罗斯比中心区域气候模型Ⅱ:北极圈气候的应用

作为ARCMIP国际计划的一部分,罗斯比中心区域气候模型(RCA2)针对整个北冰洋地区的气候作了数值模拟整合,并与来自sHEBA数据集的观测资料作了比较,RCA2标准模型对北极冬季的云量和长波辐射的模拟较实况偏多.通过引入新的云量参数化方案(该参数化方案显著地改进了云量的年循环)减少了这部分误差,确定了介于晴空向下大气长波辐射与云层底部的长波辐射的补偿率,利用可以更准确描述冰晶与太阳辐射相互作用的辐射方案修正了模型,从而使得模型对云-太阳辐射间的相互作用的描述更接近实际.在模拟晴空辐射部分,由于太阳辐射大气透射率过大,经常在边界层云的顶部产生正偏差.引入真实海冰和积雪两种表面反照率的时间变化,对准确模拟地面能量净收支是至关重要的.同样,为了准确模拟北极圈地区近地面的热力学过程,将雪面温度作为预报量引入模型中也似乎是必不可少的.     

海岸带可持续管理(SUCOZOMA)计划:成果与挑战

1996年由瑞典环境战略研究基金会发起的"海岸带可持续管理"(SUCOZOMA)研究计划是人们公认的全球、地区及国家日益严重的海岸带问题所促成的.该计划探讨了沿海富营养化、捕捞实践以及过度开发的海岸资源等复杂问题,集中致力于多学科性,利益相关者之间的合作,并把重点放在公众和决策者认为最严重的问题上,当该计划于2004年结束时,共计完成或接近完成了22篇博士论文,出版了约100篇文章.40多位科学家参与了该计划.哥德堡大学是开展该研究的主要单位,但在斯德哥尔摩大学,贝耶(Beijer)研究所,以及瑞典皇家科学院Kristineberg海洋研究站和国家渔业委员会内也设有重要的科研小组.在计划实施期间,建立了利益相关人员网络,"海岸带可持续管理"(SUCOZOMA)为众多与海岸带综合管理(ICZM)相关的政治和行政管理程序作出了贡献.SUCOZOMA的成果可分为不同的类别.计划两个阶段中许多项目产生了可称为技术性的或实用的成果可供在下列方面直接应用,例如:贻贝养殖,产卵场的恢复和维护,海豹安全渔具或开发不足鱼种的可持续捕捞.其他的成果具有政策性的特点,这些成果的影响只有在新政策付诸实施时才能得到适当的评估.SUCOZOMA产生了有关海岸科学和管理的、同时涉及有效开展面向终端用户的多学科计划所需机构的重要的新知识.     

Juvenile Survival in a Population of Neotropical Migrant Birds

Determination of population productivity of Neotropical migrant birds and assessment of breeding habitat quality have been based on population densities and nesting success. Data on juvenile survival improve our estimates of population productivity, provide information on factors during the post-fledging period that affect this productivity and, with comparative data, enable us to better assess breeding habitat quality. We present the first estimate of post-fledging juvenile survival in a population of Neotropical migrant birds. We studied post-fledging survival in a population of Wood Thrush ( Hylocichla mustelina) in southern Missouri, (U.S.) an area hypothesized to contain source populations. Nesting success during our study period was 0.266, and individual survival within the nest was 0.245. Post-fledging survival during the first 8 weeks after fledging was 0.423. Survival varied significantly between post-fledging weekly age classes, with survival of weeks 1, 2, 3, and 4 through 8 being 0.716, 0.930, 0.637, and 1.00, respectively. Probability of predation after fledging was 0.506. Probability of mortality by other causes was 0.071. Probability of predation varied by weekly age class and may have been related to behaviors occurring at different developmental stages. Post-fledging survival was not correlated with nestling mass and did not change throughout the course of the breeding season. Analysis of the source/sink status of the population based on our estimates of nesting success and post-fledging survival indicates that young were being produced below replacement levels during our study period. Large-scale management decisions should take into account potential fluctuations in the productivity of Neotropical migrant populations over time. Data on post-fledging juvenile survival are needed from other populations of Neotropical migrant birds to more accurately assess differential productivity between populations and better assess breeding habitat quality.     

