BASELINE: Natural baseline quality in European aquifers - A basis for aquifer management

• Research unit: EU RFP
• Project number: 99.0847

Key words (English)

Water quality; sustainability; monitoring; groundwater age; chemical and isotopic components

Alternative project number (English)

EU project number: EVK1-1999-00006

Research programs (English)

EU-programme: 5. Frame Research Programme - 1.4a.1 Sustainable management and quality of water

Short description (English)

See abstract

Partners and International Organizations (English)

Coordinator: British Geological Survey (UK)

Abstract (English)

It was defined as one of the main deliverable of WP5 (WP leader: Switzerland) to provide a tracer dataset that covers the full range of occurring timescales in the selected reference aquifers. A selection of aquifers was chosen to demonstrate the applicability of the most important available modern tracer techniques. Dating tools and techniques are crucial within this project because the BASELINE quality of groundwater is highly influenced by the residence time within a specific geological formation. In the last year all planned sampling campaigns were completed. Besides the already sampled aquifers (UK Triassic Sandstone aquifer, Quaternary sand aquifers at Odense) samples were taken from the Fontainebleau Sand aquifer in the Paris Basin). Additionally, samples were analysed from the Donana aquifer (mainly 14C) and the Ledo Paniselian aquifer (14C, noble gases). The measurements are nearly completed and the interpretation of the data is going on. The data collected by the group of WP5 will be completed with results from other BASELINE partners. Up to now, the following scientific Highlights are worth mentioning:
General
· A complete set of modern dating methods could be applied in the selected reference aquifers. Estimations of age stratigraphy of phreatic aquifers and of the age sequence in confined groundwater systems could be obtained.
UK Triassic Sandstone aquifer
· 39Ar activities decrease steadily in direction of groundwater flow and subsurface production is of minor importance.
· A fairly well correlation between 39Ar and 4He data was observed.
· '14C ages' seem to be too high compared with estimations derived from 39Ar activities.
· With 39Ar calibrated 4He accumulation rates agree with calculated production rates in rock
· A distinctive chemical evolution as function of residence time was observed.
Odense
· Residence times estimated from 3H/3He, SF6 and 85Kr measurements agree roughly. It seems that CFC ages overestimate the 'true' age because of degradation under reducing conditions.
· The combination and comparison of suitable tracer data leads to reliable dating results and additional information about flow dynamics.
Ledo Paniselian
· The substantial dataset leads to a better understanding of the potentially powerful 14C and 4He methods

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 99.0847