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 --
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