Transport and Variability of Fecal Bacteria in Carbonate Conglomerate Aquifers
Article first published online: 30 JUL 2010
Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association
Volume 49, Issue 1, pages 77–84, January/February 2011
How to Cite
Goeppert, N. and Goldscheider, N. (2011), Transport and Variability of Fecal Bacteria in Carbonate Conglomerate Aquifers. Groundwater, 49: 77–84. doi: 10.1111/j.1745-6584.2010.00741.x
- Issue published online: 22 DEC 2010
- Article first published online: 30 JUL 2010
- Received May 2009, accepted June 2010.
Clastic sedimentary rocks are generally considered non-karstifiable and thus less vulnerable to pathogen contamination than karst aquifers. However, dissolution phenomena have been observed in clastic carbonate conglomerates of the Subalpine Molasse zone of the northern Alps and other regions of Europe, indicating karstification and high vulnerability, which is currently not considered for source protection zoning. Therefore, a research program was established at the Hochgrat site (Austria/Germany), as a demonstration that karst-like characteristics, flow behavior, and high vulnerability to microbial contamination are possible in this type of aquifer. The study included geomorphologic mapping, comparative multi-tracer tests with fluorescent dyes and bacteria-sized fluorescent microspheres, and analyses of fecal indicator bacteria (FIB) in spring waters during different seasons. Results demonstrate that (1) flow velocities in carbonate conglomerates are similar as in typical karst aquifers, often exceeding 100 m/h; (2) microbial contaminants are rapidly transported toward springs; and (3) the magnitude and seasonal pattern of FIB variability depends on the land use in the spring catchment and its altitude. Different groundwater protection strategies that currently applied are consequently required in regions formed by karstified carbonatic clastic rocks, taking into account their high degree of heterogeneity and vulnerability.