USGS - science for a changing world

South Florida Information Access (SOFIA)


publications > open file report > ofr 97-454

U.S. Department of the Interior
U.S. Geological Survey
OFR-97-454

Geochemistry of Surface and Pore Water at USGS Coring Sites in Wetlands of South Florida: 1994 and 1995

Open-File Report 97-454

by William H. Orem1 , Harry E. Lerch1 , and Peter Rawlik2

1 U.S. Geological Survey, 956 National Center, Reston, VA 20192
2 South Florida Water Management District, 3301 Gun Club Road, West Palm Beach., FL 33416-4680

Abstract
Introduction
Study Area
Coring & Pore Water Extraction
Analytical Methods
Results & Discussion
Summary
Acknowledgments
References
PDF Version

Abstract

In this report, we present preliminary data on surface and pore water geochemistry from 22 sites in south Florida sampled during 1994 and 1995. These results are part of a larger study designed to evaluate the role of biogeochemical processes in sediments in the cycling of carbon, nitrogen, phosphorus, and sulfur in the south Florida ecosystem. The data are briefly discussed in regard to regional trends in the concentrations of chemical species, and general diagenetic processes in sediments. These results are part of a larger study designed to evaluate the role of biogeochemical processes in sediments in the cycling of carbon, nitrogen, phosphorus, and sulfur in the south Florida ecosystem. These elements play a crucial role in regulating organic sedimentation, nutrient dynamics, redox conditions, and the biogeochemistry of mercury in the threatened wetlands of south Florida.

Pore water samples for chemical analyis were obtained using a piston corer/squeezer designed to avoid compression of the sediment and avoid oxidation and contamination of the pore water samples. Results show distinct regional trends in both surface water and pore water geochemistry. Most chemical species in surface and pore water show peak concentrations in Water Conservation Area 2A, with diminishing concentrations to the south and west into Water Conservation Area 3A, and Everglades National Park. The largest differences observed were for phosphate and sulfide, with concentrations in pore waters in Water Conservation Area 2A up to 500x higher than concentrations observed in freshwater marsh areas of Water Conservation Area 3A and Everglades National Park. Sites near the Hillsboro Canal in Water Conservation Area 2A are heavily contaminated with both phosphorus and sulfur. Pore water profiles for dissolved reactive phosphate suggest that recycling of phosphorus at these contaminated sites occurs primarily in the upper 20 cm of sediment. High levels of sulfide in pore water in Water Conservation Area 2A may inhibit mercury methylation here. At sites in Water Conservation Area 3A south of Alligator Alley, sulfide levels are much lower and sulfate reduction in the sediments here may be conducive to methyl mercury formation. Concentration versus depth profiles of biogeochemically important chemical species in pore water at most sites are smoth curves amenable to modelling using standard diagenetic equations. This should allow prediction of rates of biogeochemical processes in these sediments for incorporation in ecosystem models.

Go ahead to Introduction


Related information:

SOFIA Projects:

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.



| Disclaimer | Privacy Statement | Accessibility |

U.S. Department of the Interior, U.S. Geological Survey
This page is: http://sofia.usgs.gov/publications/ofr/97-454/index.html
Comments and suggestions? Contact: Heather Henkel - Webmaster
Last updated: 04 September, 2013 @ 02:04 PM (KP)