Camelin McKay
Pronouns: she/her
Research Mentor(s): Diana Velazquez
Research Mentor School/College/Department: / SNRE
Program: UROP
Session: Session 2 (10:00am – 10:50am)
Authors: Camelin McKay, Diana Velazquez
Abstract
As earth’s climate warms, more freshwater lakes are reaching anoxia (low oxygen levels) which has a significant effect on overall ecosystem health. Dissolved oxygen levels are important for determining nutrient cycling, affecting lake productivity. Nitrogen is an important nutrient, as it is often a limiting nutrient in aquatic environments, and its processes can be recorded through nitrogen isotope (d15N) signatures in lake sediments. An isotope is a different form of the same element, differing in their number of protons which affects its chemical properties. The d15N notation expresses the relative ratio of the heavier N15 isotope to the lighter N14 isotope. Middle Island Sinkhole (MIS) is an anoxic, karst formation located in Lake Huron which could be used as a modern analog to future lacustrine environments affected by climate change. MIS is unique for its relatively low nitrogen isotope signatures (-3.2 to 1.6‰) and its anoxic environment. In this way, MIS is a valuable model system for understanding how anoxic freshwater conditions affect nitrogen processes in lake sediments. We created a database comprising nitrogen and carbon isotopic signatures from lakes around the world, including other parameters such as O2 classifications (oxic versus anoxic), trophic level, lake area and maximum depth. We included oxygenated and anoxic lakes in order to determine if there are general differences between these lakes’ sediments. The database will be used as a proxy to determine the parameters which affect nitrogen isotope values in anoxic lacustrine environments. At present, each lake exhibits unique clustering in its d15N and d13C signatures, and future work will focus on what drives this relationship.