Female house martins (Delichon urbica) reduce egg androgen deposition in response to a challenge of their immune system

Female birds deposit in the yolks of eggs substantial amounts of androgens, such as testosterone and androstenedione. These androgens have been shown to speed up nestling development, induce a fast development of ornaments and increase dominance in adults. Experiments in several species have reported that females invest greater amounts of androgens in the eggs fathered by attractive males, suggesting that yolk androgen is a costly investment for either the offspring or the mother. There is some evidence that nestling immunocompetence may be partially suppressed by high levels of yolk androgens, but it is not known whether this is also the case for females. We tested this hypothesis in the house martin by inducing an immune challenge through an injection of sheep red blood cells, a standard challenge of the humoral immune system. Experimental birds laid eggs with lower amounts of yolk androstenedione than controls, and there was a similar non-significant trend for testosterone. Furthermore, the probability of laying a replacement clutch was higher for birds that had laid a first clutch with relatively high levels of yolk testosterone. These results suggest that yolk androgen deposition is limited by immune costs in the female, and that only females in good condition may afford to invest high levels of androgen in eggs in this species.     

Aspiration and sampling efficiencies of the TSP and louvered particulate matter inlets

An experimental system was developed for the rapid measurement of the aspiration/transfer efficiency of aerosol samplers in a wind tunnel. We attempted to measure the aspiration and particle transfer characteristics of two inlets commonly used for sampling airborne Particulate Matter (PM): the 'Total Suspended Particulate' or TSP inlet, and the louvered 'dichotomous sampler inlet' typically used in sampling PM10 or PM2.5. We were able to determine the fraction of the external aerosol that enters the inlet and is transferred through it, and hence is available for collection by a filter, or further size fractionation into PM10 or PM2.5. This 'sampling efficiency' was analysed as a function of dimensionless aerodynamic parameters in order to understand the factors governing inlet performance. We found that for the louvered inlet the sampling efficiency increases as the external wind increases. Under all conditions expected in practical use the louvered inlet aspirates sufficient PM to allow either PM10 or PM2.5 to be selected downstream. The TSP inlet's sampling efficiency decreases with increasing external wind, and the TSP inlet is likely to under-sample the coarse end of the PM10 fraction at moderate and high external winds. As this inlet is generally not used with a downstream size fractionator, changes in sampling efficiency directly affect the measured aerosol concentration. We also investigated whether it is possible to dimensionally scale the PM inlets to operate at either higher or lower flow rates, while preserving the same sampling characteristics as the current full-scale, 16.67 L min(-1) versions. In the case of the louvered inlet, our results indicate that scaling to lower flow rates is possible; scaling to higher flow rates was not tested. For the TSP sampler, the sampling efficiency changes if the sampler is scaled to operate at smaller or larger flow rates, leading to unreliable performance.     

Effects of off-road vehicles on coastal foredunes at Fire Island,New York,USA

The effects of off-road vehicles (ORVs) on the dune system of Fire Island National Seashore, New York, USA, were examined through a detailed, two-year field study. The experimental approach was adopted in order to evaluate the environmental effects of ORVs in this zone. Adjacent control and impact sites were established in two locations. Vehicle impacts were applied at the equivalent rate of one vehicle pass per week. Monitoring of foredune vegetation through sequential quadrat surveys and construction of sea-ward limit maps showed a significant loss of vegetation resulting from ORV impacting. Loss of vegetation resulted in an alteration of the natural foredune profile, which could increase dune erosion during storm wave attack.     

