Prepared in Cooperation with the Strategic Environmental Research and Development Program (SERDP), April 2008.
Biochemical Indicators for the Bioavailability of Organic Carbon in Ground Water
Article first published online: 12 SEP 2008
Journal compilation © 2008 National Ground Water Association. No claim to original US government works
Volume 47, Issue 1, pages 108–121, January - February 2009
How to Cite
Chapelle, F. H., Bradley, P. M., Goode, D. J., Tiedeman, C., Lacombe, P. J., Kaiser, K. and Benner, R. (2009), Biochemical Indicators for the Bioavailability of Organic Carbon in Ground Water. Ground Water, 47: 108–121. doi: 10.1111/j.1745-6584.2008.00493.x
- Issue published online: 7 JAN 2009
- Article first published online: 12 SEP 2008
- Received December 2007, accepted July 2008.
The bioavailability of total organic carbon (TOC) was examined in ground water from two hydrologically distinct aquifers using biochemical indicators widely employed in chemical oceanography. Concentrations of total hydrolyzable neutral sugars (THNS), total hydrolyzable amino acids (THAA), and carbon-normalized percentages of TOC present as THNS and THAA (referred to as “yields”) were assessed as indicators of bioavailability. A shallow coastal plain aquifer in Kings Bay, Georgia, was characterized by relatively high concentrations (425 to 1492 μM; 5.1 to 17.9 mg/L) of TOC but relatively low THNS and THAA yields (∼0.2%–1.0%). These low yields are consistent with the highly biodegraded nature of TOC mobilized from relatively ancient (Pleistocene) sediments overlying the aquifer. In contrast, a shallow fractured rock aquifer in West Trenton, New Jersey, exhibited lower TOC concentrations (47 to 325 μM; 0.6 to 3.9 mg/L) but higher THNS and THAA yields (∼1% to 4%). These higher yields were consistent with the younger, and thus more bioavailable, TOC being mobilized from modern soils overlying the aquifer. Consistent with these apparent differences in TOC bioavailability, no significant correlation between TOC and dissolved inorganic carbon (DIC), a product of organic carbon mineralization, was observed at Kings Bay, whereas a strong correlation was observed at West Trenton. In contrast to TOC, THNS and THAA concentrations were observed to correlate with DIC at the Kings Bay site. These observations suggest that biochemical indicators such as THNS and THAA may provide information concerning the bioavailability of organic carbon present in ground water that is not available from TOC measurements alone.