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Sulfat-dominierter BTEX-Abbau im Grundwasser eines ehemaligen Gaswerksstandortes

Wisotzky, Frank, Eckert, Paul
Grundwasser 1997 v.2 no.1 pp. 11-20
BTEX (benzene, toluene, ethylbenzene, xylene), aquifers, benzene, biodegradation, carbon dioxide, ethylbenzene, ferric hydroxide, gravel, groundwater, groundwater contamination, manganese oxides, nitrates, oxidants, oxygen, prediction, remediation, sand, soil, sorption, sulfates, toluene, water table, xylene, Germany
In the area of a former gas-works in Düsseldorf (Germany) a soil and groundwater contamination with up to 100 mg/l BTEX (benzene, toluene, ethylbenzene and xylenes) was investigated. Benzene is the dominant aromatic hydrocarbon in the groundwater. The investigations show a natural biodegradation of BTEX by oxygen, manganese oxides, nitrate, ferric hydroxide and sulfate in the sand and gravel aquifer. Sulfate reduction is the most important degradation process in the contamined groundwater. As a product of sulfate reducion, sufids were formed in the sediments of the aquifer. A balance of oxidants is presented as a tool to quantify BTEX degradation and to differ this from sorption and dilution processes. In the contaminated area the degradation of aromatic hydrocarbons leads to the release of carbon dioxide. The highest free CO ₂ -concentration was found in the region of the groundwater table. Outgassing of CO ₂ is important and was verified by deep-specific soil-gas sampling. The knowledge of these processes in the subsoil is a requirement for making predictions for in-situ remediation effects.