RESEARCH
Research Interests
How will the ocean respond to global climate change? Currently, the ocean takes up about one quarter of the CO2 emitted by fossil fuel burning but this number could easily change in the future. In order to predict the future CO2 balance of the planet, we need to gain a mechanistic understanding of the marine carbon cycle. How does CO2 cross from the atmosphere to the ocean? Improved understanding of air-sea gas exchange will aid in answering that important question. What happens to the CO2 when it is in the ocean? Photosynthetic organisms fix CO2 into organic carbon. Some fraction of this organic carbon is exported to the deep ocean where it is separated from the atmosphere for hundreds of years. What controls the amount of photosynthetic production in the ocean? The fraction of organic carbon that is exported? In order to address these questions, I use dissolved gases as tracers to aid in understanding the global biogeochemical cycles of CO2 and O2. Noble gases are ideal tracers for physical processes affecting CO2 and O2, especially air-sea gas exchange, since they are biologically and chemically inert. The heavier noble gases Kr and Xe respond primarily to diffusive gas exchange whereas the lighter noble gases He and Ne are also sensitive to bubble processes. Thus measurements of a suite of noble gases can be used to separate and quantify different processes within air-sea gas exchange. Measurements of the triple isotopic signature of oxygen and of the ratio of O2/Ar both discretely and using an at-sea equilibrator inlet mass spectrometer (EIMS), lead to large datasets on gross production and net community production rates in the upper ocean. These rate data can be used in combination with numerical modeling to investigate issues of biological productivity and its variations and feedbacks.
Research Projects
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NES-LTER
​The LTER (Long Term Ecological Research) is a cohort of experienced scientists
and students gathering observational and experimental data over extended periods of time
and areas to study a range of ecological processes and provide the insights gained to protect
and properly manage ecosystems in an ever-changing world. There are currently 28 site-specific
projects. NES (Northeast US Shelf) is one of those sites. More information can be found here https://lternet.edu/site/northeast-u-s-shelf/.
NES focuses on spatial and temporal variability of the planktonic food web in this region and how climate change and other physical factors are impacting that system. NES covers the Gulf of Main down through the Middle Atlantic Bight, which travels down to North Carolina's coast. Continuous and discrete samples and observations of various biologic, chemical and physical componenets are taken along a primary cross-shelf transect four times a year to cover each of the four seasons. The transect spans roughly 1.75 degrees latitude (~150km) from Martha's Vinyard Coastal Observatory (MVCO) out to the Ocean Observatories Initiative (OOI) Pioneer Array located just past the outer coastal shelf break. Stanley Lab has participated in 13 of the cruises surveying this transect starting since Winter of 2018.
On each cruise, our lab takes continuous measurements of O2/Ar ratios allow us to calculate the total net community production (NCP) which can be used to estimate and follow the flow of energy in the system. We also take discrete measurements of triple oxygen isotopes (TOI), dissoled oxygen (DO), salinity, and sea surface temperature (SST). Looking back, we compare cruises and seasons to see if and how these factors have changed and any correlations between them that may arise.
- Cruise Comparisons
Spring 2018/2019: Overall similar variability in NCP seen in both years; standard deviation of 34.29 in 2018 and 39.64 is 2019. However, the medians they clustered around varied more, with 2018 at 4.673 mmol O2 m^-2 d^-1 and 2019 at 28.17 mmol O2 m^-2 d^-1. Sea surface temperature did not appear to have any correlation with NCP, while salinity and NCP seemed to exhibit a positive trend. Most interestingly, as the cruise traveled out towards the shelf (latitude decreasing) NCP increases slightly and had a brief peak around the halfway point (latitude 40.6)- maybe signifying this area to be particularly productive. Diurnal patterns also highlight higher productivity during the night.
2018 Science Center Summer Research Program Poster
2017 Science Center Summer Research Program Poster
