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At least 1,279 records · Page 71Linked to original sources
PubMed2000

Seasonal variation of hip fracture at three latitudes.

We studied the seasonal variation of hip fracture admissions at three different latitudes: Scotland (56 degrees North; 54,399 admissions); Shatin, Hong Kong (22 degrees North; 4180 admissions); and Auckland, New Zealand (36 degrees South; 2257 admissions). We calculated the extent of seasonal variation (amplitude) and the time of year of the peak value (acrophase) by fitting a sine curve to monthly data using cosinor analysis. A significant seasonal variation was found in all three countries, at a high level in Scotland (p < 0.01) and Hong Kong (p < 0.001), but just significant in New Zealand (p < 0.05). The extent of the seasonal change was very similar in Scotland and New Zealand, but, as expected, the peak in New Zealand (early September) was approximately six months ahead of Scotland (mid February). In Hong Kong, the amplitude was three times greater than in Scotland and the peak occurred a month earlier. There is neither snow nor ice in Hong Kong, and this provides powerful evidence against a major influence of conditions underfoot causing extra falls in winter. In Scotland there was a significant increase in the proportion of deaths in winter as compared to summer. The Scotland/Hong Kong amplitude difference is striking, but it is unknown whether this has a genetic or environmental explanation. The cause of seasonal death difference to a given injury is also unknown. Possible mechanisms are discussed, but the purpose is to report two new epidemiological features, without wild speculative hypotheses. The findings should be viewed as leads to further epidemiological, clinical and more basic research.

Female↗
PubMed2001

Suppressed ion chromatography methods for the routine determination of ultra low level anions and cations in ice cores.

The concentration of trace ionic species in snow and ice samples was determined using suppressed ion chromatography (IC) with conductivity detection and ultra-clean sample preparation techniques. Trace anion species were determined in a single 24-min run by combining sample preconcentration with gradient elution using Na2B4O7 eluent. The detection limits (ranging from 0.001 to 0.006 microM) are the lowest reported in the literature. Cation species were analysed by direct injection of 0.25 ml and isocratic elution with a H2SO4 eluent. The clean preparation techniques showed no evidence of a difference (Student's t-test) between Milli-Q water samples analysed directly and processed Milli-Q ice samples. These robust, ultra-clean IC methods were routinely applied to the analysis of large number of samples to produce a high-resolution trace ion ice core record from Law Dome, East Antarctica.

Anions↗
PubMed1999

Ion chromatography of nitrite at the ppb level with photometric measurement of iodine formed by post-column reaction of nitrite with iodide.

The difficulty in ion-chromatographic determination of nitrite in aqueous solutions containing a high concentration of chloride arises mainly from incomplete resolution of the peaks for these anions on the separation column whose efficiency is not high. A photometric measurement of iodine formed by a reaction of nitrite with iodide has been found to make it possible to determine, chromatographically, trace amounts of nitrite without any interference from chloride; chloride does not oxidize iodide to produce iodine. The proposed method was based on the separation of nitrite from matrix anions on a silica-based anion-exchange column with a 1.5.10(-3) M phthalate eluent (pH 5.0), followed by photometric measurement of the iodine (as triiodide) formed via a post-column reaction of the separated nitrite with iodide. The optimal conditions for the post-column reaction were established by varying the concentrations of iodide, copper(II) and nitric acid in a post-column-reaction solution and the length of a reaction tube. A calibration graph for nitrite, plotted as peak heights versus concentrations, was linear up to 1.50.10(-5) M (690 ppb). The detection limit, defined at S/N = 3, was 1.00.10(-7) M (4.60 ppb) nitrite. The presence of chloride ions up to 0.01 M did not give any interference to the determination of nitrite. This method was successfully applied to the determination of nitrite in lake water, river water, sewage works water and snow samples without any pretreatment.

Chromatography, Ion Exchange↗
PubMed2003

Acquisition of freezing tolerance in early autumn and seasonal changes in gall water content influence inoculative freezing of gall fly larvae, Eurosta solidaginis (Diptera, Tephritidae).

