Tag Archives: Mercury

The Arctic was not what I expected

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.

 

Banks_Island
Banks Island – Location of the Thomsen River

 

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.

surprisingly green
Thomsen River Bank
surprisingly green 2
Grassy hillsides in northern Aulavik Park

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.

slumps in the distance
Black streaks of visible permafrost slumping in Aulavik Park

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.

sampling
Water sampling in southern Aulavik Park

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 [1]. 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.

References

  1. 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
  2. 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
  3. 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

How I ended up in the Arctic

By Sara Pedro

I became interested in contamination of the polar regions during my master’s while researching mercury concentrations in Antarctic Gentoo penguins (Pygoscelis papua). This species spends their complete life cycle in many of the sub-Antarctic islands, such as South Georgia and the Kerguelen Islands, and reproduce in colonies of about 320 000 breeding pairs (Borboroglu and Boersma 2013). Because of their large numbers, wide distribution in the Antarctic Ocean, and easy access, Gentoo penguins are good biomonitors of local contaminant concentrations; a major reason we studied this species. We found that mercury concentrations in Gentoo penguins were not at concerning levels (Pedro et al. 2015). Nevertheless, the fact that mercury accumulates in species in the Antarctic, one of the most remote regions in the world, indicates the widespread contamination of pollutants released mostly in industrialized areas.

In transitioning to my PhD, I switched poles to focus on the Arctic. Like in the Antarctic, the Arctic region is impacted by global pollution. At the same time, the Arctic has been facing marked sea-ice loss associated with increasing temperatures. The Arctic is more susceptible to these changes in climate than other regions around the globe (Screen and Simmonds 2010) due to the albedo effect: less sea-ice to reflect solar radiation leads to more absorption by the ‘darker’ ocean surface. Because contaminants are transported by air and oceanic currents, climate change will likely alter contaminant dynamics and pathways into Arctic ecosystems (Macdonald et al. 2005). One situation that leads to this change in contaminant dynamics is the alteration of Arctic food web structure, such as the replacement of native with invasive prey fish.

My current PhD project at the University of Connecticut focuses on legacy persistent organic pollutants (POPs) and mercury in invasive versus native prey fish in the Eastern Canadian Arctic, and consequent levels in ringed seals (Pusa hispida). Legacy POPs include several pesticides and polychlorinated biphenyls (PCBs) that can travel long distances, often by atmospheric transport, eventually accumulating in remote regions. These POPs take a long time to break down in the environment, and can accumulate in animals to potentially cause toxic effects (Letcher et al. 2010). Mercury is released mainly during gold mining and coal burning and is transported to remote regions where, similarly to POPs, it can accumulate in the food web and cause toxic effects (Dietz et al. 2013).

With the recent increases in average temperatures in the Arctic, some fish species have expanded their habitat ranges from boreal areas to more northern regions and are now found more frequently in the Canadian Arctic. Studies on Arctic seabird and marine mammal diets suggest that invasive fish such as capelin (Mallotus villosus) and sand lance (Ammodytes sp.) are replacing Arctic cod (Boreogadus saida) as the most important prey species in lower Arctic regions (Provencher et al. 2012; Chambellant et al. 2013; Hop and Gjøsæter 2013). Although POPs and mercury are transported to the Arctic, they are still at higher environmental levels closer to the direct sources (e.g. intense agricultural areas, waste incineration). A switch in diet from native to invasive fishes may therefore change ringed seal contaminant burdens. My PhD research will compare contaminant levels in invasive capelin and sand lance to Arctic native fish species, including Arctic cod. I will also determine contaminant levels in ringed seals to better understand how climate change impacts contaminant transfer in Arctic food webs. The results of this project are also important for local communities because, although they do not eat these invasive and native Arctic fishes in particular, locals eat Arctic marine mammals, such as ringed seals that feed on these fishes.

Part of this project includes visiting the local communities in the Arctic that are the most affected by these habitat changes. Arviat, Nunavut is one of the communities collaborating in this project and participated in collecting fish samples. This was my opportunity to visit the Arctic! Last spring, I flew up to Arviat (Figure 1) and gave a few talks regarding preliminary results of my research at the high school, the Arctic College, and the Hunters and Trappers Association.

Figure 1: Town of Arviat, Nunavut (left) in the Eastern Canadian Arctic (right).

