By Neal Bailey
I was surprised from the moment I stepped off the bush plane. No exposed rock, snow, or cold winds. Instead, a sunny and warm stretch of flat, mossy soil extended to a low crest of hills ahead. There were a handful of fuel barrels placed strategically across the landscape as markers – an attempt to impose some sort of border on the landscape. There was a cabin – Green Cabin; a single room with a table, some supplies, and a small camp oven. Everything else was the Arctic summer- the blaze of a sun that swung overhead in a perpetual arc. I hadn’t read that it would be hot. I had, however, read about the mosquitos. They saw us, correctly, as their only chance for blood, and I applaud their persistence. Persistence, in the Arctic, is key.
Aulavik sees few visitors; in a typical year, perhaps a dozen people set foot there. Usually, these few are either Parks Canada employees on a survey, or people looking for a chance to canoe up the most northerly navigable river in North America. The costs and conditions involved are both forbidding – planes need to be specially chartered, supplies need to be carried, and the terrain is vast and almost playfully unfriendly. The sheer isolation of the place is what makes it interesting to a scientist; here we have a corner of the world almost as far from human impacts as possible, and yet still the shadows of our influence loom. Each year, the winter grows softer and the summer season longer. The northern reaches of the Thomsen valley looked more like Scottish highlands than a classical Arctic scene; rolling terrain draped in bright green. Rain falls constantly, a stark contrast to the Arctic desert pictured in textbooks.
As a researcher, I’d come to Aulavik to look at permafrost slumps, and how they chemically impact the aquatic ecosystem. The damage is obvious – jagged scars of black earth run down the sides of mountains, draining into muddy riverbanks below. It’s visible from miles away. What’s less visible is what is actually in the slumps. The clear water of the Thomsen River flows brown for kilometers downstream of the muddy wounds, but without samples to analyze, such descriptions are meaningless. So, we began a canoe trip spanning over 100 km, riding the Thomsen as it rolls into the Arctic Ocean.
Soils provide records of the past, and the sediments of Aulavik, locked in permafrost, tell a history different from the rocky spars of the eastern Arctic. Southern soils are sandy, dull and pale brown, whereas the northern reaches of the park darken to near black. Mounds of vegetation give way underfoot, releasing pools of tea-colored water in each footprint; in moments, those footprints vanish as the ground springs back, seemingly eager to erase any trace of our presence. Strange patterns of narrow gullies and raised hillocks stretch across the valleys, interspersed by shallow, dark lakes. No one has ever cultivated these lands, and nobody is sure what’s in the ground. This is why we need to gather samples from both the soil itself and the water in tandem.
Sample gathering for trace metals in water is challenging. Out in the field, in the snow and wind, there can be many complications. We needed two people for the clean hands-dirty hands protocol – one person is ‘clean hands’ and is the only one who comes into direct contact with the sampling environment, the samples themselves, and the containers that hold the samples. The other is ‘dirty hands’, and is responsible for handling more or less everything else. This method is designed to avoid contamination at all costs, and under harsh conditions it’s absolutely necessary to make sure everything is done properly. The biggest complication was never the weather, but the ‘wildlife’: when the temperature got above 6 degrees or so, bugs would start appearing, like some strange haze rising from the soil.
Thankfully it was usually too cold (we were in Canada’s coldest spot for a while there!) but when they could fly, they would fly into everything: sample bottles, gloves (as you’re putting them on), clothes, hair, ziplock bags, open mouths.
Permafrost cores were also collected. Depending on what’s in the permafrost, there are a huge variety of ways the slumps could impact the waters. Heavy metals such as mercury could find their way into phytoplankton, the base of the food chain. Mercury in particular can be methylated via bacterial processes and then easily sequester itself into basal biota, at which point it poses a risk to more complex forms of life further up the food chain . Mercury was suspect number 1 in the tests we conducted.
Tests are ongoing, but initial analysis reveals a pristine river, with minimal mercury impacts in even the densest slumps. This, at least, is good news for the ecosystem. So far. Only total mercury concentration has been examined to date, and mercury’s toxicity varies drastically depending on speciation. Of key interest are organo-mercury compounds, which are not only very toxic but tend to sequester in tissue and biomagnify up the food chain [2,3]. Depending on the methyl mercury (and to a less extent dimethyl mercury, which usually degrades into methyl mercury in situ), the river’s fish population may have excessive mercury loads.
On the carbon side, chemical changes are obvious; the volume of soil and nutrients draining into the river from the permafrost melt is massive. Organic carbon compounds form the bedrock for all manner of food webs in natural waters, but whether this is good news or not is up for debate. Rapid changes in fragile, easily disturbed ecosystems have a habit of causing problems, even if it would at first appear that a simple equation of more food equals more productive river would apply. As we look into the specifics of the system, we can hopefully answer questions about the river’s health and apply them to similar Arctic ecosystems, many of which are changing rapidly today.
Neal Bailey studies environmental chemistry at University of Manitoba. Previously a writer, he was drawn to environmental science both for its contemporary relevance, and the option to work in both laboratory and natural environments.
- Chasar et al; Mercury Cycling in Stream Ecosystems. 3. Trophic Dynamics and Methylmercury Bioaccumulation; Environmental Science and Technology (2009), Vol 43 Issue 8 pp 2733-2739
- Morel F. M. M., Kraepiel A. M. L., Amyot M.; The Chemical Cycle and Bioaccumulation of Mercury; Annual Review of Ecology and Systematics (1998), Vol 29 pp 543-566
- Mason R. P., Reinfelder J. R., Morel F. M. M.; Bioaccumulation of Mercury and Methylmercury; Water Air and Soil Pollution (1995), Vol 80 Issue 1-4 pp 915-921