DEW Line Research Articles

Modeling [formula omitted] mixture thermodynamics using various equations of state (EoSs) with emphasis on the potential of the SPUNG EoS

CO2–water is a very important mixture in the Carbon Capture and Storage (CCS) industry. The mixture can have a broad range of concentrations, from water as an impurity in CO2 transport to high water concentrations in sequestration processes. CO2–water mixture is challenging due to the polar nature that induces difficulties describing the interaction between CO2 and water when modeling the behavior. The work focuses on the evaluation of the predictability of the extended corresponding state equation SPUNG in dealing with CO2–water thermodynamics. The evaluation is done by comparing the behavior of SPUNG equation of state (EoS) to experimental data, and two other EoSs of a different class. The two other EoSs are the cubic equation Soave–Redlich–Kwong (SRK) with van der Waals mixing rules, and SRK with Huron–Vidal mixing rules.The predictability of the single and liquid rich phase densities, two-phase solubilities and dew line is investigated over a wide range of pressures, temperatures and mixture compositions. The results show better density prediction using SPUNG EoS over all the evaluated conditions compared to SRKs with a potential of improvements by changing the reference fluid. However, the CO2 solubility prediction using SPUNG requires the use of other mixing rules that can account for the polar nature of the system.

Thermal conductivity of refrigerant R-415A in the vapor phase

Thermal conductivity of refrigerant R-415A in the vapor phase has been studied by the steady-state method of coaxial cylinders in the range of temperatures 308–415 K and pressures 0.12–1.68 MPa. The approximation dependence of thermal conductivity on pressure and temperature was determined. Thermal conductivity on the dew line and in the ideal gas state was calculated.

Experimental study of thermal conductivity of the R-407C refrigerant in the vapor phase

Thermal conductivity of the gaseous R-407C refrigerant was investigated by the coaxial cylinders method within the temperature range of 303–425 K and the pressure range of 0.7–2.1 MPa. Approximating dependence of thermal conductivity on pressure and temperature was obtained. Thermal conductivity on dew line and in ideal gas state was calculated. The comparison is performed of the data obtained with those available in the literature.

Experimental study of thermal conductivity of refrigerant R-409A in vapor phase

Thermal conductivity of refrigerant R-409A in vapor phase was studied in the range of temperatures 306–425 K and pressures 0.12–1.33 MPa. Measurements were performed with the stationary method of coaxial cylinders. Uncertainty of experimental data on thermal conductivity was 1.5–2.5 %, and errors of temperature and pressure measurements did not exceed 0.05 K and 4 kPa, respectively. Approximating dependence of thermal conductivity on pressure and temperature was obtained. Thermal conductivity on dew line and in ideal gas state was calculated.

The air pressure effect on the homogeneous nucleation of carbon dioxide by molecular simulation

Vapour–liquid equilibria (VLE) and the influence of an inert carrier gas on homogeneous vapour to liquid nucleation are investigated by molecular simulation for quaternary mixtures of carbon dioxide, nitrogen, oxygen, and argon. Canonical ensemble molecular dynamics simulation using the Yasuoka–Matsumoto method is applied to nucleation in supersaturated vapours that contain more carbon dioxide than in the saturated state at the dew line. Established molecular models are employed that are known to accurately reproduce the VLE of the pure fluids as well as their binary and ternary mixtures. On the basis of these models, also the quaternary VLE properties of the bulk fluid are determined with the Grand Equilibrium method. Simulation results for the carrier gas influence on the nucleation rate are compared with the classical nucleation theory (CNT) considering the ‘pressure effect’ [Phys. Rev. Lett. 101: 125703 (2008)]. It is found that the presence of air as a carrier gas decreases the nucleation rate only slightly and, in particular, to a significantly lower extent than predicted by CNT. The nucleation rate of carbon dioxide is generally underestimated by CNT, leading to a deviation between one and two orders of magnitude for pure carbon dioxide in the vicinity of the spinodal line and up to three orders of magnitude in the presence of air as a carrier gas. Furthermore, CNT predicts a temperature dependence of the nucleation rate in the spinodal limit, which cannot be confirmed by molecular simulation.

