Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of the exposure to organohalogen compounds (OHCs) in Arctic biota, there has been a considerable number of new Arctic effect studies. Here, we provide an update on the state of the knowledge of OHC, and also include mercury, exposure and/or associated effects in key Arctic marine and terrestrial mammal and bird species as well as in fish by reviewing the literature published since the last AMAP assessment in 2010. We aimed at updating the knowledge of how single but also combined health effects are or can be associated to the exposure to single compounds or mixtures of OHCs. We also focussed on assessing both potential individual as well as population health impacts using population-specific exposure data post 2000. We have identified quantifiable effects on vitamin metabolism, immune functioning, thyroid and steroid hormone balances, oxidative stress, tissue pathology, and reproduction. As with the previous assessment, a wealth of documentation is available for biological effects in marine mammals and seabirds, and sentinel species such as the sledge dog and Arctic fox, but information for terrestrial vertebrates and fish remain scarce. While hormones and vitamins are thoroughly studied, oxidative stress, immunotoxic and reproductive effects need further investigation. Depending on the species and population, some OHCs and mercury tissue contaminant burdens post 2000 were observed to be high enough to exceed putative risk threshold levels that have been previously estimated for non-target species or populations outside the Arctic. In this assessment, we made use of risk quotient calculations to summarize the cumulative effects of different OHC classes and mercury for which critical body burdens can be estimated for wildlife across the Arctic. As our ultimate goal is to better predict or estimate the effects of OHCs and mercury in Arctic wildlife at the individual, population and ecosystem level, there remain numerous knowledge gaps on the biological effects of exposure in Arctic biota. These knowledge gaps include the establishment of concentration thresholds for individual compounds as well as for realistic cocktail mixtures that in fact indicate biologically relevant, and not statistically determined, health effects for specific species and subpopulations. Finally, we provide future perspectives on understanding Arctic wildlife health using new in vivo, in vitro, and in silico techniques, and provide case studies on multiple stressors to show that future assessments would benefit from significant efforts to integrate human health, wildlife ecology and retrospective and forecasting aspects into assessing the biological effects of OHC and mercury exposure in Arctic wildlife and fish.

In montane regions, ongoing and future shrinkage of glacier cover, coupled with a shortening snow cover period, can pro-foundly alter river hydrology but also lead to the release of long-range contaminants, such as mercury (Hg), deposited and stored in snow and ice. In this study, field data coupled with hydrological and atmospheric models were used to estimate the contributions of atmospherically-deposited Hg released by snow or glacier ice melt, and from direct atmospheric deposition, to Kusawa Lake, in subarctic Yukon, Canada. The estimated net Hg accumulation rate in supraglacial snow obtained from field samples is 0.55 mu g m(-2) a(-1). The direct annual atmospheric Hg flux to Kusawa Lake, obtained from model simulations, and which includes summertime wet deposition, is similar to 6 times larger, averaging 3.04 mu g m(-2) a(-1). The estimated mass of Hg from snow/ice meltwater entering the lake annually is 0.6 kg, while direct atmospheric deposition to the lake may contribute a further 0.4 kg, totaling 1.0 kg a(-1). Levels of Hg in cores taken from glaciers in the catchment's headwaters are mostly above expected pre-industrial values, which suggests that some Hg now being released from glaciers is legacy anthropogenic Hg that accumulated in the past 150 years. At present, the delivery of Hg from melting glacial ice is the largest known source to Kusawa Lake, followed by contemporary atmospheric inputs (direct or via runoff). Efforts should be made to quantify other potential sources, such as subglacial meltwater, runoff from wetlands/forest, or melting permafrost, to better constrain the Hg balance in montane lake catchments of this region. (C) 2018 Elsevier Ltd. All rights reserved.

