Evaluation of the Sulfate Dynamics in Groundwater by Means of Environmental Isotopes

• Published in: Isotopes in environmental and health studies 2002-06, Vol.38 (2), p.103-119
• Main Authors: Trettin, R., Knöller, K., Loosli, H. H., Kowski, P.
• Format: Article
• Language: English
• Subjects: Environmental Monitoring - methods; Groundwater; hydrogen isotopes; Isotopes; oxygen; stable isotopes; sulfate; Sulfates - analysis; sulfur isotopes; tritium; Water - chemistry
• ISSN: 1025-6016; 1477-2639
• DOI: 10.1080/10256010208033318

Elevated sulfate concentrations and their heterogeneous distribution in the drinking water catchment area Torgau-Mockritz (Germany) were investigated by means of multiple isotope signatures such as δ 34 S, δ 18 O-H 2 O, δD, tritium, and 85 Kr. δ 34 S values of the groundwater sulfate vary between -19...+ 37‰ CDT. No simple correlation exists between sulfate concentrations and δ 34 S. Superimposition of different sulfur sources and mobilization processes combined with a complicated groundwater movement create a complex distribution pattern. The oxidation of reduced sedimentary sulfur has to be regarded as a main source of dissolved sulfate at least regionally. Tritium and 14 C data revealed that old groundwater can be excluded as source for high sulfate contents. Correlated temporal variations in the concentrations of tritium and sulfate are observed in deeper sampling positions. Highly variable δ 18 O and δD, as detected in parts of the catchment area, indicate local influences of surface water infiltration into the aquifer. The spatial distribution of isotope signatures enables the identification of zones with descending younger water or hindered groundwater movement and hence provides useful hints for flow modeling.