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Course:EOSC270/2023/Toxic Substances in Arctic Ecosystems

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What is the problem?

Figure 1: Example of Arctic Ecosystem[1].

Introduction

The Arctic is a remote and sparsely populated area with little industry. Despite minimal industrial emissions, chemical pollution is a serious threat to ecosystems and populations of the area. The most prominent contaminants found in the Arctic include persistent organic pollutants (POPs) such as DDT, PCBs, and dioxins, and heavy metals, such as mercury and lead. Both are harmful as they accumulate in the environment and pose a threat to ecological and human health[2].

Toxic Substances found in the Arctic

Persistent Organic Pollutants (POPs)

Persistent organic pollutants (POPs) incorporate a multitude of toxic substances and their byproducts that are caused by anthropogenic inputs. In the Arctic, POPs classified as organohalogen contaminants are particularly detrimental due to their stable chemical makeup and long half-life. These characteristics, along with being fat-soluble, cause them to persist in the environment, be transported by wind and ocean currents, and build up in food webs[3]. POPs come in two main forms, the first being halogenated chemicals which are hard to break down in the environment due to the strong bonds between carbons and halogens such as Chlorine, Bromine or Fluorine. There are also non-halogenated chemicals, which are persistent in the environment due to the stability of the chemical compound[4]. Persistent organic pollutants enter the environment through their use in industrial applications, pesticides/insecticides, and can be generated as by-products of many industrial processes. Some of the most prominent in the Arctic include DDT (dichloro-diphenyl-trichloroethane), the first modern synthetic insecticide produced, and PCBs (polychlorinated biphenyls), used in many industrial applications from electrical, heat transfer, and hydraulic equipment to plasticizers in paints, plastics, and rubber products[5].

Heavy Metals

Metals occur naturally in the environment in different forms. They can appear as ions dissolved in water, as vapours, salts, or minerals, and can be bound in molecules or attached to particles in the air. Natural and anthropogenic processes and sources emit heavy metals into air and water. Despite the fact that many plants and animals depend on metals for micronutrients, certain forms can be toxic and harmful to the ecosystem. In the Arctic, heavy metals are released into the environment from natural sources (rock weathering and permafrost thawing) and anthropogenic factors (mining, industrial processes, and burning of fossil fuels). Metals are elements, meaning that they cannot degrade, only change form. Once they are released, they can persist in soil, air, and water for extended periods of time. The most prominent in nature are mercury, cadmium, arsenic, chromium, nickel, copper, and lead. When mixed with water, mercury converts into methylmercury, which is highly toxic. Heavy metals that are of the most concern to the Arctic Monitoring and Assessment Programme are mercury, cadmium, and lead. This is because these metals are already found in some regions of the Arctic, and transport from other regions adds to the already naturally high levels[6].

How do these toxic substances get to the Arctic?

Figure 2: Pathways of Pollutants to the Arctic[7].

The Arctic is a sparsely populated region with very little large-scale industrial development, meaning that the area inputs minimal amounts of toxic substances, like POPs and heavy metals, into the environment. Most of the toxic substances that build up in the Arctic originate in more southern regions. In lower latitudes, toxic substances are released into the environment through industrial processes such as wastewater disposal, atmospheric deposition, and runoff. After these toxins are released into the atmosphere, they migrate north towards the Arctic by way of atmospheric circulation, ocean currents, river input, and some migratory species[8].

Atmospheric Circulation

Although the atmosphere contains a small amount of contaminants compared to its overall volume, its rapid movement makes it an important pathway for transporting contaminants to the Arctic. The transport of contaminants from mid-latitudes to the Arctic can occur as quickly as from days to weeks[9].

Figure 3: Net atmospheric transport to the Arctic, frequency of winds that drive pollutant transport from lower-latitudes, and the polar front[10].

Winds that carry contaminants to the Arctic are more frequent in the winter and spring than in the summer and fall. In the winter and spring months, the increased temperature difference between the Arctic and warmer mid-latitudes heightens the atmospheric pressure gradient and strengthens the strong westerly winds of the polar front. These strong westerly winds, reinforced by a high pressure system over Siberia that forms in the winter, push pollutants from mid-latitude North America, Europe, and Asia toward the Arctic. Additionally, contaminants such as sulfates and soot that can be broken down with the right amount of sunlight also accumulate in winter due to decreased sunlight. Similarly, particles like aerosols that are super small can remain in the atmosphere for 20-30 days in the winter due to the lack of precipitation that can ground them. In contrast, these same particles stay in the air for 2-5 days in the summer due to increased precipitation which plays a role in 'cleaning the air' and grounding the particles. Whether that is in the water, on the ice, or on land. Particles like aerosols and soot are considered "one-hop contaminants" because they can travel long distances but once they are grounded they can't re-enter the atmosphere[10]. This increase in atmospheric pollutant transport, along with decreased precipitation in the winter, causes pollutant build up in the Arctic atmosphere, also known as “Arctic Haze."

Another important process that brings chemical pollutants to the Arctic is known as the “grasshopper effect”. This happens when volatile substances, like POPs and heavy metals, evaporate in the warmer mid-latitudes, and are carried north by prevailing atmospheric winds[11]. These substances “hop”, meaning they can re-enter the atmosphere after landing on the ground, ice, or dissolving in a body of water. When they reach cooler temperatures, they condense and settle. This process continues until pollutants generated in mid-latitudes ultimately accumulate in the Arctic. Once they condense into solid particles/aerosols or dissolve into the ocean in the Arctic, they are unlikely to convert back to a gaseous state[10]. 

Ocean Currents

Figure 4: Ocean current and air flow transport of pollutants to the Arctic[12].

Thermohaline circulation, known widely as the "global conveyer belt", is a large ocean current that moves water around the globe. These currents are driven by temperature and salinity differences. Cold, salty, dense water from areas like the poles sink, and surface waters which absorb heat and freshwater move to replace this dense water. This causes a slow, yet powerful, circulation of ocean water that is important for transporting heat. However, this global circulation is also partially responsible for the transport of pollutants. In the mid-latitudes, pollutants dissolve into surface waters, and are redistributed to oceans around the globe, including the Arctic[6].

