Instructor: Jana Milford, milford@colorado.edu, 2-5542, ECME 251

The overall objective of this course is to provide broad-based coverage of the development of pollutant transport and fate models in air, water and soil, emphasizing the parallels and linkages between different media and the fundamental physics and chemistry controlling contaminant fate and transport.. Through this course, you will:

1. Understand the process principles that govern contaminant transport and transformations in multimedia environments.
2. Be able to develop more complex and realistic models by coupling various process modules as appropriate to the system being considered.
1. Gain familiarity with data sources (including compiled data and site-specific lab or field tests) and be able to apply parameter estimation techniques for fate and transport model input parameters.
1. Practice computer-aided implementation and evaluation of fate and transport models.
2. Apply fate and transport models to evaluate pollutant interactions with the biosphere, particularly in the context of human exposure modeling and health risk assessment.

Prerequisites Undergraduate fluid mechanics and computational or numerical methods

Course Elements Lecture, computer-based homeworks, group project. There is no required text book for this course, but readings will be assigned as needed from handouts and journal articles.

Motivation and Overview

Engineers and scientists are increasingly required to be familiar with contaminant behavior in all three environmental media - air, water and soil/subsurface systems. There is also increased awareness of the need to understand pollution impacts on the biosphere (humans, flora and fauna) by assessing pollution of air, water and soil systems in an integrated manner, rather than within media-specific boundaries. The primary reasons for focusing on multimedia contaminant behavior are:

• Contaminant transfer often occurs between multiple media - for example, wash-out of air pollutants by precipitation creates a source of water pollution, as in the acid rain problem. An understanding of the multimedia transport and fate of pollutants is required to assess the overall phase distribution and space-time location of the pollutant.

• Health risks to humans and ecological disturbances arise from exposure to contaminants through multiple pathways that encompass the different environmental media. Estimates of contaminant concentrations in air, water and soil are required for human health risk assessment.

• Fundamental processes underlying the transport and transformation of environmental pollutants are essentially the same in the different environmental media. Furthermore, mathematical models for transport and transformation processes, and techniques for linking these process models together, are also similar for the different environmental systems.

The first section of the course introduces environmental pollution modeling, examines the nature and key attributes of environmental pollutants, and explores equilibrium and kinetic treatment of the inter-phase transfer of contaminants between the different media. We will study contaminant characteristics and intermedia mass transfer principles using multimedia compartment models. This section of the course also covers the fundamental transport processes: advection, dispersion and diffusion, which act within individual environmental media.

After the first exam, we will turn to models of contaminant transport in the atmosphere, groundwater and surface water systems, respectively. We will study both analytical and numerical models, including models that are widely used for regulatory applications and enviromental impact assessments. Key transport and biological/chemical transformation processes in each media will be covered. Through a group modeling project, you will have the opportunity to explore in more depth a contaminant transport and transformation problem in the medium/a of your choice.

The final section of the course will provide an overview of model applications to exposure and risk assessment, allowing modeled concentrations in the environment to be translated into subsequent human health and ecological impacts. Multimedia contaminant exposure models and risk calculations will be presented. Techniques for evaluating model performance and performing sensitivity and uncertainty analyses will be discussed throughout the course.

To complete homework assignments and projects for this course, you will need an account on the simlab computers. To get your account, go into PLUS on the web at http://www.colorado.edu/plus, select the "Computing Account" button (on the left of the screen), enter your CUID and PIN, and then click on "Make account on simlab." On the next page you will input a password of their choice, and the account will usually be made in a few minutes.

Grading (tentative) Project 25%

Homework 30%

Exams 45%

Aug. 23 Introduction, overview of fate and transport models

Aug. 25 Mass balance equations, CSTR models

Aug. 27 CSTR, PFR models

Aug. 30 Nature of environmental pollutants: physical state, chemical composition, structure-reactivity relationships

Sept. 1 Toxicity and health effects; risk indices

Sept. 3 Aqueous solubility, vapor pressure, sub-cooled liquids

Sept. 6 Labor Day (no class)

Sept. 8 Environmental partitioning & partition coefficients

Sept. 10 Estimation of partition coefficients

Sept. 13 Fugacity, equilibrium multimedia models

Sept. 15 Equilibrium multimedia models

Sept. 17 Kinetic analysis of interphase transfer, two-film theory

Sept. 20 Mass transfer between water and soil

Sept. 22 Mass transfer between water and air

Sept. 24 Kinetic multimedia models

Sept. 27 Transport fundamentals: advection and molecular diffusion (random walk)

Sept. 29 Turbulent transport, first-order closure, solutions of the diffusion equation

Oct. 1 Analytical solutions of the advection-diffusion equation; Peclet and Damkohler numbers

Oct. 4 Mixed flow models; scale dependence of of dispersion parameters

Oct. 6 Exam 1

Oct. 8 AR(1) analysis of persistence, finite segment models

Oct. 11 Finite segment models, unit response matrix

Oct. 13 Finite difference equations