We examined seasonal changes in freeze tolerance and the susceptibility of larvae of the gall fly, Eurosta solidaginis to inoculative freezing within the goldenrod gall (Solidago sp.). In late September, when the water content of the galls was high (approximately 55%), more than half of the larvae froze within their galls when held at -2.5 degrees C for 24 h, and nearly all larvae froze at -4 or -6 degrees C. At this time, most larvae survived freezing at > or = -4 degrees C. By October plants had senesced, and their water content had decreased to 33%. Correspondingly, the number of larvae that froze by inoculation at -4 and -6 degrees C also decreased, however the proportion of larvae that survived freezing increased markedly. Gall water content reached its lowest value (10%) in November, when few larvae froze during exposure to subzero temperatures > or = -6 degrees C. In winter, rain and melting snow transiently increased gall water content to values as high as 64% causing many larvae to freeze when exposed to temperatures as high as -4 degrees C. However, in the absence of precipitation, gall tissues dried and, as before, larvae were not likely to freeze by inoculation. Consequently, in nature larvae freeze earlier in the autumn and/or at higher temperatures than would be predicted based on the temperature of crystallization (T(c)) of isolated larvae. However, even in early September when environmental temperatures are relatively high, larvae exhibited limited levels of freezing tolerance sufficient to protect them if they did freeze.

Adaptation, Physiological↗
PubMed1997

Effect of temperature on cold-hardiness and tissue ice formation in the adult chrysomelid beetle Melasoma collaris L.

The freeze-tolerant chrysomelid beetle Melasoma collaris overwinters in plant litter on windswept ridges or covered with snow for 8-9 months in the Norwegian alpine region. Lower lethal temperature, supercooling and melting point depression were correlated to accumulation of glycerol. The lower limit of freeze tolerance was associated with the freezing of 73-75% body water. About 23-15.5% of the body water was osmotically inactive, and the highest percentage was revealed in individuals depleted of glycerol at 21 degrees C. A shift in cooling rate from 1 degrees Cmin(-1) to 1 degrees C every 13.5min lowered nucleating temperature markedly. The alteration in nucleating activity probably arises from the structure of the haemolymph nucleating agent that functions to slow embryo growth at the slow cooling rate. An enhanced supercooling is particularly beneficial in autumn before M. collaris has accumulated glycerol, since supercooled individuals accumulate glycerol in higher concentrations than frozen ones. Freezing at higher temperatures is probably a better survival strategy during brief intervals with pronounced decrease in air temperature.

Journal Article↗
PubMed1998

Geographical and diapause-related cold tolerance in the blow fly, Calliphora vicina.

Three geographical strains of the blow fly, Calliphora vicina, were tested for cold tolerance at 0 degrees, -4 degrees and -8 degrees C. Survival to eclosion after 1 to 18 days of cold exposure was greater for diapause-destined larvae than for nondiapause-destined larvae of the two northern strains (Nallikari, Finland 65 degrees N and Edinburgh, Scotland 55 degrees N) but not for the southernmost strain (Barga, Italy 44 degrees N) where no clear differences were apparent. Diapause-destined larvae of the Edinburgh strain were more cold tolerant than those from Nallikari, at both -4 degrees and -8 degrees C, a difference possibly attributable to the long-lasting snow cover in the more northern locality, which might insulate the overwintering soil microclimate. At 0 degrees C, however, Nallikari larvae were more cold tolerant than Edinburgh or Barga. This was also the case for nondiapause-destined larvae, indicating that cold tolerance may occur, in part, independently of the diapause programme. In all three strains diapausing larvae were more cold tolerant than same-age (nondiapausing) pupae. For Nallikari, but not Barga, wandering larvae from short-day exposed flies, therefore initially programmed for diapause, but diverted from the diapause pathway by larval breeding at 19 degrees C, were significantly more cold tolerant than nondiapause larvae from long-day parents, indicating some maternal regulation of larval cold tolerance. There was, however, no evidence for an additional cold hardiness in larvae acclimatised to cold by a gradual reduction of temperature.

Journal Article↗
PubMed2002

Infection by a Hematodinium-like parasitic dinoflagellate causes Pink Crab Disease (PCD) in the edible crab Cancer pagurus.

The edible crab (Cancer pagurus) supports a large and valuable fishery in UK waters. Much of the catch is transported live to continental Europe in specially designed live-well ('vivier') vehicles. During the winter of 2000/2001, many trap-caught crabs from Guernsey, Channel Islands, UK, were reportedly moribund and pink in colour. These crabs generally died before and during vivier transportation. We provide histological, immunological, and molecular evidence that this condition is associated with infection by a Hematodinium-like dinoflagellate parasite similar to that previously reported in C. pagurus and to an infection causing seasonal mass mortalities of the Norway lobster (Nephrops norvegicus). Pathologically, every altered host bore the infection, which was characterised by very large numbers of plasmodial and vegetative stages in the haemolymph and depletion of reserve cells in the hepatopancreas. Due to the hyperpigmentation of the carapace and appendages, we have called this infection 'Pink Crab Disease' (PCD). Similar Hematodinium infections cause 'Bitter Crab Disease' in tanner and snow crabs, which has had a negative effect on their marketability. At present, little is known about the seasonality, transmission, and market impact of this infection in C. pagurus.

