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Title: Environmental isotopes as indicators of inter-aquifer mixing, Wimmera region, Murray Basin, Southeast Australia.
Authors: Cartwright, I
Weaver, TR
Cendón, DI
Swane, I
Keywords: Australia
Ground water
Carbon 14
Issue Date: 20-Oct-2010
Publisher: Elsevier
Citation: Cartwright, I., Weaver, T., Cendón, D. I., & Swane, I. (2010). Environmental isotopes as indicators of inter-aquifer mixing, Wimmera region, Murray Basin, Southeast Australia. Chemical Geology, 277(3-4), 214-226. doi:10.1016/j.chemgeo.2010.08.002
Abstract: Complex groundwater flow systems in confined aquifers that result from geological structures, stratigraphic changes, or the absence of efficient aquitards are difficult to constrain using physical parameters alone. Despite a relatively simple aquifer configuration, the distribution of groundwater total dissolved solids (TDS) concentrations, δ13C values, 87Sr/86Sr ratios, and 14C activities (a14C) in groundwater in the Wimmera region of the southern Murray Basin implies that considerable inter-aquifer flow has occurred. Given the presence of both silicate and carbonate aquifers, δ13C values and 87Sr/86Sr ratios are the key parameters that demonstrate inter-aquifer flow. Locally, between 40 and 95% of water from one aquifer has infiltrated the underlying aquifer homogenising many aspects of the groundwater geochemistry. Groundwater residence times estimated from a14C range from modern to > 30 ka and the distribution of 14C residence times confirm that inter-aquifer flow is regional scale and long term. Recharge of the deepest aquifers occurs across a broad region and not solely at the basin margins. Vertical leakage rates are ~ 6–10 × 10−3 m/year and long-term recharge rates 0.1–0.2 mm/year (< 1% of annual rainfall). Groundwater from this region is a locally valuable resource and failure to recognise that inter-aquifer flow occurs threatens the sustainability of this resource. © 2010, Elsevier Ltd.
Gov't Doc #: 3064
ISSN: 0009-2541
Appears in Collections:Journal Articles

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