Publications & Projects

Ongoing Projects

Leveraging hydrographic observations of transient tracers in the ocean to create statistical and inverse models of ocean circulation and carbon biogeochemistry supported by a GO-SHIP Tracer Postdoctoral Fellowship

Transient tracers of ocean circulation, such as chlorofluorocarbons and sulfur hexafluoride, provide a powerful means of observing and inferring ocean circulation as a primary driver of the marine carbon sink of anthropogenic carbon. This project uses the wealth of transient tracer observations of the open ocean to address persistent disagreements in the strength and trend of ocean carbon storage, which is an important regulator of Earth’s climate. While utilizing existing measurements, I will participate in repeat hydrography expeditions to perpetuate the invaluable transient tracer observation program.

Developing a particle tracking model of the Laurentian Great Lakes supported by a grant from the National Park Service to J. Austin

Particle tracking is a too used to model the transport of particles in a body of water described by a hydrodynamic model. This project combines the NOAA Great Lakes Observational Forecast Systems with OceanTracker, an open-source high-speed particle tracking package, to run simulated natural experiments of particle release and transport. These experiments are being applied to study aquatic invasive species, microplastics, and point-source pollution problems in the Laurentian Great Lakes.

Calcium carbonate saturation effects on Dreissenid mussel habitat funded by a graduate research fellowship from the Cooperative Institute for Great Lakes Research

Calcium carbonate satration state determines the solubility of calcium carbonate in aquatic environments. Organisms with shells made of calcite and aragonite (two mineral forms of calcium carbonate) are sensitive to calcium carbonate saturation state in marine environments. The potential for this environmental parameter to determine the habitat of freshwater invasive aquatic species with calcium carbonate shells has not been explored Previous work has demonstrated both calcium and pH sensitivities of Dreissenid mussels, which points towards the role of calcium carbonate saturation state as an ecological parameter of great importance. This project combines observational and experimental methods to guage the sensitivity of Dreissenid mussel development and habitat to carbonate chemical drivers.

Publications

Sandborn, D. E.; Austin, J. A.; Lafrancois, B. M. (2025). ``Developing a particle tracking model in Lake Superior’’. NPS Reports. Submitted.

Sandborn, D. E. & Minor, E. C. (2024). Underway pCO₂ surveys unravel CO₂ invasion of Lake Superior from seasonal variability. Journal of Geophysical Research: Biogeosciences, 129, e2023JG007877. doi:10.1029/2023JG007877

Pennington, S. et al. (2023). “EXCHANGE Campaign 1: A Community-Driven Baseline Characterization of Soils, Sediments, and Water Across Coastal Gradients”

Regier P. et al. (2023) “Coastal inundation regime moderates the short-term effects of sediment and soil additions on seawater oxygen and greenhouse gas dynamics: a microcosm experiment” Frontiers in Marine Science. doi: 10.3389/fmars.2023.1308590

Sandborn, D. E.; Minor, E. C.; Hill, C. “Total Alkalinity Measurement Using an Open-Source Platform”. (2023). Limnology and Oceanography Methods. doi:10.1002/lom3.10549

Sandborn, D. E. (2023). “RPi-Alkalinity: Publication Release”. Zenodo. doi: 10.5281/zenodo.7864447

Humphreys, M. P., Schiller, A. J., Sandborn, D. E., Gregor, L., Pierrot, D., van Heuven, S. M. A. C., Lewis, E. R., and Wallace, D. W. R. (2023). PyCO2SYS: marine carbonate system calculations in Python. Zenodo. doi:10.5281/zenodo.3744275.

Past Projects

Observation of pCO₂ in Lake Superior using underway instrumentation supported by a Grant-in-Aid from the University of Minnesota

The Laurentian Great Lakes act as regionally- and globally-significant carbon cycling actors, but the magnitude of their impact remains unclear due to an incomplete observational and modeling picture of their carbon biogeochemistry. This study demonstrates the use of underway instrumentation measuring pCO₂ to provide accurate measurements with high temporal and spatial resolution in the largest freshwater system by area, Lake Superior. The results of this project will point the way toward expanded carbon cycling observations and improved biogeochemical model constraints.

Expanding alkalinity measurement accessibility with open-source, low-cost instrumentation supported by a Grant-in-Aid from the University of Minnesota

This work demonstrated an instrument for total alkalinity measurement using open-source software and low-cost components with the goal of expanding measurement accessibility. Total alkalinity is a pivotal parameter for measurements of environmental water chemistry and ocean acidification. High-precision, high-accuracy measurements of alkalinity are crucial for obsrvations of water chemistry in a changing world. This study created the first total alkalinity system based on a Raspberry-Pi microcomputer to produce high-quality measurements with applications across the marine-lacustrine spectrum.

Purification of meta-Cresol Purple Dye via Flash Chromatography for Accurate Seawater pH Measurement funded by the Council on Ocean Affairs Science and Technology, California State University

This project sought to purify a pH-sensitive dye for high-precision, high-accuracy spectrophotometric pH determination of California Central Coast seawater. Flash chromatography has been demonstrated to provide a fast and easy purification method for pH-sensitive dyes. These dyes are crucial for obtaining high-quality measurements of ocean pH as a parameter of ocean acidification.