A cubic equation of state based on saturated vapor modeling and the application of model-based design of experiments for its validation

For simulation of chemical processes, a sufficiently accurate mathematical description of phase equilibria is essential. In order to achieve this, high-quality measured data and model equations are indispensable. A new gamma-function as a replacement for the common alpha-function in cubic equations of state is proposed here for polar compounds with an existing vapor phase. The equation parameters of the gamma-function are fitted to state data on the dew line instead of, as usual, on the vaporization curve. The quality of the description is compared to the customary equations of state using statistical parameters. A further validation used for the description is the prediction of caloric parameters and the comparison thereof with measured data. By means of model-based experimental design, the gamma-function and the equation of state based thereon are validated. Multiple setpoint optimization allows a uniform experimental design for validation of a vapor pressure equation and of a vapor density equation to be calculated for polar compounds. The experiments calculated optimally in this way reduce large test series to a few experiments which are significant for the specific model equation.

The DEW Line Years: Voices from the Coldest Cold War, by Frances Jewel Dickson

The DEW Line Years: Voices from the Coldest Cold War, by Frances Jewel Dickson

HOT ROCKS AND THE URANIUM Girl: Nabokov’s LOLITA

This article considers Nabokov’s Lolita as an allegory of the Cold War’s obsession with uranium, correlating the uranium rush of the 1950s with the choice of some of the key locations in the book. The incursion into United States space by the foreign agent and corrupter of youth Humbert Humbert is read through the lens of Cold War anxieties about radiation, missile attack through the DEW Line and a “mapping” of America by subversive aliens. Lolita herself is the Uranium Girl, radiant child of nuclear America under threat from the death ray of the bomb’s fallout.

Vapor Pressure, Speed of Sound, and PVT-Properties of R-404a in the Vapor Phase

The density (300–363 K, up to 3.5 MPa) and speed of sound (293–373 K, 7.5–480 kPa) in gaseous R-404a have been studied by an isochoric piezometer method and an ultrasonic interferometer, respectively. The pressures of the saturated vapor along the dew line were measured from 298 to 330 K. The experimental uncertainties of the temperature, pressure, density, and speed-of-sound measurements were estimated to be within ±20 mK, ±1.5 kPa, ±0.15%, and ±(0.1–0.2)%, respectively. On the basis of the obtained data, the isobaric molar heat capacity of R-404a was calculated for the ideal-gas state. An eight-coefficient Benedict–Webb–Rubin equation of state has been developed for the gaseous phase of R-404a.

Vapor pressure of R227ea + ethanol at 343.13 K by molecular simulation

A new molecular model for 1,1,1,2,3,3,3-heptafluoropropane (R227ea) was developed on the basis of quantum chemical calculations and optimized using experimental vapor pressure and bubble density data. In combination with an existing model for ethanol, a molecular model for the binary mixture R227ea + ethanol was defined, using the Lorentz–Berthelot combining rule. It was validated at 283.17 K, where, considering the statistical uncertainties, it agrees to the experimental vapor pressure. The vapor–liquid equilibrium, comprising both bubble line and dew line data, was predicted at 343.13 K by molecular simulation. The Peng–Robinson equation of state fails for this system.

Dawn mission and operations

Dawn is the first mission to attempt to orbit two distant planetary bodies. The objects chosen, 4 Vesta followed by 1 Ceres, are the two most massive members of the asteroid belt that appear to have been formed on either side of the dew line in the early solar nebula. This paper describes the present status of the mission development and the plans for operation at Vesta and Ceres.

