A full-scale, experimental landfarm was tested for the capacity to biodegrade oil-polluted soil under high-Arctic tundra conditions in northeast Greenland at the military outpost 9117 Station Mestersvig. Soil contaminated with Arctic diesel was transferred to the landfarm in August 2012 followed by yearly addition of fertilizer and plowing and irrigation to optimize microbial diesel biodegradation. Biodegradation was determined from changes in total petroleum hydrocarbons (TPH), enumeration of specific subpopulations of oil-degrading microorganisms (MPN), and changes in selected classes of alkylated isomers and isomer ratios. Sixty-four percent of the diesel was removed in the landfarm within the first year, but a recalcitrant fraction (18%) remained after five years. n-alkanes and naphthalenes were biodegraded as demonstrated by changing isomer ratios. Dibenzothiophenes and phenanthrenes showed almost constant isomer ratios indicating that their removal was mostly abiotic. Oil-degrading microorganisms were present for the major components of diesel (n-alkanes, alkylbenzenes and alkylnaphthalenes). The degraders showed very large population increases in the landfarm with a peak population of 1.2 × 10⁹ cells g⁻¹ of total diesel degraders. Some diesel compounds such as cycloalkanes, hydroxy-PAHs and sulfur-heterocycles had very few or no specific degraders, these compounds may consequently be degraded only by slow co-metabolic processes or not at all.

The Arctic is a unique and fragile ecosystem that needs to be preserved and protected. Despite its remoteness, plastic pollution has been documented in this region. In the coming years, it is likely to worsen since, with climate changes and the opening of new shipping routes, the human presence is going to increase in the whole area. Here, we investigated the presence of microplastics (MPs) in sub-surface water and in two mid-trophic level Arctic fishes collected off Northeast Greenland: the demersal bigeye sculpin, Triglops nybelini, and the pelagic polar cod, Boreogadus saida. Plastics debris were found in the water samples at a concentration of 2.4 items/m³ ±0.8 SD which is higher than in most seas at lower latitudes. Both fish species had eaten MPs with different proportion among the species, 34% for T. nybelini (n = 71) and 18% for B. saida (n = 85). The significant difference in the occurrence of MPs between the two species is likely a consequence of their feeding behavior and habitat. Polyethylene was the main plastic polymer for water samples (41%, n = 17) and polyester (34%, n = 156) for fish samples as analyzed by Fourier Transformed Infrared (FT-IR) spectroscopy. Our data underscore that the Arctic regions are turning into a hotspot for plastic pollution, and this calls urgently for precautionary measures.

Studying long-term trends of contaminants in Arctic biota is essential to better understand impacts of anthropogenic activities and climate change on the exposure of sensitive species and marine ecosystems. We concurrently measured temporal changes (2006–2014) in mercury (Hg) contamination of little auks (Alle alle; the most abundant Arctic seabird) and in their major zooplankton prey species (Calanoid copepods, Themisto libellula, Gammarus spp.). We found an increasing contamination of the food-chain in East Greenland during summer over the last decade. More specifically, bird contamination (determined by body feather analyses) has increased at a rate of 3.4% per year. Conversely, bird exposure to Hg during winter in the northwest Atlantic (determined by head feather analyses) decreased over the study period (at a rate of 1.5% per year), although winter concentrations remained consistently higher than during summer. By combining mercury levels measured in birds and zooplankton to isotopic analyses, our results demonstrate that inter-annual variations of Hg levels in little auks reflect changes in food-chain contamination, rather than a reorganization of the food web and a modification of seabird trophic ecology. They therefore underline the value of little auks, and Arctic seabirds in general, as bio-indicators of long-term changes in environmental contamination.

Microplastics have been reported everywhere around the globe. With very limited human activities, the Arctic is distant from major sources of microplastics. However, microplastic ingestions have been found in several Arctic marine predators, confirming their presence in this region. Nonetheless, existing information for this area remains scarce, thus there is an urgent need to quantify the contamination of Arctic marine waters. In this context, we studied microplastic abundance and composition within the zooplankton community off East Greenland. For the same area, we concurrently evaluated microplastic contamination of little auks (Alle alle), an Arctic seabird feeding on zooplankton while diving between 0 and 50 m. The study took place off East Greenland in July 2005 and 2014, under strongly contrasted sea-ice conditions. Among all samples, 97.2% of the debris found were filaments. Despite the remoteness of our study area, microplastic abundances were comparable to those of other oceans, with 0.99 ± 0.62 m−3 in the presence of sea-ice (2005), and 2.38 ± 1.11 m−3 in the nearby absence of sea-ice (2014). Microplastic rise between 2005 and 2014 might be linked to an increase in plastic production worldwide or to lower sea-ice extents in 2014, as sea-ice can represent a sink for microplastic particles, which are subsequently released to the water column upon melting. Crucially, all birds had eaten plastic filaments, and they collected high levels of microplastics compared to background levels with 9.99 and 8.99 pieces per chick meal in 2005 and 2014, respectively. Importantly, we also demonstrated that little auks took more often light colored microplastics, rather than darker ones, strongly suggesting an active contamination with birds mistaking microplastics for their natural prey. Overall, our study stresses the great vulnerability of Arctic marine species to microplastic pollution in a warming Arctic, where sea-ice melting is expected to release vast volumes of trapped debris.

