Ice Off Research Articles

Analysis of fast ice anomalies and their causes in 2023 in Prydz Bay, East Antarctica

In 2023, Antarctica experienced its lowest sea ice extent in the satellite era, with extreme polar events gaining widespread attention. Prydz Bay, where the Chinese Zhongshan Station is located, is the third largest embayment in Antarctica. Changes in sea ice, fast ice and polynyas directly affect local heat and mass exchanges between the ocean and atmosphere, as well as ecosystems and research activities. In 2023, substantial fast ice anomalies were observed in Prydz Bay: the extent of fast ice off Zhongshan Station (ZSFI) was anomalously low, while that within Barrier Bay (BaFI) was anomalously high. This study analysed the seasonal evolution and underlying main causes for the extreme conditions using ice charts, satellites and reanalysis data. From 2014 to 2022, the extent of ZSFI typically increased during the cold season, reaching a maximum of (9.41 ± 2.47) × 103 km2, whilst the Barrier Bay Polynya (BaP) persisted throughout this period. However, in 2023, ZSFI did not increase from June onwards, peaking at a maximum extent of only 5.49 × 103 km2, and the BaP closed in mid-winter, leading to the formation of extensive BaFI. Air temperature and wind speed continuously dropped in July, and these conditions persisted for approximately 1 month, leading to the closure of BaP. However, ZSFI did not expand further under these extreme meteorological conditions, indicating its independence from these factors. The limited expansion of ZSFI could be attributed to high ocean temperatures. Overall, this study provides valuable insights into the mechanisms driving extreme fast ice conditions.

Mark–recapture surveys affect nest site fidelity but not reproductive timing of male Smallmouth Bass

AbstractObjectiveFish population surveys in north‐temperate lakes are often conducted in the fall or spring when individuals are easy to capture with traditional fisheries techniques. Because some fishes are preparing to spawn or are spawning during these seasons, there is a critical need to better understand the potential influences of these surveys on decisions that are related to fish reproduction.MethodsWe tested whether spring mark–recapture surveys using fyke nets followed by electrofishing affect the reproductive behaviors of male Smallmouth Bass Micropterus dolomieu in a northern Wisconsin lake. Fyke netting, electrofishing, and whole‐lake nest snorkeling surveys were conducted during 2001–2008, and Floy‐tagged males were tracked across years to test whether capture in the fyke nets only or capture in the electrofishing survey influenced interyear nest site fidelity and reproductive timing.ResultThe mark–recapture surveys were conducted preceding the spawning of Smallmouth Bass, and returning males that were caught in the electrofishing survey nested ~50 m farther from their prior year's nest than both males that were captured only in fyke nets and males that were captured by neither method. Average interyear nest distances were ~200 m, and median interyear nest distances were ~90 m for males that were not captured in the electrofishing survey. Electrofishing and fyke netting did not influence the timing of reproduction.ConclusionSpring electrofishing surveys for Smallmouth Bass have the potential to displace breeding males from preferred nesting habitats. If displacement negatively influences fitness (i.e., age‐0 survivorship to maturation), spring electrofishing surveys would not be recommended for assessing Smallmouth Bass populations. However, spring population surveys often occur soon after ice off, and surveys that are conducted at these colder temperatures are typically less stressful and less likely to result in mortality. Future research should test for fitness implications of reduced nest site fidelity following electrofishing in Smallmouth Bass while considering potential fitness trade‐offs if surveys are moved later in the year.

Seasonal evolution of granular and columnar sea ice pore microstructure and pore network connectivity

Abstract Sea-ice pore microstructure constrains ice transport properties, affecting fluid flow relevant to oil-in-ice transport and biogeochemical processes. Motivated by a lack of pore microstructural data, in particular for granular ice and across the seasonal cycle, throat size, tortuosity, connectivity, and other microstructural variables were derived from X-ray computed tomography for brine-filled pores in seasonal landfast ice off northern Alaska. Data were obtained for granular and columnar ice during the ice growth, transition, and melt season. While granular ice exhibits a more heterogeneous pore space than columnar ice, pore and throat size distributions are comparable. The greater tortuosity of pores in granular (1.2 < τg < 1.7) compared to columnar ice (1.0 < τc < 1.1) compounded with a less interconnected pore space translates into lower permeability for granular ice during the growth season for a given porosity. The microstructural data explain findings of granular ice hindering vertical oil-in-ice transport during ice growth and transition stage. With granular ice more frequent in the changing Arctic, data from studies such as this are needed to inform improved modeling of porosity-permeability relationships.

