Visiting PhD Student Investigates Methane Cycling in Arctic Lakes

May 2, 2013 • Filed under: News — melanie.rohr

Methane’s role as a greenhouse gas and its potential to impact global climate change has catapulted it into the mainstream media and dinner table conversations, but fewer people have considered its potential as an underutilized resource. A lack of understanding and quantifying sources of methane presents an opportunity for research which is an advantage for PhD exchange student Karla Martinez-Cruz. Martinez-Cruz recently joined the WERC staff to pursue her research on methane cycling.

Methane’s higher global warming potential means that understanding and analyzing methane cycling could help future efforts to mitigate climate change or, at the very least, lead to innovations and technology in using this resource.

During her year-long stay, Martinez-Cruz will analyze Alaskan lakes to continue her PhD work on microbial methane dynamics in freshwater ecosystems. She will work with WERC’s Dr. Katey Walter Anthony. Walter Anthony’s projects have included modeling permafrost and carbon cycling in thermokarst lakes as well as estimating methane ebullition.

PhD exchange student Karla Martinez-Cruz sets up equipment in the field for her research on methane cycling in Arctic lakes

Image above: PhD exchange student Karla Martinez-Cruz sets up equipment in the field for her research on methane cycling in Arctic lakes.

Walter Anthony’s research complements Martinez-Cruz’s interests, as well as her previous research in Mexico, at Cinvestav in Mexico City. Martinez-Cruz’s past work includes quantifying methane production and atmospheric exchange of methane from water sources in Mexico City. Mexico City faces considerable problems with water quality and waste water control. After measuring methane emissions from 11 ecosystems, Martinez-Cruz and her advisor, Frederic Thalasso, professor and researcher at Cinvestav, found that most methane emissions came from dams. Furthermore, methane emissions from aquatic ecosystems constituted 2-11% of Mexico City’s total methane emissions.

From this research, Thalasso, Martinez-Cruz, and her colleague Armando Sepulveda-Jauregui looked to continue researching methane cycling. This led them to consider Arctic lakes as an area of interest. Arctic lakes are relevant to the study of methane dynamics because, as Martinez-Cruz states, some researchers believe that Arctic lakes could contribute as much as 6% of global methane sources annually. Martinez-Cruz notes that more than 50% of lakes are located in the northern hemisphere, and they constitute nearly 48% of the land’s surface in some high latitude regions. If Arctic lakes do play such a significant role in the global methane system, studying them may be a key component to understanding methane cycling in freshwater systems.

To date Martinez-Cruz has visited over 40 lakes and collected data on methane emissions and methane oxidation. Her field work began in 2011 when she came to Alaska with Thalasso and Sepulveda-Jauregui to collect methane data on a north-south transect of Alaskan lakes.
This year, Martinez-Cruz plans to continue gathering data; she also plans to take sediment cores and gather water parameters on two lakes. “My plan is to analyze the methane capture in absence of oxygen or anaerobic methane oxidation (AOM) in sediment of arctic lakes. AOM is a scarcely know process in methane cycling,” explained Martinez-Cruz. “I just collected the cores from two lakes–Vault and Donut– and I started some incubations. I still don’t have any results because AOM rates are very slow.”

While on her 2011 trip Martinez-Cruz fell in love with the Alaskan landscape and the cold weather sports that are rare in southern Mexico. During this year-long stay she hopes to find time to climb, hike, raft, ski, and take pictures of the Alaskan landscape. Martinez-Cruz says that the winter sunsets, tree covered summer landscapes, the glaciers, animals, and the northern lights all make for beautiful shots.