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Isotope evolution and contribution to geochemical investigations in aquifer storage and recovery: a case study using reclaimed water at Bolivar, South Australia
Author(s) -
Le Gal La Salle C.,
Vanderzalm J.,
Hutson J.,
Dillon P.,
Pavelic P.,
Martin R.
Publication year - 2005
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.5977
Subject(s) - dissolved organic carbon , aquifer , groundwater , dissolution , biogeochemical cycle , isotopic signature , total inorganic carbon , carbonate , geology , effluent , isotopes of carbon , carbon fibers , total organic carbon , environmental chemistry , environmental science , hydrology (agriculture) , soil science , stable isotope ratio , chemistry , carbon dioxide , environmental engineering , oceanography , materials science , physics , geotechnical engineering , organic chemistry , quantum mechanics , composite number , composite material
Aquifer storage and recovery (ASR) is an important resource management tool whereby water from an available source is stored in a suitable aquifer for later use in periods of higher demand. Important issues in ASR include maintaining the injection rate and recovering water of suitable quality. Both of these depend on subsurface biogeochemical processes. This paper investigates the use of deuterium, 18 O, 13 C, 14 C and 34 S in understanding the reactions induced by reclaimed water injection in a carbonate aquifer at Bolivar, South Australia. Additionally, the injection scheme provides a natural laboratory to observe the process of carbon isotope exchange. The injectant deuterium (−6·4 ± 2·9‰ versus Vienna standard mean ocean water (V‐SMOW)) and 18 O (−0·9 ± 0·5‰ V‐SMOW) signature is more enriched and variable than the native groundwater signature of −26 ± 1‰ and −4·4 ± 0·1‰ respectively. The variability of the injectant signature is maintained with injectant migration and is useful in constraining the portion of the injected end‐member reaching observation wells. Effluent treatment results in total dissolved inorganic carbon (TDIC) enriched in 13 C (−3·3 ± 2·5‰ versus Pee Dee belemnite) and modern carbon (100 ± 7 per cent modern carbon (pmC)), which is distinct from the native groundwater comparatively depleted in 13 C (−11 ± 1‰) and 14 C (5·6 ± 2·1 pmC). The carbon isotopic signature in groundwater 4 m from the ASR well is dominated by the injectant signature modified by some organic matter oxidation and calcite dissolution. However, with further migration to the 50 m radius, both 13 C and 14 C signatures are dominated by isotopic exchange with the matrix surface (initially in equilibrium with the ambient groundwater) and little overall dissolution. During storage, biogeochemical processes, including sulphate reduction and methanogenesis, are dominant near the ASR well. These are indicated by a sulphate decline of up to 1·5 mmol l −1 with around 12‰ enrichment in the residual sulphate (versus Canyon Diablo troilite) and the addition of TDIC enriched in 13 C, while maintaining a modern 14 C activity. Copyright © 2005 John Wiley & Sons, Ltd.