Sediment Methyl and Total Mercury Concentrations Along the Georgia and Louisiana Inner Shelf, USA

Abstract

There is a paucity of information of the distribution of mercury (Hg) in continental-shelf sediments. On average, total Hg concentrations were four times greater along the Louisiana (LA) shelf than along the Georgia (GA) shelf. Methyl Hg was only twice as great in the LA coastal sediments than in GA sediments. Methyl Hg was correlated with organic matter in sandy GA sediments, whereas it was correlated with total Hg in the LA sediments. Therefore, using single-sediment characteristics to extrapolate methyl Hg concentrations between geographical locations may not be accurate. Site- and sediment-specific calibrations of models are required to more accurately predict the extent of Hg methylation.

Keywords:

• Continental shelf sediment
• Gulf of Mexico
• Georgia bight
• mercury
• methyl mercury

Acknowledgments

This work was supported in part by the Louisiana Sea Grant Program. We thank I. Devai and Rui Tao for extraction and analyses of mercury from sediment samples. The Louisiana ship time was supported by the National Science Foundation through a CAREER grant to Sam Bentley.