Maddie Esposito ’23



Project Title

Investigation of Nitrogen Sources Contributing to Sapropel Formation in the Eastern Mediterranean

Presentation Link

View Maddie's Presentation

Certificate(s): Environmental Studies

I studied sapropel events in the Eastern Mediterranean by analyzing the nitrogen isotopic composition of organic matter preserved in foraminifera fossils. Sapropel events are periods of intense biological activity in the Mediterranean basin. Intensified summer monsoons are hypothesized to trigger sapropels by discharging excess freshwater into the Mediterranean and disrupting nutrient conditions, which results in oxygen-poor deep water and the deposition of organic matter (sapropels). Analyzing the nitrogen isotopic composition of foraminifera shells may provide insight into the nitrogen sources that fuel sapropel events. My role was to pick forams for future isotopic analysis, which involved using a basic microscope and specialized picking equipment to select individual fossils from a larger pool of sediment and isolate them according to species. I visually identified five different species of forams, picking two species per sample from 35 different samples. I refined and expanded my laboratory and sample-preparation skills through this experience. Additionally, I was introduced to the field of biogeochemistry, which is one avenue I can consider pursuing in my future independent work to bridge the gap between my interests in chemistry and geosciences.

Internship Year


Project Category

Climate and Environmental Science


Sigman Research Laboratory, Department of Geosciences, Princeton University


Daniel Sigman, Dusenbury Professor of Geological and Geophysical Sciences, Professor of Geosciences; Ellen Ai, Ph.D candidate, Geosciences