Trace elements and heavy metals in the Grand Bay National Estuarine Reserve in the northern Gulf of Mexico

• Biogeochemical/anthropogenic processes in Gulf of Mexico were studied.
• The estuary was strongly polluted by Hg and Cd and fingerprinted by As and Pb.
• Strong correlation was between organic matter & elements: Ni, Cr, Sr, Co, Zn, Cd, Cu.
• P spilling in 2005 caused increases in P & trace elements with strong correlations.
• Coal power plants may be a major source for the regional Pb based on Pb isotope ratios.

The objectives of this study are to investigate distribution of trace elements and heavy metals in the salt marsh and wetland soil and biogeochemical processes in the Grand Bay National Estuarine Research Reserve of the northern Gulf of Mexico. The results show that Hg, Cd and to some extent, As and Pb have been significantly accumulated in soils. The strongest correlations were found between concentrations of Ni and total organic matter contents. The correlations decreased in the order: Ni > Cr > Sr > Co > Zn, Cd > Cu > Cs. Strong correlations were also observed between total P and concentrations of Ni, Co, Cr, Sr, Zn, Cu, and Cd. This may be related to the P spilling accident in 2005 in the Bangs Lake site. Lead isotopic ratios in soils matched well those of North American coals, indicating the contribution of Pb through atmospheric fallout from coal power plants.

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