The BEEP project in the Baltic Sea: overview of results and outline for a regional biological effects monitoring strategy   总被引：1，自引：0，他引：1  

Lehtonen KK  Schiedek D  Köhler A  Lang T  Vuorinen PJ  Förlin L  Barsiene J  Pempkowiak J  Gercken J 《Marine pollution bulletin》2006,53(8-9):523-537

Field studies in the framework of the EU funded BEEP project (Biological Effects of Environmental Pollution in Marine Coastal Ecosystems, 2001-2004) aimed at validating and intercalibrating a battery of biomarkers of contaminant exposure and effects in selected indicator species in the Mediterranean, the North Atlantic and the Baltic Seas. Major strategic goals of the BEEP project were the development of a sensitive and cost-efficient biological effects monitoring approach, delivery of information and advice to end-user groups, and the implementation of a network of biomarker researchers around Europe. Based on the main results obtained in the Baltic Sea component of the BEEP the present paper summarises and assesses the applicability of biomarkers for different regions and species in this sea area. Moreover, a general strategy and some practical considerations for the monitoring of biological effects in the Baltic Sea are outlined.  相似文献   

An improved methodology for filling missing values in spatiotemporal climate data set     

Antti Sorjamaa  Amaury Lendasse  Yves Cornet  Eric Deleersnijder 《Computational Geosciences》2010,14(1):55-64

In this paper, an improved methodology for the determination of missing values in a spatiotemporal database is presented. This methodology performs denoising projection in order to accurately fill the missing values in the database. The improved methodology is called empirical orthogonal functions (EOF) pruning, and it is based on an original linear projection method called empirical orthogonal functions (EOF). The experiments demonstrate the performance of the improved methodology and present a comparison with the original EOF and with a widely used optimal interpolation method called objective analysis.  相似文献   

Radiometer studies of low-salinity sea ice     

Martti Tiuri  Martti Hallikainen  Antti Lääperi 《Boundary-Layer Meteorology》1978,13(1-4):361-371

Theoretical and experimental studies of ultra-high-frequency (UHF) and microwave radiometry to sense remotely the thickness and other characteristics of low-salinity (less than one per mille) sea ice are described. The experimental studies used a 600-MHz and a multichannel, multibeam, 4.7-GHz radiometer carried by a helicopter to measure the brightness temperature of different types of sea ice in the Gulf of Bothnia in 1975 and 1976.The developed theory and experiments show that the brightness temperature of low-salinity sea ice oscillates as a function of ice thickness at UHF frequencies. Due to higher attenuation, the oscillations quickly die away at 4.7 GHz and the brightness temperature reaches an almost constant value when the thickness exceeds a few decimetres. By using a three-channel UHF radiometer with suitably selected center frequencies, the oscillations can be reduced and the effective brightness temperature will grow more linearly with the ice thickness.Experiments show that ice ridges appear as thick ice at 600 MHz and as thinner ice at 4.7 GHz, thus allowing them to be detected by radio techniques.  相似文献   

Footprint Evaluation for Flux and Concentration Measurements for an Urban-Like Canopy with Coupled Lagrangian Stochastic and Large-Eddy Simulation Models   总被引：1，自引：1，他引：0  

Antti Hellsten  Sofia-M. Luukkonen  Gerald Steinfeld  Farah Kanani-Sühring  Tiina Markkanen  Leena Järvi  Juha Lento  Timo Vesala  Siegfried Raasch 《Boundary-Layer Meteorology》2015,157(2):191-217

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Asteroid taxonomic signatures from photometric phase curves     

Dagmara Anna Oszkiewicz  Edward Bowell  L.H. Wasserman  Karri Muinonen  Antti Penttilä  Tuomo Pieniluoma  David E. Trilling  Cristina A. Thomas 《Icarus》2012,219(1):283-296

