Landfill mining and waste characterization: a strategy for remediation of contaminated areas

This article describes landfill-mining tests, including excavation, screening, and fraction characterization, carried out in the Msalycke and Gladsax landfills for municipal solid waste (MSW) in Sweden. The excavated waste in these two sites was 17–22 and 23–25 years old, respectively. The main part of Msalycke was unaffected by degradation, and during excavations no substantial amount of biogas was detected. After screening, three size fractions were obtained: <18mm, 18–50mm, and >50mm. Soil amendment and anaerobic digestion with energy extraction are suggested for the first and second fraction, respectively. Incineration with energy recovery is possible with the third fraction after any coarse (inert) material is removed, and construction/demolition waste can easily be recycled provided that it is not contaminated by hazardous material. Excavated waste taken from different depths was also analysed and compared in relation to composition, calorific value, and leachate constituents.     

Cytotoxic haplosclerid sponges preferred: a field study on the diet of the dotted sea slug<Emphasis Type="Italic"> Peltodoris atromaculata</Emphasis> (Doridoidea: Nudibranchia)

Trophic specializations are widespread among opisthobranch molluscs. One purported example from the Mediterranean Sea is the dotted sea slug Peltodoris atromaculata. It has been hypothesized that this species is strongly monophagous on the sponge Petrosia ficiformis. However, the small amount of evidence that has been found for this hypothesis is based just on laboratory tests. Here we study the feeding habits and the diet of Peltodoris atromaculata in its natural habitat. We observed and videotaped 161 individuals together with the organisms on which they were found (their living substrata). Feeding scars were identified and videotaped as well. Individuals and their living substrata were sampled for further analysis in the laboratory. The composition of faeces of Peltodoris, especially undigested sponge spicules, was analyzed by light and scanning electron microscopy and compared to the composition of the living substrata. Most of the faecal samples consisted of undigested sponge spicules. Although Peltodoris was found on 11 species of sponges, only 2 of them, Petrosia spp. and Haliclona fulva, form its diet (76% out of n=121 samples). In accordance with this, feeding scars in the habitats were exclusively observed on these two sponges. Estimation of electivity indices suggests that Haliclona is preferred over Petrosia. One remarkable feature of the exclusive feeding of Peltodoris on Petrosia and Haliclona is that both sponges share specific fulvinol-like polyacetylenes that show cytotoxic activity in bioassays. Potential benefits and evolutionary aspects of this trophic specialization are discussed. Besides sponge-containing faeces, we found spicule-free faeces (24%, n= 29). These were very small in volume compared to sponge-containing faeces, and only few distinct structures were present. However, the use of food other than sponges is not necessarily indicated by this, because the spicule-free faeces might also represent left-overs from the stomach and digestive gland after sponge spicules have been released.Communicated by O. Kinne, Oldendorf/Luhe     

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.     

A world model of the growth in production and population

A model for the growth in GNP (gross national product) and population has been set up. On the basis of the present data it was found that the growth of a population is a function of GNP, and that GNP seems to follow a logistic growth.     

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.