Northern Research Legacies and the Future: A University Perspective

I am writing as a Canadian who was involved in northern research as a post-doctoral student in the 1970s and who, since then, has been involved as a researcher and educator in southern university-based northern studies. My goal is to bring together some comments on research databases and the lost generation of northern researchers, .... The and Northerners have always faced major changes; in the 20th century, these included the air industry, the DEW Line, hydroelectric dams, mines and roads. Now Northerners are facing the greatest acceleration of changes on landscapes and in communities since the 1970s. On landscapes remote from communities is a diamond industry that could supply the world with 15% of its diamonds within three years; several thousand people will be employed. Petroleum exploration (seismic and drilling) is operating today at the highest level since the 1970s. Pipeline construction projects of a size greater than ever seen in America are being proposed: the Texas of the North is the new vision. ... What are the research needs? Researchers are being urged to collect more and better data and to make better predictions. They are urged to adhere to ethics guidelines, to demonstrate the impacts of their research at the proposal stage, and to effectively transmit research results to the community. Those responsible for management policy and implementation in the are now searching for solutions, and they are finding many gaps in our knowledge. They emphasize that data are obsolete and capacity building is needed. ... Questions are being asked about jobs for university researchers who work on northern topics: are there opportunities for long-term employment, or are these dead-end jobs? How do we maintain long-term northern research programs - at least one generation in length? How can we develop value-added industries with local benefits that are complementary to the programs of multinational giants? ... Who is responsible for research that will lead to understanding, solutions, and management strategies? A few decades ago, the federal government provided research support, management policies, and policing. Now political devolution has resulted in multi-layers of governance in the North. Can we assume that this new governance system will invest in research that leads to new approaches? For example, who will invest in the monitoring of cumulative effects? If the linkage between government regulators and industry is too close, who will provide the long-term perspective so that environmental damage will not accrue to future generations? ... Maybe we should re-think the traditional role of government in light of the new power of industry. Many feel that industry-sponsored university research tarnishes the image of universities as honest brokers. ... Without budgets that reflect the realities of expensive northern research, researchers must stay close to their home institutions - and that is what they did in the 1980s and 1990s. ... I believe we need more northern research endowments in Canada. I believe we need more research and think tank nongovernmental organizations in Canada, and I believe these are increasingly important as the role of government changes from watchdog to stimulator of industry. ... There is also a need to reinterpret the 1970s information and to convert it into more usable forms. Much of this information was collected and stored in libraries and databases as private and public research collections were consolidated in the 1980s and 1990s. ... We must not forget that these resources are now much more accessible than they were in the 1970s. Finally, there is a need to capture the experience of many northern and southern people involved in the petroleum industry and many other activities in the 1970s and 1980s. ...

The Dew Line: Ditched drums and all

The Dew Line: Ditched drums and all

Contaminants in the Canadian Arctic: 5 years of progress in understanding sources, occurrence and pathways

