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Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
After decades of research biogeochemists have identified several intervals of variable marine oxygenation throughout Earth's history. These fluctuations in oxygenation have been proposed to directly correlate to changes in ancient...
Peatlands contain a significant amount of the global soil carbon, but the climate feedback affecting carbon stability within these peatland systems is still relatively unknown. Organic matter composition of peatlands plays a major role...
Trace metal biogeochemistry in the Black Sea: Dissolved and suspended-particulate chemical fractionation of transition and Class B metals
Description:
The solution speciation and solid-phase suspended particulate fractionation of the trace metals Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb were investigated in the Black Sea, the world's largest anoxic basin. Sequential filtration/ion... The Class B metals (Cu, and Pb) were high in the surface waters and decreased rapidly across the sulfide interface, consistent with metal-sulfide precipitation below the interface. The dissolved metal fractionation was dominated... With the exceptions of Al and Fe, the suspended matter trace metal fractionation was dominated by weak-acid soluble forms. Strong-acid leachable forms, probably metal-sulfide phases, were important in the deep waters for Mn, and Co.
Atmospheric nitrate deposition: A large nutrient source in north Florida watersheds
Description:
Dry deposition of nitrate, estimated from a box model based on NO$\rm\sb{x}$ emissions and rain chemistry monitoring data over the contiguous 48 states, accounts for about half of the total US NO$\rm\sb{x}$ emissions, a deposition flux... temporarily recycled in the watersheds but not retained, so that it could eventually flow to the coastal zone where N may be a limiting nutrient for marine plants. Hydrologic conditions, which exhibit variations on seasonal and longer...
Northern high-latitude freshwater systems are an essential link between terrestrial and marine carbon cycles, transporting organic matter from ecosystems on land to the Arctic Ocean. However, polar regions are warming faster than the...
Trace gas analysis in Earth systems plays an important role in planetary research. Bernard (1976) and Whiticar (1999) proposed that biologically produced methane and thermogenically or geologically produced methane could be...
Globally, karst ecosystems are experiencing anthropogenic impacts due to their high hydrologic connectivity, leading to issues including increasing color (browning) as noted in recent decades at the largest freshwater spring on Earth ...
The eastern Indian Ocean is dynamic and rich in mesoscale eddy activity, and this complex circulation has implications for biological properties. The Argo Basin, south of Java and northwest of Australia, is located in the tropical...
Ecophysiological Responses of Phytoplankton to Environmental Cues - A Laboratory Approach: Effects of Growth Light Quality on Phytoplankton and an Assessment of Carbon Utilization in Karenia Brevis
Phytoplankton are primary producers in the marine food web, providing energy and matter for higher trophic levels by fixing CO2 and inorganic nutrients into biomass. This production of particulate organic matter by marine phytoplankton, ...
Karenia brevis is a marine dinoflagellate commonly found in the Gulf of Mexico and important both ecologically and economically due to its production of the neurotoxin brevetoxin, which can cause respiratory illness in humans and...
The sources and chemistry of late winter Arctic tropospheric aerosols
Description:
Arctic aerosols at Barrow AK from 16 March to 7 May 1986 were sampled and studied for natural aerosols or natural aerosol components as well as pollutants using ion chromatography and proton induced X-ray emission analyses, and a... indicating a pollution origin. Movements of ozone-depleted air and ozone-rich air apparently caused very large in situ ozone concentration fluctuations, but the excess bromine-ozone anticorrelation argues for a chemical interaction...
The Arctic is warming at a rate twice that of other global ecosystems and changing climate conditions in the Arctic are mobilizing long frozen permafrost stores of organic carbon. In regions of extensive ground ice, thawing permafrost...
The Deepwater Horizon (DwH) blowout released 5.0x1011g C from gaseous hydrocarbon into the water column and up to 6.0x1011g C from oil (Joye et al., 2011). Oil was visible on the surface, but <0.01% of the gaseous hydrocarbon escaped the...
Climate change is radically altering the Arctic. These alterations are expected to have immense and cascading implications on the carbon cycling of the region. In particular, our interest lies in the Kolyma River (KR) as it is the...
As the Arctic warms, the ~277 Pg of carbon stored in permafrost peatlands faces an uncertain fate. Arctic and Subarctic peatlands are likely to release more methane (CH4) as permafrost thaw releases formerly-frozen carbon, thaw-induced...
The Biogeochemical Cycle of Mercury in the Northern Gulf of Mexico as Constrained by Carbon, Nitrogen, Sulfur, and Mercury Isotopic Ratios in Marine Fish
Mercury (Hg) in the environment has deleterious ecological and health affects for humans and wildlife and is primarily transferred to humans through the consumption of marine biota (USEPA, 2001). These ecological and health concerns are...
Iron: Oceanic and estuarine distributions and size fractionation
Description:
The distribution of iron in three different environments has been studied in an attempt to understand what processes control its concentration in the open ocean. In the Ochlockonee Estuary, dissolved Fe concentrations are dominated by a...
