Living in an oasis: Rapid transformations,resilience, and resistance in the North Water Area societies and ecosystems

Based on lake sediment data, archaeological findings, and historical records, we describe rapid transformations, resilience and resistance in societies and ecosystems, and their interactions in the past in the North Water area related to changes in climate and historical events. Examples are the formation of the polynya itself and the early arrival of people, ca. 4500 years ago, and later major human immigrations (different societies, cultural encounters, or abandonment) from other regions in the Arctic. While the early immigrations had relatively modest and localised effect on the ecosystem, the later-incoming culture in the early thirteenth century was marked by extensive migrations into and out of the area and abrupt shifts in hunting technologies. This has had long-lasting consequences for the local lake ecosystems. Large natural transformations in the ecosystems have also occurred over relatively short time periods related to changes in the polynya. Finally, we discuss the future perspectives for the North Water area given the many threats, but also opportunities.     

On airborne nano/micro-sized wear particles released from low-metallic automotive brakes

The paper addresses the wear particles released from commercially available “low-metallic” automotive brake pads subjected to brake dynamometer tests. Particle size distribution was measured in situ and the generated particles were collected. The collected fractions and the original bulk material were analyzed using several chemical and microscopic techniques. The experiments demonstrated that airborne wear particles with sizes between 10 nm and 20 μm were released into the air. The numbers of nanoparticles (<100 nm) were by three orders of magnitude larger when compared to the microparticles. A significant release of nanoparticles was measured when the average temperature of the rotor reached 300 °C, the combustion initiation temperature of organics present in brakes. In contrast to particle size distribution data, the microscopic analysis revealed the presence of nanoparticles, mostly in the form of agglomerates, in all captured fractions. The majority of elements present in the bulk material were also detected in the ultra-fine fraction of the wear particles.     

Diatoms as indicators in the Environmental Monitoring and Assessment Program-Surface Waters (EMAP-SW)

As a part of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program-Surface Waters (EMAP-SW), sedimentary diatom assemblages were studied from 66 lakes in the northeastern U.S.A. to evaluate the applicability of diatoms for this nation-wide monitoring program. Sediment cores were collected from the study lakes and diatoms were analyzed from the top (present-day) and bottom (pre-industrial) sediment samples. Canonical correspondence analysis (CCA) was used to examine which environmental variables correlate most closely with the distributions of diatom taxa in the top (surface) samples. Forward selection and Monte Carlo permutation tests showed that diatom species distributions were significantly related to total lakewater phosphorus (TP), pH, chloride, Secchi depth, and lake size and maximum depth. We developed weighted-averaging calibration and regression models for inferring TP (r ²=0.62), chloride (r ²=0.61), pH (r ²=0.86), and Secchi depth (r ²=0.62). An index of overall lake disturbance was also developed. Our diatom data indicate that marked changes have occurred in the study lakes since pre-industrial times as a result of anthropogenic activity.     

Shipboard Measurements of Nitrogen Dioxide,Nitrous Acid,Nitric Acid and Ozone in the Eastern Mediterranean Sea

Measurements of nitrogen dioxide, nitrous and nitric acids as well as ozone were made using newly developed instrumentation onboard the research vessel Aegeon in the Aegean Sea between 25th–29th July 2000. Typical nitrogen dioxide concentrations observed aboard the boat were 4–6 ppb (v/v) with a broad maximum of 20–30 ppb (v/v). Ozone concentrations typically ranged between 40 and 80 ppb (v/v). Mixing ratios of both nitric and nitrous acids in the ambient air of the Aegean Sea were mainly below 50 ppt (v/v). The data also showed a number of short pollution episodes with rapid changes in the concentration of reactive nitrogen compounds [nitrogen dioxide maximum up to 164 ppb (v/v), nitric acid maximum up to 12 ppb (v/v), nitrous acid maximum up to 2.7 ppb (v/v)] and ozone [maximum up to 88 ppb (v/v)]. These episodes were correlated with pollution plumes originating from boats upwind, at short distance, from the R/V Aegeon. The measurements revealed the importance of nitrous and nitric acids for the transport of nitrogen to marine biota in busy ship lanes.     

Forest fires caused by lightning as an indicator of connections between atmosphere,lithosphere, and biosphere

A significant positive correlation between the density of lightning fires and the horizontal gradient of anomalous geomagnetic field is demonstrated on the basis of studies on lichen pine forests in the Konda River basin (Khanty-Mansi Autonomous Area, Western Siberia) and analysis of published data. Schematic hypotheses of global connections in the atmosphere-lithosphere-forest-lightning fire are proposed.     

Influence of temperature on the reproductive potential of Oncholaimus oxyuris (Nematoda: Oncholaimidae)

The large nematode Oncholaimus oxyuris Ditlevsen, 1911 is a dominant predator in a shallow polyhaline brackish-water pond in Belgium. The reproductive potential of this species was calculated as the intrinsic rate of natural increase r=1/D In pN _e , in which D is the generation time, p is the percentage of females, and N _e is the number of eggs per female. The generation time varies between 570 days at 5°C and 101 days at 25°C and is the main factor in the determination of r. The relationship between r and temperature is nearly linear and is given by r=0.0013 T–0.0042. The reproductive potential of O. oxyuris is much lower than would be predicted from body size; this and the dominance of males in the population, is discussed in the light of the evolution of stable predator-prey systems.     