Nutrients influence seasonal metabolic patterns and total productivity of Arctic streams

AbstractThe seasonality of gross primary production (GPP) in streams is driven by multiple physical and chemical factors, yet incident light is often thought to be most important. In Arctic tundra streams, however, light is available in saturating amounts throughout the summer, but sharp declines in nutrient supply during the terrestrial growing season may constrain aquatic productivity. Given the opposing seasonality of these drivers, we hypothesized that “shoulder seasons”—spring and autumn—represent critical time windows when light and nutrients align to optimize rates of stream productivity in the Arctic. To test this, we measured annual patterns of GPP and biofilm accumulation in eight streams in Arctic Sweden. We found that the aquatic growing season length differed by 4 months across streams and was determined largely by the timing of ice‐off in spring. During the growing season, temporal variability in GPP for nitrogen (N) poor streams was correlated with inorganic N concentration, while in more N‐rich streams GPP was instead linked to changes in phosphorus and light. Annual GPP varied ninefold among streams and was enhanced by N availability, the length of ice‐free period, and low flood frequency. Finally, network scale estimates of GPP highlight the overall significance of the shoulder seasons, which accounted for 48% of annual productivity. We suggest that the timing of ice off and nutrient supply from land interact to regulate the annual metabolic regimes of nutrient poor, Arctic streams, leading to unexpected peaks in productivity that are offset from the terrestrial growing season.

Seasonal use of two unregulated Lake Superior tributaries by lake sturgeon

Lake sturgeon movement in two adjacent unregulated Lake Superior tributaries, the Pic and White rivers, was assessed over several years to determine seasonal use, identify potential contributing factors for entry or exit migrations, and evaluate whether sturgeon using these tributaries constituted one or two populations. A total of 95 lake sturgeon implanted with radio transmitters were tracked using multiple stationary receivers augmented with boat-based manual surveillance during peak movement times. Both rivers were used by lake sturgeon during the open water (“ice off”) season. In general, spawning sturgeon moved to the first insuperable barrier (i.e., natural rapids) during the spawning season, and then moved downstream to deeper pools in mid- to late summer. Non-spawning sturgeon moved into the river concurrently but remained in lower portions of the river. Lake sturgeon emigrated from the Pic River and resided in Lake Superior during the winter season whereas a small portion of radio transmittered sturgeon, originally sampled in the Pic River, overwintered in the White River. River discharge and the interaction between discharge and water temperature were correlated with upstream movement, and river discharge was also correlated with outmigration. No genetic structuring was apparent between Sturgeon within the two rivers, consistent with telemetry data showing radio-tagged fish moving readily between the rivers. This study provided pertinent seasonal use information of unregulated Great Lake tributaries and may contribute to planning processes for future hydroelectric developments to minimize disruptions to lake Sturgeon populations.

Thermodynamics of Fast Ice off the Northeast Coast of Greenland (79°N) Over a Full Year (2012–2013)

