Aqueous Environmental Geochemistry

1
Aqueous Environmental Geochemistry Spring
2008 Dr. Md. Khalequzzaman
2
Introduction

• What is science? How is science done? What
  steps are involved in designing and carrying out
  a scientific experiment?
• What is Aq.Env.Geochem?
• Why do we care about Aq. Env. Geochem?
• The CWA, SDWA, RCRA, CERCLA, SARA, NPDES, PPA,
  etc.
• What are some practical examples
  (http//www.aaienvcorp.com/aai.mov )as to why we
  need to learn about water quality?
• Industries, gas stations, refineries, mining,
  landfills, banks, sewage..
• How is this course different from the
  hydrogeology and /or a chemistry course dealing
  with water chemistry?

3
Introduction (contd)

• Is the composition of natural water (i.e. in the
  vapor, surface and GW) just H2O? Why not?
• Do we really want or need pure H2O for various
  uses?
• What is the diff. between national primary and
  secondary drinking water standards and
  irrigation water standards?
• What types of chemicals are present in water in
  dissolved forms? In what forms (ions, molecules,
  etc.) do the dissolved chemicals exist in water?

4
Drinking/Irrigation Water Standards

• What are some common sources of water pollution?
• What is the relative ranking of sources of
  pollution and types of pollutants?
• What techniques or analytical methods are used to
  determine these chemicals?
• What constituents are regulated by Drinking Water
  and Irrigation Water Standards?
• What units of measurements are commonly used in
  water chemistry analysis?
• Check out Textbook pages 15-17 and other sources
• See Textbook Table 8-10

5
Graphical Representation of Data

• What are some graphical methods in which we can
  report water quality (chemical) data?
• Collins Stacked-bar, Stiffs diagram (Mauchas
  vector), Colbys kite, Schoellers nomograph,
  Piper Diagrapm, Durovs, Box plot, Chem. Facies,
  Contours, spatial/time series, etc.
• What are some advantages and disadvantages of
  each?
• Aquachem and PHREEQC

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Equilibrium Solubility Index

• Thermodynamic principles in chemical reactions
• Enthalpy, Free Energy (chem. potential), and
  Entropy
• See pages 10-15 19-20 in textbook
• What is chemical equilibrium and mass action law?
  What is ionic activity product (IAP)?
• How does IAP relate to saturation index (S.I.)?
  How is this concept used in water chemistry?
• What are some examples of master variables? Why
  are they called as such?

7
Conceptual Framework of Water Flow Path

• What is a conceptual framework of (ground)water
  flow and why do we need one?
• Where has the water been, for how long, what did
  it experience?
• Planning, managing, interpreting, predicting
  water chem. data
• How (and why) does water quality change as it
  moves thru atmosphere, hydrosphere, biosphere,
  and lithosphere?
• Check out Textbook pages 5-10 for example
• What factors and processes control the
  composition of water at various stages of its
  movement?
• Probably the most important but open-ended topic
  for us

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Chemical Reactions

• What are some major chemical reactions in water?
• Solution-precipitation, acid-base, redox,
  ion-exchange, complexation, etc.
• Also check out Textbook pages 12-13 for example
• Well talk about some of these in-depth in coming
  weeks

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Dissolved Gases, Alkalinity-Acidity Hardness

• Why and how gases dissolve in water?
• Role dissolve gases play in water chemistry
• Difference between pH and acidity
• Sources and types of acidity
• -how to determine or calculate acidity
• Sources of alkalinity and types of alkalinity
• How to determine alkalinity
• How to convert Alk. in CaCO3 mg/L to HCO3-