My research falls into three major categories listed below.  Although these topics appear to be unrelated, they are all linked in their focus on fluxes of water, solutes, and isotopes caused by biogeochemical reactions coupled with flow. In many cases these processes relate to interactions of surface water and groundwater.  Bibliographies of some recent papers in each topic are provided by links in the titles.

Carbonate karst aquifers

Most of my research on karst aquifers has been on the Floridan aquifer, but I have also been working extensively in the Bahamas and lately in the Yucatan.  My research focuses on how water flowing through conduits exchanges with water of the high-porosity matrix rocks.  I have also been active in developing tools to measure and predict fluxes of nutrients through carbonate karst watersheds.  I have recently been working on controls of redox conditions of carbonate aquifers from organic carbon remineralization  and how redox conditions affect metal mobilization and greenhouse gas production and consumption.  I currently lead a Research Coordination Network on Carbonate Critical Zones.  See more information here.

 

Coastal aquifers and sea level change

I am interested in quantifying fluxes of water from coastal aquifers and its significance to water quality in estuarine and coastal surface water.  This work has focused mostly on Indian River Lagoon on the east coast of Florida, but other areas include Tampa Bay, Bahamas, Barbados, Brazil, and the Yucatan.  One particular emphasis of this work is the redox chemistry of lagoon sediment pore water and the relationships between remineralization of organic carbon and metal mobilization and greenhouse gas fluxes.  My most recent work has been on the effects of sea level rise on these estuarine processes.

 

Weathering following ice sheet retreat

Retreat of continental ice sheets has exposed about 15% of Earth’s terrestrial landscape.  My interest in these landscapes is to assess how exposure and related weathering, plant colonization and succession, and biogeochemical reactions have altered fluxes of solutes, nutrients, and radiogenic isotopes to coastal regions and modify fluxes and consumption of greenhouse gases in Earth’s atmosphere.  This work has focused on several watersheds in southwest and south Greenland.  This work is being supported through a recent NSF grant; see Project Summary here.