1 / 7

Random Walk Contaminant Spread

This study examines the spread of the contaminant Methyl Parathion through a random walk simulation, focusing on its effects on Delphia Magna, a small freshwater crustacean. Utilizing EPA methodologies, the simulation models the contaminant's movement within a defined system and measures acute toxicity based on median lethal doses (LC50) and effective concentrations (EC50). Key variables such as the number of organisms, the size of the system, and the amount of contaminant are manipulated, allowing for comprehensive analysis of organism mortality over specified timeframes.

ormand
Télécharger la présentation

Random Walk Contaminant Spread

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Random Walk Contaminant Spread By Parrish Myers DSES-6620 Simulation Modeling and Analysis Spring 2002

  2. Median Lethal-Dose Acute Toxicity • Procedure Modeled after EPA SOP #2024 • Data Obtained from EPA • Organism: Delphia Magna • small freshwater crustacean • Contaminant: Methyl Parathion • insecticideLC50 = 0.14 ppb • EC50 = 0.09 – 0.2 ppb

  3. Simulation Assumptions • 2d • Contaminant spread: random walk of constant step size and not drift • The contaminant starts at the center of the system (0,0) • The contaminant is assumed discrete, containing N groups of molecules • Exits for molecule groups: • wander beyond system boundary • collision with an organism • Stochastic susceptibility for organisms • The organisms are stationary

  4. State Variables Modifiable • Number of Molecule Groups • Number of Organisms • Size of System System • System Time • Number of Dead Organisms • Number of Remaining Contaminant Molecule Groups • Radius of Contaminant

  5. RWCS System Area Organism Contaminant Simulation Controls Amount of Contaminant Number of Organisms Size of System State Variables State of Simulation

  6. Simulation Procedure • Keep system size at 50.0 and the number of organisms at 10 • Start with an amount of contaminant small enough to have minimal effect • Record the number of dead organisms at: • 1-Hour, 24-Hours, and 48-Hours • Increase the amount of contaminant and repeat step 3. • When organism mortality becomes 80%-90% STOP! • Tally data and find LD50.

  7. Simulation Results

More Related