In the Atlantic Ocean, thermohaline circulation moves northward as warm surface water. As this water moves up along the industrialized east coast of North America, it picks up pollutants. These pollutants move with the Gulf Stream, cooling and sinking into the deep ocean. From mid-latitudes, the North Atlantic Current transports ocean water and accompanying pollutants east towards Europe. From there, the North Atlantic current moves northward and transitions into the Norwegian Atlantic current before entering the Arctic Ocean through the Fram Strait and eventually transitioning into the West Spitsbergen current[4].

Similar to the Atlantic Ocean, ocean circulation in the North Pacific Ocean moves northward, though these currents are not considered part of global thermohaline circulation. The current system that brings water from the Pacific Ocean to the Arctic Ocean is still influenced by temperature and salinity differences, but is faster and more localized. Pollutants are deposited into the Pacific in the industrialized mid-latitudes, and are transported north toward the Arctic. Higher sea level in the North Pacific compared to the North Atlantic forces a barotropic flow of water through the Bering Strait and into the Arctic Ocean[13]. Three oceanographic currents flow into the Bering Strait from the North Bering Sea: the Anadyr Current, Bering Shelf Current, and the Alaska Coastal Current. On the Arctic side of the Being Strait, three currents emerge and flow into the Chukchi Sea and western Arctic Ocean: the Alaska Coastal Current, Bering Sea Summer Water, and Bering Sea Winter Water[14].

Figure 5: Major Pan-Arctic Drainage - Terrestrial Inputs[15].

Terrestrial Input

Chemicals in terrestrial environments have two main fates, depending on whether they are soluble or insoluble in water. Pollutants that are water soluble dissolve into water and are carried to the ocean via snow melt, surface water, ground water, and rivers where they are distributed via ocean currents. Pollutants that are insoluble get absorbed into particles in soil or sediment, with which they can erode into waterways and possibly be transported to the ocean. Rivers play a large role in long distance transport to the Arctic of pollutants that are generated in terrestrial environments in lower latitudes. Catchment areas of rivers accumulate contaminants from agricultural runoff such as pesticides/insecticides, municipal and industrial sewage, and inputs from mining, oil, and gas exploitation. Peak flow of rivers into the Arctic occurs in June and July, coinciding with the greatest transport of river ice. This combination of high ice and water flow can cause jams, which lead to flooding of terrestrial areas. This is especially harmful in flat landscapes, like the Russian tundra, where flooding can cover vast areas. These kinds of floods typically leave contaminant-filled sediments on the flood surface. Although this removes contaminants from the river flow initially, sequential flooding can pick up previously deposited contaminants and contaminants that were not previously in the river pathway and transport them to the Arctic Ocean[16].

Migratory Species

Some species that only spend part of the year in the Arctic, then travel to less extreme climates during the rest of the year. During the winter when there is less productivity, and therefore less nutrients, these species will migrate south to areas that are both more nutritious and much more contaminated than that experienced in the Arctic. These migratory destinations can be extremely polluted with sources such as sewage lagoons, garbage dumps and agricultural/industrial catchment areas. Consequently, this results in the transfer of contaminants from southern destinations to the Arctic. The contaminant levels that are found in the bodies of these migratory species are not reflective of the environment of one particular area. For instance, the high levels of contaminants found in Arctic bird eggs are more likely to reflect their southern habitat, than that of the Arctic[17].

What happens once the toxic substances reach the Arctic?

Figure 6: The Polar Vortex and Polar Jet Stream isolate air in the Arctic[18].

Due to the region's extremely cold temperatures and unique atmospheric and oceanic circulation patterns, the Arctic acts as a semi-isolated sink for chemical pollutants. Once pollutants travel northward and reach the Arctic, they become more stable and unlikely to decompose in the cold conditions. On top of this, they are unlikely to migrate back south.

Figure 7: Distribution of water masses and salinity in Arctic Ocean - Shows shallow Fram/Bering Straits and Stratification[19].

Atmospheric Circulation in the Arctic

The circulation patterns of the Arctic region are unique and contribute to how pollutants become trapped in this area. One important feature being the polar vortex, a large low-pressure system that forms in the stratosphere of the Arctic and circulates air. This vortex, along with the polar jet stream, a high-altitude fast-moving wind current that flows around the polar vortex, creates a barrier between the cold atmosphere of the Arctic and the air in the warmer lower latitudes. Due to this isolation, pollutants like persistent organic pollutants and heavy metals that get to the Arctic via long-distance transport become trapped[20].

Oceanic Circulation in the Arctic

The strong clockwise circulation of water and minimal efflux of polluted deep water in the Arctic Ocean also traps chemical pollutants. The converging flow of water in the Beaufort gyre, the large downwelling gyre in the Arctic, drives transport of pollutants into deep water and traps accumulated for years. These pollutants circulate in the Arctic, and are not dispersed. The only major outflows of water from the Arctic Ocean are from the Fram Strait or the Canadian Arctic Archipelagos. Additionally, these outflows are primarily surface water. This mostly is due to the strong stratification and shallow sills of the Arctic Ocean. These characteristics make it difficult for deep, pollutant ridden water to flow out to the Atlantic Ocean. As surface waters move southward, they either move through the Fram Strait and the East Greenland Current carries them to the North Atlantic, or they move through narrow channels in the Canadian Arctic Archipelagos (Nares Strait, Lancaster Sound, and Jones Sound) and the Baffin Island Current carries them to the Labrador Sea[21].

Sea Ice Formation in the Arctic

Toxic pollutants in the air and ocean can get physically trapped in sea ice during formation. When ice forms from ocean water, contaminants like heavy metals and persistent organic pollutants that are bound to the water molecules become encapsulated in the ice structure. Chemical pollutants also deposit onto snow and ice through wet deposition (falling with precipitation) and dry deposition (settling from atmosphere). As toxic substances like POPs and heavy metal do not degrade, they can be trapped in ice for decades, or until they get released due to degradation of the ice itself. Seasonal melting, and melting caused by warming global temperatures, releases these pollutants into the ocean, where they can be redistributed into local ecosystems[22].

