Transport and Variability of Fecal Bacteria in Carbonate Conglomerate Aquifers

Abstract

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.

Sustained Anthropogenic Impact in Carter Saltpeter Cave, Carter County, Tennessee and the Potential Effects on Manganese Cycling

“…As a result, indirect methods of water monitoring for microbial contaminants are frequently employed by researchers: culture-based studies of water to detect coliform bacteria (Mikell et al, 1996;Rusterholtz and Mallory, 1994), molecular techniques to identify the presence/absence of fecal indicators and endemic species in karst systems (Ahmed et al, 2008;Johnson et al, 2011;Johnston et al, 2012;Porter, 2007;Roslev and Bukh, 2011), and the use of fluorescent dyetracers and microspheres to model water flow and pathogen dispersal in conduit systems (Goeppert and Goldscheider, 2011). Direct study of karst environments is restricted to open conduits that are large enough to allow for human movement and environmental manipulation.…”

Karst geomorphology of carbonatic conglomerates in the Folded Molasse zone of the Northern Alps (Austria/Germany)

“…High levels of faecal bacteria were found in spring waters, which can be attributed to the short transit times in the aquifer. These findings demonstrate that karstified conglomerates show similar hydrogeological characteristics typical of limestone karst aquifers, and the same spring water contamination problems (Goeppert and Goldscheider, 2011).…”

Development of Population and Technical Infrastructure in Municipalities of the Moravian Karst: Potential Influence on the Organic Pollution of Water

“…Jakékoliv kontaminace těchto zdrojů odpadní vodou, tedy i komunální odpadní vodou, bývá pro obyvatele těchto oblastí a turistických ruch velké ohrožení. Proto jsou v krasových oblastech státem podporovány výstavby ČOV, které mohou zásadním způsobem zlepšit kvalitu povrchových vod (Andreo et al, 2006;Pronk et al, 2007;Haakh, 2010;Goeppert a Goldscheider, 2011;Jiang, 2013). Jsou známé případy kontaminace této krasové vody např.…”