Fishermen's interests and cooperation: preconditions for joint management of Swedish coastal fisheries

The participation of fishermen in fisheries management is discussed with varying ideas under the notions of "co-management", "participatory management" or "local management". Empirical studies within Swedish fishery have thrown new light on the preconditions for fishermen's participation in fisheries management. Among the important factors influencing failure or success are the two which we discuss here: the question of articulation, organization and representation of interests of fishermen and the question of trust between the groups that are usually cooperating in resource management, fishermen, governmental administrators and researchers. The research summarized has addressed the interests of fishermen with regard to resource management, local fisheries management, and participation of fishermen. The overarching question connecting the three themes is: How can the interests of fishermen be represented better within fisheries management? Interests and trust, "soft facts", can be as important for the success or failure of fisheries management and participation as can "hard facts" such as ownership rights, quantity and quality of resources or monetary value of resources.     

Aqueous photolysis of the iron (III) complexes of NTA, EDTA and DTPA

The rate of photolysis of iron complexes with three common complexing agents, NTA, EDTA and DTPA was analysed. Aqueous solutions of each complex were illuminated in a Xenotest 1200. Using a sun spectrum from 60°N (Stockholm latitude), environmentally related half lifetimes were calculated.

The half lifetimes were 43, 11 and 8 min for the three 1:1 complexes, resp., dissolved in the top layer of a water system and illuminated at the yearly maximum of sun light in the specified area. In the environment several factors operate to reduce this rate. However, photolytic degradation pathways seem to be an important environmental fate of these substances.     

In situ biodegradation determined by carbon isotope fractionation of aromatic hydrocarbons in an anaerobic landfill leachate plume (Vejen,Denmark)

Concentrations and isotopic compositions (13C/12C) of aromatic hydrocarbons were determined in eight samples obtained from the strongly anoxic part of the leachate plume downgradient from the Vejen Landfill (Denmark), where methanogenic, sulfate-reducing and iron-reducing conditions were observed. Despite the heterogeneous distribution of the compounds in the plume, the isotope fractionation proved that ethylbenzene and m/p-xylene were subject to significant biodegradation within the strongly anoxic plume. The isotope fractionation factors (alphaC) for the degradation of the m/p-xylene (1.0015) and ethylbenzene (1.0021) obtained from the field observations were similar to factors previously determined for the anaerobic degradation of toluene and o-xylene in laboratory experiments, and suggest that in situ biodegradation is one major process controlling the fate of these contaminants in this aquifer. The isotope fractionation determined for 1,2,4-trimethylbenzene and 2-ethyltoluene suggested in situ biodegradation; however, the isotopic composition did not correlate well with the respective concentration as expressed by the Rayleigh equation. Some other compounds (1,2,3-trimethylbenzene, o-xylene, naphthalene and fenchone) did not show significant enrichments in delta13C values along the flow path. The compound concentrations were too low for accurate isotope analyses of benzene, toluene, 1- and 2-methylnaphthalene, while interferences in the chromatography made it impossible to evaluate the isotopic composition for 4-ethyltoluene, 1,3,5-trimethylbenzene and camphor.In addition to demonstrating the potential of assessing isotopic fractionation as a means for documenting the in situ biodegradation of complex mixtures of aromatic hydrocarbons in leachate plumes, this study also illustrates the difficulties for data interpretation in complex plumes and high analytical uncertainties for isotope analysis of organic compounds in low concentration ranges.     

The Rossby Centre Regional Atmospheric Climate Model part I: model climatology and performance for the present climate over Europe

The Rossby Centre Atmospheric Regional Climate Model (RCA2) is described and simulation results, for the present climate over Europe, are evaluated against available observations. Systematic biases in the models mean climate and climate variability are documented and key parameterization weaknesses identified. The quality of near-surface parameters is investigated in some detail, particularly temperature, precipitation, the surface energy budget and cloud cover. The model simulates the recent, observed climate and variability with a high degree of realism. Compensating errors in the components of the surface radiation budget are highlighted and the fundamental causes of these biases are traced to the relevant aspects of the cloud, precipitation and radiation parameterizations. The model has a tendency to precipitate too frequently at small rates, this has a direct impact on the simulation of cloud-radiation interaction and surface temperatures. Great care must be taken in the use of observations to evaluate high resolution RCMs, when they are forced by analyzed boundary conditions. This is particularly true with respect to precipitation and cloudiness, where observational uncertainty is often larger than the RCM bias.