Altitude dependent 137Cs concentrations in different plant species in alpine agricultural areas

The Gastein valley in the Central Part of the Austrian Alps was one of the regions most heavily affected by fallout of the Chernobyl nuclear catastrophe, depositing (137)Cs inventory up to 70 kBq/m(2) in May 1986. In many studies dealing with the uptake of (137)Cs by vegetation used for farming, a significant correlation between (137)Cs concentration in the plants and altitude a.s.l. has been observed. In order to quantify the influence of the composition of plant communities on the average (137)Cs concentration in vegetation on farmland, plant-specific activity concentrations in plant species have been determined. Alongside a transect from valley sites at 850 m a.s.l. to alpine pastures at 1660 m, the aggregated transfer factors C(ag) (m(2)/kg) have been measured for plant communities and plant species. C(ag) values for mixed vegetation are more or less similar in valley sites, but they increase exponentially with a doubling height of 122+/-22 m above appr. 1200 m altitude a.s.l. On average all species are affected by this increase in a similar way. C(ag) values of ubiquitous plant indicate that the composition of plant communities is of minor importance for the contamination of mixed vegetation.     

Introduction of cob(I)alamin as an analytical tool: application to reaction-kinetic studies of oxiranes

The strongly nucleophilic cob(I)alamin, i.e. Vitamin B₁₂ with Co(III) reduced to Co(I), is introduced as a trapping agent in the determination of concentrations of electrophilic reagents. This compound was applied, in comparison with the previously used moderately reactive nicotinamide (H.J.C.F. Nelis and J.E. Sinsheimer (1981). Anal. Biochem., 115, 151.). Oxiranes, metabolites of 1-alkenes, were chosen as model electrophiles. The reagents (nicotinamide and cob(I)alamin) were evaluated in the determination of the rates of reaction toward valine methylamide, a model of N-terminal valines in hemoglobin often used for monitoring of doses in vivo of genotoxic carcinogens. The rate constants for reaction at 37°C with valine methylamide (k _VMA) determined by the cob(I)alamin and nicotinamide procedure, respectively, were for ethylene oxide (1.6, 1.7), propylene oxide (0.9, 1.1), 1,2-epoxybutane (0.7, 0.8) and 1,2-epoxyoctane (0.5, 0.6) M^?1?h^?1, decreasing with increasing number of carbons of the oxirane. Concentrations of oxiranes trapped with nicotinamide are underrated in reaction mixtures containing valine methylamide due to consumption by reaction with the competing nucleophile, a disturbance that is not observed in trapping with cob(I)alamin which reacts about 10⁵ times faster than nicotinamide. Cob(I)alamin which was demonstrated to be an efficient nucleophile for trapping of electrophiles, also in the presence of competing nucleophiles, is promising as an analytical tool in toxicological studies of reactive compounds. Furthermore, cob(I)alamin can be used to detect, measure and compare electrophilic reactivity of chemical substances, a property that is associated with genotoxic potency.     

A wasting syndrome in Swedish moose (Alces alces): background and current hypotheses

In the 1980s, people in Sweden frequently responded to moose (Alces alces) found dead or in poor physical condition. The number of moose submitted for routine investigations to the National Veterinary Institute (SVA) increased tenfold and the hunters in Alvsborg County were especially concerned. Later, a complex wasting syndrome was described and reports of moose suffering from the syndrome have been collected since 1991. Today, there is no definitive answer as to the underlying causel(s) of the syndrome, but there are several plausible hypotheses that can be divided into two groups: food-related and host-parasite related. The food-related hypotheses are postulated to have any of the following ultimate causes: acidification/liming, browser density/food production or pollution. Our view is that few of the hypotheses have been critically tested. Most of the hypotheses are supported by some observations, which is to be expected because these are post-hoc attempts to explain these very observations.     

Biodiversity, distributions and adaptations of Arctic species in the context of environmental change

The individual of a species is the basic unit which responds to climate and UV-B changes, and it responds over a wide range of time scales. The diversity of animal, plant and microbial species appears to be low in the Arctic, and decreases from the boreal forests to the polar deserts of the extreme North but primitive species are particularly abundant. This latitudinal decline is associated with an increase in super-dominant species that occupy a wide range of habitats. Climate warming is expected to reduce the abundance and restrict the ranges of such species and to affect species at their northern range boundaries more than in the South: some Arctic animal and plant specialists could face extinction. Species most likely to expand into tundra are boreal species that currently exist as outlier populations in the Arctic. Many plant species have characteristics that allow them to survive short snow-free growing seasons, low solar angles, permafrost and low soil temperatures, low nutrient availability and physical disturbance. Many of these characteristics are likely to limit species' responses to climate warming, but mainly because of poor competitive ability compared with potential immigrant species. Terrestrial Arctic animals possess many adaptations that enable them to persist under a wide range of temperatures in the Arctic. Many escape unfavorable weather and resource shortage by winter dormancy or by migration. The biotic environment of Arctic animal species is relatively simple with few enemies, competitors, diseases, parasites and available food resources. Terrestrial Arctic animals are likely to be most vulnerable to warmer and drier summers, climatic changes that interfere with migration routes and staging areas, altered snow conditions and freeze-thaw cycles in winter, climate-induced disruption of the seasonal timing of reproduction and development, and influx of new competitors, predators, parasites and diseases. Arctic microorganisms are also well adapted to the Arctic's climate: some can metabolize at temperatures down to -39 degrees C. Cyanobacteria and algae have a wide range of adaptive strategies that allow them to avoid, or at least minimize UV injury. Microorganisms can tolerate most environmental conditions and they have short generation times which can facilitate rapid adaptation to new environments. In contrast, Arctic plant and animal species are very likely to change their distributions rather than evolve significantly in response to warming.     