Animals↗
PubMed2004

[Seasonal variation in strokes incidence and the influence of the meteorological conditions].

The aim of this paper was to study the seasonal and Monthly distribution of different subtypes of strokes, and also the influence of the most usual meteorological factors on their incidence. The study, based on the population-based data of the Dijon register of stroke (France), involved 3287 patients with a cerebrovascular event during the Years 1985-1998. The seasonal distribution pointed out a summer decrease for all stroke subtypes. The cerebrovascular risk was the highest in autumn for small artery atheroma infarcts and for cerebral infarcts and, among these later, for cardioembolic infarcts and large artery atheroma infarcts, as well as for subarachnoid hemorrhages and for the total number of strokes. It was followed by spring (total number of strokes, small artery atheroma infarcts, cerebral infarcts) and/or winter (subarachnoid hemorrhages, cerebral infarcts, cardioembolic infarcts and large artery atheroma infarcts). For intracerebral hemorrhages, the risk peaked in spring and secondly in autumn. But the difference from one season to another was significant only for total number of strokes, cerebral infarcts and, among the later, for cardioembolic infarcts and large artery atheroma infarcts. As regards the Monthly distribution, the difference between Months was significant only for the total number of strokes and cerebral infarcts, with a minimum from July to September and a maximum in October for the later. Correlations with meteorological data were found for the total number of strokes, cerebral infarcts, cardioembolic infarcts, large artery atheroma infarcts and small artery atheroma infarcts. They showed an influence of temperature and relative humidity of the day of stroke or of the one to five days before. Correlations with wind speed, duration of sunshine or snow, even if less frequent, could also be found. Such results sometimes differ from those of some earlier studies, for which the climate and the risk factors were not the same, showing that regional epidemiological studies are necessary in order to determine the relations between seasons, meteorological factors and strokes.

Adolescent↗
PubMed2001

Microbial degradation of mefenoxam in rhizosphere of Zinnia angustifolia.

The fate of the fungicide mefenoxam was studied in a containerized rhizosphere system. The rhizosphere system used Zinnia angustifolia (Tropic Snow) in a bark/sand potting mix and was compared to bulk potting mix (no plants). Rhizosphere microbial populations were allowed to establish for 3 weeks prior to fungicide addition (20 microg per g mix). Mefenoxam and degradation product concentrations were determined by High HPLC or capillary electrophoresis after extraction. Seventy eight percent of the fungicide originally applied to the rhizosphere was degraded after 21 days compared to 44% in bulk system (no plant). The primary degradation product was the free acid N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-DL-alanine, which accounted for 71% of the applied parent chemical after 30 days. N-(2,6-dimethylphenyl)-acetamide was also detected, but in lesser amounts. Bacterial populations in the rhizosphere increased during the 30-day period, which correlated with an increase in degradation of the parent compound. Pure cultures of Pseudomonas fluorescens and Chrysobacterium indologenes isolated from the rhizosphere system could degrade the applied fungicide (10 microg/ml) almost completely to the free acid within 54 h.

Alanine↗
PubMed2001

A rapid and sensitive method for methyl tert-butyl ether analysis in water samples by use of solid phase microextraction and gas chromatography-mass spectrometry.

This work describes a rapid and sensitive solid-phase microextraction (SPME) method for the isolation and analysis of methyl tert-butyl ether in water samples. Methyl tert-butyl ether was extracted from aqueous solutions using SPME fibre coated with Divinylbenzene/Carboxen/polydimethylsiloxane (30 microm film thickness) and analysed by GC-MS with a Hewlett Packard 6890/5973 system equipped with a capillary column coated with Vocol (30 m x 0.25 mm, 1.5 microm film thickness). Extraction parameters and chromatographic separation conditions were optimised. The developed method showed good analytical performance in terms of precision (RSD between 2% and 8%) and accuracy (mean recovery from 96% to 104%) with a detection limit of 14 ppt. Finally the method was applied to surface, tap and commercial mineral water samples, as well as snow samples collected along a busy road of Bologna town area. The median concentration of methyl tert-butyl ether in all these samples (0.05-0.4 ppb) was well below the maximum aqueous contamination levels in water adopted in the United States (13 ppb).

Carcinogens↗
PubMed2001

Global-scale environmental transport of persistent organic pollutants.