How does this problem impact marine ecosystems?

How pollutants enter Arctic food webs

Bioconcentration: The process in which contaminants are directly acquired by plants and animals from sources like the air, water and soil. Organisms that acquire these pollutants from the environment include: phytoplankton that absorb pollutants directly during photosynthesis, zooplankton that are capable of taking up pollutants through their gills, filter feeders that take up pollutants from the water they filter, and benthic organisms that ingest pollutants trapped in ocean sediments. How these toxins are obtained depends on the structure of the chemical. For instance, lipid soluble contaminants can end up in the fat reserves of animals, and water soluble contaminants can be obtained through gills or membranes in the gut [23].

Figure 8: Process of Bioconcentration, Bioaccumulation and Biomagnification[24].

Bioaccumulation: Once pollutants are ingested by organisms, whether via bioconcentration or through ingesting other organisms that have pollutants in their system, they build up over time within the organism. A study done on Icelandic Gyrfalcons demonstrates the accumulation of these pollutants with age. Amongst birds that were found dead, concentrations of DDT and DDE, two persistent organic pollutants, in recently hatched birds were around 100 nanograms per gram muscle. In ten-month old birds, this concentration increased by 100-fold, and twenty-month old birds showed a 1000-fold increase. Given the young age of birds whose pollutant levels were reported, it is likely that the average concentrations within the rest of the population were much higher[5]. Bioaccumulation occurs when an organism takes up pollutants faster than they can break down and excrete them. Toxins such as persistent organic pollutants and heavy metals that are very stable, and particularly those that are fat-soluble, are subject to a large amount of bioaccumulation. The effects of the pollutants on the organism will be determined by the concentration of the contaminants from the source and the organism's ability to get rid of these contaminants. As the mechanisms used to break down these pollutants are often species-specific, meaning they vary from organism to organism, some species are highly susceptible to this accumulation, and some can more easily break down and excrete the pollutants[23]. One study showed that Arctic pond zooplankton communities containing Daphnia had methylmercury (MeHg) concentrations that were five times higher than communities dominated by copepods, due to species-specific processes that allow Daphnia to accumulate more MeHg[25].


Biomagnification: As you move up the Arctic food chain, the concentration of pollutants within the organisms will increase. This happens due to higher level organisms accumulate more toxins than the organisms below them as they consume more contaminated prey. Even if pollutant levels in an environment are low, this passing of accumulation up trophic levels can cause effects in top predators. Compared to other ecosystems, the Arctic marine ecosystem has a long food chain which allows these toxins to magnify drastically as they reach higher trophic levels[23].

Adaptations of Arctic species that make them vulnerable to pollutants

Organisms in the Arctic face the challenges of seasonal food-shortage, extreme cold, and living in an ice-covered environment. In order to survive, they have evolved to have specific adaptations for this harsh environment. However, most of these adaptations listed below also make them highly vulnerable to chemical pollutants, especially POPs and heavy metals.

Energy Stored as Fat

Due to the low productive seasons that are present in the Arctic, organisms have adaptations that allow them to produce and accumulate more fat than organisms at lower latitudes. This adaptation isn't without trade offs, as many toxins are fat soluble, meaning they can accumulate in the fat of animals. In the winter when food is limited, the fat that has been accumulated throughout the productive season is used but the contaminants that have been accumulating in these fat reserves remain in the body of the organism. The entrance of both nutrients and contaminants into bodies of water in the spring via runoff and ice melt allows for easy access to the food web[26].

Life History of Arctic species (k-selected)

Many of the species in the Arctic are K-selected species, meaning they have a slow growth rate, late maturation, and long lives. This is a great adaptation to have when recourses are limited, but this increases the amount of time contaminants have to accumulate in these organisms. K-selected lichen and mosses have an increased ability to acquire materials from the air as they depend on their above ground surface area to obtain nutrients rather than roots. This would be consequential to organisms that eat these types of plants as they contain more contaminants than other plants. Additionally, due to these longer life spans of animals in the Arctic there are significantly more contaminants moving from one trophic level to the next[26].

Isolated regions of high species richness

Due to the lack of nutrients in the Arctic, organisms will accumulate where nutrients are “readily available”. For instance, there the high productivity at the ice edge which supports large populations of animals such as sea birds. Additionally, sea mammals and birds will gather at large gaps within the pack ice. Having a large portion of the food web in close proximity allows for easy entry of contaminants into the food web[26].

Direct impact on Arctic organisms

Pollutants in the Arctic have a significant impact on organisms of every trophic level. Starting from the species that take pollutants into the food chain via bioconcentration, these pollutants have negative effects on all species in the ecosystem as they work their way up the food chain. Though organisms at higher trophic levels experience more severe effects due to biomagnification, every organism that is effected impacts the health of the ecosystem overall.

Figure 9: Phytoplankton under Arctic Sea Ice[27].

Producers

Primary producers are the base of all Arctic ecosystems, as they provide energy and oxygen for other organisms. As toxins are deposited into ocean water, they are taken up by primary producers like phytoplankton and sea-ice algae. Studies have shown that persistent organic pollutants, like PCBs, decrease both the rate of growth and photosynthesis in primary producers. Heavy metals, like cadmium and mercury, have shown to cause cell damage, inhibition of biosynthesis of photosynthetic pigments (chlorophyll/carotenoid), and disruption of photosynthetic machinery[28].

Consumers

Consumers in the Arctic primarily take up pollutants through bioaccumulation. They ingest producers or lower-level consumers that have already taken up pollutants, and these pollutants build up in the consumer. This build up has been shown to cause growth, developmental, and reproductive defects. One study found persistent organic pollutant concentrations in the eggs of a population of peregrine falcons that breed in Northern Canada high enough to cause eggshell thinning and failure to reproduce. They found PCB concentrations of 8.3 micrograms per gram egg and DDE concentration of 4.5 micrograms per gram egg. This population is small and frequently fluctuates, making them difficult to monitor, however in the 1990s pollutant concentrations in this populations were still high enough to cause thinning. Samples taken in 1991 showed 28% of egg clutches showed thinning greater than the threshold level that is associated with failure to reproduce. In fish, mercury exposure can cause deformaties such as misshapen fins, malformed gill structure, and malformed jaw structure[29].

