Using hydrogeochemistry to understand inter-aquifer mixing in the on-shore part of the Gippsland Basin, southeast Australia

作者：Hofmann H^*; Cartwright Ian

来源：Applied Geochemistry, 2013, 33: 84-103.

DOI：10.1016/j.apgeochem.2013.02.004

Groundwater in the Latrobe Valley in the Gippsland Basin of southeast Australia is important for domestic, agricultural and industrial uses. This sedimentary basin contains a number of aquifers that are used for water supply, dewatered for open pit coal mining, and which are potentially influenced by off-shore oil and gas production. Major ion chemistry together with stable and Sr isotope data imply that the main hydrogeochemical processes are evapotranspiration with minor silicate and carbonate weathering; methanogenesis and SO4 reduction in reduced groundwater associated with coal deposits have also occurred. Groundwater has estimated C-14 ages of up to 36 ka and is largely H-3 free. Carbon-14 ages are irregularly distributed and poorly correlated with depth and distance from the basin margins. The observations that the geochemistry of groundwater in aquifers with different mineralogies are similar and the distribution of C-14 ages is irregular implies that the aquifers are hydraulically connected and horizontal as well as vertical inter-aquifer mixing occurs. The connection of shallow and deeper aquifers poses a risk for the groundwater resources in Gippsland as contaminants can migrate across aquifers and dewatering of shallow units may impact deeper parts of the groundwater system.

• 出版日期2013-6