SEDIMENT OXYGEN DEMAND IN TIDAL CREEK STUDY SITES OF SOUTHEASTERN NORTH CAROLINA

Numerous tidal creeks in Coastal Southeastern North Carolina show periodic hypoxia and anoxia problems, possibly related to anthropogenic inputs. These creeks also show periodic algal blooms, which likely affect oxygen demand rates. In this study, rates of oxygen loss were measured as sediment oxygen demand (SOD) and water-column biochemical oxygen demand (BOD5). Selected tidal creek sites were sampled monthly from July 2001 to August 2002 in collaboration with the Tidal Creeks monitoring project to identify any trends that may be evident concerning SOD and BOD rates. Positive SOD rates range from 0.15 to 8.90 g O2 m-2 d-1. BOD rates ranged from 0.00 to 5.20 mg l-1. Preliminary results show that oxygen loss to sediments is greater than oxygen loss in the water column during some parts of the year, indicating that SOD must be considered in evaluating causes of water column hypoxia and anoxia. Percent organic content, grain size, total suspended solids of sediments and water flow were also determined in addition to routine water quality measurements. Correlation analyses were used to assess the effect of these variables, and selected land use variables, on SOD and BOD.