By Katrina Dix
What does laundry detergent have in common with climate change? Patrick Hatcher, Ph.D., a professor of chemistry and biochemistry at ¹ú²úÂ×Àí, can explain. From tropical Bermuda to glacial cores, Dr. Hatcher has spent decades studying natural organic matter on a grand scale. His 35 years in academia follow a successful nearly 20-year career with the U.S. government, first as an oceanographer at the National Oceanic and Atmospheric Administration and then as a chemist with the U.S. Geological Survey. At Penn State, The Ohio State University and now at ¹ú²úÂ×Àí since 2006, Dr. Hatcher, one of the top 2% most cited researchers globally, has contributed significant research on environmental science. Recently, he sat down with us to talk about peat formation, ice cores — and Oxiclean.
Why did you choose to study chemistry, and how have your research interests evolved over the course of your career?
I received a chemistry set when I was 14 or 15. You could make things, take chemicals and react them and create something new. That was really intriguing. I experimented with high-energy reactions. I don’t know what my parents would have thought about that — they didn’t find out about it.
I started studying natural organic matter in graduate school. I did undergraduate research at N.C. State, but I was just making compounds and antibiotics and that sort of thing in the lab. I wasn't involved in studies of natural organic matter there.ÌýMy first foray into studies of this nature occurred when I did my master's thesis on organic matter being accumulated in Bermuda. I traveled to Bermuda and cored Mangrove Lake, and that was the basis of my master's thesis, in 1974. And I incorporated it into my Ph.D. as well, because of the uniqueness.
How would you describe your field and its impact on the world?
Natural organic matter is all around us. There are three main reservoirs of carbon that cycle on shorter timescales – that is, less than thousands of years. Those are marine organic matter, inorganic carbon in the atmosphere and terrestrial soils and vegetation. So, if we burn down forests for agriculture, we’re accelerating the release of carbon dioxide. There's a natural balance that exists on Earth right now, and if we disturb that, we basically threaten the stability of the climate.
It would be a drastic action to do something about it. The process of reverting back to the trend that existed prior to the Industrial Revolution is enormous. We've become a society that uses carbon a lot. Oxidized organic matter and fossil fuels are the primary source of much of that carbon that's being used and essentially converted to carbon dioxide. And until we change that, the carbon dioxide levels in the atmosphere are going to increase. Over my lifetime, CO₂ levels have nearly doubled. We need to reverse that trend — or learn to live with it.
What is your current research focus?
My research right now is looking at the oxidation of organic matter in soils and sediments, specifically abiotic decomposition.
There are multiple oxidation processes, but one of the major ones is abiotic. There's also biotic, which basically is decomposition by microorganisms, and there's photodegradation, which is the sunlight and bleaching that occurs. Abiotic oxidation occurs naturally with the organic matter catalyzed by iron or other elements.
Most of what we know about the impact of increased levels of COâ‚‚ and climate change is based on modeling. There are a lot of models out there that talk about the change in climate as a function of COâ‚‚ levels in the atmosphere and the like, and many of those models are imprecise. There are many assumptions. One of the big assumptions has to do with the oxidation of organic matter on these soils and sediments, and how fast that transition occurs, how fast the COâ‚‚ is being produced from that material and how much of it is stored for millennia rather than rapidly decomposed.
Abiotic decomposition is very much like what you do to wash your clothes. You're trying to get the dirt out, so you oxidize the organic matter. You use bleaching agents, and you might use Oxiclean. Oxiclean is basically a material that produces OH radicals. (Ed. note: OH, or hydroxyl, radicals are highly reactive molecules consisting of one hydrogen atom and one oxygen atom with a free electron.)Ìý
OH radicals are produced in the natural environment. They’re in rain, they're in soil. The fungi produce them to essentially break down the organic matter. They're almost ubiquitous on Earth. And they attack organic matter, be it from waste products, all kinds of organic sources, natural sources in the forest, soil and everything.
Abiotic decomposition has been kind of ignored. Most people who study modeling of carbon flow through the reservoirs talk about biodegradation, and think it's microbial, and that may be the major one. There's recognition that photochemistry is also important, but photochemistry is only valid when it's exposed to sunlight, and once you bury something in the soil, there's no more sunlight. In the ocean, the sunlight penetrates maybe less than 100 meters. In rivers, it's less.Ìý
But abiotic processes have not been addressed adequately, in our opinion, and so that's where we're spending a lot of time, looking at that process to see how important it is relative to the two others. It gives us a better picture of what is controlling climate change. The key to understanding the future is looking at the past, what's happened, and trying to understand and rectify that process.
How did your research shape your understanding of climate change?
My understanding of climate change evolved over time. Studying Bermuda’s Mangrove Lake showed us how sea levels had risen significantly. A professor on my committee was examining sea level rise by dating the peat layers in the lake, which produced a "sea level curve." I have a copy of that on my desk, because we’re continuing that study. It’s relevant to some of the work I’m doing right now.
The carbon dioxide level of the Earth’s atmosphere has changed dramatically in the past. Prior to the Industrial Revolution, there are records of CO₂ being really, really high. In fact, when the dinosaurs were running around millions and millions of years ago, the climate was very mild. They’re finding alligators’ skeletons in Alaska. During the peat-forming era, when huge amounts of coal were formed and deposited, the climate was basically tropical almost everywhere, largely due to the buildup of carbon dioxide.
Man has survived for millions of years, but dinosaurs roamed the earth for millions and millions of years, and they suddenly disappeared. Things change dramatically over the history of the Earth. Geologically, we have a much better appreciation for what can happen, but it's going to happen on time scales of millions of years, not just a few hundred or less. Now, though, we see the doubling of atmospheric COâ‚‚ in our lifetimes. That's scary, because that's accelerating, and it's superimposed upon a normal cycle that is known to exist on the earth.
The key to understanding the future is looking at the past. People can map out the cycle of carbon dioxide and other elements over time using, for example, ice core records. You can see the changes in atmospheric chemistry over that period of time, you can get an idea of what the atmosphere was like, maybe a million years ago, and you can map those out. When you do that, you can see that when the Industrial Revolution came about, there's a big increase in carbon dioxide that's much more rapid than what was historically going on. So we know that we've impacted the climate, and the question is, how much can we tolerate?
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