AbstractNorske Øer Ice Barrier (NØIB) is a vast region of fast ice off northeast Greenland. To understand its thermodynamics, an ice mass balance buoy (IMB) was deployed in late August 2012. The IMB operated for a full year, providing unique year‐round observations of air, snow, ice, and upper ocean. Here, we examine atmospheric conditions and snow and sea ice evolution, derive the ocean heat flux at the deployment site, and investigate the effect of snow on the sea ice mass balance. Although an extremely low surface air temperature of −52°C was recorded at the IMB site, the sum of freezing‐degree days (4,848 K·d) is similar to that in the central Arctic. The maximum snow depth 0.73 m (on 29 May 2013, when ice was 2.19 m thick) is thicker than typically observed on level Arctic landfast ice and drift ice, and thick snow appears common in this region. Ocean heat flux was large in autumn and early winter (>7 W m−2), attributed in part to local solar heating of surface waters in summer and advected ocean heat later in the year. The combination of high ocean heat flux and thick snow resulted in a net loss of ice at the ice bottom over the year. A one‐dimensional sea ice model suggests that the thick snow cover limits bottom ice growth significantly. The heavy snow load could potentially have contributed 0.29 m snow ice; however, we cannot unambiguously prove this happened.

Multimodel simulation of vertical gas transfer in a temperate lake

Abstract. In recent decades, several lake models of varying complexity have been developed and incorporated into numerical weather prediction systems and climate models. To foster enhanced forecasting ability and verification, improvement of these lake models remains essential. This especially applies to the limited simulation capabilities of biogeochemical processes in lakes and greenhouse gas exchanges with the atmosphere. Here we present multi-model simulations of physical variables and dissolved gas dynamics in a temperate lake (Harp Lake, Canada). The five models (ALBM, FLake, LAKE, LAKEoneD, MTCR-1) considered within this most recent round of the Lake Model Intercomparison Project (LakeMIP) all captured the seasonal temperature variability well. In contrast, none of the models is able to reproduce the exact dates of ice cover and ice off, leading to considerable errors in the simulation of eddy diffusivity around those dates. We then conducted an additional modeling experiment with a diffusing passive tracer to isolate the effect of the eddy diffusivity on gas concentration. Remarkably, sophisticated k−ε models do not demonstrate a significant difference in the vertical diffusion of a passive tracer compared to models with much simpler turbulence closures. All the models simulate less intensive spring overturn compared to autumn. Reduced mixing in the models consequently leads to the accumulation of the passive tracer distribution in the water column. The lake models with a comprehensive biogeochemical module, such as the ALBM and LAKE, predict dissolved oxygen dynamics adequate to the observed data. However, for the surface carbon dioxide concentration the correlation between modeled (ALBM, LAKE) and observed data is weak (∼0.3). Overall our results indicate the need to improve the representation of physical and biogeochemical processes in lake models, thereby contributing to enhanced weather prediction and climate projection capabilities.

Toward a Consistent Definition between Satellite and Model Clear-Sky Radiative Fluxes

AbstractA new method of determining clear-sky radiative fluxes from satellite observations for climate model evaluation is presented. The method consists of applying adjustment factors to existing satellite clear-sky broadband radiative fluxes that make the observed and simulated clear-sky flux definitions more consistent. The adjustment factors are determined from the difference between observation-based radiative transfer model calculations of monthly mean clear-sky fluxes obtained by ignoring clouds in the atmospheric column and by weighting hourly mean clear-sky fluxes with imager-based clear-area fractions. The global mean longwave (LW) adjustment factor is −2.2 W m−2at the top of the atmosphere and 2.7 W m−2at the surface. The LW adjustment factors are pronounced at high latitudes during winter and in regions with high upper-tropospheric humidity and cirrus cloud cover, such as over the west tropical Pacific, and the South Pacific and intertropical convergence zones. In the shortwave (SW), global mean adjustment is 0.5 W m−2at TOA and −1.9 W m−2at the surface. It is most pronounced over sea ice off of Antarctica and over heavy aerosol regions, such as eastern China. However, interannual variations in the regional SW and LW adjustment factors are small compared to those in cloud radiative effect. After applying the LW adjustment factors, differences in zonal mean cloud radiative effect between observations and climate models decrease markedly between 60°S and 60°N and poleward of 65°N. The largest regional improvements occur over the west tropical Pacific and Indian Oceans. In contrast, the impact of the SW adjustment factors is much smaller.

