A 3 H/ 3 He Study of Ground Water Flow in a Fractured Bedrock Aquifer
1998; Wiley; Volume: 36; Issue: 4 Linguagem: Inglês
10.1111/j.1745-6584.1998.tb02841.x
ISSN1745-6584
AutoresWerner Aeschbach, Peter Schlösser, M. Stute, H. James Simpson, Andrea Ludin, Jordan F. Clark,
Tópico(s)Methane Hydrates and Related Phenomena
ResumoAbstract The concentrations of tritium, helium isotopes, and neon have been measured in ground water from a fractured bedrock aquifer in a densely populated suburban area near New York City. Samples were obtained from heavily pumped production wells of a regional water supply company. Helium and neon concentrations exceed the values for air‐saturated water, which is explained by the addition of unfractionated atmospheric air, radiogenic helium, and tritiogenic 3 He. The identification of the composition of these excess components allows reliable separation of the tritiogenic 3 He concentration, and hence the calculation of the 3 H/ 3 He ages of the ground water. Comparison of the combined tritium plus tritiogenic 3 He concentrations with the historical record of tritium input from precipitation confirms that the 3 H/ 3 He data are self‐consistent and provides constraints on the degree of mixing or helium loss. The distribution of 3 H/ 3 He ages is related to the large‐scale topography of the study area and the depth of the wells. Furthermore, correlations between the 3 H/ 3 He ages and concentrations of total dissolved solids and total CO 2 show that the ages contain meaningful information related to the temporal changes of the ground water chemistry.
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