“Mudding about” in a mangrove swamp on the coast of French Guiana
The School of Marine and Atmospheric Sciences incorporates two distinct but closely-related units that organize and conduct its research and educational programs. On the atmospheric side, there is the Institute for Terrestrial and Planetary Atmospheres (ITPA). The marine realm is the primary purview of the Marine Sciences Research Center (MSRC). While frequent and close collaboration between scientists from each unit is a hallmark of how SoMAS operates, at least one of the School’s faculty, Dr. John E. Mak, has his feet firmly planted in both environments (as well as on terra firma!).
John Mak is an atmospheric and marine chemist and an Associate Professor in ITPA. He and his students use stable and radioisotopes as traces to elucidate chemical reactions and transport processes in the environment. Isotopes of an element have slightly different chemical and physical properties because of their mass differences (due to different numbers of neutrons in the nucleus). For some elements, these mass differences are large enough for many physical, chemical and biological processes or reactions to “fractionate” or change the relative proportions of the isotopes. As a result of fractionation processes, materials often develop unique and detectable isotopic compositions (ratios of heavy to light isotopes), which may be indicative of their source or of the processes that formed them. Using isotopic tracers, Mak can learn how things happen within and between the atmosphere and the ocean, today as well as in the past.
Work with colleagues in France, Mak, Zhihui Wang (a postdoctoral scientist at SoMAS) and Key Hong Park (a PhD student at SoMAS) recently co-authored a paper featured in the December 3 issue of Science magazine on their research examining biomass burning in the southern hemisphere. “Basically, we reconstructed biomass burning over the last 650 years in the southern hemisphere and we did that by looking at ice cores. We measured the stable isotopes of carbon monoxide from [Antarctic] ice cores, which is the first time anyone has ever done that,” said Mak. He and his team have been working on the project for four years, two of which involved the study of ice cores.
Alex Guenther and John Mak
“There seems to be a correlation between general climatic conditions, temperature/precipitation, and the rate of biomass burning but it’s sort of hard to say because it’s difficult to reconstruct specific precipitation patterns accurately and quantitatively; but, qualitatively, it seems that the two coincide,” said Mak. “The implications are pretty clear that biomass burning has gone up and down in the past 650 years in the southern hemisphere…in a way that we would not have predicted. It appears that there were bigger changes over the last thousand years in the terrestrial environment than we really knew about before.”
Another of Mak’s current projects is being conducted in the US Forest Service’s Manitou Experimental Forest in Colorado. This work uses a proton transfer reaction time of flight mass spectrometer (TOFMS), an instrument that precisely measures a wide range of masses in the atmosphere, allowing for the measurement of oxygenated reactive gases. The instrument is one of only three of its kind in the United States. The project focuses on the role of the biosphere in atmospheric chemistry.
“If you’re interested in the chemistry of the atmosphere and you want to know what controls that chemistry, you want to know the role of the biosphere, like forests, and how much they influence regional chemistry,” explained Mak.
Scientists have been studying the effects of biogenic emissions, or trace gases, since the 1980’s. “There’s still a lot we don’t know,” said Mak. “We want to try to separate and understand biogenic versus anthropogenic influences on chemistry and climate. We think it’s important. The instrumentation that we have today allows us to better understand the processes involved. We think there’s going to be a lot of interesting stuff coming out of it.”
John Mak and colleague Dr. Alex Guenther, senior scientist at the National Center for Atmospheric Research, in Mongolia
Mak has also worked on a project tracing the loss of the hydroxyl radical (OH) from the atmosphere by using 14C monoxide as a tracer. Carbon-14 monoxide is used, said Mak, because it is produced throughout the Earth’s atmosphere, and later removed by OH. If the atmospheric 14C inventory is measured, the loss rate of OH can be calculated. “OH is the most important atmospheric oxidant,” explained Mak. “It’s very, very reactive. It’s very short-lived and there’s not much there, but it’s responsible for the removal of almost all reactive trace gases in the atmosphere, so it’s often referred to as the “detergent” of the atmosphere; it removes carbon monoxide, methane, ethane, propane–any sort of reduced compound. It will most likely react with OH and be removed by that, so it cleans up the atmosphere. It’s a natural detergent.”
Most of Mak’s studies are funded by the National Science Foundation, the nation’s premier federal agency supporting research. Recently, he had an opportunity to spend time on the other side of the funding arrangement, serving for three years as the Program Director for NSF’s Atmospheric Chemistry Program (ATC) under an Intergovernmental Personnel Act (IPA) assignment. As Program Director, Mak evaluated proposals for potential research grants. He noted that the position allowed him to approve some interesting proposals. “That’s one advantage of being a program director. You can guide the focus of the atmospheric chemistry program,” said Mak. “You can have an influence as to what kind of research is supported at the national level, which is kind of neat.”
The position also gave Mak an appreciation of how dedicated program officers are at NSF. “I was impressed by my colleagues in NSF and, of course, I learned quite a bit about the funding mechanism and about the overall priorities, national priorities…I learned quite a bit,” said Mak.
While he was at NSF, Mak retained his position on the SoMAS faculty, conducting his research and supervising his students at something of a distance. He returned full-time to Stony Brook in October 2010.