Recent studies of contaminants under the Canadian Northern Contaminants Program (NCP) have substantially enhanced our understanding of the pathways by which contaminants enter Canada’s Arctic and move through terrestrial and marine ecosystems there. Building on a previous review (Barrie et al., Arctic contaminants: sources, occurrence and pathways. Sci Total Environ 1992:1–74), we highlight new knowledge developed under the NCP on the sources, occurrence and pathways of contaminants (organochlorines, Hg, Pb and Cd, PAHs, artificial radionuclides). Starting from the global scale, we examine emission histories and sources for selected contaminants focussing especially on the organochlorines. Physical and chemical properties, transport processes in the environment (e.g. winds, currents, partitioning), and models are then used to identify, understand and illustrate the connection between the contaminant sources in industrial and agricultural regions to the south and the eventual arrival of contaminants in remote regions of the Arctic. Within the Arctic, we examine how contaminants impinge on marine and terrestrial pathways and how they are subsequently either removed to sinks or remain where they can enter the biosphere. As a way to focus this synthesis on key concerns of northern residents, a number of special topics are examined including: a mass balance for HCH and toxaphene (CHBs) in the Arctic Ocean; a comparison of PCB sources within Canada’s Arctic (Dew Line Sites) with PCBs imported through long-range transport; an evaluation of concerns posed by three priority metals — Hg, Pb and Cd; an evaluation of the risks from artificial radionuclides in the ocean; a review of what is known about new-generation pesticides that are replacing the organochlorines; and a comparison of natural vs. anthropogenic sources of PAH in the Arctic. The reseArch and syntheses provide compelling evidence for close connectivity between the global emission of contaminants from industrial and agricultural activities and the Arctic. For semi-volatile compounds that partition strongly into cold water (e.g. HCH) we have seen an inevitable loading of Arctic aquatic reservoirs. Drastic HCH emission reductions have been rapidly followed by reduced atmospheric burdens with the result that the major reservoir and transport agent has become the ocean. In the Arctic, it will take decades for the upper ocean to clear itself of HCH. For compounds that partition strongly onto particles, and for which the soil reservoir is most important (e.g. PCBs), we have seen a delay in their arrival in the Arctic and some fractionation toward more volatile compounds (e.g. lower-chlorinated PCBs). Despite banning the production of PCB in the 1970s, and despite decreases of PCBs in environmental compartments in temperate regions, the Arctic presently shows little evidence of reduced PCB loadings. We anticipate a delay in PCB reductions in the Arctic and environmental lifetimes measured in decades. Although artificial radionuclides have caused great concern due to their direct disposal on Russian Shelves, they are found to pose little threat to Canadian waters and, indeed, much of the radionuclide inventory can be explained as remnant global fallout, which was sharply curtailed in the 1960s, and waste emissions released under license by the European reprocessing plants. Although Cd poses a human dietary concern both for terrestrial and marine mammals, we find little evidence that Cd in marine systems has been impacted by human activities. There is evidence of contaminant Pb in the Arctic, but loadings appear presently to be decreasing due to source controls (e.g. removal of Pb from gasoline) in Europe and North America. Of the metals, Hg provokes the greatest concern; loadings appear to be increasing in the Arctic due to global human activities, but such loadings are not evenly distributed nor are the pathways by which they enter and move within the Arctic well understood.

Spatial and temporal trends of contaminants in Canadian Arctic freshwater and terrestrial ecosystems: a review

The state of knowledge of contaminants in Canadian Arctic biota of the freshwater and terrestrial ecosystems has advanced enormously since the publication of the first major reviews by Lockhart et al. and Thomas et al. in The Science of the Total Environment in 1992. The most significant gains are new knowledge of spatial trends of organochlorines and heavy metal contaminants in terrestrial animals, such as caribou and mink, and in waterfowl, where no information was previously available. Spatial trends in freshwater fish have been broadened, especially in the Yukon, where contaminant measurements of, for example, organochlorines were previously non-existent. A review of contaminants data for fish from the Northwest Territories, Yukon and northern Quebec showed mercury as the one contaminant which consistently exceeds guideline limits for subsistence consumption or commercial sale. Lake trout and northern pike in the Canadian Shield lakes of the Northwest Territories and northern Quebec generally had the most elevated levels. Levels of other heavy metals were generally not elevated in fish. Toxaphene was the major organochlorine contaminant in all fish analyzed. The concentrations of organochlorine contaminants in fish appear to be a function not only of trophic level but of other aspects of the lake ecosystem. Among Arctic terrestrial mammals, PCBs and cadmium were the most prominent contaminants in the species analyzed. Relatively high levels (10–60 μg g −1) of cadmium were observed in kidney and liver of caribou from the Yukon, the Northwest Territories and northern Quebec, with concentrations in western herds being higher than in those from the east. For the organochlorine contaminants, a west to east increase in ΣPCBs, HCB and ΣHCH was found in caribou, probably as a result of the predominant west to east/north-east atmospheric circulation pattern which delivers these contaminants from industrialized regions of central and eastern North America to the Arctic via long-range atmospheric transport. Radiocesium contamination of lichens and caribou has continued to decrease. Significant contamination by PCBs and lead of soils and vascular plants was observed in the immediate vicinity and within a 20-km radius of DEW line sites in the Canadian Arctic. There was also evidence for transfer of PCBs from plants to lemmings. There was no evidence, however, that large mammals such as caribou living in the general area of the DEW line sites had elevated levels of PCBs. There is very limited temporal trend information for most contaminants in biota of Arctic terrestrial and freshwater environments.