We explore the correlation between an asteroid’s taxonomy and photometric phase curve using the H, G₁₂ photometric phase function, with the shape of the phase function described by the single parameter G₁₂. We explore the usability of G₁₂ in taxonomic classification for individual objects, asteroid families, and dynamical groups. We conclude that the mean values of G₁₂ for the considered taxonomic complexes are statistically different, and also discuss the overall shape of the G₁₂ distribution for each taxonomic complex. Based on the values of G₁₂ for about half a million asteroids, we compute the probabilities of C, S, and X complex membership for each asteroid. For an individual asteroid, these probabilities are rather evenly distributed over all of the complexes, thus preventing meaningful classification. We then present and discuss the G₁₂ distributions for asteroid families, and predict the taxonomic complex preponderance for asteroid families given the distribution of G₁₂ in each family. For certain asteroid families, the probabilistic prediction of taxonomic complex preponderance can clearly be made. In particular, the C complex preponderant families are the easiest to detect, the Dora and Themis families being prime examples of such families. We continue by presenting the G₁₂-based distribution of taxonomic complexes throughout the main asteroid belt in the proper element phase space. The Nysa–Polana family shows two distinct regions in the proper element space with different G₁₂ values dominating in each region. We conclude that the G₁₂-based probabilistic distribution of taxonomic complexes through the main belt agrees with the general view of C complex asteroid proportion increasing towards the outer belt. We conclude that the G₁₂ photometric parameter cannot be used in determining taxonomic complex for individual asteroids, but it can be utilized in the statistical treatment of asteroid families and different regions of the main asteroid belt.  相似文献   

Causes, effects and control of seasonal frost action in railways     

Antti Nurmikolu  Mika Silvast 《寒旱区科学》2013,5(4):0363-0367

Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain track geometry. Challenges culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased track maintenance and need for temporary speed restrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on non-frost-susceptible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and subsoil in frost action. In new construction the material specifications, design procedures and construction methods have been developed to ensure adequate performance of track substructures, but special challenges exist in managing existing tracks that were not designed for modern requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on integration of track geometry and ground penetrating radar (GPR) data has been developed and is summarized in this paper.  相似文献   

Emplacement and inflation of natrocarbonatitic lava flows during the March–April 2006 eruption of Oldoinyo Lengai,Tanzania     

Hannes B. Mattsson  Jaana Vuorinen 《Bulletin of Volcanology》2009,71(3):301-311

The most voluminous eruption of natrocarbonatite lava hitherto recorded on Earth occurred at Oldoinyo Lengai in March–April 2006. The lava flows produced in this eruption range from blocky 'a'a type to smooth-surfaced inflated pahoehoe. We measured lava inflation features (i.e. one tumulus and three pressure ridges) that formed in the various pahoehoe flows emplaced in this event. The inflation features within the main crater of Oldoinyo Lengai are relatively small-scale, measuring 1-5 m in width, 2.5–24.4 m in length and with inflation clefts less than 0.4 m deep. Their small sizes are in contrast to a tumulus that formed on the northwestern slope of the volcano (situated ~1140 m below the crater floor). The tumulus is roughly circular, measures 17.5 × 16.0 m, and is cut by a 4.4 m deep axial inflation cleft exposing two separate flow units. We measured the elastic properties (i.e. shear- and bulk moduli) of natrocarbonatitic crust and find that these are similar to those reported for basaltic crust, and that there is no direct correlation between magmastatic head and pressure required to form tumuli. All inflated flows in the 2006 event were confined by lateral barriers (main crater, erosional channel or erosional gully) suggesting that the two most important factors for endogenous growth in natrocarbonatitic lava flows are (1) lateral barriers that prevent widening of the flow, and (2) influx of new material beneath the viscoelastic and brittle crust.  相似文献   

The dependence of organohalogen compound concentrations on herring age and size in the Bothnian Sea, northern Baltic     

Parmanne R  Hallikainen A  Isosaari P  Kiviranta H  Koistinen J  Laine O  Rantakokko P  Vuorinen PJ  Vartiainen T 《Marine pollution bulletin》2006,52(2):149-161

