Publication Details (including relevant citation information):
Creswell, J. E.; Kerr, S. C.; Meyer, M. H.; Babiarz, C. L.; Shafer, M. M.; Armstrong, D. E.; Roden, E. E. 2008. Temporal and spatial distribution of total mercury and methylmercury in hyporheic sediments of the Allequash Creek wetland. Journal of Geophysical Research - Biogeosciences 113(G00C02). doi: 10.1029/2008JG000742.
Hyporheic pore water samples were collected from two sites within the Allequash
Creek wetland, in Vilas County, northern Wisconsin, from August 2003 to October 2004.
Samples were collected simultaneously at the surface and at 2, 5, 7, 10, and 15 cm below
the sediment-water interface. Concentration ranges were 3.7 to 58 pM for inorganic
mercury, <0.5 to 16 pM for methylmercury, 3.02 to 152 mM and 0.38 to 96.6 mM for
oxidized and reduced iron, respectively, 1.28 to 48.2 mM and< 0.05 to 9.76 mM for
oxidized and reduced sulfur, respectively, and 109 to 689 mM for dissolved organic
carbon. These concentrations are typical of anoxic environments such as wetlands and
lake sediments. These data were used to gain a better understanding of the processes
controlling spatial and temporal variability of inorganic mercury and methylmercury.
Findings show that conditions conducive to mercury methylation exist in the hyporheic
zone, especially in late summer, when accumulation of reduced iron and sulfide are
indicative of microbial iron and sulfate reduction. Methylmercury concentrations also
peak in late summer, with the highest concentrations appearing 2 to 10 cm below the
sediment-water interface. While there is a general covariance of total mercury and
methylmercury over the depth profile, poor correlation was observed over time,
highlighting the dynamic nature of hyporheic zone conditions and suggesting changes in
mercury speciation and partitioning.
Address (URL): http://dx.doi.org/10.1029/2008JG000742