The Greenland Ice Sheet (GrIS) is melting at an alarming rate. Supraglacial melt water flows into moulins that drain to the base of the ice sheet, and enhances basal flow. Ultimately, large quantities of melt water are expelled into the...
In the uppermost millimeters of shallow submerged coastal sediments, photosynthesis by microalgae and cyanobacteria during daylight hours can cause oxygen supersaturation of sediment porewater, leading to bubble formation. In shallow...
The aeolian transport of aerosols (mineral dust from desert areas, smoke and ash from biomass burning, and from anthropogenic emissions) is an important process for introducing bioactive trace elements to the surface ocean and can have a...
Quantifying Earth's carbon budget remains an imperative task in the carbon cycle science community. Among its challenges, assessing carbon fluxes over the Arctic Ocean remains an arduous task, due to its remoteness and difficulty to...
Spatial and Interannual Variability in Export Efficiency and the Biological Pump in an Eastern Boundary Current Upwelling System with Substantial Lateral Advection
Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often...
Climate change is melting glaciers and altering watershed biogeochemistry across the globe, particularly in regions dominated by mountain glaciers, such as southeast Alaska. Glacier dominated watersheds exhibit distinct dissolved organic...
Atmosphere-biosphere exchange plays a key role in the global cycles of water and carbon. Air pollution can alter these processes and induce climate perturbations and feedbacks. Surface ozone (O3) is an air pollutant and greenhouse gas...
Nitrate (NO3-) and uranium (U) are priority co-contaminants at U.S. Department of Energy (DOE) managed nuclear legacy waste sites, where nitric acid was extensively used to process uranium waste. This combination of a low pH and mixed...
Microbiology of bioturbated sediments: The burrows of Callianassa and the deposit-feeding system of Ptychodera
Description:
A need exists for information on sedimentary microbes, expecially at the level of specific populations, and particularly with respect to their interactions with benthic macrofauna. Two examples were documented. First, biochemical and conventional analyses were used to characterize the microbial food resources and digestive efficiency of Ptychodera bahamensis, an enteropneust hemichordate. Sediment was collected from freshly extruded fecal casts... Second, the same methods were used to characterize the microbial populations within the burrow of Callianassa trilobata, a decapod crustacean. Sediment was collected from the burrow lining, burrow matrix, and ambient, subsurface sediment...
Climate change is decreasing watershed glacial coverage throughout Alaska, impacting the biogeochemistry of downstream ecosystems. We collected streamwater fortnightly over the glacial runoff period from three streams of varying...
Concurrent with the rapid increase in population on Earth in recent centuries has been an increase in fossil fuel combustion, clearing of land and burning (slash and burn agriculture), as well as increasing natural wildfires, all of...
Stable isotopes as tracers of methane oxidation in the rhizosphere and at the sediment-water interface in Florida wetlands
Description:
Consistent with the presence of CH$\sb4$ oxidizing bacteria at the sediment-water interface in a north Florida flooded forest and in Everglades Cladium marshes with peat soils, CH$\sb4$ emitted from the flood water was enriched in $\sp... Stable isotopes gave no indication that CH$\sb4$ oxidation was occurring in the rhizosphere of Everglades Cladium marshes. Rhizospheric oxidation did not cause $\sp{13}$C enriched CH$\sb4$ to enter the plant and be emitted to the... A carbon budget developed for the flooded forest indicated that the carbon remineralization rate of soil organic matter was dependent on the hydo condition (flooded/dry) of the forest. The rate under dry conditions was 33.72 mol C m$\sp{... Due to the presence of insoluble organic surface films on the flood water in the flooded forest, which retard the transfer of gases across the water-air interface, calculation of fluxes from Fick's First Law overestimates the diffusive...
Polynuclear aromatic hydrocarbons: Sediment and plant interactions
Description:
The plants and sediments of two shallow, sub-tropical lakes in north Florida (Lake Jackson and Lake Hall located in Leon County) were sampled, identified, and analyzed for PAH content at 16 different stations quarterly. Stations were... The PAH content of rooted vegetation was found to have a significant relationship with the concentrations of PAHs in the sediments upon which they grew. There was no relationship between the PAH concentrations in non-rooted plants and... It was conclusively shown that the sediment PAHs exerted a deleterious effect on the growth of the subject aquatic macrophytes, and that the PAHs from the sediment entered the plants through their root systems. These experiments showed... There were species-specific differences in the degree of accumulation of sediment PAHs. Saturation phenomena for PAH bioconcentration were observed. A model was developed that incorporated equilibrium constants, constants for adsorption...
After the Deepwater Horizon (DWH) blowout, MC252 crude oil was washed onto the shores of the northeastern Gulf of Mexico. Weathered oil was buried in sandy Florida beaches in the form of sands covered by oil films, small oil particles, ...
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