Fourteen polybrominated diphenyl ethers (PBDEs), 14 non-BDE flame retardants (FRs), and 25 organochlorine pesticides (OCPs) were analyzed in air samples collected at Little Fox Lake (LFL) in Canada's Yukon Territory from August 2011 to December 2014. LFL is a long-term monitoring station operated under the Northern Contaminants Program (NCP) and one of only a few stations that contribute to the assessment of air pollution levels and pathways to the sub-Arctic region. BDE-47 was the most abundant congener among the 14 PBDEs, followed by BDE-99. Non-BDE FRs pentabromotoluene (PBT) and dechlorane plus (DP) were detected in all the samples. Dechlorane 602, 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), hexabromobenzene (HBB), and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) were also detected in >75% of all samples. PBDEs have shown a decreasing tendency as of 2013, which may reflect the phase-out of penta- and octa-BDE mixtures has led to significant decline in the atmosphere. The highest concentrations of OCPs were observed for hexachlorobenzene (HCB), with a median concentration of 61 pg/m(3), followed by α-hexachlorocyclohexane (α-HCH) and α-endosulfan. Potential source contribution function (PSCF) highlights Northern Canada, Pacific, and East Asia as potential sources in warm seasons; whereas in cold seasons, the chemicals mainly came from the Pacific Rim.

The Canadian Arctic has vast freshwater resources, and fish are important in the diet of many Northerners. Mercury is a contaminant of concern because of its potential toxicity and elevated bioaccumulation in some fish populations. Over the last decade, significant advances have been made in characterizing the cycling and fate of mercury in these freshwater environments. Large amounts of new data on concentrations, speciation and fluxes of Hg are provided and summarized for water and sediment, which were virtually absent for the Canadian Arctic a decade ago. The biogeochemical processes that control the speciation of mercury remain poorly resolved, including the sites and controls of methylmercury production. Food web studies have examined the roles of Hg uptake, trophic transfer, and diet for Hg bioaccumulation in fish, and, in particular, advances have been made in identifying determinants of mercury levels in lake-dwelling and sea-run forms of Arctic char. In a comparison of common freshwater fish species that were sampled across the Canadian Arctic between 2002 and 2009, no geographic patterns or regional hotspots were evident. Over the last two to four decades, Hg concentrations have increased in some monitored populations of fish in the Mackenzie River Basin while other populations from the Yukon and Nunavut showed no change or a slight decline. The different Hg trends indicate that the drivers of temporal change may be regional or habitat-specific. The Canadian Arctic is undergoing profound environmental change, and preliminary evidence suggests that it may be impacting the cycling and bioaccumulation of mercury. Further research is needed to investigate climate change impacts on the Hg cycle as well as biogeochemical controls of methylmercury production and the processes leading to increasing Hg levels in some fish populations in the Canadian Arctic.

Environmental context Some long-lived organic contaminants, such as chlorinated organics, brominated flame retardants and polycyclic aromatic hydrocarbons, can undergo transport through the atmosphere to remote regions. A series of measurements of these compounds taken over almost 3 years in the air at a remote location was combined with meteorological data to try to reveal potential source areas. After adjusting several parameters to optimise the method’s ability to identify sources it was found that for most contaminants no definitive sources are revealed. Abstract A suite of brominated flame retardants, chlorinated organic pesticides and some metabolites thereof were analysed in week-long and day-long air samples collected at Little Fox Lake in Canada’s Yukon Territory from 2007 to 2009. Several trajectory-based methods for source region identification were applied to this dataset, as well as to polycyclic aromatic hydrocarbon (PAH) concentrations in those same samples reported previously. A type of concentration weighted trajectory (CWT) analysis, using a modified grid to avoid difficulties near the Earth’s poles, and removing trajectory endpoints at altitudes greater than 700m did not identify distinct source regions for most analytes. Decreasing the spatial resolution of the grid made interpretation simpler but reinforced patterns that may have stemmed from single trajectories. The potential source contribution function (PSCF) is similar to CWT but treats the concentration data categorically, rather than numerically. PSCF provides more distinct results, highlighting the Arctic Ocean as a potential source of para,para′-dichlorodiphenyldichloroethene and both northern Siberia and Canada’s Yukon and Northwest Territories as potential sources of PAHs. To simulate the uncertainty associated with individual trajectories, a set of trajectories was also generated for six points surrounding the sampling station and included in the trajectory analyses. This had the effect of smoothing the CWT and PSCF values for those analytes with no clearly definable sources, and highlighting the source regions for the two that did. For the bulk of the analytes discussed here, Little Fox Lake is well positioned to act as a background monitoring site.

