Geographic distribution of selected elements in the livers of polar bears from Greenland, Canada and the United States

To assess geographic distributions of elements in the Arctic we compared essential and non-essential elements in the livers of polar bears (Ursus maritimus) collected from five regions within Canada in 2002, in Alaska between 1994 and 1999 and from the northwest and east coasts of Greenland between 1988 and 2000. As, Hg, Pb and Se varied with age, and Co and Zn with gender, which limited spatial comparisons across all populations to Cd, which was highest in Greenland bears. Collectively, geographic relationships appeared similar to past studies with little change in concentration over time in Canada and Greenland for most elements; Hg and Se were higher in some Canadian populations in 2002 as compared to 1982 and 1984. Concentrations of most elements in the polar bears did not exceed toxicity thresholds, although Cd and Hg exceeded levels correlated with the formation of hepatic lesions in laboratory animals.     

Accelerated delivery of polychlorinated biphenyls (PCBs) in recent sediments near a large seabird colony in Arctic Canada

Polychlorinated biphenyls (PCBs) were measured in sediment cores from ponds located near a large seabird colony at Cape Vera, Devon Island, Arctic Canada. Surface sediment PCB concentrations were ∼5× greater in seabird-affected sites relative to a nearby control pond and were correlated with independent indicators of seabird activity including, sedimentary δ¹⁵N and lakewater chlorophyll a and cadmium concentrations. PCB fluxes were amongst the highest recorded from the High Arctic, ranging from 290 to 2400 ng m⁻² yr⁻¹. Despite a widespread ban of PCBs in the mid-1970s, PCB accumulation rates in our cores increased, with the highest values recorded in the most recent sediments. Possible mechanisms for the recent PCB increases include a vertical flux step driven by seabird-delivered nutrients and/or delayed loading of PCBs from the catchment into the ponds. The high PCB levels recorded in the seabird-affected sites suggest that seabird colonies are exposing coastal ecosystems to elevated levels of contaminants.     

A field survey—Staroe lake suffering from atmospheric deposition in the region north of the Arctic Circle

Background, aim, and scope  The Arctic holds large stores of minerals, and extracted materials are provided to the world’s economy; in this sense, the Arctic issue associated with mining is not local but global. In a part of the Arctic region (the Kola Peninsula, 66–70° N and 28–41° E), metal levels are generally elevated in the lake sediment. There is a question as to what results in elevated metal levels—a natural process (naturally abundant minerals) or an anthropogenic process (mining and metallurgy). In terms of solving this question, Staroe lake located on the Kola Peninsula was researched as a case study. Materials and methods  The following parameters were determined in relation with Staroe lake: (1) the current quality of the lake’s water—each 1,000-ml sample was collected at a surface point and a deep point (near the bottom layer), and the collected samples were directly analyzed after filtration; (2) atmospheric bulk deposition—bulk deposition was collected using a set of three rainwater samplers near the lake. In addition, bulk deposition was collected in a background site (250 km to the southwest of the smelter complex) as a reference; and (3) sediment profile (plus principal component analysis)—lake-bottom sediment was collected by an open-gravimetric column sampler equipped with an automatic diaphragm. After collection, the sample columns were cut at a 1-cm interval for analysis. Eigenvalues and variances by factor were calculated from the correlation coefficients. Results  The obtained data show that (1) naturally poor elements (Cu, Ni, Si, and SO₄ ²⁻) dominantly influence the lake’s water quality; (2) they are transported from the anthropogenic sources to the study lake through the atmospheric pathway; (3) mainly the contents of Cu, Ni, Sr, and Ca have influenced the sediment quality since the 1950s, corresponding to the industrial movement; and (4) Cu, Ni, and Sr originate from an anthropogenic source (smelter), and Ca originates from both natural and anthropogenic sources. Discussion  As compared with the Russian standard (San Pin 2.1.980–00), the contents of NO₃ ⁻ (50.3 ± 0.1 mg l⁻¹) and particulates (2.3 ± 0.2 mg l⁻¹) exceeded the standard levels (0.7 mg l⁻¹ NO₃ ⁻ and 45 mg l⁻¹ particulates); Staroe lake may be slightly contaminated. However, the contamination factor (comparison with the background data) implies that Staroe lake is considerably contaminated. There is a strong possibility that fine overburden detritus (<0.1 mm diameter) may be transported from an open pit to the study lake by natural forces such as wind. Although it is difficult to suppose that one factor dominantly affects the sediment quality, it follows from a factor analysis that factors 1 and 2 account for about 70% of the total variance: Factor 1 is the most dominant, and factor 2 is the second most dominant in the variability of sediment quality. It is considered that Cu, Sr, and Ni in factor 1 originate from anthropogenic sources because they are poor in sediment rocks. Conclusions  The field survey conducted in Staroe lake can give the following answers to the key objectives: (1) The present water quality is affected by Cu, Ni, Si, and SO₄ ²⁻ in light of the contamination factor, and these elements originate from anthropogenic sources (the smelter and the open pit) and are transported to the lake through the atmospheric pathway; (2) the sediment profile and statistic analysis show that the lake quality has been influenced by deposition of metals since the 1950s; and (3) Cu, Ni, Sr, and Ca have influenced the sediment quality in light of the most dominant factor—Cu, Ni, and Sr originate from an anthropogenic source, whereas Ca comes from both natural and anthropogenic sources. Recommendations and perspectives  The presented lake survey shows that the dispersion of human-related pollutants via the atmospheric pathway takes place in the Arctic region. If the current pollution continues without countermeasures, the high-latitude environment may lose its original characteristics; hence, this subject is important when considering how to implement a wide range of environmental protection measures in the Arctic.     

