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.     

Chemical and morphological characteristics of key tree species of the Carpathian Mountains

Concentrations of Al, B, Ca, Cu, Fe, K, Mg, Mn, N, Na, P, S and Zn in the foliage of white fir (Abies alba), Norway spruce (Picea abies) and common beech (Fagus sylvatica) from 25 sites of the Carpathian Mts. forests (Czech Republic, Poland, Romania, Slovakia and Ukraine) are discussed in a context of their limit values. S/N ratio was different from optimum in 90% of localities when compared with the European limit values. Likewise we found increase of Fe and Cu concentrations compared with their background levels in 100% of locations. Mn concentrations were increased in 76% of localities. Mn mobilization values indicate the disturbance of physiological balance leading to the change of the ratio with Fe. SEM-investigation of foliage waxes from 25 sites in the Carpathian Mts. showed, that there is a statistically significant difference in mean wax quality. Epistomatal waxes were damaged as indicated by increased development of net and amorphous waxes. The most damaged stomata in spruce needles were from Yablunitsa, Synevir and Brenna; in fir needles from Stoliky, and in beech leaves from Malá Fatra, Morské Oko and Beregomet. Spruce needles in the Carpathian Mts. had more damaged stomata than fir needles and beech leaves. Spruce seems to be the most sensitive tree species to environmental stresses including air pollution in forests of the Carpathian Mountains. Foliage surfaces of three forest tree species contained Al, Si, Ca, Fe, Mg, K, Cl, Mn, Na, Ni and Ti in all studied localities. Presence of nutrition elements (Ca, Fe, Mg, K and Mn) on foliage surface hinders opening and closing stomata and it is not physiologically usable for tree species.     

Studies on the indicator for heavy metal contamination in environments (1) Heavy metal contents of hair,nail and moustache

Heavy metal (Hg, Pb, Cd, Cu, Ni, Fe, Zn, and Mn) contents of the samples from 10 males were followed throughout a year. The values were characteristic of the individuals, and some correlationships between the contents of different metals were shown.     

Commentary: assessment of past infiltration fluxes through Yucca Mountain on the basis of the secondary mineral record-is it a viable methodology?

Two papers recently published in the Journal of Contaminant Hydrology by Marshall et al. [Marshall, B.D., Neymark, L.A., Peterman, Z.E., 2003. Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada. J. Contam. Hydrol. 62-63, 237-247] and Xu et al. [Xu, T., Sonnenthal, E., Bodvarsson, G., 2003. A reaction-transport model for calcite precipitation and evaluation of infiltration fluxes in unsaturated fractured rock. J. Contam. Hydrol. 64, 113-127] attempt to assess past volumes of seepage and infiltration fluxes through the vadose zone of Yucca Mountain, Nevada, on the basis of the modeling of the spatial distribution of secondary calcite. In this commentary, we argue that the employed methodology is not viable. In addition, the thermal boundary conditions used in simulations do not correspond to the temperatures of the mineral forming fluids established on the basis of the fluid inclusion studies.     

不确定性及建议

在北极气候影响评估(ACIA)中,一项气候及紫外线B辐射变化对北极陆地生态系统影响的评估着重强调了预期中的变暖的深远意义,尤其是变暖在未来生态系统功能、生物多样性,以及对气候的反馈方面的深远意义.然而,尽管在有些地理区域和有些学科,我们目前对气候和紫外线B辐射驱动下生态过程及生态变化的了解已算充分,但在其他区域及学科,这种了解是微弱的.即使随着北极地区研究成果的积累和新技术的引用,近来我们的预测能力已空前提高,我们目前的了解程度也还受到各种各样的不确定性的限制.这项评估是在每一种都含有不确定性的一系列方式方法,以及常常远非完整的数据集的基础上完成的.不确定性从各种方法和概念框架而来,从不可预测的意外事件、从对模型的缺乏验证、从未来温室气体排放及气候变化的一些特别情景的应用而不是预测而来.此项评估中,以减少不确定性为目的的建议比比皆是,而且涉及所有学科.然而,一再出现的主题是在北极这样人烟稀少的偏远地区,环境变化及其影响的实验、观察及监测活动达到足够的空间广度和时间长度是极其重要的.     

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.     

