Redox zonation and organic matter oxidation in palaeogroundwater of glacial origin from the Baltic Artesian Basin ...
Ordovician-Cambrian aquifer system (O-Cm) in the northern part of the Baltic Artesian Basin (BAB), Estonia, is part of a unique groundwater reservoir where groundwater originating from glacial meltwater recharge from the Scandinavian Ice Sheet is preserved. The distribution of redox zones in the ano...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
Elsevier
2018
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.7892/boris.118494 https://boris.unibe.ch/118494/ |
| Summary: | Ordovician-Cambrian aquifer system (O-Cm) in the northern part of the Baltic Artesian Basin (BAB), Estonia, is part of a unique groundwater reservoir where groundwater originating from glacial meltwater recharge from the Scandinavian Ice Sheet is preserved. The distribution of redox zones in the anoxic O-Cm aquifer system is unusual. Strongly reducing conditions are found near the modern recharge area characterized by low concentrations of sulphate (<5 mg·L⁻¹) and the presence of CH₄ (up to 3.26 vol%). The concentrations of SO₄²⁻ increase and concentrations of CH₄ decrease farther down the groundwater flow path. Sulphate in fresh glacial palaeogroundwater originates probably from pyrite oxidation while brackish waters have gained their sulphate through mixing with relict saline formation waters residing in the deeper parts of the aquifer system. Stable isotopic composition of sulphate, especially relations between δ¹⁸OSO4-δ¹⁸Owater (∆¹⁸OSO4-H2O from +20.5 to +31.1‰) and δ³⁴SSO4-δ³⁴SH2S (∆³⁴SSO4-H2S value ... |
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