A statistically robust method was applied to 83 time-series of mercury in Arctic biota from marine, freshwater and terrestrial ecosystems with the purpose of generating a 'meta-analysis' of temporal trend data collected over the past two to three decades, mostly under the auspices of the Arctic Monitoring and Assessment Program (AMAP). Sampling locations ranged from Alaska in the west to northern Scandinavia in the east. Information from recently published temporal trend studies was tabulated to supplement the results of the statistical analyses. No generally consistent trend was evident across tissues and species from the circumpolar Arctic during the last 30years or so. However, there was a clear west-to-east gradient in the occurrence of recent increasing Hg trends, with larger numbers and a higher proportion of biotic datasets in the Canadian and Greenland region of the Arctic showing significant increases than in the North Atlantic Arctic. Most of the increasing datasets were for marine species, especially marine mammals. A total of 16 (19%) out of the 83 time-series could be classified as "adequate", where adequate is defined as the number of actual monitoring years in a time-series being equal to or greater than the number of years of sampling required to detect a 5% annual change in Hg concentrations, with a significance level of P<0.05 and 80% statistical power. At the time of the previous AMAP Assessment, only 10% of the Hg time-series were deemed adequate. If an additional 5years of data were to be added to the current set of time-series, it is predicted that 53% of time-series would become adequate.

Data and sample contributors (Section 5.3): Jon Aars, Magnus Andersen, Gert Asmund, Aurore Aubail, Anders Bignert, Erik Born, Birgit Braune, Maria Dam, Rune Dietz, Marlene Evans, Thomas Evans, Mary Gamberg, Nikolaus (Klaus) Gantner, Norman Green, Helga Gunnlaugsdóttir, Kurunthachalam Kannan, Robert Letcher, Derek Muir, Kristin Ólafsdóttir, Aristeo Renzoni, Frank Rigét, Pat Roach, Christian Sonne, Gary Stern, Øystein Wiig, Simon Wilson

Polycyclic aromatic hydrocarbons (PAH) were measured in air samples at a remote air monitoring site established in the Yukon Territory, Canada as part of a global project (International Polar Year; IPY) to study the potential for atmospheric long-range transport of anthropogenic pollutants to the Arctic. Gas- and particle-phase PAH were collected in polyurethane foam plugs and on glass fibre filters respectively from August 2007 to October 2009. PAH concentrations were found to be highest in the winter months and lowest in summer. The gas/particle partitioning coefficients of 3–5 ringed PAH were computed and seasonal averages were compared. In the summer time, lower molecular mass PAH exhibited relatively higher partitioning into the particle-phase. This particle-phase partitioning led to the shallowest slopes being recorded during summer for the log–log correlation plots between the PAH partition coefficients and their sub-cooled vapour pressures. Air mass back trajectories suggest that local impacts may be more important during the summer time which is marked by increased camping activities at camping sites in the proximity of the sampling station. In conclusion, both summer and wintertime variations in PAH concentrations and gas/particle partitioning are considered to be source- and phototransformation-dependent rather than dependent on temperature-driven shifts in equilibrium partitioning.

An apparatus has been designed and built for testing the effects, on moderate-sized objects, of cushioned decelerations having magnitudes ranging up to several hundred g [where g = normal Earth gravitational acceleration (approximately 9.8 m/s(exp 2))].