Figure 10: Beluga Whales in the Arctic[30].

Apex Predators

Due to biomagnification, organisms at the top of the food chain suffer the greatest impacts of ingested toxins. High-level predators are effected in all the ways consumers are, but they have also shown more severe effects. Effects on these organisms include organ failure, neurological damage, hormone imbalance, and weakened immune system One study found that mercury concentrations in population of Arctic biota such as polar bear, belugas, pilot whales, hooded seals, and Arctic char tissues that exceed toxicological thresholds. The concentrations in the brain of beluga whales in the Beaufort sea have been linked to neurochemical effects. Certain polar bear and pilot whale populations had mercury concentrations in their liver and kidneys high enough to exceed the threshold values for liver and kidney damage[31].


What is the extent of the problem?

The Importance of Arctic Ecosystems

As the Arctic is a remote area with very little development and population, it is easily overlooked. It is important to understand why Arctic ecosystems are important in order to raise awareness for how detrimental the effects of a disrupted Arctic ecosystem could be globally. Without awareness, mitigation of pollutants in the Arctic will not happen and ecosystems will continue to suffer.

Indigenous Communities

Figure 11: Members of an Inuit community on the hunt for a whale[32].

Indigenous communities, such as the Inuit, Sámi, and Chukchi, have lived in the Arctic and relied on its ecosystems for thousands of years. Their culture, as well as their diet, are built upon their connection with the Arctic. They depend on hunting, fishing, and gathering species like Arctic char, whales, seals, and caribou not only for their diet, but also for economic support. Like in organisms within the Arctic food chains, Indigenous communities are effected by bioaccumulation and biomagnification of pollutants like persistent organic pollutants and heavy metals. Studies have already shown how these pollutants are currently impacting members of these communities. For example, levels of DDT, a persistent organic pollutant, in the breast milk of indigenous populations in the Arctic has been liked to reproductive issues. Other possible effects of pollutants like these on Arctic communities include: neurological effects, immunosuppression, and even cancer[33]. In conclusion, persistent pollutant concentrations in the Arctic threaten both the lifestyle and health of Indigenous communities that rely on these ecosystems.

Global Food Chains

As mentioned earlier, there are many species, like cod and herring, that fluctuate between the Arctic Ocean and warmer southern oceans. This means that these species from lower latitudes rely heavily on the Arctic ecosystem environment for part of their life history. Many species of birds and fish use the Arctic as a breeding ground and utilize its food sources. If pollutants impact both primary producers and smaller consumers that these migratory species rely on for food, their populations will be impacted in response. These migratory species are also part of food chains in lower latitudes, meaning harm to their populations impacts food chains globally, ultimately decreasing global biodiversity[34].

Figure 12: Capelin - A small pelagic fish in the smelt family[35].

Fisheries

Arctic ecosystems are also important for global fisheries. Some migratory species that rely on the support of Arctic ecosystems, like Atlantic cod, herring, and salmon, are vital to global fisheries. Exposure to pollutants and decreased productivity due to pollutants in the Arctic will lead to reproductive issues and decreased survival rates for these important species. The Arctic Ocean is also home to a magnitude of fish species that are commercially valuable. These include: capelin, Arctic char, and Greenland halibut. As pollutants impact Arctic ecosystems, stocks of these commercially valuable fish will drop, possibly leading to the collapse of this major global fishery[36].



Past vs. Present - Comparing Arctic Toxin Concentrations from the 1900s to Current Day

DDT and the Fight Against Malaria

DDT is one of the most prominent POPs worldwide; although synthesized in 1874, the chemical has been used as an insecticide since 1939, with it's peak usage between 1946 and 1972[37]. UNEP reports DDT usage has been used mostly in countries that suffer from malaria (and also visceral leishmaniasis - another life-threatening disease spread by mosquitos), where African regions are most affected. Indoor Residual Spraying (IRS)[38] was a method that was used historically to repel mosquitoes by spraying DDT on interior surfaces as a chemical irritant, which overtime will end up in terrain, local waters, and the aerosol components end up in wind circulations. Not only this, but WHO found that the IRS method, especially when used excessively, poses a threat to human health[38]. Ultimately, IRS is a direct way that DDT has entered the environment circulations and thus in the Arctic, especially in the early 1900s-2000s.

While China manufactured DDT up until 2007[37], countries in Africa are still using manufactured DDT[37]. Otherwise, the Stockholm Convention has banned DDT production and use everywhere else[37].

**Female mosquitoes act as vectors of disease transport, most commonly known for the spread of the malaria parasite (most deadly of the parasites is P. falciparum), causing devastation and death in human populations - especially affecting infants, in tropical and subtropical regions[39].

The Stockholm Convention

The United Nations Environment Program (UNEP) manages the Stockholm Convention treaty that went into effect on May 17, 2004[37]. This is a global treaty involving all 193 countries that are permanent representatives to both the United Nations (UN) and the UNEP - it was developed with the aim to reduce and limit POPs worldwide. Since it was created, the Stockholm Convention formalized the global ban[37] of DDT in agricultural use, but it has yet to completely eradicate DDT associated with fighting the spread of malaria (India and many countries in Africa). The treaty called for India to cease production of DDT by 2024, but the deadline was not met[40] and the deadline to comply was extended by five years.

Legacy Pollutants

Figure 13: from Zhang et al., 2024, showing global representation of legacy POP concentrations (pg/liter) in the oceans from pre-2000s to 2023

As previously discussed, the toxins affecting the Arctic are very difficult to remove once they have entered the Arctic ecosystem. This is due to the persistent contaminating nature of the chemicals, and also due to the environmental conditions that make up the Arctic. Legacy pollutants are a consequence of industrial and agricultural advances from pre-2000s and are responsible for the majority of pollutant concentrations in oceans (including the Arctic) currently[29].

Monitoring from the 1980s has allowed for a comprehensive dataset to be formed, showing trends in legacy POP concentrations[41]. The dataset has a conclusive trend that shows a significant increase in legacy POP concentrations in marine waters (which includes the Arctic) from the 1980s to 2023[41].