Commemorating the Cold War in Canada: Considering the DEW Line

The Cold War has yet to become an integral part of the Canadian national identity. The postwar period of nuclear tension remains largely uncommemorated in any official or practical sense, and the limitations of national commemoration policies militate against any quick designations. Canadian federal heritage properties legislation is circumscribed by a fortyyear rule, and the Historic Sites and Monuments Board of Canada

Effects of local and distant contaminant sources: polychlorinated biphenyls and other organochlorines in bottom-dwelling animals from an Arctic estuary

Elevated concentrations of organochlorines in the tissues of large marine predators in the Canadian Arctic are well documented. This paper presents some of the first data on the composition and distribution of chlorinated organic compounds in some arctic coastal animals found at lower levels of the marine food chain. Organisms include bottom-dwelling invertebrates: clams (Mya truncata), mussels (Mytilus edulis), sea urchins (Strongylocentrotus droebachiensis) and fish: sculpins (Myoxocephalus quadricornis). The majority of samples were collected in the vicinity of Cambridge Bay, Northwest Territories (NWT), Canada; however, samples were also collected near another inhabited area (Hall Beach, NWT) and at a reference site (Wellington Bay, NWT). PCBs and other organochlorines typically originate in more industrialized parts of the northern hemisphere, enter the Arctic, and are subsequently biomagnified. In this study, differences in the PCB congener compositions and concentrations, as well as the relative concentrations of a large suite of organochlorines in biota, allowed the discrimination between local and distant PCB sources. Terrestrial runoff from southern Victoria Island, NWT, has resulted in localized elevation of PCBs and chlorinated pesticides in marine sediment and bottom-dwelling animals. The major inputs of PCBs to coastal waters within Cambridge Bay were derived from local sources (the hamlet dump and DEW Line site). In addition, transport from more distant sources via riverine input accounts for locally elevated concentrations of other organochlorines in upper Cambridge Bay. This process may also account for concentrations of all measured organochlorines that are higher in Wellington Bay than in Queen Maud Gulf. The high PCB concentrations in the whole tissue (excluding liver) or livers of four-horned sculpins in Cambridge Bay (up to 220 ng/g and 1950 ng/g, respectively) and, to a lesser extent, Wellington Bay (3.8 ng/g and 47 ng/g, respectively) reflect a strong tendency for biomagnification of PCBs in coastal benthic communities.

Arctic terrestrial ecosystem contamination

Limited data have been collected on the presence of contaminants in the Arctic terrestrial ecosystem, with the exception of radioactive fallout from atmospheric weapons testing. Although southern and temperate biological systems have largely cleansed themselves of radioactive fallout deposited during the 1950s and 1960s, Arctic environments have not. Lichens accumulate radioactivity more than many other plants because of their large surface area and long life span; the presence and persistence of radioisotopes in the Arctic is of concern because of the lichen → reindeer → human ecosystem. Effective biological half-life of cesium 137 is reckoned to be substantially less than its physical half-life. The database on organochlorines in Canadian Arctic terrestrial mammals and birds is very limited, but indications are that the air/plant/animal contaminant pathway is the major route of these compounds into the terrestrial food chain. For terrestrial herbivores, the most abundant organochlorine is usually hexachlorobenzene followed by hexachlorocyclohexane isomers. PCB accumulation favours the hexachlorobiphenyl, pentachlorobiphenyl and heptachlorobiphenyl homologous series. The concentrations of the various classes of organochlorine compounds are substantially lower in terrestrial herbivore tissues than in marine mammal tissues. PCBs and DDT are the most abundant residues in peregrine falcons (a terrestrial carnivore) reaching average levels of 9.2 and 10.4 μg · g −1, respectively, more than 10 times higher than other organochlorines and higher than in marine mammals, including the polar bear. Contaminants from local sources include metals from mining activities, hydrocarbons and waste drilling fluids from oil and gas exploration and production, wastes from DEW line sites, naturally occurring radionuclides associated with uranium mineralization, and smoke containing SO 2 and H 2SO 4 aerosol from the Smoking Hills at Cape Bathurst, N.W.T.

