Publications
First Author
Williams, Olivia L., et al. "Mechanisms and magnitude of dissolved silica release from a New England salt marsh." Biogeochemistry 161.3 (2022): 251-271.
Coauthor
Martin, Kaden C., et al. "Greenland Ice cores reveal a south‐to‐north difference in Holocene thermal maximum timings." Geophysical Research Letters 51.24 (2024).
Brooks, T. W., et al. "Geochemical data supporting investigation of solute and particle cycling and fluxes from two tidal wetlands on the south shore of Cape Cod, Massachusetts, 2012-19 (ver. 3.0, January 2025)." (2021).
Presentations
“Methods Updates on Noble Gas Extraction at Oregon State University” (Poster, AGU Fall Meeting 2024)
“‘Science for its Own Sake’: The English Colonial Legacy in Polar Science”
Cornell Cryosphere Group, September 2024 (Invited)
COLDEX Annual Meeting, September 2024 (Keynote)
CEOAS Radical Earth Science Equity Transformations (RESET) Seminar, Spring 2024
"Denali Basal Ice δ15N Updates" (Talk, Denali Ice Core Research Summit 2024)
"Methods development in noble gas extraction for melt layer identification" (Poster, IceCOMM 2024)
"Development of a new noble gas extraction method in ice cores" (Poster, AGU Fall Meeting 2023)
"New δ18Oatm data indicate Denali ice core record includes full Holocene" (Poster, Ice Core Open Science Meeting 2023)
"New δ18Oatm data from the Denali ice core" (Talk, Denali Ice Core Research Summit 2022)
"New application of noble gas ratios to generate Arctic melt records" (Poster, IPICS 2022)
"Mechanisms of Silica Availability in a New England Salt Marsh" (Poster, AGU Fall Meeting 2020)
Noble Gases in Ice Cores
The Arctic is currently experiencing warming at a rate approaching four times the global average. This warming has driven large changes in the cryosphere: the Greenland Ice Sheet is currently the single largest contributor to sea level. Melt layers, or bubble-free layers in ice cores where surface melt percolates down into pore spaces and refreezes, are used as a proxy for positive-degree days when local temperatures rose above 0°C. Studying patterns of melting in past warm periods can illuminate how sensitive Greenland surface processes are to broader climate patterns. Noble gas elemental ratios may be used to identify melt layers in ice cores, as heavier noble gases like krypton (Kr) and xenon (Xe) become enriched in meltwater relative to lighter gases like argon (Ar) and nitrogen (N2). We have developed a wet extraction method targeted to produce low-volume, high-precision, high-resolution noble gas measurements with the goal of developing melt chronologies for several key warm periods across ice core sites in the Arctic. We measure δ15N with a mean precision of 15 per meg (0.015‰) standard error, in addition to elemental and isotopic concentrations of Ar, Kr, and Xe using a peak jumping mass spectrometry method. [2025 AGU Abstract]
Dissolved Silica Cycling in Marshes
Salt marshes are sites of silica (SiO2) cycling and export to adjacent coastal systems, where silica availability can exert an important control over coastal marine primary productivity. Mineral weathering and biologic fixation concentrate silica in these systems; however, the relative contributions of geologic versus biogenic silica dissolution to this export were not known. We collected water samples from the tidal creek of a relatively undisturbed New England (USA) salt marsh over 13 tidal cycles in spring, summer, and fall 2014–2016 to determine patterns of dissolved silica (DSi) concentration in the water entering and leaving the marsh. DSi concentrations in the tidal creek peaked in the summer and were at a minimum in the fall. Additionally, we analyzed DSi concentrations and Ge/Si ratios in marsh porewater and groundwater samples as a tracer of DSi origin. Ge/Si ratios in the porewater, subterranean estuary, and fresh groundwater averaged 6.3 ± 0.31 µmol/mol, which is consistent with production via silicate weathering rather than biogenic silica dissolution. These results highlight a previously unstudied role marsh sediment plays in coastal biogeochemistry by supplying DSi to coastal ecosystems. This marsh exported 1170 mmol DSi m−2 year−1, 85% of which originated from porewater exchange, with minor contributions from brackish groundwater discharge from the subterranean estuary. Examining these values in the context of the other known DSi inputs indicates that coastal marshes provide ~ 75% of the annual silica inputs into the adjacent estuary, Waquoit Bay.