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PubMed2004

Polar ocean stratification in a cold climate.

The low-latitude ocean is strongly stratified by the warmth of its surface water. As a result, the great volume of the deep ocean has easiest access to the atmosphere through the polar surface ocean. In the modern polar ocean during the winter, the vertical distribution of temperature promotes overturning, with colder water over warmer, while the salinity distribution typically promotes stratification, with fresher water over saltier. However, the sensitivity of seawater density to temperature is reduced as temperature approaches the freezing point, with potential consequences for global ocean circulation under cold climates. Here we present deep-sea records of biogenic opal accumulation and sedimentary nitrogen isotopic composition from the Subarctic North Pacific Ocean and the Southern Ocean. These records indicate that vertical stratification increased in both northern and southern high latitudes 2.7 million years ago, when Northern Hemisphere glaciation intensified in association with global cooling during the late Pliocene epoch. We propose that the cooling caused this increased stratification by weakening the role of temperature in polar ocean density structure so as to reduce its opposition to the stratifying effect of the vertical salinity distribution. The shift towards stratification in the polar ocean 2.7 million years ago may have increased the quantity of carbon dioxide trapped in the abyss, amplifying the global cooling.

Animals↗
PubMed2005

Morphometric characteristics of the ophthalmic rete in the goose living at high altitudes and cold climate conditions.

This study has aimed at observing in detail the degree of complexity in the formation of the ophthalmic rete in geese living at high altitudes and very cold climate conditions in Kars and its province of Turkey. The 15 adult geese were injected with red and blue coloured latex, dissection was performed, the rete was examined, and the vessels were counted macroscopically and by stereoscopic microscopy. The size and the afferent and efferent vessels of the rete were mostly in parallel with the literature. The numbers of the vessels in the rete of the male and female geese were between 8.3 +/- 1.1 and 9.3 +/- 1.1 in arteries, and 8.6 +/- 1.4 and 10.5 +/- 1.3 in veins respectively. The results suggest that the ophthalmic rete in the goose living at high altitudes and very cold conditions may tend to be less complex, which might be the result of the relatively less cooling needs of the brain at cold conditions.

Altitude↗
PubMed2003

Cold climate BMPs: solving the management puzzle.

Snowmelt runoff and rain-on-snow events present some of the highest pollutant loading and most difficult management challenges in the course of a year in regions with cold climate. Frozen conduits, thick ice layers, low biological activity, altered chemistry, and saturated or frozen ground conditions all work against effective treatment of melt runoff. Understanding the source, evolution and transition that occurs within a melt event, and defining the management objectives for specific receiving waters will help focus the search for effective management techniques. Solving the management puzzle means putting together a strategy for both soluble and solids-associated water pollutants.

Cities↗
PubMed2005

BTEX degradation in a cold-climate wetland system.

A pilot-scale subsurface vertical-flow wetland system was constructed at the former BP Refinery in Casper, Wyoming in order to determine benzene, toluene, ethylbenzene and xylene (BTEX) degradation rates in a cold-climate application. The pilot system, consisting of 4 cells, each dosed at a nominal flow rate of 5.4 cubic metres per day, was operated between August and December 2002. The pilot tested the effects of wetland mulch and aeration on system performance. Areal rate constants (kA values) were calculated based on an assumed three tanks in series (3TIS). The presence of wetland sod and aeration both improved treatment performance. Mean kA values were 244 m/yr for cells without sod or aeration, and improved to 356 m/yr for cells with sod and aeration. Based on the results of the pilot system, a full-scale wetland system (capable of operating at 6,000 m3/day) was started up in May 2003. The full-scale system achieved permit compliance within one week of startup, but is currently being loaded at only 45% of the design hydraulic load, and 15% of the design BTEX mass load, resulting in a mean kA value of approximately 350 m/yr.

Biodegradation, Environmental↗
PubMed2003

A computer simulation of the oxygen balance in a cold climate winter storage WSP during the critical spring warm-up period.

The paper considers factors that determine the oxygen balance in extreme climate waste stabilisation ponds during the critical spring warm-up period. At this time BOD load on the pond is a maximum, due to accumulation of wastewater under the ice during the winter. The paper describes the operation of a typical cold climate WSP and the events leading to a balanced steady state system as spring develops into summer. A mathematical model to simulate conditions within a batch fed experimental pond over the transient period is described. To model temperature changes in the water body experimental data were fitted to a generalised equation based on diurnal fluctuations in air temperature. The results are plotted in a normalised form and show the diurnal fluctuation and time lapse as the depth of the pond increases. Maximum daily water temperature lags behind maximum light intensity. Bacterial growth is simulated by a Monod kinetic model in which growth rate depends on initial substrate concentration; temperature compensation is applied using a temperature activity coefficient. Oxygen utilisation is calculated from substrate removal. Algal growth rate is more complicated as it is affected by temperature and light availability. Algal oxygen production potential is considered in terms of its primary metabolite yield, which is then used in a Monod equation to estimate the growth rate. The model uses a mass balance approach to determine dissolved oxygen concentration in the pond. The model is still in a simple form but shows reasonable agreement, in terms of events and time lapses, to measured parameters in experimental ponds recovering from ice cover.

Bacteria↗
PubMed2002

Burn injuries after latissimus dorsi breast reconstruction in a cold climate.

The transposed and 'native' skin of a reconstructed breast using autogenous tissue transfer has impaired sensation. Two cases of thermal injury following latissimus dorsi breast reconstruction are reported. Both cases were due to the overnight application of a hot-water bottle to the reconstructed breast. We suggest that all patients should be warned of this potential complication especially in cold climates.

Journal Article↗
PubMed2005

High performance constructed wetlands for cold climates.

In 1991, the first subsurface flow constructed wetland for treatment of domestic wastewater was built in Norway. Today, this method is rapidly becoming a popular method for wastewater treatment in rural Norway. This is due to excellent performance even during winter and low maintenance. The systems can be constructed regardless of site conditions. The Norwegian concept for small constructed wetlands is based on the use of a septic tank followed by an aerobic vertical down-flow biofilter succeeded by a subsurface horizontal-flow constructed wetland. The aerobic biofilter, prior to the subsurface flow stage, is essential to remove BOD and achieve nitrification in a climate where the plants are dormant during the cold season. When designed according to present guidelines a consistent P-removal of > 90% can be expected for 15 years using natural iron or calcium rich sand or a new manufactured lightweight aggregate with P-sorption capacities, which exceeds most natural media. When the media is saturated with P it can be used as soil conditioner and P-fertilizer. Nitrogen removal in the range of 40-60% is achieved. Removal of indicator bacteria is high and < 1000 thermotolerant coliforms/100 ml is normally achieved.

Biodegradation, Environmental↗
PubMed1998

Decay rates in a cold climate region: a review of cases involving advanced decomposition from the Medical Examiner's Office in Edmonton, Alberta.

Previous research into postmortem interval (PMI) estimation has been restricted to temperate and arid climates. Results suggest that decomposition rates may be significantly slower in cold weather regions. Preliminary research to conduct a cold weather time since death study has begun in Edmonton, which experiences mean monthly temperatures below freezing five months of the year. A case review at Edmonton's Office of the Chief Medical Examiner from 1990 to 1996 provided background information on a sample of 20 cases involving advanced decomposition, with partial to complete skeletonization of remains. Cases with a PMI of less than seven months were compared with regional weather records to establish the mean PMI temperature. Results indicate that skeletonization can occur in less than six weeks in summer and four months in winter, despite freezing temperatures. In some cases, postmortem animal activity accelerated decomposition rates.

Adult↗