A report discusses the development of a flexible thermal-insulation material for cryogenic tanks in next-generation spacecraft. This material is denoted Advanced Reusable All-temperature Multimode Insulation System (ARAMIS). The report begins by describing the need for ARAMIS and the technological challenges of developing a single material that is useable throughout the temperature range from storage of liquid hydrogen (20 K) to atmospheric-reentry heating (>2,000 K), has the requisite low thermal conductivity, resists condensation of moisture without need for a gas purge, and withstands reentry heating for a 400-mission lifetime. The report then discusses laboratory apparatuses for testing materials that have been and will be considered as candidates for the development of ARAMIS.

Over 1999-2002, an extensive series of contaminant studies was conducted on freshwater biota of Canada's Arctic and Subarctic regions. The majority of inorganic contaminant studies focused on mercury and fish. While mercury concentrations were low in benthic feeding fish such as whitefish, predatory fish such as lake trout, pike, and walleye frequently had mercury levels which exceeded 0.2 mu g/g, the consumption guideline for frequent consumers of fish, and 0.5 mu g/g, the guideline for the commercial use of fish. Numerous consumption advisories were issued for lakes along the Mackenzie River. Relatively high mercury levels appear to be due to a combination of relatively old fish populations (because of light fishing pressures) and tend to be more prevalent in smaller lakes where warmer summer water temperatures and watershed influences result in greater mercury and methyl mercury inputs. Mercury levels were substantially lower in char than in lake trout, possibly due to a combination of a less fish-rich diet, a colder environment, and smaller MeHg watershed inputs. Less research has been conducted on other metals but some, such as rubidium, show pronounced variations in concentration that may be related to geological influences. Temporal trend monitoring has revealed little evidence of declining mercury levels in fish that can be attributed to declining atmospheric inputs. Because mercury follows complex pathways in the environment, other factors may operate to counteract reductions in atmospheric mercury sources, e.g., climatic variability, changes in the commercial fishery, and interactions between fish species.Most organochlorine (OC) investigations were based on long term trend monitoring and focused on char (Cornwallis Island), burbot (Great Slave Lake, Yukon lakes, Slave River at Fort Smith, Mackenzie River at Fort Good Hope) and lake trout (Yukon lakes, Great Slave Lake). There was strong evidence of declining OC concentrations in char, particularly Sigma HCH and Sigma chlordane, which may reflect a response to declining atmospheric inputs. Endosulfan concentrations increased, as in the atmosphere. There also was evidence of declining OC concentrations in burbot in the Slave and Mackenzie rivers but not in Great Slave Lake and Yukon lakes. OC concentrations decreased in lake trout in Yukon lakes in the 2000s, most probably because of changes in the fish themselves (i.e., reduced lipid content, condition factor) and possibly climatic variability. Similarly, OCs declined in Great Slave Lake trout. New research on PDBEs and perfluorinated compounds determined that these contaminants are widespread in freshwater fish and concentrations may be increasing.Global warming is a major issue of concern for Arctic and Subarctic waters and may have adverse impacts on contaminant levels in fish and other biota. There is a need for contaminant studies in the north to be broadened to investigate climatic effects. In addition, monitoring studies should be broadened to consider factors affecting other aspects of fish biology. Foremost among these is integrating contaminant monitoring studies on lakes such as Lake Laberge and Great Slave Lake with stock assessment studies. Ecosystem based studies should be conducted on Great Slave Lake and Lake Laberge to more effectively understand contaminant trends and should consider inputs (atmospheric, river inflow, resupension), losses (sedimentation, volatilization), and biological pathways. Crown Copyright (c) 2005 Published by Elsevier B.V. All rights reserved.

Many planetary and Earth science missions require cooling to increase sensitivity and reduce thermal noise of detectors, for preserving high Isp propellants, or for protecting instruments from hostile environments. For space applications, such cooling requires reliable, efficient, long-life coolers that are relatively compact, lightweight, and have low vibration. We have developed and are developing coolers that meet these requirements over a wide range of temperatures. These include pulse tube coolers cooling from 300 K to below 6 K, a magnetic cooler cooling from 10 K to 2 K, a 3He sorption cooler cooling from 2 K to 0.3 K and a helium dilution cooler cooling from 0.3 K to 0.05 K. Details of these coolers and their advantages are presented.