The concentrations and composition profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, polybrominated diphenyl ethers and polychlorinated naphthalenes were determined in herring individuals collected from the commercial catches of the Bothnian Sea, northern Baltic. The median age of herring was 5.0 years and in the muscle the median toxic equivalent concentration of PCDD/Fs was 5.6 WHO(PCDD/F)-TEQ pg/g fresh weight (fw) and that of PCBs 2.7 WHO(PCB)-TEQ pg/g fw. The median sum concentration of PBDEs was 1.4 ng/g fw and that of PCNs 0.1 ng/g fw. Differences in age-dependent accumulation between the organohalogen groups and individual congeners were major. In the Bothnian Sea the content of organohalogen compounds in herring is obviously elevated due to the availability and large proportion of Mysis crustaceans in their diet. More intensive fishing could reduce the concentrations of organohalogens, including the abundant, accumulative and toxic 2,3,4,7,8-PeCDF congener in the Baltic herring catch.  相似文献   

Incremental distributed modelling investigation in a small agricultural catchment: 1. Overland flow with comparison with the unit hydrograph model     

Antti Taskinen  Michael Bruen 《水文研究》2007,21(1):80-91

A distributed overland flow model is presented and the test results compared with those of the unit hydrograph (UH) model. Infiltration excess in the overland model was calculated using both a modified Green and Ampt (G–A) method and a more complicated method that keeps track of the soil moisture content. The two‐dimensional partial differential flow equations with kinematic flow approximation were solved using both backward‐central explicit and implicit finite‐difference schemes. Moreover, a baseflow component was added to the flow model. Each part of the model was built by replacing a process by a parallel process or by adding a completely new component. When the model was developed and validated in small agricultural fields in southern Finland, comparisons were made between corresponding processes and the significance of added components were estimated in order to find out whether increased model complexity improves the model performance. Apart from the basic model, all the other distributed models outperformed the UH approach. The implicit scheme was clearly more accurate than the explicit scheme, and the baseflow component improved the results significantly. There was no major difference between the performances of the infiltration models, but the G–A method was more stable and much faster. The approaches that were best in the calibration were also the best in the verification. The full distributed model provides a potential method for running water‐quality models and testing their different processes. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Incremental distributed modelling investigation in a small agricultural catchment: 2. Erosion and phosphorus transport     

Antti Taskinen  Michael Bruen 《水文研究》2007,21(1):92-102

Distributed physically based erosion and phosphorus (P) transport models, run by the overland flow model described in Taskinen and Bruen (2006. Hydrological Processes 20 : this issue), are described. In the erosion model, the additional components to the basic model were the outflow of the particles by infiltration and a new model component, i.e. deposition when rainfall stops. Two ways of calculating the shielding factor due to the flow depth were compared. The P transport model had both dissolved P (DP) and particulate P (PP) components. The processes included in the DP model were desorption from the soil surface, advection, storage in the overland flow and infiltration. The PP model accounted for advection, storage in the flow, infiltration, detachment from the soil surface by flow and rainfall and deposition both when transport capacity of suspended solids (SS) is exceeded and when rainfall ceases. When the models were developed and validated in small agricultural fields of cohesive soil types in southern Finland, comparisons were made between corresponding processes and the significance of added components were estimated in order to find out whether increased model complexity improves the model performance. The sedigraphs were found to follow the dynamics of rainfall, emphasizing the importance of the rainfall splash component. The basic model was too slow to react to changes in rainfall and flow rates, but infiltration and deposition that acts during the cessation in rainfall improved the model significantly by enabling the modelled SS to fall sharply enough. The shielding effect of flow depth from the splash detachment was found to play a significant role. Transport capacity should also be included in erosion models when they are applied to cohesive soils. In this study, the Yalin method worked well. A strong correlation was obvious between the measured SS and total P concentrations, indicating that the main form of P in runoff is PP. This emphasizes the importance of a good sediment transport model in P transport modelling. The submodel used for DP desorption from the soil surface produced plausible results without any calibration. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献