北极陆地生态系统的碳循环与全球温暖化

根据最新研究资料，综述并分析了全球温暖化与北极陆地生态系统碳循环的关系，指出近代全球大气ＣＯ２和ＣＨ４浓度显著增加，并呈现日益加剧的趋势；这些温室气体的浓度上升与全球温暖化密切相关，自本世纪７０年代开始，北极地区的夏季温度显著上升．通过分析北极陆地生态系统的碳循环及其基本特征，发现北极陆地生态系统是一个巨大的土壤碳库，占全球土壤碳库总量的２３７％—３２３％；虽然该系统目前起着大气ＣＯ２汇的作用，但大气ＣＯ２浓度增加导致的气温上升将对北极土壤碳库和ＣＯ２的源汇功能产生深刻影响．     

铅稳定同位素在示踪环境污染中的应用

根据Pb同位素的地球化学特点,分析了Pb同位素在示踪环境污染中的理论基础.从国内外大量研究实例出发,总结了近年来Pb同位素在示踪工业Pb污染的应用现状,肯定了Pb同位素在示踪Pb工业污染中的地位和作用.结合我国首次北极考察海洋大气气溶胶铅稳定同位素的初步研究,笔者认为研究环境系统有关对象(如大气、海水、冰雪和沉积物等)的Pb同位素组成,通过其Pb同位素混合模型计算和源区参数计算,可有效示踪Pb工业污染的来源、分布和远距离传输规律.      

Assisted species migration and hybridization to conserve cold-adapted plants under climate change

Temperature rise due to climate change is putting many arctic and alpine plants at risk of extinction because their ability to react is outpaced by the speed of climate change. We considered assisted species migration (ASM) and hybridization as methods to conserve cold-adapted species (or the genes thereof) and to minimize the potential perturbation of ecosystems due to climate change. Assisted species migration is the deliberate movement of individuals from their current location to where the species’ ecological requirements will be matched under climate projections. Hybridization refers to crossbreeding of closely related species, where for arctic and alpine plants, 1 parent is the threatened cold-adapted and the other its reproductively compatible, warm-adapted sibling. Traditionally, hybridization is viewed as negative and leading to a loss of biodiversity, even though hybridization has increased biodiversity over geological times. Furthermore, the incorporation of warm-adapted genes into a hybrid may be the only means for the persistence of increasingly more maladapted, cold-adapted species. If approached with thorough consideration of fitness-related parameters of the source population and acknowledgement of the important role hybridization has played in shaping current biodiversity, ASM and hybridization could help save partial or whole genomes of key cold-adapted species at risk due to climate change with minimal negative effects on ecosystem functioning.     

