Geostatistical modeling of benthic organic carbon and sediment oxygen demand within a blackwater river: Contribution to low dissolved oxygen levels

Blackwater streams are found throughout the Coastal Plain of the southeastern United States and are characterized by a series of instream floodplain swamps that play a crucial role in the water quality of these systems.  Elevated benthic organic carbon (BOC) concentrations have been shown to be positively correlated with sediment oxygen demand (SOD) and are a likely driver for many of these streams violating the dissolved oxygen (DO) standard within the state of Georgia.  This study extends previous work and investigates not only the patchiness and distribution of BOC at the reach scale but also identify areas prone to high SOD at representative 3^rd and 5^th order locations.  SOD was shown to be spatially correlated with differences in distribution likely a result of the differing hydrologic regime and watershed position.  Mapping of floodplain soils at the landscape scale show that areas similar to those investigated are common and prevalent in higher order streams.  DO dynamics within these systems are a mix of natural and anthropogenic influences, but this study unequivocally illustrates the importance of instream swamps, elevated BOC levels, and SOD on the watershed scale and supports the idea that many of these streams have naturally low DO levels.