In areas where production of HCHs, DDTs, and HCBs were banned, the direct, local marine environments generally saw a decrease in the last five decades. However, over time, the Northern Hemisphere (NH) exhibits a higher accumulation of toxins compared to the Southern Hemisphere (SH). Toxins are spread from their original starting point through estuaries, rivers, and oceanic circulation. Zhang et al., 2024, saw the spreading of these toxins resulted in a "significant increase in the concentration of [HCH, DDT, PCB, and their isomers] from 1990 to 2016 (P < 0.05)" in the Arctic Ocean and in it's adjacent seas[41]. Figure 4 allows the visual breakdown of these trends across 12 difference oceans and seas.

Animal Case Study - The Polar Bear

How these toxins affect a keystone species in the Arctic: The polar bear (Ursus maritimus)

Due to being at the top of the food chain in the Arctic, polar bears are continually consuming the "Chemical Cocktail," a mixture of pollutants that have bioaccumulated in the polar bear's diet (most notably, the Ringed Seal, or the Pusa hispida). Sacco and James, 2004[42], underwent research that analyzed how - and if - polar bears can metabolize the chemical cocktail, with a focus on those that do the most harm (PCBs).

Figure 14: taken from Andrew Derocher's "Pollution in Polar Bears" from Polar Bears International. An Arctic food chain, tracing from a primary producer (algae) to our keystone predator species (the polar bear).

Bioaccumulated toxic chemicals affect polar bear immune system, growth, bones, organs, overall survival and behaviour. As mentioned previously, polar bears are an example of an Arctic organism that have an adaptation that allows energy to be stored as fat. This is beneficial during times when food is scarce and temperatures are low - but many pollutants, PCBs specifically, are lipophilic[42] - which means that a diet composed of mostly fat is also a diet that has the highest uptake of HCHs, DDTs, PCBs, PBDEs, and CHLs.

The polar bear metabolizes toxins in two major "phases," which is similar to how the polar bear metabolizes drugs. Researchers propose that the second step, glucuronidation, plays a crucial role in dealing with certain molecules in the chemical cocktail, but it is not able to completely metabolize most toxins[42].

Unfortunately, in the Arctic food web, the polar bear’s metabolism is one of the most effective Arctic organism metabolisms when it comes to clearing toxins.[42] Other Arctic organisms that have less efficient metabolisms are at even more of a risk, so this does not bode well for the Arctic ecosystem. Not only this, but the polar bear is a top predator and a keystone species in the Arctic, so when it comes to ecosystem outlook, this case study shows that it will be the end of the ecosystem if pollutants in the Arctic are not able to be cleared. If polar bears die out due to toxic food sources, the food web will be thrown off. Humans, arctic cod, copepods, diatoms, and algae will all show major population fluctuations.[43] Extinction of the polar bears would be so significant that the news would be international - so at the very least, it might bring more people’s attention to the extent of the devastation the Arctic is currently facing.

Future Outlook For Arctic Ecosystems

Figure 15: Arctic Sea Ice Minimum Trends show decreased ice cover[44].

Sea Ice & Permafrost Melt

Despite global initiatives to reduce emissions of persistent organic pollutants, heavy metals, and similar substances that could damage ecosystem health being a step in the right direction, a warming future could be detrimental to the state of pollutant concentrations in the Arctic. If global warming continues to melt Arctic sea ice and permafrost, the outlook for the future becomes less positive. As sea ice acts as a sink for pollutants, and permafrost a natural reservoir of heavy metals, their thawing could release trapped pollutants that have been accumulating over decades. The release of these substances will introduce them back into the atmosphere, ocean, and food webs. If this possibility becomes a reality, the Arctic will shift from being a pollutant sink to being another source, amplifying the effects of pollutants like heavy metals and persistent organic pollutants[22].

Given the impact, what are the solutions?

Local Solutions

In 1991 there was an introduction of the Arctic Environmental Protection Strategy (AEPS) which was adopted by the 8 circumpolar countries (Canada, Denmark/Greenland, Iceland, Norway, Sweden, the Soviet Union and the United States)[45].

The objectives of this strategy include:

  1. Protect arctic ecosystems and humans
  2. Providing for the protection, enhancement, and restoration of Arctic environmental and sustainable utilization and allocation of natural resources, this includes the utilization by local communities and indigenous peoples.
  3. Recognize and accommodate traditional and cultural needs, values and practices of indigenous peoples, in regards to the protection of the Arctic.
  4. Consistently review the state of the Arctic environment
  5. Identify, reduce and eventually “eliminate pollution”

Five groups were created to implement the AEPS:

1) Arctic Monitoring and Assessment Programme (AMAP)

  • Monitor and assess the levels and impact of anthropogenic pollutants in the Arctic environment
  • Focuses on 3 pollutants (POP, heavy metals, and radioactivity)

2) Conservation of Arctic Flora and Fauna (CAFF)

  • Exchange information and coordinate research on Arctic flora and fauna including habitats and species

3) Emergency Prevention, Prepardness and Response (EPPR)

  • Create a plan as to how to cooperate in order to respond to threats of  “Arctic environmental emergencies”

4) Protection of the Arctic Marine Environment (PAME)

  • Takes preventative measures in regards to marine pollution in the Arctic, no matter the origin of the pollution

5) Sustainable Development and Utilization (SDU)

  • Proposes actionable items for governments to take in order to meet goals for the development of sustainable practices in the Arctic, including the utilization of renewable resources by indigenous peoples.[45]

Global Solutions

Looking at solutions from a more global perspective, there are changes that can be made at the root of the issue, preventing pollutants from continuing to seep into the terrain, air, and water circulations and eventually ending up in the Arctic.

Alternatives to DDT Usage Against Spread of Malaria

Modern medicine has developed vaccines and methods to prevent the spread of malaria, without the environmental damage and harm to human/wildlife health that DDT causes. The World Health Organization (WHO) recommends implementation of the RTS,S/AS01 (Mosquirix) and R21/Matrix-M malaria vaccines in children under two years of age[46] in areas where the spread of malaria is rampant. As of 2024, WHO reports that at least 30 countries in Africa are aiming to implement one or both vaccines into their healthcare programs,[46] with the goal to see a decrease in the spread of malaria, thus leading to less DDT usage, thus ultimately limiting more production of pollutants that end up in the Arctic.