In order to realistically simulate both chemistry and transport of atmospheric organic pollutants, it is indispensable that the applied models explicitly include coupling between different components of the global environment such as atmosphere, hydrosphere, cryosphere and soil system. A model with such properties is presented. The atmospheric part of the model is based on the equations in a general contravariant form which permits easy changes of the coordinate system by redefining the metric tensor of a specifically employed coordinate system. Considering a need to include explicitly the terrain effects, the terrain following spherical coordinate system is chosen from among many possible coordinate systems. This particular system is a combination of the Gal-Chen coordinates, commonly employed in mesoscale meteorological models, and the spherical coordinates, typical for global atmospheric models. In addition to atmospheric transport, the model also simulates the exchange between air and different types of underlying surfaces such as water, soil, snow, and ice. This approach permits a realistic representation of absorption and delayed re-emission of pollutants from the surface to the atmosphere and, consequently, allows to capture hysteresis-like effects of the exchange between the atmosphere and the other components of the system. In this model, the most comprehensive numerical representation of the exchange is that for soil. In particular, the model includes a realistic soil module which simulates both diffusion and convection of a tracer driven by evaporation from the soil, precipitation, and gravity. The model is applied to a long-term simulation of the transport of pesticides (hexachlorocyclohexanes in particular). Emission fluxes from the soil are rigorously computed on the basis of the realistic data of the agricultural application. All four modelled systems, i.e. atmosphere, soil, hydrosphere and cryosphere, are driven by objectively analysed meteorological data supplemented, when necessary, by climatological information. Therefore, the verification against the observed data is possible. The comparison of the model results and the observations taken at remote stations in the Arctic indicates that the presented global modelling system is able to capture both trends and short-term components in the observed time series of the concentrations, and therefore, provides a useful tool for the evaluation of the source receptor relationships.

Air Movements↗
PubMed2002

Investigation of the soil radon variation during the winter months in Sapporo, Japan.

Soil radon was measured from late October 2000 to January 2001 at three test sites on the campus of Hokkaido University in Sapporo, Japan. Factors affecting radon concentrations were investigated with relation to meteorological data, as well as soil 226Ra content, mineral composition, water content, and pH, Eh and conductivity. Soil radon varied with time and with sampling site appreciably, in a manner unaltered by the surface geology. However, the ratio of radon isotopes (220Rn/222Rn) in the soil was constant within each sampling site, regardless of varying concentration of these nuclides during the monitoring period. Snow covering on the soil surfaces may affect the 222Rn concentration.

Environmental Monitoring↗
PubMed2002

Uptake of atmospheric mercury by deionized water and aqueous solutions of inorganic salts at acidic, neutral and alkaline pH.

Mercury (Hg) is well known as a toxic environmental pollutant that is among the most highly bioconcentrated trace metals in the human food chain. The atmosphere is one of the most important media for the environmental cycling of mercury, since it not only receives mercury emitted from natural sources such as volcanoes and soil and water surfaces but also from anthropogenic sources such as fossil fuel combustion, mining and metal smelting. Although atmospheric mercury exists in different physical and chemical forms, as much as 90% can occur as elemental vapour Hg0, depending on the geographic location and time of year. Atmospheric mercury can be deposited to aquatic ecosystems through both wet (rain or snow) and dry (vapour adsorption and particulate deposition) processes. The purpose of the present study was to measure, under laboratory conditions, the rate of deposition of gaseous, elemental mercury (Hg0) to deionized water and to solutions of inorganic salt species of varying ionic strengths with a pH range of 2-12. In deionized water the highest deposition rates occurred at both low (pH 2) and high (pH 12). The addition of different species of salt of various concentrations for the most part had only slight effects on the absorption and retention of atmospheric Hg0. The low pH solutions of various salt concentrations and the high pH solutions of high salt concentrations tested in this study generally showed a greater tendency to absorb and retain atmospheric Hg0 than those at a pH closer to neutral.

Adsorption↗
PubMed1999

Baseline concentrations of elements in the Antarctic macrolichen Umbilicaria decussata

Total concentrations of major and trace elements were determined in samples of the epilithic lichen Umbilicaria decussata from 24 ice-free areas in coastal Victoria Land (Antarctica). Overall average concentrations of trace elements except Cd were the lowest ever reported for lichens of the genus Umbilicaria. Specifically, the mean level of Pb in lichens from granitic rocks (0.46 +/- 0.18 microg g(-1) dry wt) was more than four times lower than the lowest record in Arctic lichens. No impact of local human activities was detected, but the elemental composition of U. decussata was affected by entrapment of soil or rock dust particles and probably by uptake of soluble elements from substrate. Relationships between elements and their distribution patterns in the study area indicated that the marine environment is the main source of major ions and perhaps of Cd in lichens. Accumulation of P was detected in samples from coastal sites frequented by seabirds. Although the present results can be taken as baseline levels of major and trace elements in Antarctic U. decussata from substrates with very different geochemical features, further research is necessary to evaluate the relative element contribution from each substrate with respect to those from snow, marine aerosol, salt encrustations and guano.

