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   

Developmental disorders in larvae of eelpout (Zoarces viviparus) from German and Swedish Baltic coastal waters     

Gercken J  Förlin L  Andersson J 《Marine pollution bulletin》2006,53(8-9):497-507

Pregnant eelpout were collected for several years at German and Swedish Baltic coastal stations with different impact of pollutants and the prevalence of fry abnormalities compared between sites. Mortality of apparently normal developed larvae was observed with high variability in both German and Swedish sites. Malformation of larvae was a prominent disorder at all German stations with a prevalence ranging from about 50% up to a maximum of 90% in almost all analysed samples. At the Swedish stations malformation rates were significantly lower (range: 0-6%). Growth retardation of fry was clearly more prominent in eelpout from German coastal waters as well. Taken together the field data suggests that impaired larval development was associated with the state of environmental pollution at the sampling locations.  相似文献   

Shergottites Dhofar 019, SaU 005, Shergotty,and Zagami: 40Ar‐39Ar chronology and trapped Martian atmospheric and interior argon     

Ekaterina V. KOROCHANTSEVA  Mario TRIELOFF  Alexei I. BUIKIN  Jens HOPP 《Meteoritics & planetary science》2009,44(2):293-321

Abstract— We report a high‐resolution ⁴⁰Ar‐³⁹Ar study of mineral separates and whole‐rock samples of olivine‐phyric (Dhofar 019, Sayh al Uhaymir [SaU] 005) and basaltic (Shergotty, Zagami) shergottites. Excess argon is present in all samples. The highest (⁴⁰Ar/³⁶Ar)_trapped ratios are found for argon in pyroxene melt inclusions (?1500), maskelynite (?1200), impact glass (?1800) of Shergotty and impact glass of SaU 005 (?1200). A high (⁴⁰Ar/³⁶Ar)_trapped component‐usually uniquely ascribed to Martian atmosphere‐can also originate from the Martian interior, indicating a heterogeneous Martian mantle composition. As additional explanation of variable high (⁴⁰Ar/³⁶Ar)_trapped ratios in shocked shergottites, we suggest argon implantation from a “transient atmosphere” during impact induced degassing. The best ⁴⁰Ar‐³⁹Ar age estimate for Dhofar 019 is 642 ± 72 Ma (maskelynite). SaU 005 samples are between 700–900 Ma old. Relatively high ⁴⁰Ar‐³⁹Ar ages of melt inclusions within Dhofar 019 (1086 ± 252 Ma) and SaU 005 olivine (885 ± 66 Ma) could date entrapment of a magmatic liquid during early olivine crystallization, or reflect unrecognized excess ⁴⁰Ar components. The youngest ⁴⁰Ar‐³⁹Ar age of Shergotty separates (maskelynite) is ?370 Ma, that of Zagami is ?200 Ma. The ⁴⁰Ar‐³⁹Ar chronology of Dhofar 019 and SaU 005 indicate >1 Ga ages. Apparent ages uncorrected for trapped (e.g., Martian atmosphere, mantle) argon components approach 4.5 Ga, but are not caused by inherited ⁴⁰Ar, because excess ⁴⁰Ar is supported by ³⁶Ar_trapped. Young ages obtained by ⁴⁰Ar‐³⁹Ar and other chronometers argue for primary rather than secondary events. The cosmic ray exposure ages calculated from cosmogenic argon are 15.7 ± 0.7 Ma (Dhofar 019), 1.0–1.6 Ma (SaU 005), 2.1–2.5 Ma (Shergotty) and 2.2–3.0 Ma (Zagami).  相似文献   

Zoning of platinum group mineral assemblages in the UG2 chromitite determined through in situ SEM-EDS-based image analysis   总被引：1，自引：0，他引：1  

Ronald J. Voordouw  Jens Gutzmer  Nicolas J. Beukes 《Mineralium Deposita》2010,45(2):147-159