Alternatives to Pesticide Usage in Agriculture

Neem Tree (Azadirachta indica) based Products as Biopesticides:

  • Azadirachtin is a chemical extract from the plant that interrupts normal insect reproductive processes, feeding habits, and normal development[47].
  • One hesitation from this biopesticide is that Azadirachtin-A shows evidence of immediate degradation when exposed to sunlight, so future research needs to find solutions/further explore this setback. Since sunlight is a fundamental component of agriculture, it is crucial that the pesticide can withstand it[47].
  • However, the benefits of implementing neem based pesticides would be extensive since they are non toxic and will not harm the Arctic. They are naturally derived and are not a synthetic, man-made chemical like DDT[47].

Bacillus thuringiensis as a Microbial Biopesticide:

  • The bacteria can be used to develop genetically modified crops (Bt-GM crops) which have intense insecticidal properties but do not harm human health or damage the environment in the way traditional pesticides do[48].
  • One hesitation that needs more research before this can be implemented as a solution is the idea that genetically modified plants using bacteria may lead to antibody-resistant diseases in humans that consume crops that have been modified. Therefore, this solution to limit pesticide pollution in the Arctic requires future research[48].
  • Other than the harm reduction, another benefit from this biopesticide is that it is much more cost effective and is produced continuously for a much longer amount of time, compared to traditional pesticides that need to be continually manufactured[48].

Bioindicators to Monitor Progress

In combination with preventative and restorative efforts, establishing monitoring systems for the Arctic can help ensure solutions are delivered in an efficient manner.

Figure 16: Images from the Arctic, a graphic made on Canva.

Fish and invertebrates

  • These species are widely exposed to POPs through sediments, water, and diet, making them helpful in identifying all around pollution levels in the Arctic environment[49].
  • As primary consumers, these species are consumed by and will have their own pollution concentrations transferred onto the majority of the remaining species of higher trophic levels[49]. This includes humans (especially Inuit populations). This is another reason why they are good bioindicators.

Ringed Seals and Polar Bears

  • The especially harmful POPs known as organohalogen contaminants (OHCs) affect Ringed Seals and Polar Bears to an extreme degree[49].
  • These two species are at the top trophic levels, higher than fish and invertebrates, which means these animals used as bioindicators will show the final location of pollutants - it will allow scientists to monitor how many pollutants are still making it to the top of the food web.

Removing Legacy Pollutants from the Arctic

As mentioned previously, legacy pollutants have incredibly long half lives, which are then influenced by environmental factors (the Arctic shows an increased half-life for most toxins)[41].

Therefore, it's imperative that initiatives should be taken to speed up the removal of pollutants from environments at risk, because the half lives are not short enough to rid the Arctic of toxins before damage is done (as seen with the polar bear case study and other effects mentioned on members of the Arctic food web).

There are some avenues of research that can be helpful regarding future removal. These include:

Chemical Approaches

  • Chemical processes that can be used to degrade legacy pollutants include: Homogenous/Heterogenous Photocatalysis, Photo-Fenton, Photolysis of H2O2 & Ozone, and Anodic Oxidation[50].

Biological Approaches

  • Biological processes that can be used to degrade legacy pollutants include: Biosparging & Bioventing, Land Farming, Biostimulation, Bioaugmentation, Slurry Reactors, and Mycoremediation & Phytoremediation[50].

Physical Approaches

  • Physical processes that can be used to degrade legacy pollutants include: Irradiation, Osmosis & RO, Adsorption, Electro-Coagulation, Ion-Exchange, and Membrane Filtration[50].

Mhlongo et al., 2022[51], explains that many of the above methods are limited by costs and high amounts of energy consumption required.

Once again, it is seen that global solutions to both removing and limiting pollutants in the Arctic are limited by political, economic, industrial, and societal factors of the world. Lack of proper healthcare (access to malaria vaccines), lack of funding for legacy pollutant removal methods (chemical, biological, and physical), and lack of clean energy sources are all contributing to usage of harmful toxins. To save the Arctic, we must also save our societies, our economies, and our sustainable industrial/agricultural practices at the same time.

