Marsha Allen, Cosmochemist and Hydrogeologist

What is your favorite part about being a scientist, and how did you become interested in science?

I never thought I could or would be a scientist, because I never knew that it was actually an option for me. I knew I wanted to be educated and it was along that journey I fell in love with geology at Mount Holyoke College. Under the mentorship of Dr. Harold Connolly at the American Museum of Natural History in 2009 and Dr. Steve Dunn at Mt Holyoke College, I started my first research projected analyzing a Calcium Aluminum Inclusion found within the Allende meteorite. CAI’s inclusions are the oldest rocks to form in our solar system approximately 4.5 billion years ago.

Having something that old in my hands caused so many emotions, and I wanted to understand all of the processes that formed the minerals to the creation of the rock as it moved away from the sun.

I also completed my masters’ thesis on analyzing three samples of the Chelyabinsk meteorite that impacted Russia in 2013 at Brooklyn College under the mentorship of Dr. John Chamberlain. For that project, I used the mineralogy and petrographic features to quantify the amount of impact events and mineral evolution the meteorite experienced after breaking away from its parent asteroid.

I recently started my PhD at the University of Massachusetts Amherst specializing in my other passion hydrogeology with Dr. David

An image from Marsha’s research on the Chelyabinsk meteorite. The image on the left is a thin slice of the meteorite, with chondrules (black spheres which are mineral grains that grow in meteorites), and fractures (black lines) caused by the meteorite impact. The images on the right are the same thin section under the microscope in XPL (cross-polarized light, which is used to enhance minerals under the microscope; the different colors are different minerals).

Boutt’s research group. My dissertation project aims to quantify and understand the seasonal trends of recharge to the water storage on the island of Tobago, by creating an annual water budget. It will be based on the islands annual precipitation, runoff, evapotranspiration, stream and river discharge, and infiltration into the subsurface using a transient flow groundwater modeling and geochemical analysis.

X-ray map showing different minerals within a thin section (very thin slice of rock) taken from the Chelyabinsk meteorite. The different colors represent different minerals: red is silica; green is calcium; and blue is aluminum.

What do you do?

In a nutshell, I am trying to quantify the amount of water stored in the subsurface of the island as time passes. This means that the hydrologic water budget depends on the changes of variables such as precipitation, evapotranspiration, and runoff.

I am also learning how to use isotopic ratio of hydrogen (tritium) to determine the age of water. This is important since you have an understanding of whether the water from a well is recharged by rainfall or by a deep (i.e. old) underground source.

How does your research contribute to the betterment of society?

Today, it is becoming more imperative to understand and use potable water sustainably. We see many countries or regions of the world experiencing drastic shifts in climate leading to severe droughts or massive flooding related issues. My research is directly related to climate change, since its behavior completely shifts the amount of groundwater stored in the subsurface. Thus, quantifying the amount of water stored in the subsurface at any period in time is important to sustainable water management for all countries.

Marsha doing field work in Death Valley, California, as part of her PhD research.

What are your data, and how do you obtain it?

In hydrogeology, we use a combination of data types and sources to complete an analysis. Some of these are: geological maps, well information (i.e. hydraulic conductivity and depth to water table) precipitation samples and amounts, surface water samples, and remote sensing just to name a few. All of these types of data and samples are then analyzed through various processes to produce the final result.

What advice would you give to young aspiring scientists?

I would tell any budding scientist to make sure to study a topic they are passionate about, because it actually makes the entire process enjoyable. I think it is also important to be well rounded and have a strong foundation in all science topics.

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