Net Carbon Exchange Across the Arctic Tundra-Boreal Forest Transition in Alaska 1981–2000

Shifts in the carbon balance of high-latitude ecosystems could result from differential responses of vegetation and soil processes to changing moisture and temperature regimes and to a lengthening of the growing season. Although shrub expansion and northward movement of treeline should increase carbon inputs, the effects of these vegetation changes on net carbon exchange have not been evaluated. We selected low shrub, tall shrub, and forest tundra sites near treeline in northwestern Alaska, representing the major structural transitions expected in response to warming. In these sites, we measured aboveground net primary production (ANPP) and vegetation and soil carbon and nitrogen pools, and used these data to parameterize the Terrestrial Ecosystem Model. We simulated the response of carbon balance components to air temperature and precipitation trends during 1981–2000. In areas experiencing warmer and dryer conditions, Net Primary Production (NPP) decreased and heterotrophic respiration (R _H ) increased, leading to a decrease in Net Ecosystem Production (NEP). In warmer and wetter conditions NPP increased, but the response was exceeded by an increase in R _H ; therefore, NEP also decreased. Lastly, in colder and wetter regions, the increase in NPP exceeded a small decline in R _H , leading to an increase in NEP. The net effect for the region was a slight gain in ecosystem carbon storage over the 20 year period. This research highlights the potential importance of spatial variability in ecosystem responses to climate change in assessing the response of carbon storage in northern Alaska over the last two decades.     

Effects of food availability on dispersal and cub sex ratio in the Mednyi Arctic fox

Since the Pleistocene, Arctic foxes, Alopex lagopus, on Mednyi Island in the North Pacific have been isolated in a small area with rich food resources and no other terrestrial carnivores. This situation provides an unusually simple system within which the effect of food dispersion on demography and social organisation was examined. We studied the composition, location and dispersal of 67 Arctic fox groups and mapped their major food resources (seabird colonies) during 1994–2000 on Mednyi. We compared our observations with the predictions of models of sex-ratio determination. Our observations are most consistent with the predictions of Julliard's (2000) model, where mothers are expected to produce more offspring of the most dispersing sex in low-quality habitats, and more offspring of the most philopatric sex in high-quality habitats. The polygynous foxes on Mednyi Island lived where the principal food resources were patchily distributed (present on 11% of the shoreline), and cub survival to dispersal age or reproductive adult was higher in rich (25/45) than in poor (24/79) home ranges. Furthermore, dispersal was strongly sex-biased: most females (60%) remained on their natal ranges, whereas very few males (9%) did so. Significantly more female than male cubs (54 compared with 24) emerged from dens in resource rich ranges, whereas the sex ratio on poor ranges was approximately equal (51 females and 56 males). While our observations are also to some extent consistent with the local resource enhancement (LRE) hypothesis (which predicts a bias towards the sex most likely to cooperate with parents), this does not account for the observed spatial variability.     

Effects of ovarian fluid on sperm velocity in Arctic charr (Salvelinus alpinus)

Numbers of studies in externally fertilizing fish species provide evidence for an effect of ovarian fluid on sperm motility characteristics such as duration of forward mobility, velocity or percent motile sperm cells. Yet, because of variations among females in the quality of their ovarian fluid, such effects might differ between individuals. Additionally, ovarian fluid from different females could also be expected to affect each ejaculate differently, resulting in cryptic female choice. In this study on Artic charr (Salvelnius alpinus), sperm velocity from several males was measured in the diluted ovarian fluid of several females according to a fully balanced crossing design. This design allowed us to estimate variations among females in the effect of their ovarian fluid on the velocity of sperm from different males, and to detect variations among males in the ability of their sperm to swim in ovarian fluid. Sperm velocity was estimated by computer-assisted sperm analysis. Average velocity was found to vary among females, with some females having constantly higher velocity measurements in their ovarian fluid, and among males, indicating that some males had overall faster sperm in ovarian fluid than others. Moreover, variation in sperm velocity was shown to depend on individual female-male interactions. Our results document that females vary in the effect of their ovarian fluid on sperm velocity and that their ovarian fluid may stimulate sperm velocity according to individual characteristics of males. This latter result suggests a potential mechanism for cryptic female choice.

Tourism in the high north: Management challenges and recreation opportunity spectrum planning in Svalbard,Norway

The Arctic is subject to considerable pressure from a rapidly expanding world tourism industry and increasing demands for oil and gas resources. The archipelago of Svalbard in the Norwegian high arctic contains the most accessible islands in the entire Arctic, but despite extensive use of the resources, they still contain some of the last true wilderness lands in Europe. The growth in tourism with visitors from all parts of the world combined with coal mining and oil and gas exploration call for a coordinated environmental policy. A research-based management plan for tourism and recreation has now been developed. Some management problems were encountered in designing a recreation opportunity spectrum plan for this extremely vulnerable environment. Although Svalbard in many ways is a unique area, the challenges to management are comparable to those found in regions further south.