Dear David Parkhurst, I have simulated instantaneous degassing of methane from a landfill leachate plume using a 1D horizontal PHREEQC flowpath model and simulating formation of a gas-phase if the total gas pressure exceeded the hydrostatic pressure (see my PhD thesis at: http://www.geo.vu.nl/users/breb/). The formed gas-phase was removed in order to simulate the loss of gas from the plume (chapter 5 thesis). I simulated methane degassing as well in another 1D vertical transport model of the rising plume fringe (chapter 6 in thesis). However, I do not know how to simulate detailed/real gas-transport towards the atmosphere in PHREEQC. Methane gas could for example re-dissolve in aerobic water above the leachate plume...This would be interesting to add to the model. Therefore my question: Is it possible to transfer a gasphase from a lower cell to an upper cell using BASIC statements in the RATES command? For example, a PHREEQC vertical column model has 100 cells, where cell 100 is the deepest cell and cell 1 is at the groundwater table. A gas-phase is formed in cell 40 because the gas pressure exceeds hydrostatic pressure. Is it possible to transfer the gas-phase from cell 40 to the upper cell 39? On its turn a gas-phase may form in cell 39 because of transfer of the gas-phase from lower cell 40 and/or by reactions in cell 39, so the gas-phase from cell 39 is then transported to cell 38, etc. I think you need to formulate a RATES/KINETICS statement for each cell where the gas-phase from the neighboring lower cell is added to the the current cell where is may dissolve or not... This model would then assume that gas-transport and degassing/re-dissolution is a fast equilibrium process. Is this possible in PHREEQC (with PUT and GET functions, CEL_NO?)? Sincerely, Boris van Breukelen -- Dr. Boris M. van Breukelen http://www.geo.vu.nl/users/breb/ phone 31-20-4447265 | fax. 31-20-4449940 | e-mail: boris.van.breukelen@xxxxxxxxxx Department of Hydro(geo)logy, Faculty of Earth and Life Sciences, Vrije Universiteit De Boelelaan 1085 (room C420), 1081 HV Amsterdam, the Netherlands --
Please note that some U.S. Geological Survey (USGS) information accessed through this page may be preliminary in nature and presented prior to final review and approval by the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user.
Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
The URL of this page is:
Last modified: $Date: 2005-09-13 21:04:21 -0600 (Tue, 13 Sep 2005) $
Visitor number 2961 since Jan 22, 1998.