G. Buckau et al., Groundwater in-situ generation of aquatic humic and fulvic acids and the mineralization of sedimentary organic carbon, APPL GEOCH, 15(6), 2000, pp. 819-832
In this paper the groundwater in-situ generation of dissolved organic carbo
n (DOC) is discussed based on the origin of groundwaters, their physico-che
mical and isotopic properties, chemical composition and the dissolved inorg
anic carbon (DIC) concentration and its C-13 content. Three aquifer systems
are investigated. Two of these have relatively well defined hydrological a
nd geochemical conditions (Fuhrberg and Munich) and are used as reference s
ystems. The third aquifer (Gorleben) is a complex system containing DOC con
centrations up to 200 mg C/L in deep groundwaters. From this aquifer system
19 groundwaters from different hydrogeochemical conditions are analyzed. T
he in-situ generation of DOC is found to occur in conjunction with the micr
obiologically mediated mineralization of sedimentary organic carbon (SOC).
Thereby, SO4 is reduced and phosphate is released into the groundwater. Whe
re SO4 is depleted, the mineralization of SOC occurs via fermentation, resu
lting in CH4 generation. (C) 200 Elsevier Science Ltd. All rights reserved.