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Stable Isotopes and the Power of Small Things to Create Big Changes

When the pandemic began in March 2020, it shut down almost all inessential activities and drastically slowed down society; the subsequent drop in greenhouse gas emissions from varying industries and the clearing of air pollution was a stark reminder of just how strongly human activity and human behavior is causing climate change. While this may have been astounding to some, it comes as no shock to scientists like Professor Miquel Gonzalez-Meler in the Department of Biological Sciences at the University of Illinois at Chicago, who studies how stable isotopes of biologically critical elements (e.g., carbon, oxygen, and nitrogen) cycle throughout the environment and atmosphere. I recently was lucky enough to speak with Professor Gonzalez-Meler about the work he does in his lab, including his recent expedition to the Arctic. Despite the fact that I am majoring in ecology and evolutionary biology, my conversation with Professor Gonzalez-Meler helped me to see even more clearly how powerfully climate change can and will affect the health and processes of ecosystems. 

The Gonzalez-Meler lab conducts ecological and environmental research that uses stable isotopes to learn more about ecosystem processes. Isotopes are forms of the same element with the same number of protons but differing numbers of neutrons, resulting in different masses. Stable isotopes, in particular, have a long enough half-life (the time it takes for half of the amount of isotope to decay) so that they are able to be present in large enough quantities to study in the environment. All of the elements that are important to life, with the exception of phosphorus, have stable isotopes; for example, carbon-14 is a stable isotope of carbon used frequently in the practice of carbon dating. Stable isotopes are a broadly applicable tool that can be used to track how elements move between the land, the oceans, and the atmosphere, and although this may sound very niche, according to Professor Gonzalez-Meler, “You can use carbon isotopes to tell if someone is a vegetarian, and you can use oxygen isotopes to tell if someone spent their spring break in Florida.” 

In the Gonzalez-Meler lab, much of their research uses the isotope carbon-13 to study physiological changes in plants and other environmental impacts. The carbon-13 concentrations in a plant reveal a lot of information about the environment a plant is in, because the amount of carbon-13 which assimilates into a plant is a function of its environment. For example, the amount of carbon-13 a plant has assimilated can reveal if it is growing in drought conditions or an arid environment and can indicate the plant’s physiological response to water stress. In the atmosphere, observing diluted amounts of carbon-13 indicates that more carbon is entering the atmosphere from manmade sources because carbon-13 is barely present in oil, which is burned for fuel. 

Recently, Professor Gonzalez-Meler took his research to the edge of the earth by traveling to the Arctic with a group from UIC that included Honors Students Theressa Ewa, Samira Umar and Humair Raziuddin, who also participated in the Northwest Passage project last summer. They observed the isotope oxygen-18 concentrations in the ice off the coast of Greenland and compared it to the concentration of oxygen-18 in sea ice. While this may not sound very important, the oxygen-18 concentrations of the ice reveal the source of the water that formed the ice and knowing the source of water provides crucial information about how melting ice affects the productivity of the ocean. The team expected the productivity of the ocean to be increasing, but they were surprised to see that the productivity was decreasing. Gonzalez-Meler says that taking more air and water samples from the Arctic can be used to help understand the interactions between the cryosphere, the land, and the freshwater exports into the Arctic Ocean. 

Stable isotopes are an incredibly useful tool when it comes to understanding biogeochemical cycling, and as climate change causes more environmental and ecosystem changes, getting the best possible understanding of how things move through Earth’s atmosphere and ecosystems will help reveal the changes that Earth’s ecosystems can be expected to face. A documentary film, Frozen Obsession, directed and produced by David Clark and shot in 4K, follows the 18-day, 2,000-mile Northwest Passage Project expedition through the Canadian Arctic.  The film was broadcast on PBS in April and is streaming on the PBS website.