The European collaborative study on mosaicism in chorionic villus sampling: Data from 1986 to 1987

Data on a total of 11 855 diagnostic chorionic villus samples obtained in the years 1986 and 1987 were compiled from a questionnaire filled in by 36 European cytogenetic centres. Mosaicism was reported in 141 cases. The cytogenetic findings were followed by induced abortion in 24 cases. Spontaneous abortion was observed in nine mosaic pregnancies, a rate not significantly different from that observed for CVS in total. Mosaicism was found in 1.2 per cent of analyses by direct analysis/short-term culture, in contrast to the 0.6 per cent found after long-term culture. Evidence for fetal non-mosaicism was found in 99 of the 141 cases. The finding of mosaicism in first-trimester CVS should always elicit further analyses, preferably after amniocentesis, to substantiate the suspected fetal chromosome aberration.     

Environmental pollutants in the Swedish marine ecosystem, with special emphasis on polybrominated diphenyl ethers (PBDE)

Levels of polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and perfluorinated organic compounds (PFCs) were analysed in whole herring (Clupea harengus) and sprat (Sprattus sprattus), eggs from common eider (Somateria mollissima) and eggs and livers from herring gull (Larus argentatus) from the Swedish west coast. The contaminant values obtained were compared with published values from the Arctic marine ecosystem. Tetra- and penta-brominated PBDEs were detected at low levels in herring, sprat and common eider (ΣPBDE 0.3-2.0 ng g⁻¹ ww), while the levels were higher in the herring gull samples (ΣPBDE 1.3-29.9 ng g⁻¹ ww). Hexa-decaBDEs were also found in samples from herring gulls. Eggs from herring gulls from the sub-Arctic contained four times more PBDE than the Swedish herring gulls eggs. Fish samples from the Arctic had two times higher levels of PBDEs and DDTs than similar samples from Sweden. The higher levels of contaminants in fish and seabirds from the Arctic reflect differences in transport processes, feeding ecology (reflected by trophic levels) and metabolism. PBDEs contributed to <10% of the total contaminant load in all investigated samples. The relative contribution of DDTs was higher in fish and bird samples from the Arctic when compared to Swedish samples, e.g. 65% in glaucous gull livers compared to 10% in herring gull livers. This study shows that even though the Swedish west coast is more urban than the Arctic, higher pollutants levels are found in seabird species from the Arctic.     

Cost-Effectiveness of Alternative Strategies in Mitigating the Greenhouse Impact of Waste Management in Three Communities of Different Size

Mitigation and Adaptation Strategies for Global Change - Waste management is a significant source of methane (CH4) emissions. CH4 is second to carbon dioxide (CO2) the most important anthropogenic...     

瑞典驼鹿(Alces alces)萎缩综合症:背景及当前的假说

20世纪80年代,在瑞典人们经常发现驼鹿死亡或身体状况差的情况.递交给瑞典国立兽医研究所(SVA)进行尸体常规检查的驼鹿数目增加了10倍之多.艾尔夫斯堡(Alvsborg)的狩猎者们对此尤为关注.随后,人们对驼鹿这一复杂的萎缩综合症进行了相关描述并从1991年开始收集有关患病驼鹿的报道.迄今为止,仍未找到该综合症确定的潜在病因,但人们提出了一些可能的假说以解释此综合症.这些假说基本上可以分为两类:食物相关假说和宿主-寄生虫相关假说.食物相关假说认为萎缩综合症有如下根本原因:酸化/撒石灰、采食动物密度/食物产量或污染.上述假说很少经严格实验检验,多半实验仅为一些观察结果支持,之所以这些假说与人们的预计相吻合,是因为这些假说是事后试图解释这些观察到的现象而提出的.     

北极陆地生态系统、气候及紫外线辐射的历史演变

在末次盛冰期,地球上很多大陆都被大量的冰层所覆盖,一些浅海域的海床露出水面将先前分离的大陆连接起来.尽管存在一些适宜于动植物生长而未被冰层覆盖的地区,但其年平均气温仍比更新世时期低10～13℃.在盏冰期的几千年时间内冰川开始消融,其显著特征是气候在大约18000～11400年以前出现了一系列的波动.气候在更新世度过一个温暖期后,开始了一个缓慢的全面变冷的过程,这导致了一系列为期几百年至几千年的气候波动,例如发生在大约13世纪晚期至19世纪早期的"小冰期".在最近150000年的气候变化过程中,北极的各种生态系统和生物组成在近10000年接近其最低分布范围.大冰期结束时的全球大范围急剧升温导致了许多物种的消失,这使北极地区的生物多样性大大降低.因此,北极生态系统以及大型脊椎动物等北极生物的生存正在受到威胁,尤其是目前以及将来的全球变暖都会进一步给它们带来重大灾难.已有的证据表明,就像更新世早期的情形那样,北极地区的树线很有可能会进一步向北发展,并迅速进入到苔原地区,从而减小苔原带,这就会进一步增加北极地区物种灭绝的可能性.一些物种将很有可能向北扩大它们的领地,并取代该地区原有的物种.在更新世早期,由于北极地区的海平面相对较低,当树线入侵到现在的海岸地区时,苔原带至少能够在北极圈的一部分低地区域生存,而从目前来看,未来的海平面极有可能上升,这将会对北极苔原带和其它无树生态系统的分布施加进一步的限制.很显然,全球现在的气候状况对北极生态系统带来的负面影响超出更新世的任何时期,很有可能是巨大的,尤其是当各种环境变化(例如紫外线B的增加,大气中氮化合物的沉积,重金属和酸污染,放射性污染物,生物栖息地破碎化)共同作用于北极生态系统时的影响也是前所未有之际.