Soil science’s Yakun Zhang and Alfred Hartemink are scanning 1,481 soil samples from 388 soil profiles collected in Antarctica between 1975 and 1986 by James Bockheim. The project will provide information about the project and what it means for studies of soils and climate change.

Boxes of soil samples collected in Antarctica

Could you give some details about the project?

This project aims at developing a new understanding and provide a baseline of the diversity of soils in Antarctica by integrating the state-of-the-art soil spectroscopy techniques. These samples are  a unique and historical scientific collection in the world, and we are fortunate to have these legacy soil samples in our department.

What kinds of scans are you doing?

We will use three state-of-the-art spectrometers to scan these soil samples. The first one is the X-ray fluorescence (XRF) spectrometer, which measures total concentrations of multiple elements, including Mg, Al, Fe, Si, Ca, Mg, Mn, Ti, Zr, Cr, Sr, Rb, Cd, Ni and Pb.

The second one is the visible and near-infrared (vis-NIR) spectrometer and mid-infrared (MIR) spectrometers measuring absorbance spectra at 350–2500 nm and 2500–25000 nm, which provide multiple spectral features related to organic functional groups (e.g., aliphatic groups, amide, aromatics, carbohydrates), clay mineralogy, quartz, and carbonates.

The third one is the X-ray diffraction (XRD), which measures the types and structure of minerals in the soil.

Scanning finely ground soil samples with a MIR spectrometer by Moira Keith (Env Science BS, 2022) at the FD Hole Lab in the Department of Soil Science.

The XRF provides geochemical signatures whereas the XRD provides information about the soil weathering processes and the associated controlling factors. The Vis-NIR and MIR provide information about how organic matter accumulates in the soils of Antarctica.

Additionally, we aim to use vis-NIR and MIR spectra to predict key soil microbial properties.

In much of our research in Wisconsin we have been using these spectrometers to study soil characterization and link them to soil distribution and forming processes, and agricultural management. There is lack of such information for soils collected from polar regions.

What are you hoping to learn?

From the scanning, we will generate an extensive soil data library that will be used to gain new insights about the soils of Antarctica. Under the pressure of global warming, the icesheet and permafrost in Antarctica is reduced, leading to a changing microclimate favoring soil formation. It is largely unknown how the soils change and what the feedback is between the changes in the soil and the changes in the climate. In essence, we aim to increase our understanding of the hydropedological and biogeochemical processes that alter the soils of Antarctica. Building a comprehensive spectral library of Antarctica soil samples will also allow for comparison of data from current and future soil studies in Antarctica.