Studies in the Terrestrial Biosphere, the Atmosphere, and Ice Cores

Starting with the work of Ben Houlton, we have collaborated with the group of Lars Hedin in the Department of Ecology and Evolutionary Biology in isotope studies of terrestrial N cycling. We have also worked on the nitrate N and O isotopes in rain, snow, and ice as tracers of reactive nitrogen sources and processing in the modern and ancient atmosphere.

References

3 Publications
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Nitrogen isotope dynamics of the Cariaco Basin, Venezuela
We report 15N/14N measurements of water column nitrate and ammonium, sinking particles, and sediments from the Cariaco Basin, an anoxic marine basin off the coast of Venezuela. Water column denitrification occurring in the basin has only a very small isotopic imprint on nitrate in the basin because nitrate consumption is nearly complete in the…
CO2 effects on taxonomic composition and nutrient utilization in an Equatorial Pacific phytoplankton assemblage
We report the results of a field incubation experiment demonstrating a substantial shift in the taxonomic composition of Equatorial Pacific phytoplankton assemblages exposed to CO2 levels of 150 and 750 ppm (dissolved CO2 ∼3 to 25 μM). By the end of the experiment, the phytoplankton community in all samples was dominated by diatoms and Phaeocystis…
Nitrogen isotopic response of prokaryotic and eukaryotic phytoplankton to nitrate availability in Sargasso Sea surface waters
Taxon-specific nitrogen (N) isotope data from the summertime Sargasso Sea have previously suggested reliance of prokaryotic phytoplankton on regenerated N but a greater importance of nitrate assimilation for eukaryotic phytoplankton. To investigate this further, particles collected in the summer from 100 m at the Bermuda Atlantic Time-series…