Rehmann et al 00 WRR virus Reply to Comment on Stoch anal of virus transport in aquifers

WATER RESOURCES RESEARCH, VOL. 36, NO. 7, PAGES 1983–1984, JULY 2000ReplyLinda L. C. RehmannHammonton, New JerseyClaire WeltySchool of Environmental Science, Engineering, and Policy, Drexel University, Philadelphia, PennsylvaniaRonald W. HarveyU.S. Geological Survey, Water Resources Division, Boulder, ColoradoWe thank Ginn [this issue] for his interest in and close colloid filtration appears as a loss term in the local-scale equa-inspection of our paper. His comments raise some points re- tion for free virus transport, the complexity of the mean resultgarding the paper by Rehmann et al. [1999] that we wish to (30a) makes it difficult to discern the implications of the het-clarify. erogeneous filtration term. Until our model is validated, whichGinn first comments on the finding that our mean model we explicitly stated as an important next step in this work, wecould predict virus breakthrough preceding that of a conser- cannot state in quantitative detail how the model will comparevative tracer. Ginn states that “size exclusion is the exclusion of to Monte Carlo or other relevant simulation results.suspended colloids or particles from lower-velocity regions of Ginn also notes that if the ln K variance is taken to zero inpore space due to the size of the suspended material particle.” the mean equation, the effective velocity of the viruses (v )eThe phenomenon that Ginn defines as size exclusion, generally reduces to the mean pore water and the remainingreferred ...