Hybrid-electric system truth test: Energy analysis of Toyota Prius IV in real urban drive conditions

The experimental work, carried out through road tests in the city of Rome (Italy), assesses the energy performance of the Toyota Prius IV generation with Full Hybrid traction system under real conditions of use in the urban environment.The evaluation was carried out through a data collection campaign on a 37 km urban route, in both fast-flowing sections and traffic-congested areas of Rome. On this route, 60 driving tests were carried out by individual with different characteristics in terms of gender, age and hybrid technology driving experience.In particular, the analysis involved the operation as ZEV (Zero Emission Vehicle) vehicle, the hybrid system Power flows, fuel consumption and yields.The most relevant results relate to the high percentage (in time and space) of operation in ZEV mode: this mode is achieved both in “electric” operation, that is, with power output to the wheels by the electric motor only (with the ICE off), and in the inertial operation, i.e. without power output to the wheels (always with ICE off).Another important result concerns the high overall efficiency of the hybrid traction system, obtained thanks to the high average yield of the ICE, and especially through the very high deceleration energy recovery. The recovered energy provides a very significant contribution to the total energy needed by the wheels for the car movement purposes and, in particular, provides the vast majority of electricity required by the electric motor.

Arctic fox dispersal from Svalbard to Canada: one female’s long run across sea ice

We report the first satellite tracking of natal dispersal by an Arctic fox (Vulpes lagopus) between continents and High-Arctic ecosystems. A young female left Spitsbergen (Svalbard Archipelago, Norway) on 26 March 2018 and reached Ellesmere Island, Nunavut, Canada, 76 days later, after travelling a cumulative distance of 3506 km, bringing her ca. 1789 km away (straight-line distance) from her natal area. The total cumulative distance travelled during the entire tracking period, starting when she left her natal area on 1 March 2018 and ending when she settled on Ellesmere Island on 1 July 2018, was 4415 km. This is among the longest dispersal events ever recorded for an Arctic fox. Crossing extensive stretches of sea ice and glaciers, the female moved at an average rate of 46.3 km/day ± 41.1 SD. The maximum movement rate was 155 km/day and occurred on the ice sheet in northern Greenland. This is the fastest movement rate recorded for this species. The northernmost location recorded was on the sea ice off northern Greenland at a latitude of 84.7°N. The Arctic fox was of the blue colour morph typical for coastal environments, where Arctic foxes are adapted to food webs without lemmings but with substantial inputs of marine food resources. The Arctic fox settled on Ellesmere Island in a food web with lemmings, thereby switching ecosystems. Our observation supports evidence of gene flow across Arctic regions, including those seasonally bridged by sea ice, found in studies of the circumpolar genetic structure of Arctic fox populations. View the supplementary animation. This article has a related Erratum.

Airborne and underwater acoustic repertoire of hooded seals (Cystophora cristata): Cornerstone for acoustic monitoring

The hooded seal is a migratory species inhabiting the North Atlantic. They whelp and breed during mid- to late March on pack ice near Jan Mayen Island, in the Davis Strait, off the northeastern Newfoundland coast, and in the Gulf of St. Lawrence. After breeding, hooded seals return to the pack ice off eastern Greenland to moult during June and July, and then they disperse broadly for summer and fall before returning to their respective breeding areas. Passive acoustic monitoring conducted over spatial scales consistent with known and potential habitat of the hooded seal could add insight into seasonal, diel, and spatial occurrence patterns of this species. To better characterize its acoustic repertoire (notably underwater calls), airborne and underwater acoustic signals of hooded seals were recorded during their breeding season on the pack ice in the Gulf of St. Lawrence from 12 to 17 March 2018. Hood and septum noises were the predominant sounds heard from males on the ice surface. Hooded seal underwater acoustic repertoire is larger and more diverse than has been previously described. Using the dataset from an extended acoustic monitoring program along Canada’s East Coast, some clues are provided about the seasonal distribution of hooded seals.

