Above: Compilation of pictures from previous Arctic fieldwork in Barrow, Alaska. Check this out for some great scenery and a glimpse into life in the field.
In recent years it has become apparent snow and ice are highly reactive. Photochemical processes (sunlight-induced) drive the production of a variety of compounds within snow and ice and these can be released to the atmosphere, impacting atmospheric chemistry in substantial ways. What happens to the man-made pollutants that deposit with and to snow/ice, however, is largely unknown. Also, the chemistry happening due to naturally occurring materials in the snow and ice is not well characterized. Our research goal is to understand these processes better.
Snow and ice should be clean, right? Especially in the polar regions which are far removed from most human influence, right? It is true, these were once considered to be pristine areas, far removed from the reach of man-made pollutants. Unfortunately, we now know that significant long-range transport of contaminants such as heavy metals and persistent organic pollutants (POPs) reaches the polar regions.
Many of these pollutants have toxic effects to living organisms. The concerns over negative health effects motivates us to study the environmental fate of pollutants and the potential for their transformation into more, or less, toxic compounds. This is particularly important in Arctic regions where indigenous peoples depend on subsistence living practices for their main food sources (hunting, fishing, whaling, etc).
WHY SHOULD WE CARE???
The field of snow and ice chemistry is relatively new, and we have a lot to learn. Processes happening in snow and ice are unique, so we can’t necessarily apply what we know about for example, aquatic chemistry, directly to snow and ice. In a way, we are starting from scratch. There are a host of processes happening in snow and ice (even without the influence of man-made pollutants) – and we’d really like to understand what kinds of chemistry “Mother Nature” is doing.
In relation to the man-made pollutants, transformations of these materials in snow and ice could have vast implications for atmospheric chemistry processes, contaminant transport, and ecosystem health. The polar regions are unique in the fact that they sit in darkness during winter, until a slow sunrise leads to 24-hour sunlit conditions. Pollutants deposited in the dark winter will have the opportunity to build-up until the polar sunrise, when photochemical processes are fueled by 24-hours of continuous irradiance from the sun. Upon snowmelt, contaminants (or their degradation products) present in accumulating snow will be transferred with melt water to the terrestrial/aquatic environment, potentially resulting in a “surge” of toxic chemicals into the overlying atmosphere or surrounding environment (or potentially reduced toxicity species if photochemistry converts the deposited contaminant into a more benign compound). Because the indigenous populations in the Arctic rely primarily on subsistence living, these contaminants will work their way up the food chain and eventually make their way into humans. Already, negative effects are being evidenced in Arctic wildlife – so ecosystem health is at risk as we speak. We need to better understand the processes that affect pollutants – and potentially what compounds they are turning into – if we are to have any chance of mitigating the potential negative impacts.
Studies of photochemical processes in ice and snow are urgently needed to 1.) better understand the wide range of chemistry that can happen in ice and snow 2.) better understand the mechanisms at play and 3.) fully characterize what products are produced (and thus potentially released to the surrounding environment). Armed with this information, we can then better understand the impacts that surface photochemistry might have on the overlying atmosphere and surrounding ecosystem, and how future climate change might impact such processes.
Our research activities include laboratory experiments to:
- determine the photochemical behavior of a variety of natural and man-made materials in frozen water media (snow and ice)
- determine if other chemicals present in the snow or ice can affect the chemistry (e.g. photosensitizers)
- determine how the rates of reaction and mechanisms vary between liquid and frozen water
A component of the research also involves field work in the Arctic environment. Here we investigate:
- Does the chemistry we observe in the laboratory experiments occur under natural environmental conditions?
- How does the rate of the chemistry compare to lab experiments? How do rates vary with the depth of snow or ice?
- What is released to the environment as a result of this chemistry?
- Some of the pollutants we study include PCBs, brominated flame retardants, chlorinated pesticides, among others. In terms of the “natural” constituents, we are particularly interested in the chemistry of dissolved organic matter in snow and ice.
You made it this far! Congratulations! Here is a silly video as a reward for reading to the end. 🙂