A rapid method of extracting meiobenthic nematodes and copepods from mud and detritus

The extraction of nematodes and harpacticoid copepods from muddy sediments or sediments containing a large amount of organic detritus can be achieved through a series of centrifugations or the material in a saccharose solution of at least 900 g/l. The number of individuals appearing in the supernatant after each centrifugation forms a geometric series, with a ratio which is dependent on the amount of material, the concentration of the saccharose solution, and the acceleration of the centrifuge. Knowledge of this ratio allows an estimation of density after only one centrifugation. More than 90% of the animals present in the sample can be extracted after only two centrifugations.     

Cumulative effects of climate warming and other human activities on freshwaters of Arctic and subarctic North America

Despite their generally isolated geographic locations, the freshwaters of the north are subjected to a wide spectrum of environmental stressors. High-latitude regions are especially sensitive to the effects of recent climatic warming, which have already resulted in marked regime shifts in the biological communities of many Arctic lakes and ponds. Important drivers of these limnological changes have included changes in the amount and duration of snow and ice cover, and, for rivers and lakes in their deltas, the frequency and extent of spring floods. Other important climate-related shifts include alterations in evaporation and precipitation ratios, marked changes in the quality and quantity of lake and river water inflows due to accelerated glacier and permafrost melting, and declining percentages of precipitation that falls as snow. The depletion of stratospheric ozone over the north, together with the clarity of many Arctic lakes, renders them especially susceptible to damage from ultraviolet radiation. In addition, the long-range atmospheric transport of pollutants, coupled with the focusing effects of contaminant transport from biological vectors to some local ecosystems (e.g., salmon nursery lakes, ponds draining seabird colonies) and biomagnification in long food chains, have led to elevated concentrations of many persistent organic pollutants (e.g., insecticides, which have never been used in Arctic regions) and other pollutants (e.g., mercury). Rapid development of gas and oil pipelines, mining for diamonds and metals, increases in human populations, and the development of all-season roads, seaports, and hydroelectric dams will stress northern aquatic ecosystems. The cumulative effects of these stresses will be far more serious than those caused by changing climate alone.     

Deposition rates on smooth surfaces and coagulation of aerosol particles inside a test chamber

Because aerosol particle deposition is an important factor in indoor air quality, many empirical and theoretical studies have attempted to understand the process. In this study, we estimated the deposition rate of aerosol particles on smooth aluminum surfaces inside a test chamber. We investigated the influence of turbulent intensity due to ventilation and fan operation. We also investigated two important processes in particle deposition: turbophoresis, which is significant for micron particles, and coagulation, which is relevant to ultrafine particles (UFP diameter <0.1 μm) at high particle concentrations. Our analysis included semi-empirical estimates of the deposition rates that were compared to available deposition models and verified with simulations of an aerosol dynamics model. In agreement with previous studies, this study found that induced turbulent intensity greatly enhanced deposition rates of fine particles (FP diameter <1 μm). The deposition rate of FP was proportional to the ventilation rate, and it increased monotonically with fan speed. With our setup, turbophoresis was very important for coarse particles larger than 5 μm. The coagulation of aerosol particles was insignificant when the particle concentration was less than 10⁴ cm^?3 during fan operation. The model simulation results verified that the aerosol dynamics module incorporated in our Multi-Compartment and Size-Resolved Indoor Aerosol Model (MC-SIAM) was valid. The behavior of aerosol particles inside our chamber was similar to that found in real-life conditions with the same ventilation rates (0.018–0.39 h^?1) and similar air mixing modes. Therefore, our findings provide insight into indoor particle behavior.     

Contamination of an arctic terrestrial food web with marine-derived persistent organic pollutants transported by breeding seabirds

At Cape Vera, Devon Island (Nunavut, Canada), a colony of northern fulmars (Fulmarus glacialis) concentrates and releases contaminants through their guano to the environment. We determined whether persistent organic pollutants (POPs) from seabirds were transferred to coastal food webs. Snow buntings (Plectrophenax nivalis) were the most contaminated species, with ∑PCB and ∑DDT (mean: 168, 106 ng/g ww) concentrations surpassing environmental guidelines for protecting wildlife. When examined collectively, PCB congeners and DDT in jewel lichen (Xanthoria elegans) were lower in samples taken farther from the seabird colony, and increased with increasing δ¹⁵N values. However, only concentrations of p’p-DDE:∑DDT and PCB-95 were significantly correlated inversely with distance from the seabird cliffs. Linkages between marine-derived POPs and their concentrations in terrestrial mammals were less clear. Our study provides novel contaminant data for these species and supports biovector transport as a source of organic contaminants to certain components of the terrestrial food web.