Spatial and Temporal Variation in Methane Concentrations, Fluxes, and Sources in Lakes in Arctic Alaska

AbstractClimate warming may lead to a positive feedback of increased emissions of CH4 from sediments beneath Arctic lakes, but the contribution of these lakes to the global CH4 budget is poorly quantified. Here we present results of a study of CH4 concentrations and sources from a series of 50 lakes in Arctic Alaska across an 80,000 km2 spatial gradient and a 2 year time period. We measured dissolved CH4 concentrations and stable isotopes of CH4 in lakes in the North Slope of Alaska in August 2014 and 2015 and April 2015 (under ice). Stable isotopes indicated that biogenic CH4 dominated versus thermogenic sources, with both acetate fermentation and carbonate reduction sources. Dissolved CH4 was about 100 times higher under the ice than during the summer, indicating that the spring ice off period is a large source of atmospheric CH4. Open‐water dissolved CH4 concentrations had a negative relationship with latitude in both years of our study, although CH4 fluxes were consistent among a subset of lakes measured along a ~150 km north to south transect in both years (14 lakes in 2014 and 12 in 2015). Dissolved CH4 concentrations and fluxes were significantly higher in August 2015 versus August 2014, concurrent with a 3°C higher mean water temperature in 2015 versus 2014. Much longer‐term monitoring is needed, however, to conclude that CH4 emissions from Arctic lakes mirror observed warming trends. This study provides valuable baseline data and can inform methods for future studies investigating carbon cycle‐climate change feedbacks in Alaskan Arctic lakes.

Lake ice and temperature trends for Ontario and Manitoba: 2001 to 2014

AbstractLakes are a prominent geographic feature in northern landscapes and play an important role in understanding regional climate systems. In order to better model changes within climate systems, it is important to study lake ice processes. Although the availability of records for lake ice through ground measurements has declined in recent years, the increased use of remote sensing provides an alternative to this. Using a preclassified snow and ice remote sensing product with a 500‐m resolution, based on images from the Moderate Resolution Imaging Spectroradiometer (MODIS/MOD10A1), and the use of measured and reanalysis temperature data, this study evaluated lake ice phenology dates in connection to recent trends in temperature and 0 °C isotherms within Ontario and Manitoba between 2001 and 2014. Temperature trends indicated both regional warming and cooling, with significant cooling observed in Southern Ontario (p < .05) and significant warming in Southern Manitoba (p < .1) during the fall. Spatial analysis of the trends in the lake ice data showed significant clustering of significant trends in ice on dates (p < .01). When analysing the trends in ice phenology in connection to the trends in temperature, it was found that 70% of lakes experienced a change in the ice on date with the expected change in temperature and 85% of lakes for ice off date. When shifting ice on and ice off dates are investigated in relation to 0 °C isotherms, it was seen that 80% of ice on dates and 100% of ice off dates shifted in sync with the isotherm dates. This demonstrates that the ice phenology of lakes in Ontario and Manitoba, Canada, is responding to short‐term variability in temperature. The MODIS product could be used to investigate ice phenology on a large scale and contribute towards expanding existing records of ice phenology. Establishing long‐term ice records could be a valuable asset for other research ranging from water balance studies to the response of lake biota under changing climate.

The variability of surface radiation fluxes over landfast sea ice near Zhongshan station, east Antarctica during austral spring

ABSTRACTSurface radiative fluxes over landfast sea ice off Zhongshan station have been measured in austral spring for five springs between 2010 and 2015. Downward and upward solar radiation vary diurnally with maximum amplitudes of 473 and 290 W m−2, respectively. The maximum and minimum long-wave radiation values of the mean diurnal cycle are 218 and 210 W m−2 for downward radiation, 277 and 259 W m−2 for upward radiation and 125 and −52 W m−2 for net radiation. The albedo has a U-shaped mean diurnal cycle with a minimum of 0.64 at noon. Sea ice thickness is in the growth phase for most spring days, but can be disturbed by synoptic processes. The surface temperature largely determines the occurrence of ice melting. Surface downward and upward long-wave radiation show synoptic oscillations with a 5–8 day period and intraseasonal variability with a 12–45 day period. The amplitudes of the diurnal, synoptic and intraseasonal variability show some differences during the five austral springs considered here. The intraseasonal and synoptic variability of downward and upward long-wave radiation are associated with the variability of cloud cover and surface temperature induced by the atmospheric circulation.

