Boron Isotopes as an Artificial Tracer.

Autor: Quast, Konrad W., Lansey, Kevin, Arnold, Robert, Bassett, Randy L., Rincon, Martha
Předmět:
Zdroj: Ground Water; May/Jun2006, Vol. 44 Issue 3, p453-466, 14p, 8 Charts, 8 Graphs, 2 Maps
Abstrakt: A field study was conducted using a combination of intrinsic and artificial tracers to estimate travel times and dilution during transport of infiltrate from a reclaimed water infiltration basin to nearby monitoring wells. A major study objective was to validate boric acid enriched in 10B as an artificial tracer. Basin 10E at the Rio Hondo Spreading Grounds in Whittier, California, was the site of the test. The basin normally receives a mixture of treated municipal waste water, purchased State Project water, and local runoff from the San Gabriel River. Approximately 3.5 kg of 10B-enriched boric acid was dispersed among 2.05 × 105 m3 of basin water to initiate the experiment. The resultant median δ11B in the infiltration basin was −71‰. Prior to tracer addition, the basin water had an intrinsic δ11B of +2‰. Local monitoring wells that were used to assess travel times had δ11B values of +5‰ and +8‰ at the time of tracer addition. Analytic results supported an assumption that boron is conserved during ground water transport and that boron enriched in 10B is a useful artificial tracer. Several intrinsic tracers were used to reinforce the boric acid tracer findings. These included stable isotopes of oxygen (δ18O) and hydrogen (δD), sulfate concentration, and the boron to chloride ratio. Xenon isotopes, 136Xe and 124Xe, also supported boron isotope results. Xenon isotopes were added to the recharge basin as dissolved gases by investigators from the Lawrence Livermore National Laboratory. [ABSTRACT FROM AUTHOR]
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