References

  1. ↑ Arctic Ecosystem. (n.d.). Retrieved from Dive & Discover. https://divediscover.whoi.edu/polar-regions/arctic-ecosystem/. Missing or empty |title= (help)
  2. ↑ US EPA. (2018). Persistent Organic Pollutants: A Global Issue, A Global Response | US EPA. Retrieved from US EPA website: https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response. Missing or empty |title= (help); Missing or empty |url= (help)
  3. ↑ Li, Y.-F., Kallenborn, R., & Zhang, Z. (2024). Persistent organic pollutants and chemicals of emerging Arctic concern in the Arctic environment. Environmental Science and Ecotechnology, 18, 100332. https://doi.org/10.1016/j.ese.2023.100332. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  4. ↑ 4.0 4.1 Wenjing, Guo; Bohu, Pan; Sugunadevi, Sakkiah; Gokhan, Yavas; Weigong, Ge; Wen, Zou; Weida, Tong; Huixiao, Hong (2019). "Persistent Organic Pollutants in Food: Contamination Sources, Health Effects and Detection Methods". PubMed.
  5. ↑ 5.0 5.1 AMAP, 1997. Arctic Pollution Issues: A State of the Arctic Environment Report. Arctic monitoring and Assessment Programme (AMAP), Oslo, Norway. xii+188 pp.72-91. https://www.amap.no/documents/doc/arctic-pollution-issues-a-state-of-the-arctic-environment-report/67. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  6. ↑ 6.0 6.1 AMAP, 1997. Arctic Pollution Issues: A State of the Arctic Environment Report. Arctic monitoring and Assessment Programme (AMAP), Oslo, Norway. xii+188 pp.94-109. https://www.amap.no/documents/doc/arctic-pollution-issues-a-state-of-the-arctic-environment-report/67. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  7. ↑ Discovering the Arctic. (2018). Arctic pollution. https://discoveringthearctic.org.uk/science/arctic-science/arctic-pollution/. Missing or empty |title= (help)
  8. ↑ Xie, Z., Zhang, P., Wu, Z., Zhang, S., Wei, L., Mi, L., … Mi, W. (2022). Legacy and emerging organic contaminants in the polar regions. Science of the Total Environment, 835, 155376. https://doi.org/10.1016/j.scitotenv.2022.155376. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  9. ↑ Arctic Pollution Issues: A state of the Arctic environment report. Oslo, Norway: AMAP. 1997. p. 22. ISBN 82-7655-060-6. |first= missing |last= (help)
  10. ↑ 10.0 10.1 10.2 Arctic pollution issues: A state of the Arctic environment report. Oslo, Norway: AMAP. 1997. pp. 22–23. ISBN 82-7655-060-6. |first= missing |last= (help)
  11. ↑ Dusik, J. (2018, November 16). Grasshopper effect serves pollutants onto plates of Arctic peoples. https://www.unep.org/news-and-stories/story/grasshopper-effect-serves-pollutants-plates-arctic-peoples. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  12. ↑ Prowse, Trent D; Furgal, Chris M; Wrona, Frederick John; Reist, Jim (2009). "Implications of Climate Change for Northern Canada: Freshwater, Marine, and Terrestrial Ecosystems". AMBIO – via PubMed.
  13. ↑ Rudels, B., & Carmack, E. (2022). Arctic Ocean Water Mass Structure and Circulation. Oceanography, 35. https://doi.org/10.5670/oceanog.2022.116. Missing or empty |title= (help); Missing or empty |url= (help)CS1 maint: multiple names: authors list (link)
  14. ↑ Brigham, L. (n.d.). Bering Strait Region Case Study. (PDF) https://www.pame.is/images/03_Projects/AMSA/AMSA_Background_Research_Docs/Scenarios/5.5-Bering-Strait-Region-Case-Study.pdf. Missing or empty |title= (help)
  15. ↑ Shiklomanov, A., Déry, S., Mikhail Tretiakov, Yang, D., Dmitry Magritsky, Georgiadi, A., & Tang, W. (2020). River Freshwater Flux to the Arctic Ocean. Springer EBooks, 703–738. https://doi.org/10.1007/978-3-030-50930-9_24. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  16. ↑ Arctic pollution issues: A state of the Arctic Environment report. Oslo, Norway: Arctic Monitoring and Assessment Programme (AMAP). 1997. pp. 24–33. ISBN 82-7655-060-6. |first= missing |last= (help)
  17. ↑ Arctic Pollution Issues: A State of the Arctic Environment Report. Oslo, Norway: Arctic monitoring and Assessment Programme (AMAP). 1997. p. 43. ISBN 82-7655-060-6. |first= missing |last= (help)
  18. ↑ Gardiner, L. S. (n.d.). Why Polar Air Keeps Breaking out of the Arctic | Center for Science Education. https://scied.ucar.edu/learning-zone/climate-change-impacts/why-polar-air-keeps-breaking-out-arctic. Missing or empty |title= (help)
  19. ↑ Aagaard, K., & Carmack, E. C. (1989). The role of sea ice and other fresh water in the Arctic circulation. Journal of Geophysical Research, 94(C10), 14485. https://doi.org/10.1029/jc094ic10p14485. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  20. ↑ Lindsey, R. (2021, March 5). Understanding the Arctic polar vortex | NOAA Climate.gov. Retrieved from www.climate.gov website: https://www.climate.gov/news-features/understanding-climate/understanding-arctic-polar-vortex. Missing or empty |title= (help); Missing or empty |url= (help)CS1 maint: multiple names: authors list (link)
  21. ↑ Woodgate, R. (2013). Arctic Ocean Circulation: Going Around At the Top Of the World | Learn Science at Scitable. Retrieved from www.nature.com website: https://www.nature.com/scitable/knowledge/library/arctic-ocean-circulation-going-around-at-the-102811553/. Missing or empty |title= (help); Missing or empty |url= (help)
  22. ↑ 22.0 22.1 Arnold, C. (2023). Pristine or Polluted? (pp. 26–31). Retrieved from https://www.uarctic.org/media/a0mfkf55/polar-pollution-10128-pdf-2023-08-28-2-54.pdf. Missing or empty |title= (help); Missing or empty |url= (help)
  23. ↑ 23.0 23.1 23.2 AMAP (1997). Arctic Pollution Issues: A State of the Arctic Environment Report. Oslo, Norway: Arctic monitoring and Assessment Programme (AMAP). p. 48. ISBN 82-7655-060-6.
  24. ↑ Routti, Heli; Balto, Ann Kristin (December 2020). "An Invisible Enemy". NORSK POLARINSTITUTUTT. Retrieved April 10 2025. Check date values in: |access-date= (help)