Polychlorinated biphenyls (PCBs) chiral signatures were measured in Greenland sharks (Somniosus microcephalus) and their potential prey in arctic marine food webs from Canada (Cumberland Sound) and Europe (Svalbard) to assess temporal and spatial variation in PCB contamination at the stereoisomer level. Marine mammals had species-specific enantiomer fractions (EFs), likely due to a combination of in vivo biotransformation and direct trophic transfer. Greenland sharks from Cumberland Sound in 2007–2008 had similar EFs to those sharks collected a decade ago in the same location (PCBs 91, 136 and 149) and also similar to their conspecifics from Svalbard for some PCB congeners (PCBs 95, 136 and 149). However, other PCB EFs in the sharks varied temporally (PCB 91) or spatially (PCB 95), suggesting a possible spatiotemporal variation in their diets, since biotransformation capacity was unlikely to have varied within this species from region to region or over the time frame studied.

The global distribution and long-range transport of polyfluoroalkyl substances (PFASs) were investigated using seawater samples collected from the Greenland Sea, East Atlantic Ocean and the Southern Ocean in 2009–2010. Elevated levels of ΣPFASs were detected in the North Atlantic Ocean with the concentrations ranging from 130 to 650 pg/L. In the Greenland Sea, the ΣPFASs concentrations ranged from 45 to 280 pg/L, and five most frequently detected compounds were perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS). PFOA (15 pg/L) and PFOS (25–45 pg/L) were occasionally found in the Southern Ocean. In the Atlantic Ocean, the ΣPFASs concentration decreased from 2007 to 2010. The elevated PFOA level that resulted from melting snow and ice in Greenland Sea implies that the Arctic may have been driven by climate change and turned to be a source of PFASs for the marine ecosystem.

The spatial distribution of polybrominated diphenyl ethers (PBDEs) and several alternative non-PBDE, non-regulated brominated flame retardants (BFRs) in air and seawater and the air–seawater exchange was investigated in East Greenland Sea using high-volume air and water samples. Total PBDE concentrations (Ó₁₀PBDEs) ranged from 0.09 to 1.8 pg m⁻³ in the atmosphere and from 0.03 to 0.64 pg L⁻¹ in seawater. Two alternative BFRs, Hexabromobenzene (HBB) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), showed similar concentrations and spatial trends as PBDEs. The air–seawater gas exchange was dominated by deposition with fluxes up to −492 and −1044 pg m⁻² day⁻¹ for BDE-47 and DPTE, respectively. This study shows the first occurrence of HBB, DPTE and other alternative flame retardants (e.g., pentabromotoluene (PBT)) in the Arctic atmosphere and seawater indicating that they have a similar long-range atmospheric transport potential (LRAT) as the banned PBDEs.

Identification of mining-related contaminants is important in order to assess the spreading of contaminants from mining as well as for site remediation purposes. This study focuses on lead (Pb) contamination in biota near the abandoned ‘Black Angel Mine’ in West Greenland in the period 1988-2008. Stable Pb isotope ratios and total Pb concentrations were determined in lichens, seaweed and mussels as well as in marine sediments. The results show that natural background Pb (207Pb/206Pb: 0.704-0.767) and Pb originating from the mine ore (207Pb/206Pb: 0.955) have distinct isotopic fingerprints. Total Pb in lichens, seaweed, and mussels was measured at values up to 633, 19 and 1536 mg kg-1 dry weight, respectively, and is shown to be a mixture of natural Pb and ore-Pb. This enables quantification of mining-related Pb and shows that application of Pb isotope data is a valuable tool for monitoring mining pollution.

Biological degradation is the main process for oil degradation in a subsurface oil plume. There is, however, little information on the biodegradation potential of Arctic, marine subsurface environments. We therefore investigated oil biodegradation in microcosms at 2 °C containing Arctic subsurface seawater from the Disko Bay (Greenland) and crude oil at three concentrations of 2.5–10 mg/L. Within 71 days, the total petroleum hydrocarbon concentration decreased only by 18 ± 18% for an initial concentration of 5 mg/L. The saturated alkanes nC13-nC30 and the isoprenoids iC18-iC21 were biodegraded at all concentrations indicating a substantial potential for biodegradation of these compound classes. Polycyclic aromatic compounds (PACs) disappeared from the oil phase, but dissolution was the main process of removal. Analysis of diagnostic ratios indicated almost no PAC biodegradation except for the C1-naphthalenes. To conclude, the marine subsurface microorganisms from the Disko Bay had the potential for biodegradation of n-alkanes and isoprenoids while the metabolically complex and toxic PACs and their alkylated homologs remained almost unchanged.

Microplastics (MPs) are polluting the Arctic, but our understanding of their abundance, distribution, and sources is limited. This study quantified MPs down to 10 μm in marine waters of the most populated region in Greenland. A new plastic-free pump-filter system was used to collect MPs from surface waters in the fjord Nuup Kangerlua close to Nuuk. Additionally, we took samples by horizontal tows with a bongo net (300 μm mesh-size). The median concentrations were 142 MPs m⁻³ and 0.12 MPs m⁻³ in the pump and bongo samples, respectively. The most abundant polymer was polyester across stations and sampling types. Fibers were the dominant shape in the bongo samples, while non-fibrous particles dominated in the pump samples. MP abundance was lower in the fjord and increased close to Nuuk and towards the open ocean, indicating that Nuuk is an important point source for MPs. In both samples, concentrations of MPs increased with decreasing size, illustrating the importance of quantifying the smallest fraction of MPs. Thus, the use of methods allowing for a quantification of the smallest MPs is vital to reduce the underestimation of MP concentrations in the environment. The smallest size fraction is also most available to plankton-feeding marine invertebrates and an important entry point for MPs into marine food webs. At the found concentrations, immediate adverse effects on the pelagic food webs are unlikely. However, growing anthropogenic activities could increase the risk of MPs to affect the sensitive Arctic ecosystem.