September 30 to October 4, 2024

Geochemical Modeling: PHREEQC and Beyond

Geochemical Modeling: PHREEQC and Beyond

Join us September 30 to October 4, 2024, at the Geochemical Modeling: PHREEQC and Beyond Conference and Course event to learn about best practices and innovative projects using PHREEQC, a powerful reaction/transport modeling tool developed by the U.S. Geological Survey and used by water agencies and consultants to perform aqueous geochemical calculations. This event offers presentations by industry leaders, networking opportunities with water purveyors and regulatory agencies, and the opportunity to expand your knowledge and capabilities using PHREEQC.

Who Should Attend?

—Environmental scientists and practitioners
—Researchers, academics, and students
—Geochemical modelers and developers
—Federal, state, and local government agencies
—Water managers

Monday, September 30 - Tuesday, October 1, 2024 (2 days)

Wednesday, October 2 - noon on Friday, October 4, 2024 (2.5 days)

The Short Course is limited to 25 participants.


Conference registration includes breakfast, lunch, afternoon snack, coffee, and a Monday evening reception. Dinner is not included.

The Short Course is limited to 25 participants. Short course registration includes breakfast, afternoon snack, and coffee. Lunch and dinner are not included.


Keynote Speakers

The keynote address will be presented by PHREEQC developers David Parkhurst and Tony Appelo.

  • David Parkhurst

    David Parkhurst

    David Parkhurst has worked for over 40 years in the fields of hydrology and geochemistry—including model development, field studies, laboratory work, teaching, and supervisory roles. He and coworkers have developed the geochemical model PHREEQC, which is the most widely used program of its kind in the world. PhreeqcRM, which encapsulates the capabilities of PHREEQC, is the most used geochemical module for reactive-transport models. He has worked on multiple field studies, including the Potomac River Estuary, the Tri-State lead and zinc mines, the Central Oklahoma Aquifer, Cape Cod, and aquifer storage-recovery studies. He has taught more than 40 short courses at the U.S. Geological Survey and at universities in the United State, Europe, and China.

  • Tony Appelo

    Tony Appelo

    Tony Appelo’s interest is to develop hydrochemistry into a quantitative science in which computer models help to unravel complicated reactions in laboratory experiments and field studies. With Dieke Postma he wrote the popular textbook “Geochemistry, groundwater and pollution”. He (co-)authored papers on ion exchange during fresh/salt water displacements in laboratory columns and aquifers, redox reactions with pyrite and manganese oxides, multicomponent diffusion of tracers in clay rocks, electro-migration in the natural environment and in column experiments. With David Parkhurst, the computer program PHREEQC was developed into the practical tool that has made it the present-day standard in hydrogeochemical modeling.

Event Location

Bethesda North Marriott Hotel & Conference Center
5701 Marinelli Road
Rockville, MD 20852

(301) 822-9200
Link to website

Event Contacts

Please contact for details regarding the conference and short course. We are also looking for event sponsors.

Future Updates for Interested Participants

Please provide your contact information via the Google form linked below to indicate your interest in attending this conference and be added to our email list so you can receive news and updates regarding event registration, abstract submission, and more:

Geochemical Modeling: PHREEQC and Beyond (

Call for Abstracts

Abstracts are due May 24, 2024. Visit our Abstract Submission page for session topics and to submit your abstract.

Event Organizers

The Geochemical Modeling: PHREEQC and Beyond event is organized by S.S. Papadopulos & Associates, GSI Environmental, Summit Water Resources, University of Nebraska, and ObjectiveGeochemistry.

Organizing Committee: Tony Appelo, Vivek Bedekar, Brad Bessinger, Erica DiFilippo, Max Giannetta, Beth Hoagland, Sorab Panday, David Parkhurst, Chittaranjan Ray, and Matt Tonkin.

  • S.S. Papadopulos & Associates, Inc.
  • GSI Environmental
  • Summit Water Resources
  • University of Nebraska
  • ObjectiveGeochemistry

Event Sponsors

Seeking event sponsors! Check back for more information on sponsorship opportunities or contact the event organizers at


    Marriott Bethesda North

    5151, Pooks Hill Road Bethesda, MD United States, 20814

    Registration period

    February 15, 2024 - 16:42 until September 20, 2024 - 23:59

    Submission period

    February 15, 2024 - 16:42 until May 24, 2024 - 23:59

    Contact us

    If you have any questions, please contact .

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