On the extraordinary snow on the sea ice off East Antarctica in late winter, 2012

In late winter-early spring 2012, the second Sea Ice Physics and Ecosystems Experiment (SIPEX II) was conducted off Wilkes Land, East Antarctica, onboard R/V Aurora Australis. The sea-ice conditions were characterized by significantly thick first-year ice and snow, trapping the ship for about 10 days in the near coastal region. The deep snow cover was particularly remarkable, in that its average value of 0.45m was almost three times that observed between 1992 and 2007 in the region. To reveal factors responsible, we used in situ observations and ERA-Interim reanalysis (1990–2012) to examine the relative contribution of the different components of the local-regional snow mass balance equation i.e., snow accumulation on sea ice, precipitation minus evaporation (P–E), and loss by (i) snow-ice formation and (ii) entering into leads due to drifting snow. Results show no evidence for significantly high P–E in the winter of 2012. Ice core analysis has shown that although the snow-ice layer was relatively thin, indicating less transformation from snow to snow-ice in 2012 as compared to measurements from 2007, the difference was not enough to explain the extraordinarily deep snow. Based on these results, we deduce that lower loss of snow into leads was probably responsible for the extraordinary snow in 2012. Statistical analysis and satellite images suggest that the reduction in loss of snow into leads is attributed to rough ice surface associated with active deformation processes and larger floe size due to sea-ice expansion. This highlights the importance of snow-sea ice interaction in determining the mean snow depth on Antarctic sea ice.

Recruitment of sympatric vendace (Coregonus albula) and whitefish (C. lavaretus) is affected by different environmental factors

AbstractVendace and whitefish in Lake Osensjøen (boreal south‐east Norway) were studied by means of gillnet test fishing (1976–2013) and hydro acoustic acquisition (1986–2011). Vendace increased in number between 1998 and 2009 while growth and size at maturity decreased. The relative density of whitefish decreased in the pelagic habitat, whereas growth and size remained the same. Both species exhibited varying year‐class strength. Whereas strong year‐classes of both species became less frequent after 1980 than before this, this seemed to change after 2000, especially for vendace. Generalised additive models suggested a strong positive relationship between July/August mean air temperature and year‐class strength of both vendace and whitefish. Whitefish recruitment was also negatively affected by the new regulation regime implemented since 1981, and positively correlated with water level after hatching and by late ice off. The reason for the diverging impacts of environmental factors on the two species may be that vendace spawn in deeper waters that whitefish do. The results indicate that increasing summer temperatures benefit recruitment of both species, whereas low water level and early ice off will harm whitefish recruitment. Both trends are caused by climate warming. It may be speculated that increased density of the specialised plankton feeding vendace may affect the algal community through increased predation on herbivorous zooplankton and potentially affect the trophic state of the lake.

Dissolved iron and iron(II) distributions beneath the pack ice in the East Antarctic (120°E) during the winter/spring transition

Distributions of dissolved iron (dFe) and its reduced form, Fe(II), to a depth of 1000m were investigated under the seasonal pack ice off East Antarctica during the Sea Ice Physics and Ecosystem experiment (SIPEX-2) sea-ice voyage in September–October 2012. Concentrations of dFe were elevated up to five-fold relative to Southern Ocean background concentrations and were spatially variable. The mean dFe concentration was 0.44±0.4nM, with a range from 0.09 to 3.05nM. Profiles of dFe were more variable within and among stations than were macronutrients, suggesting that coupling between these biologically-essential elements was weak at the time of the study. Brine rejection and drainage from sea ice are estimated to be the dominant contributors to elevated dFe concentrations in the mixed layer, but mass budget considerations indicate that estimated dFe fluxes from brine input alone are insufficient to account for all observed dFe. Melting icebergs and shelf sediments are suspected to provide the additional dFe. Fe(II) was mostly below the detection limit but elevated at depth near the continental shelf, implying that benthic processes are a source of reduced Fe in bottom waters. The data indicate that dFe builds up under the seasonal sea-ice cover during winter and that reduction of Fe may be hampered in early spring by several factors such as lack of electron donors, low biological productivity and inadequate light below the sea ice. The accumulated dFe pool in the mixed layer is expected to contribute to the formation of the spring bloom as the ice retreats.

