groundwater quality and geochemistry - epoc...apr 28, 2017 · and geochemistry environmental...
TRANSCRIPT
Groundwater Quality
and Geochemistry
Environmental Professionals'
Organization of Connecticut
April 28, 2017
Course Instructor:
Stephen P. Garabedian, Ph.D.
1. Introduction
What are the geochemical principles on which the
fate and transport of organics and metals are based?
What are typical background concentrations of
organics and metals in New England aquifers?
What are the geochemical conditions in which the
fate and transport of organics and metals in
groundwater can be interpreted?
“Concepts, Facts, and Case Studies”
Focus Questions:
Course Outline
1. Introduction
2. Principles of Aqueous Geochemistry
3. Principles of Organic Geochemistry
4. Groundwater Geochemistry
5. Case Study: Cape Cod Sewage Plume
6. Organics - Hydrocarbons
7. Solvents
Course Outline contd.
8. Metals - Zinc
9. Cadmium
10. Chromium
11. Arsenic
12. Lead
13. Mercury
14. Arsenic Plumes
15. Summary and Assessment
Overview
The geochemical conditions for the fate and
transport of organics and metals in ground-
water systems are the result of interactions
between solids, liquids, gases, and microbial
populations.
These interactions are strongly
influenced by, and in turn
affect, man-made conditions
(e.g. contamination).
Overview contd. The primary factors influencing the occurrence
and concentrations of organics and metals are:
1) sources (natural or man-made),
2) water chemistry (major ions/gases, pH),
3) adsorption reactions (surface chemistry),
4) oxidation-reduction (redox) reactions,
5) precipitation-dissolution (mineral) reactions.
- Often these factors are not in hydrologic or
chemical equilibrium, and concentrations can
and will change over space and time.
Some Major Classes
of Groundwater Pollutants
- Pathogens: (Bacteria, Viruses, Protozoa)
- Major/Minor Ions (e.g. NaCl, Fluoride, Iron)
- Sewage, Fertilizers, and Nitrate (Methemoglobinemia)
- Pesticides (e.g. Insecticides, Herbicides, Fungicides)
- Industrial Chemicals (e.g. Plasticizers, PCBs)
- Hydrocarbons (e.g. Crude Oil, BTEX, MTBE)
- Volatile Organic Compounds: (e.g. PCE, TCE)
- Metals (e.g. Chromium, Arsenic)
- Radioactive Materials (e.g. Radon, Uranium)
- Leachates (e.g. Landfills, CAFO, Mine Tailings)
Periodic Table with
Carbon in green, Metals* in red
Major Elements in yellow
*As, Cd, Cr, Hg, Pb, Zn; and Fe
References and Acknowledgments
- Please Note References in Appendix
- Acknowledgment and grateful thanks to my many colleagues at the USGS, particularly Denis LeBlanc and Doug Kent
Next
Aqueous Geochemistry