My visit in April was short and sweet, consisting of 4 different flights each way… 8 flights in three days (luckily, none of the flights were delayed)! Given the thaw doesn’t happen until June/July in Arviat, late April means snow boots and warm coats. Hudson Bay was a beautiful, expansive white plain (Figure 2)! However, I could tell that it was the spring for them. The locals were walking on the streets, kids were out playing and the roads were clear enough to easily drive through. Everyone looked happy and they were very welcoming. At the high school, I gave a few talks to different classes about my research. The students were interested and engaged, and I even got the wise question “So why does this matter?” from a 12-year-old. Another girl told me that she didn’t like fish and when I asked what she eats instead, she told me about how her father hunts caribou. She invited me to join them on a hunt. If it weren’t for my tight schedule, I would have definitely gone out for a caribou hunt! In this region, they mostly depend on caribou (Rangifer tarandus), seals, and Arctic char (Salvelinus alpinus) for subsistence. High school students will often miss classes and come in tired because the main priority for many of them is to help their families hunt and fish.

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Figure 2: Frozen Hudson Bay in Arviat, NU

After visiting the high school, I went to the Arctic College (Figure 3). Most of the students were gone for the summer but I met a few that stick around and volunteer for research projects. Getting locals involved in environmental research in these remote regions is very important given their sensitivity to climate change and environmental pollution. Fishers and hunters at the Hunters and Trappers Association are concerned about having contaminants in their food, since they depend largely on local food sources. The Arctic Monitoring and Assessment Program (AMAP) has been monitoring contaminants in the Canadian Arctic for over twenty years. The levels of some POPs, such as DDT and PCBs have been declining or have stabilized in the Arctic, mostly since the Stockholm Convention to ban these contaminants (Stockholm Convention 2008). However other contaminants such as mercury have been increasing in some Arctic animals (Riget et al. 2010; McKinney et al. 2015). As a polar environmental scientist, it is my duty to continue researching the impacts of climate change on contaminant levels in these remote regions and to address the communities’ questions and concerns.

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Figure 3: Arctic College, Arviat, NU

Being able to visit one of the most fascinating regions in the world while doing environmental research is why I enjoy being a scientist!

Sara Pedro has a Master’s in Ecology and is currently a PhD student in the Natural Resources and the Environment department of the University of Connecticut, CT.

References:

Borboroglu PG, Boersma PD (2013) Penguins: Natural History and Conservation. University of Washington Press, Seattle

Chambellant M, Stirling I, Ferguson SH (2013) Temporal variation in western Hudson Bay ringed seal (Phoca hispida) diet in relation to environment. Mar Ecol Prog Ser 481:269.

Dietz R, Sonne C, Basu N, et al (2013) What are the toxicological effects of mercury in Arctic biota? Sci Total Environ 443:775–790. doi: 10.1016/j.scitotenv.2012.11.046

Hop H, Gjøsæter H (2013) Polar cod (Boreogadus saida) and capelin (Mallotus villosus) as key species in marine food webs of the Arctic and the Barents Sea. Mar Biol Res 9:878–894.

Letcher RJ, Bustnes JO, Dietz R, et al (2010) Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish. Sci Total Environ 408:2995–3043. doi: 10.1016/j.scitotenv.2009.10.038

Macdonald RW, Harner T, Fyfe J (2005) Recent climate change in the Arctic and its impact on contaminant pathways and interpretation of temporal trend data. Sci Total Environ 342:5–86. doi: 10.1016/j.scitotenv.2004.12.059

McKinney MA, Pedro S, Dietz R, et al (2015) A review of ecological impacts of global climate change on persistent organic pollutant and mercury pathways and exposures in arctic marine ecosystems. Curr Zool 61:617–628.

Pedro S, Xavier JC, Tavares S, et al (2015) Mercury accumulation in gentoo penguins Pygoscelis papua: spatial, temporal and sexual intraspecific variations. Polar Biol. doi: 10.1007/s00300-015-1697-9

Provencher JF, Gaston  AJ, O’Hara PD, Gilchrist HG (2012) Seabird diet indicates changing Arctic marine communities in eastern Canada. Mar Ecol Prog Ser 454:171–182. doi: 10.3354/meps09299

Riget F, Bignert A, Braune B, et al (2010) Temporal trends of legacy POPs in Arctic biota, an update. Sci Total Environ 408:2874–2884. doi: 10.1016/j.scitotenv.2009.07.036

Screen JA, Simmonds I (2010) The central role of diminishing sea ice in recent Arctic temperature amplification. Nature 464:1334–1337. doi: 10.1038/nature09051

Stockholm Convention (2008) Listing of POPs in the Stockholm Convention. http://chm.pops.int/TheConvention/ThePOPs/ListingofPOPs/tabid/2509/Default.aspx. Accessed 28 May 2015