John Thomas Crowell, Jr. (1898-1985)

Jack Crowell supported, led, and advised the work of innumerable people for many years in Greenland, northern Canada, the Arctic Ocean and Antarctica. He was a master mariner by training and he applied the discipline and skills of that calling throughout the transition of polar development from the age of sail to the jet age. ... every aspect of polar activity and development interested him, and he gave it his best support for more than forty years. ... [In 1953] Crowell joined the staff of the Northeast Air Command at Fort Pepperell in St. John's, Newfoundland, as a technical advisor in the Arctic Division. He was thus directly involved in planning and the initial site landings for DEW Line stations in Canada and HIRAN sites on the Greenland Ice Cap. He was advisor to the reactivation of T-3, Fletcher's Ice Island, in the Arctic Ocean for the International Geophysical Year, and he was subsequently advisor to the U.S. Air Force for the examination of unprepared emergency airstrips at Polaris Promontory, Hall Land, and Bronlund's Fiord, Peary Land, North Greenland. Crowell then joined the National Science Foundation as special projects officer. He was responsible for the conversion and commissioning of the Eltanin for Antarctic oceanographic research, for the planning and construction of the research vessel Hero, and for planning an Arctic Ocean drifting research barge - a concept that has not yet come to pass. Crowell made two trips for NSF on icebreakers to the Antarctic Peninsula to select a site for Palmer Station. ... An island in Frobisher Bay, Baffin Island, a harbor in Labrador, and a mountain in Antarctica are named for Crowell ....

Correlations among combustion effluent species at Barrow, Alaska: Aerosol black carbon, carbon dioxide, and methane

As part of the second Arctic Gas and Aerosol Sampling Program (AGASP II) continuous measurements of atmospheric aerosol black carbon (BC) were made at the NOAA/GMCC observatory at Barrow, Alaska (71°19′N, 156°36′W) during the period March 21–April 22, 1986. Black carbon is produced only by incomplete combustion of carbonaceous materials and so is a particularly useful atmospheric indicator of anthropogenic activities. The BC data have been analyzed together with the concurrent measurements of carbon dioxide (CO2), methane (CH4), and condensation nuclei (CN) that are routinely made at the observatory. All four species showed elevated and highly variable concentrations due to local human activities, principally in the township of Barrow, 7 km to the southwest, and at the DEW Line radar installation 1 km to the northwest. We distinguish between those periods of the record that are affected by local activities and those that are not, on the basis of the short-term (periods of up to 1 hour) variability of the continuous CO2 and CN records, with large short-term variabilities indicating local sources. We identified seven periods of time (events) with durations ranging from 13 to 37 hours when the BC, CO2, and CH4 concentrations changed smoothly over time, were highly correlated with each other, and were not influenced by local activities. These events had BC/CO2 ratios in the range (50–103)×10−6. These ratios are dimensionless since we convert the CO2 concentrations to units of ng m−3 of carbon. Such values of BC/CO2 are characteristic of the combustion effluent from large installations burning heavy fuel oil or coal, automobiles, and domestic-scale natural gas usage. We conclude that these events are indicative of air masses that have been polluted with combustion emissions in a distant location and then transported to the Arctic. In the absence of species-selective loss mechanisms, these air masses will maintain their combustion effluent signatures during the transport. The BC/CO2 ratios found for the local combustion activities are consistent with those expected from known combustion processes.