  25. ↑ Chételat, J., & Amyot, M. (2009). Elevated methylmercury in High ArcticDaphniaand the role of productivity in controlling their distribution. Global Change Biology, 15(3), 706–718. https://doi.org/10.1111/j.1365-2486.2008.01729.x. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  26. ↑ 26.0 26.1 26.2 Arctic Pollution Issues: A State of the Arctic Environment Report. Oslo, Norway: Arctic Monitoring and Assessment Programme (AMAP). 1997. pp. 36–40. ISBN 82-7655-060-6. |first= missing |last= (help)
  27. ↑ Setta, S. (2020, October 9). It’s a cold, cold winter for Arctic phytoplankton. https://oceanbites.org/its-a-cold-cold-winter-for-arctic-phytoplankton/. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  28. ↑ Permana, R., & Akbarsyah, N. (2021). Phytoplankton Susceptibility Towards Toxic Heavy Metal Cadmium: Mechanism and Its Recent Updates. (PDF) https://www.worldnewsnaturalsciences.com/wp-content/uploads/2021/06/WNOFNS-38-2021-83-97.pdf. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  29. ↑ 29.0 29.1 AMAP, P.O. Box 8100 Dep., N-0032 Oslo Norway. 188 Pp. 1997, 1997, pp. 188–188, Arctic Pollution Issues: A State of the Arctic Environment Report, https://go.exlibris.link/fbbnMQnM. Accessed 10 Apr. 2025. Missing or empty |title= (help); Missing or empty |url= (help)CS1 maint: multiple names: authors list (link) Cite error: Invalid <ref> tag; name ":10" defined multiple times with different content
  30. ↑ Washington, U. of. (2018, February 21). Beluga Whales Dive Deeper, Longer to Find Food in Arctic - Research & Development World. https://www.rdworldonline.com/beluga-whales-dive-deeper-longer-to-find-food-in-arctic/. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  31. ↑ Lehnherr, I. (2014). Methylmercury biogeochemistry: a review with special reference to Arctic aquatic ecosystems. Environmental Reviews, 22(3), 229–243. https://doi.org/10.1139/er-2013-0059. Missing or empty |title= (help); Missing or empty |url= (help)CS1 maint: multiple names: authors list (link)
  32. ↑ A whale hunt is an act of prayer for an Inuit community north of the Arctic Circle | Aeon Videos. (2024). https://aeon.co/videos/a-whale-hunt-is-an-act-of-prayer-for-an-inuit-community-north-of-the-arctic-circle. Missing or empty |title= (help)
  33. ↑ AMAP, 1997. Arctic Pollution Issues: A State of the Arctic Environment Report. Arctic monitoring and Assessment Programme (AMAP), Oslo, Norway. xii+188 pp.172-186. https://www.amap.no/documents/download/78/inline. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  34. ↑ Bates, S. (2020, November 20). Arctic Animals’ Movement Patterns are Shifting in Different Ways as the Climate Changes - NASA. https://www.nasa.gov/science-research/earth-science/arctic-animals-movement-patterns-are-shifting-in-different-ways-as-the-climate-changes/. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  35. ↑ Skaret, G. (2019, March 28). Capelin in the Barents Sea. https://www.hi.no/en/hi/temasider/species/capelin-in-the-barents-sea. Missing or empty |title= (help)CS1 maint: multiple names: authors list (link)
  36. ↑ Baldursson, S. (n.d.). UNIVERSITY OF THE ARCTIC Module 11 Living Resources in the Arctic Marine Environment. (PDF) https://www.uarctic.org/media/334493/mod11_7n0vV.pdf. Missing or empty |title= (help)
  37. ↑ 37.0 37.1 37.2 37.3 37.4 37.5 "Alternatives to DDT". United Nations Environment Program (UNEP).
  38. ↑ 38.0 38.1 World Health Organization. (‎2011)‎. The use of DDT in malaria vector control: WHO position statement. World Health Organization. https://iris.who.int/handle/10665/69945
  39. ↑ Tsoumani, Maria E. "Malaria Vaccines: From the Past towards the mRNA Vaccine Era". Vaccines. 11: 1452 – via MDPI.
  40. ↑ Choubey, Jitendra (March 16, 2024). "Centre extends DDT production for 5 more years to meet demand from African countries". The New Indian Express.
  41. ↑ 41.0 41.1 41.2 41.3 Zhang, Xue; Li, Li; Xie, Zhiyong; Ma, Jianmin; Li, Yi-Fan; Cai, Minghong; Ren, Nan-Qi; Kallenborn, Roland; Zhang, Zi-Feng. "Exploring global oceanic persistence and ecological effects of legacy persistent organic pollutants across five decades". Science Advances. 10: 39 – via American Association for the Advancement of Science.
  42. ↑ 42.0 42.1 42.2 42.3 Sacco, James C.; James, Margaret O. (2004). "Glucuronidation in the Polar Bear (Ursus maritimus)". Marine Environmental Research. vol 58: 475–479 – via Elsevier Science Direct.
  43. ↑ Derocher, Andrew (December 11, 2018). "Pollution in Polar Bears". Polar Bears International.
  44. ↑ NASA. (2022). Arctic Sea Ice Minimum | NASA Global Climate Change. https://climate.nasa.gov/vital-signs/arctic-sea-ice/?intent=121. Missing or empty |title= (help)
  45. ↑ 45.0 45.1 Arctic Pollution Issues: A State of the Arctic Environment Report. Oslo, Norway: Arctic monitoring and Assessment Programme (AMAP). 1997. pp. 1–2. ISBN 82-7655-060-6. |first= missing |last= (help)
  46. ↑ 46.0 46.1 "Malaria vaccines (RTS,S and R21)". World Health Organization.
  47. ↑ 47.0 47.1 47.2 Bajwa, Amna & Ahmad, Aftab. (2012). Potential applications of Neem based products as biopesticides. 3. 116-120. https://www.researchgate.net/publication/263973149_Potential_applications_of_Neem_based_products_as_biopesticides#fullTextFileContent
  48. ↑ 48.0 48.1 48.2 Kumar, P., Kamle, M., Borah, R. et al. Bacillus thuringiensis as microbial biopesticide: uses and application for sustainable agriculture. Egypt J Biol Pest Control 31, 95 (2021). https://doi.org/10.1186/s41938-021-00440-3
  49. ↑ 49.0 49.1 49.2 Brown, Tanya M.; Macdonald, Robie W.; Muir, Derek C. C.; Letcher, Robert J. "The distribution and trends of persistent organic pollutants and mercury in marine mammals from Canada's Eastern Arctic". Science of The Total Environment. 618: 500–517.
  50. ↑ 50.0 50.1 50.2 Gaur, Nisha; Dutta, Dhiraj; Singh, Ayushi; Dubey, Rama; Kamboj, Dev Vrat. "Recent advances in the elimination of persistent organic pollutants by photocatalysis". Frontiers (Toxicology, Pollution and the Environment). |chapter= ignored (help)
  51. ↑ Mhlongo, Siyabonga Aubrey; Sibali, Linda Lunga; Malematja, Kholofelo Clifford; Ndibewu, Peter P. "Occurrence and Removal of Persistent Organic Pollutants (POPs)". Persistent Organic Pollutants (POPs) - Monitoring, Impact and Treatment. IntechOpen.
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