Tritium/³He Dating of River Infiltration: An Example from the Danube in the Szigetköz Area, Hungary

Abstract

3H, He, 4He, and Ne data were obtained from a shallow ground‐water system being recharged by bank infiltration from the Danube River in northwestern Hungary. After correting for excess air, 4He and Ne concentrations reflect a recharge temperature of about 9° C., close to the mean annual temperature of the Danube (10.4° C). Values of H plus 3Hetrit (“initial tritium”) as a function of the tritium/He age are consistent with time series measurements of tritium in the Danube. Tritium/ He ages increase linearly as a function of distance from the Danube along ground‐water flow lines. A horizontal flow velocity of about 530 m yr1 was derived from the age gradient. Most of the deviations between measured Danube tritium data and ground‐water tritium/He data can be explained by dispersive mixing.

Improving noble gas based paleoclimate reconstruction and groundwater dating using 20Ne/22Ne ratios

“…The water ages predicted by the PR-model appear unrealistically large. Stute et al, 1997) is not practicable in the CT-aquifers because the 3 H at recharge is strongly affected by the transport through the unsaturated zone. Hence, only the inclusion of the Ne isotopes in the analysis provides an objective, i.e., data-based, criterion to identify the 3 H-3 He water ages predicted by the CE-model to be more reliable than those predicted by the PR-model.…”

Experimental investigations on the formation of excess air in quasi-saturated porous media

“…In these cases, usually the equilibrium concentration of the considered gas has to be determined, which implies that the excess air component has to be separated from the total measured dissolved gas concentration. Examples of trace gas methods in groundwater which are sensitive to excess air are the dating of groundwater with 3 H- 3 He (Schlosser et al, 1988;Stute et al, 1997;Aeschbach-Hertig et al, 1998) and SF 6 (Busenberg and Plummer, 2000), and the determination of paleorecharge conditions, especially the infiltration temperature (Mazor, 1972;Andrews and Lee, 1979;Stute and Schlosser, 1993;Stute et al, 1995). Besides the relevance of excess air for trace gas methods in groundwater, the excess air component itself most probably conveys information about past climatic and recharge conditions as well as aquifer characteristics (Heaton et al, 1986;Wilson and McNeill, 1997;Stute and Talma, 1998;Aeschbach-Hertig et al, 2001).…”

Noble Gases in Lakes and Ground Waters

“…Microbial degradation of CFC-11 under anaerobic conditions has been observed in several studies (e.g., Lovley and Woodward 1992;Oster et al 1996). Local contamination is a serious and widespread, but still not fully understood problem (Thompson and Hayes 1979;Busenberg and Plummer 1992;B6hlke et al 1997;Beyerle et al 1999a). A fundamental problem for the CFC-method is the nearly constant atmospheric mixing ratios in recent years, making alternatives such as SF6 attractive for dating of very young ground water.…”