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Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater

March 20, 2012

Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA254) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems.

Publication Year 2012
Title Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater
DOI 10.1111/j.1745-6584.2011.00835.x
Authors Francis H. Chapelle, Paul M. Bradley, Peter B. McMahon, Karl Kaiser, Ron Benner
Publication Type Article
Publication Subtype Journal Article
Series Title Ground Water
Index ID 70037778
Record Source USGS Publications Warehouse
USGS Organization South Carolina Water Science Center