Dating of groundwaters by ¹⁴C-analysis of dissolved humic substances

• Fulvic acids of the DOC of five deep (139-409 m) groundwaters were recovered (adsorption on DEAE-cellulose) and used for age determination (14C determined by accelerator mass spectrometry), and compared with fulvic acids recovered from a shallow groundwater and a surface water. The composition of the seven different fulvic acids was similar, despite variations in hydrochemical conditions and residence times, indicating a high stability of this molecular weight fraction. The ages calculated from the 14C-content of the fulvic acid fraction (600 to 10000 y) are less than the ages indicated from analyses of the dissolved carbonate (data available for three sites). Using a fraction of the DOC with high stability (like the fulvic acid fraction) as a 14C-source when assessing the ages of subsurface waters, appears to be superior to using dissolved carbonate.

Ämnesord

LANTBRUKSVETENSKAPER  -- Annan lantbruksvetenskap -- Miljö- och naturvårdsvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Other Agricultural Sciences -- Environmental Sciences related to Agriculture and Land-use (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Groundwater

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