Julia Kelson

Evaporation in Soils from Triple Oxygen Isotopes

Dr. Julia Kelson is a sedimentary geochemist and a paleoclimatologist who works as an assistant professor in the Department of Earth and Atmospheric Sciences at the University of Indiana, Bloomington. She received her PhD from the University of Washington and did a postdoc at the University of Michigan. She also worked with the department's Dr. Landon Burgener during graduate school. She presented on evaporation in soils from triple oxygen isotopes within paleoclimatology.

As a paleoclimatologist, Dr. Kelson works to understand the hydrology in land-based soils of ancient climates, specifically in the early Eocene and mid-Cretaceous time periods. Historically, scientists have used δ18O (delta-O-18) to measure such data as the temperature of precipitation, interactions between minerals and groundwater, and several other processes. The issue with δ18O, however, is evaporation, which makes measuring other relevant data, such as atmospheric circulation patterns or amount of rainfall, extremely difficult to do. Dr. Kelson believes she's found a solution.

Until recently, the scientific community largely overlooked δ17O because it seemed to have most of the same properties as δ18O. However, recent studies have revealed that δ17O has at least one unique characteristic that distinguishes it from δ18O. Evaporated water soils appear to have less δ17O and more δ18O, meaning δ17O is affected by evaporation. This signifies that the ambiguities that result from using δ18O can be constrained with δ17O, providing a possible solution to Dr. Kelson's dilemma.

Before Dr. Kelson used δ17O to help her study ancient climates, she decided to test it out on modern soils. Using samples from New Mexico, Idaho, and the Mojave Desert, each with different levels of aridity, Dr. Kelson studied the δ17O and d-excess (deviation in hydrogen isotopes) in each of the samples. She found that evaporation does indeed drive covariation within the two measurements.

This exciting development gives new insight into how soil carbonates form. It also allows for paleoclimatologists to better account for temperature and evaporation. These new tools broaden perspective into paleo-terrestrial environments and help scientists understand more about how hydroclimates are changing in the modern world.