Journal Article↗
PubMed1999

Determination of group parameters for organically bound chlorine, bromine and iodine in precipitation

The presence of organically bound halogens in precipitation was studied by first adsorbing organics on activated carbon and then analysing the chloride, bromide and iodide formed during combustion of the carbon. A standard instrument for the group parameter AOX (adsorbable organic halogens) was used for the combustion. The halides formed were trapped in an alkaline solution and analysed by capillary zone electrophoresis. The method described enabled determination of sub-ppb concentrations of the group parameters AOCl, AOBr and AOI (adsorbable organic chlorine, bromine and iodine, respectively). Analysis of rain and snow collected at different sites in Europe showed that organochlorines were responsible for the major part of the AOX content in all samples collected. Organically bound bromine was found in sub-ppb concentrations in all of the samples, whereas organic iodine was detected in only two of the samples.

Journal Article↗
PubMed2000

Assessing the consequences of global change for forest disturbance from herbivores and pathogens.

Herbivores and pathogens impact the species composition, ecosystem function, and socioeconomic value of forests. Herbivores and pathogens are an integral part of forests, but sometimes produce undesirable effects and a degradation of forest resources. In the United States, a few species of forest pests routinely have significant impacts on up to 20 million ha of forest with economic costs that probably exceed $1 billion/year. Climatic change could alter patterns of disturbance from herbivores and pathogens through: (1) direct effects on the development and survival of herbivores and pathogens; (2) physiological changes in tree defenses; and (3) indirect effects from changes in the abundance of natural enemies (e.g. parasitoids of insect herbivores), mutualists (e.g. insect vectors of tree pathogens), and competitors. Because of their short life cycles, mobility, reproductive potential, and physiological sensitivity to temperature, even modest climate change will have rapid impacts on the distribution and abundance of many forest insects and pathogens. We identify 32 syndromes of biotic disturbance in North American forests that should be carefully evaluated for their responses to climate change: 15 insect herbivores, browsing mammals; 12 pathogens; 1 plant parasite; and 3 undiagnosed patterns of forest decline. It is probable that climatic effects on some herbivores and pathogens will impact on biodiversity, recreation, property value, forest industry, and even water quality. Some scenarios are beneficial (e.g. decreased snow cover may increase winter mortality of some insect pests), but many are detrimental (e.g. warming tends to accelerate insect development rate and facilitate range expansions of pests and climate change tends to produce a mismatch between mature trees and their environment, which can increase vulnerability to herbivores and pathogens). Changes in forest disturbance can produce feedback to climate through affects on water and carbon flux in forest ecosystems; one alarming scenario is that climate warming may increase insect outbreaks in boreal forests, which would tend to increase forest fires and exacerbate further climate warming by releasing carbon stores from boreal ecosystems. We suggest a list of research priorities that will allow us to refine these risk assessments and adopt forest management strategies that anticipate changes in biotic disturbance regimes and mitigate the ecological, social, and economic risks.

Animal Nutritional Physiological Phenomena↗
PubMed2000

Influence of the Sostanj coal-fired thermal power plant on mercury and methyl mercury concentrations in Lake Velenje, Slovenia

Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.

Journal Article↗
PubMed2001

Variation in river water temperatures in an upland stream over a 30-year period.

Stream water temperature data from the Girnock burn, a 30-km2 catchment in Scotland were examined for systematic variation across 30 years of record (1968-1997). The data suggest that there has been no change in mean annual temperature with time, but at a seasonal level there is some indication of an increase in mean daily maximum temperatures during the winter (December to February) and spring (March to May) seasons. For the spring season, there is also evidence that mean temperature has increased. There are no apparent or obvious changes in stream flow to account for this. The strong relationship between air and stream temperatures (r2 = 0.96) implies that changes in the stream are the result of changes in the climate. It is possible that this may occur as a result of the effect of increasing air temperatures which may have also reduced the influence of snow and snowmelt on the catchment during the winter and spring seasons.

Journal Article↗