Late winter under ice pelagic microbial communities in the high Arctic Ocean and the impact of short-term exposure to elevated CO2 levels.

Polar Oceans are natural CO2 sinks because of the enhanced solubility of CO2 in cold water. The Arctic Ocean is at additional risk of accelerated ocean acidification (OA) because of freshwater inputs from sea ice and rivers, which influence the carbonate system. Winter conditions in the Arctic are of interest because of both cold temperatures and limited CO2 venting to the atmosphere when sea ice is present. Earlier OA experiments on Arctic microbial communities conducted in the absence of ice cover, hinted at shifts in taxa dominance and diversity under lowered pH. The Catlin Arctic Survey provided an opportunity to conduct in situ, under-ice, OA experiments during late Arctic winter. Seawater was collected from under the sea ice off Ellef Ringnes Island, and communities were exposed to three CO2 levels for 6 days. Phylogenetic diversity was greater in the attached fraction compared to the free-living fraction in situ, in the controls and in the treatments. The dominant taxa in all cases were Gammaproteobacteria but acidification had little effect compared to the effects of containment. Phylogenetic net relatedness indices suggested that acidification may have decreased the diversity within some bacterial orders, but overall there was no clear trend. Within the experimental communities, alkalinity best explained the variance among samples and replicates, suggesting subtle changes in the carbonate system need to be considered in such experiments. We conclude that under ice communities have the capacity to respond either by selection or phenotypic plasticity to heightened CO2 levels over the short term.

Research on Ice-Broken Effect of Granulated Rubber Asphalt Mixture High-Elastic Deck Pavement on Bridge

They are researched about the influence of ice-broken performance of granulated crumb rubber amount of admixture, thickness of pavement layer, thickness of ice layer and temperature to granulated crumb rubber asphalt mixture by the method of laboratory simulation test. From the research it is indicated that the closer the granulated crumb rubber approach to upper surface of mixture, the larger the amount of admixture is, the more thickness the surface of granulated crumb rubber asphalt mixture is, the better effect of wiping ice off will be. With the reduction of temperature and increase of ice layer thickness, the effect of wiping ice off through granulated crumb rubber asphalt mixture will weaken gradually.

Scurvy as a factor in the loss of the 1845 Franklin expedition to the Arctic: a reconsideration

In 1845, an expedition, commanded by Sir John Franklin, set out to discover the Northwest Passage. The ships entered the Canadian Arctic, and from September 1846 were beset in ice off King William Island. A note left by the expedition in May 1847 reported all was well, but by April 1848, 24 of the 129 men had died. The ice-locked ships were deserted in April 1848, but the 105 survivors were so weakened that all perished before they could reach safety. The causes of the morbidity and mortality aboard the ships have long been debated, and many commentators have argued that scurvy was an important factor. This study evaluates the historical evidence for the likely effectiveness of anti-scorbutic precautions taken on polar voyages at that time, and investigates whether the skeletal remains associated with the expedition provide evidence for scurvy. Skeletal remains available for study were carefully examined for pathological changes, and lesions potentially consistent with scurvy were subject to histological analysis. Where remains were no longer accessible, use was made of published osteological work. It is argued that the anti-scorbutic measures customarily taken on mid 19th century British naval polar voyages were such that there is no a priori reason to suppose that scurvy should have been a problem prior to the desertion of the ships. The analysis of the skeletal evidence provided little in the way of bony lesions consistent with the disease, and cannot therefore be used to support the presence of scurvy. Factors other than scurvy may been the main causes of morbidity and mortality in the 11 months prior to the desertion of the ships. Copyright © 2012 John Wiley & Sons, Ltd.