We have developed a suspension system using pre-tensioned titanium alloy wires to support a 1 Watt Radioisotope Heating Unit (RHU) for a mission to Mars. This suspension is very strong in all directions and has quite low thermal conduction between the RHU and its colder surroundings. This will allow the RHU to operate at 250 degreesC for generating electrical power from an attached thermoelectric converter (TEC) after surviving multiple 300 G impacts on the Martian surface. We have tested the Suspension under impact loads that have the same duration as the impacts expected from the air-bag cushions planned for the Mars mission. The suspension survives impacts of 500 G with the RHU canister at room temperature and at 250 degreesC. We calculate that with the RHU at 250 degreesC there will be only 86 mW of heat conducted through the support structure. This design in intended for use with multilayer insulation in a good vacuum. We estimate that the conduction through such insulation would be 75 mW. This leaves more than 800 mW of the heat from the RHU to flow through the TEC. yielding more than 40 mW of electrical power.

New materials are being designed to allow the implementation of innovative concepts in future space transportation vehicles. In present day spacecraft, launch vehicles consist of an overall structure in which the cryogenic propellant tanks are mounted in a framework covered by an aeroshell. In NASA s next generation space transportation vehicles the innovative concept of conformal propellant tanks will be utilized. In addition to containing the propellants the cryogen tanks will serve as part of the main vehicle structure. This concept enables significant reduction in launch mass, Crucial to this approach will be the development of a material that will serve not only as cryogenic insulation on the launchpad and early in flight, but also as a thermal protection system (TPS), protecting the vehicle on re-entry. Prior to selection for this challenging application various material properties are to be assessed. The present paper discusses experimental results on the thermal conductivity of a preliminary candidate material (an aerogel-impregnated shuttle tile) in the presence of helium gas, Data have been taken at room temperature and near 80K at pressures ranging from latm down to 20mTorr. The capability to extend the tests down to lower temperatures (4K) was not utilized considering the noted adsorptive qualities of the open cell structure of the tile.

We have developed a shallow, single-cycle, helium dilution refrigerator that contains rather coarse metal sponge to study the ability to control the location of the liquid helium for microgravity applications. We have tested the refrigerator on the ground while tilting to put the mixing chamber either somewhat above or somewhat below the still. We calculated that the system could be tilted between 5 degrees and 10 degrees in either direction without interrupting the cooling. The initial test of this refrigerator gave cooling to below 0.060 K and operation for tilts of +/-16 degrees. The insights gained from this refrigerator allow the design of a continuously operating version. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.

A dilution refrigerator (DR) is the most common precooling stage for sub-millikelvin demagnetization experiments. The usefulness of the DR comes from its ability to provide cooling at 0.02-0.04 K for long periods of time while the heat of magnetization is being rejected by the demagnetization stage. In order to make these advantages of the DR available to researchers who need the microgravity of space for their experiments, we are developing a continuously-operating DR that will function in microgravity.We have previously demonstrated that the liquid helium of the DR can be controlled by the use of capillary forces in sintered metal sponges. We have found, however, that the small pores needed to control large heights of liquid on the ground are too small to allow sufficient liquid flow for effective cooling.We have built a shallow single-cycle version of the refrigerator that does not require large heights of liquid to be supported by capillary forces. The liquid chambers are next to each other and are filled with sinter with relatively open pores; these pores will allow much freer flow of the helium. The gravity independence of this design will be tested by tilting the system so that one chamber is slightly above or below the other and by inverting both chambers. The operation of the refrigerator should be unaffected by tilts of 5-10 degrees or by the inversion of the chambers.A design for a continuously-operating dilution refrigerator is presented. It includes all the advantages of the single-cycle refrigerator while adding the large advantage of continuous cooling for long periods of time.