Office of Ground Water Tech MM 96.01 To: "File WRD Archive, , Reston, VA "
Subject: Office of Ground Water Tech MM 96.01 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 01 Feb 1996 15:01:22 -0500 From: "Velvie E Stockdale, Office Automation Assistant, Reston, VA " In Reply Refer To: January 26, 1996 Mail Stop 411 OFFICE OF GROUND WATER TECHNICAL MEMORANDUM NO. 96.01 Subject: GROUND WATER -- Release of Water-Resources Investigations Report 95-4227, "User's guide to PHREEQC-A computer program for speciation, reaction-path, advective-transport, and inverse geochemical calculations" by David L. Parkhurst The subject report describes a new geochemical model named PHREEQC. PHREEQC is derived from the Fortran program PHREEQE, but it has been completely rewritten in C with the addition of many new capabilities. The new code has all the capabilities of PHREEQE and WATEQ4F. Additional capabilities compared to PHREEQE include: enhanced speciation modeling; inclusion of ion exchange, surface complexation, and gas bubble formation; keeping track of masses of minerals and determining the stable phase assemblage; and simple advective transport modeling in combination with the available chemistry. In addition, the code is capable of the inverse modeling calculations, but not the isotopic calculations, included in NETPATH. An enhancement not included in NETPATH is the ability to account for uncertainties in the analytical data used in inverse modeling. We recommend that this report be brought to the attention of technical and management personnel concerned with ground-water geochemistry. The Hydrologic Analysis Support Section (HASS) is handling the distribution of PHREEQC within the Water Resources Division. The software is accessible on the World Wide Web, using Mosaic or similar World Wide Web reader, from the internal Hydrologic Software page (http:// hassrvares.er.usgs.gov/) and by anonymous FTP from hassrvares.er.usgs.gov (18.104.22.168) in the /pub/software/ geochemical/phreeqc/UNIX directory. The README file in the distribution package contains installation instructions. A postscript version of the report is also included in the distribution package. The next WRDAPP tape from HASS, available in the next few weeks, will include PHREEQC. If there are problems installing the software, contact HASS by electronic mail (h2osoft) or by telephone (Steve Regan 703-648-5896). Development copies of the DOS and UNIX versions of PHREEQC and other geochemical modeling software are maintained at the internet address ftp brrcrftp.cr.usgs.gov as described in the report. Additional copies of the report are available from the author. /s/ William M. Alley Chief, Office of Ground Water Distribution: A, B, PO, and S (memo only) DC (memo and report)