispersion model assumes steady-state conditions, meaning the wind speed, wind direction, and emissions are constant over time. This assumption often does not reflect real-world variability, especially in cases like stubble burning, where emissions can fluctuate.
Step 2: Analyzing the Options
Option (A) is correct because the Gaussian dispersion model assumes steady-state conditions, which is often not true in real-world atmospheric conditions, particularly in the case of stubble burning.
Option (B) is correct because the conventional Gaussian model does not account for wet and dry deposition, which can significantly affect the concentration of pollutants over time.
Option (C) is correct because the model does not handle chemical transformations of pollutants, such as reactions that occur in the atmosphere, which can alter the composition and toxicity of the pollutants.
Option (D) is incorrect because conventional Gaussian dispersion models generally require less computational resources than chemical transport models, which need to account for additional variables like chemical reactions.
Thus, the correct answers are (A), (B), and (C).