环境变化背景下北极生物的多样性、分布及其适应性

生物个体是对气候变化和紫外线B(UV－B)辐射变化产生反应的基础,而且这种反应会在各种时间尺度上发生.北极地区的动物、植物以及微生物种类的多样性从表面上看是低的,而且从北方针叶林到极地荒漠逐渐减少,但其原始物种却很丰富.与这种物种多样性随纬向梯度减少的趋势相反,一些空间分布范围很广的单一优势物种的优势度则呈增长趋势.全球气候变暖可能会减少该地区的物种多样性,并限制到这些物种的分布范围,尤其是在该地区生物分布的北部边缘,一些极地特有的动物和植物种类会面临着灭绝的危险.最有可能侵入苔原地带的物种是那些目前生存在极地外缘的北方地区生物.许多植物都具有自身的特征使它们能够在以下环境中生存短暂的无冰雪覆盖的生长季节,低的太阳高度角,永久冻结地带及低的土壤温度,贫乏的养分获取条件以及极少的物理扰动.以上这些特征有些可能会限制当地物种对气候变暖的反应,但其最主要的因素是这些物种与那些潜在的入侵物种相比缺乏竞争能力.北极地区陆生动物拥有许多适应特性,这使它们能够适应北极地区剧烈的温度变化.许多动物通过冬眠或迁移来逃避极地地区的恶劣天气和资源短缺.北极地区动物生存的生物环境则相对简单几乎没有天敌、竞争者、疾病、寄生生物,但同时食物资源也很短缺.极地陆生动物可能对由气候变化带来的温暖而干旱的夏季非常不适应,这种变化将会影响到动物的迁移路线、途中栖息地,并会改变冬季积雪的状况和冻融的循环过程.气候变化还会改变动物繁殖和发育的季节,并会引来新的竞争者、捕食者、寄生生物以及疾病等.极地微生物也能很好地适应该地区的气候一些微生物甚至在-39℃的低温下还能进行代谢活动.蓝藻细菌和藻类生物有着很广泛的适应策略,这能够使它们避免(至少可以减少)紫外线的伤害.微生物能够忍受许多环境条件,而且其生长周期很短,这些特点将使它们能很快适应新的生存环境.与此形成对比的是,极地植物和动物很可能通过改变其分布范围而不是积极的生物进化来适应环境的变暖.     

在物种水平上生物对气候和紫外线B辐射预期变化的响应

控制实验表明,不同物种对每个环境因子变化变量产生的响应也存在着差异.植物往往对营养元素的变化反应最为强烈,尤其是氮素的增加.夏季增温实验表明,木本植物对温度的升高表现出了积极的响应,而地衣、苔藓类植物的丰富度却因增温而降低.物种对增温的响应主要受水分有效性和雪覆盖程度控制.在气候保持湿润的情况下,伴随着夏季温度的升高,许多无脊椎动物种群的数量都有所增加.实验表明,CO2浓度和紫外线B(UV-B)辐射的增加对植物和动物影响较小,但是,一些微生物和真菌却对紫外线B辐射的增加非常敏感,甚至可能会因此产生一些诱导突变而引起流行传染病的爆发.苔原土壤的加温、CO2浓度的升高以及矿物质营养的改善一般都会增加微生物的活动.在温带气候中,藻类往往比蓝藻细菌更占优势.冬季结冰-解冻过程的增加会导致冻壳的形成,从而会大大降低许多陆生动物的冬季存活率,改变这些动物群体的动态过程.厚的积雪会使驯鹿等植食性动物很难采食到雪下的草类植物,同时也不利于其逃避食肉动物的追捕.而无雪期的提前到来则可能会加速植物的生长.物种对气候变化的响应最初可能出现在亚种这一水平上一个具有很高遗传/群系多样性的北极植物或动物物种,演化历史已经使其具有一种适应不同环境条件的能力,这将使它们能够很快适应未来的环境变化.本土知识(IK)、航空照片和卫星图像表明一些物种的分布已经发生了变化北极植被更加趋向灌木化,而且生长也更加旺盛；北极驯鹿的分布范围最近也发生了变化；一些原来在树线以南区域活动的害虫和鸟类也在北极被发现.与此相对应,大多数在北极地区进行繁殖鸟类的数量却都在下降.根据一些模型的预测,随着气候的变暖,苔原带鸟类的数量将会大幅度地下降.据物种-气候响应模型预测,由于受到气候变暖的影响,北极地区现有物种在未来的潜在分布范围都将大大缩小和向北退缩,而一些无脊椎动物和微生物则很可能会迅速向北扩展到北极地区.     

Biomimetic chemical degradation of polychlorobiphenyls below 100°C

PCBs were rapidly degraded by hydroxy radicals formed in the biomimetic degradation systems of superoxide, ferric chloride, and hydrogen peroxide at high concentrations below 100°C. The degradation rates of Kanechlor KC 300, KC 400, KC 500 and KC 600 were 95.4%, 89.1%, 59.9% and 47.9%, respectively. The generation of carbon dioxide gas was recognized and chloride ion showed 89.9 – 102.7% of the theoretical yield in the degradation of KC 300, KC 400 and KC 500.     

Ground level ozone concentrations and its association with NOx and meteorological parameters in Kathmandu valley, Nepal

This paper summarizes the results of a yearlong continuous measurements of gaseous pollutants, NO, NO₂, NO_x and O₃ in the ambient air at Kathmandu valley. Measured concentration of the pollutants in study area is a function of time. NO, NO₂ and O₃ peak occurred in succession in presence of sunlight. At the time of maximum O₃ concentration most of the NO_x are utilized. The diurnal cycle of ground level ozone concentrations, revealed mid-day peak with lower nocturnal concentrations and inverse relationship exists between O₃ and NO_x, which are evidences of photochemical O₃ formation. The observed ground level ozone during monsoon is slight lower than the pre-monsoon value. Further, lack of rainfall and higher temperature, solar radiation in the pre-monsoon have given rise to the gradual build up of ozone and it is lowest during winter. Ground level ozone concentrations measured during bandha (general strike) and weekend are 19% and 13% higher than those measured during weekdays. The most effective ozone abatement strategy for Kathmandu Valley may be control of NO_x emissions.