Indicative mean transit time estimation from δ18O values as groundwater vulnerability indicator in karst-fissure aquifers

Abstract

Ideally, groundwater vulnerability assessment should take into account potential contaminant breakthrough curve, characterized by transit time, relative change of contamination concentration (input/output) and duration of overstepped concentration. Still, a majority of groundwater vulnerability assessment methods that tend to be more physically based count only with the value of mean transit time (MTT), the elapsed time when groundwater can exit the aquifer after its recharge. In this paper, indicative values of MTT derived from single d 18 O sampling values were used to estimate intrinsic vulnerability of individual springs occurring on the Muránska planina Plateau (Slovakia). For 295 springs sampled within 10 days, d 18 O was found in the range between -10.90 and -7.32 %, without signs of altitudinal effect. According to International Atomic Energy Agency (IAEA) Global Network of Isotopes in Precipitation (GNIP) stations, significant contrast in precipitation d 18 O values was found several weeks before sampling. Indicative MTT value, e max MTT (estimated longest possible mean transit time), was calculated from sine wave course of monitored precipitation isotopic composition, d 18 O value in the spring groundwater sample and altitudes of sampled point and precipitation station. Estimated e max MTT values suggest that heavier oxygen isotopes in samples probably reflect quick circulation and a more vulnerable environment as influenced by enriched summer precipitation. Depleted d 18 O suggests lower vulnerability represented by higher e max MTT values.

Karst water resources in a changing world: Review of solute transport modelling approaches

“…In groundwater studies, water age is often denoted as residence time which indicates the time between the water entrance and leave (Aquilina et al, 2003;Maloszewski et al, 1992;Małoszewski & Zuber, 1993;Plummer et al, 1998aPlummer et al, , 1998b whereas travel time is defined as the time required for a volume of water moving across the specified flow paths. The knowledge of water age and/or its distributionsdistributions of the different water agesis particularly useful for revealing the vulnerability of karst aquifers to the contamination risks (Malík et al, 2016;Musgrove et al, 2023;Çallı et al, 2023a) as it provides valuable insight into the karst system's underlying mixing, storage, and transport characteristics (i.e., piston flow, complete mixing) (Figure 3). For instance, the karst aquifers characterized by (relatively) younger water age (i.e., shorter travel time) are often at the risk of contamination problem due to the system's rapid response whilst the karst systems represented with older groundwater ages (i.e., longer residence time) is often an indication of the sufficient time for the contaminant attenuation processes (Figure 3).…”

Karsztos víztartók sérülékenységi térképezési megközelítései a Gömör-Tornai-karszt példáján

“…A VULK módszer (Jeannin et al, 2001) A későbbiekben a módszertan négy fő ágon fejlődött tovább, részben vagy egészében követve a DRASTIC, EPIK, PI és VULK módszerek koncepcióját (2.3. ábra). A származtatott módszerek (Andreo et al, 2006;Andreo et al, 2009;Brosig et al, 2008;Butscher és Huggenberger, 2008, 2009aCichocki et al, 2004;Daly et al, 2002;Davis et al, 2002;Jimenez-Madrid et al, 2013;Koutsi és Stournaras, 2011;Kralik és Keimel, 2003;Malik és Svasta, 1999;Nguyet és Goldscheider, 2006;Petelet-Giraud et al, 2000;Plagnes et al, 2010;Plagnes et al, 2005;Ravbar és Goldscheider, 2007;Vias et al, 2006) Szőnyi et al, 2004). Lóczy (2006) részletes irodalmi áttekintést nyújtott a karsztvidékek sérülékenységi térképezésének lehetőségeiről.…”

Transit Time index (TTi) as an adaptation of the humification index to illustrate transit time differences in karst hydrosystems: application to the karst springs of the Fontaine de Vaucluse system (southeastern France)

“…Serène et al: Transit Time index archized network of karst conduits allows for a fast transit of recharge which is very specific to karst systems (White, 2002) and makes it essential to develop natural tracers of transit on short timescales (< 6 months). Natural tracers of stored water include major element contents, isotopes, and dissolved gas (Malík et al, 2016;Musgrove et al, 2019;Pérotin et al, 2021;Zhang et al, 2021), but few of these tracers allow fast infiltration to be characterized. Indeed, natural tracers of transit time of this range must, by definition, see their contents vary at this timescale.…”