In situ scanning electron microscopy–energy dispersive X-ray spectrometry analysis of platinum group minerals (PGM) and base metal sulfides in the UG2 chromitite shows that this ore body is zoned along at least ∼6 km of strike. The uppermost part of the UG2 chromitite, referred to as the leader seam, is ∼16 cm thick and has a PGM assemblage that is dominated by PGE arsenides, sulpho-arsenides, and alloys (∼70 vol.% of all PGM), which are typical secondary PGM assemblages in other segments of UG2. This is the first time such laterally persistent secondary assemblages have been identified in the UG2 chromitite, as previously, they were only known to occur adjacent to transgressive fluid-bearing structures (e.g., pipes, faults). The underlying main seam is thicker (one to nine seams totaling ∼130 cm) and has a PGM assemblage that consists mostly of Pt sulfide, Pt–Pd sulfide, Pt–Rh–Cu sulfide, laurite, and Fe–Pt alloys (∼85 vol.% of all PGM), typically regarded as primary magmatic constituents of UG2 chromitite. There are, however, some subtle vertical changes in the PGM assemblages of the main seam that include the occasional presence of secondary assemblages in the top and bottom parts. The origin of these secondary PGM assemblages is related to alteration by hydrothermal fluids and/or fluid-rich melts that infiltrated during crystallization of the UG2 and may possibly have been derived from the UG2 chromitite itself.  相似文献   

A critical political ecology of cotton and soil fertility in Mali     

Tor A. Benjaminsen  Jens B. Aune 《Geoforum》2010,41(4):647-656

The aim of this article is to analyse the influence of commodified cotton production on soil fertility in southern Mali. From the late 1950s and until recently, production of both cash-crop cotton and food crops have increased rapidly in this region, giving it a reputation of being an African ‘success story’. The flip side of this economic success is, however, said to be environmental degradation especially in terms of loss of soil fertility. We collected 273 soil samples in 19 villages located in various zones of land use intensity. In each village, the samples were collected on up to six different land use types varying with intensification. The analysis of the soil samples showed that soil fertility was highest in the sacred groves that have been protected and never cultivated. However, comparing soils under continuous cultivation and soils under fallow no clear trends in soil fertility were found. Cotton yields have declined since the early 1990s, while the total use of fertilisers has increased. This is often interpreted as proof of soil exhaustion, but there is no clear indication in this study that cotton-cereal rotation as practiced by smallholders in southern Mali reduces soil fertility. We argue that the decline in yields has been caused by an extensification process. Cotton fields expanded rapidly, due to attractive cotton prices in the 1990s, leading to falling investments per ha and cultivation of more marginal lands. These findings also have implications for a political ecology of commodity production and lead us to argue for an open-ended and empirically based ‘critical political ecology’.  相似文献   

Experiments on the photophoretic motion of chondrules and dust aggregates—Indications for the transport of matter in protoplanetary disks     

Gerhard Wurm  Jens Teiser  Henning Haack 《Icarus》2010,208(1):482-491

In a set of 16 drop tower experiments the motion of sub-millimeter to millimeter-sized particles under microgravity was observed. Illumination by a halogen lamp induced acceleration of the particles due to photophoresis. Photophoresis on dust-free chondrules, on chondrules, glass spheres and metal spheres covered with SiC dust and on pure SiC dust aggregates was studied. This is the first time that photophoretic motion of millimeter-sized particles has been studied experimentally. The absolute values for the photophoretic force are consistent with theoretical expectations for spherical particles. The strength of the photophoretic force varies for chondrules, dust covered particles and pure dust from low to strong, respectively. The measurements support the idea that photophoresis in the early Solar System can be efficient to transport solid particles outward.  相似文献   

How to survive a Lunar night     

Stephan Ulamec  Jens Biele  Ed Trollope 《Planetary and Space Science》2010,58(14-15):1985-1995

In the frame of the recent worldwide activities of Lunar research, including various studies for surface stations, the aspect of longevity of such stations has been identified as a particular technical challenge. The reason for this lies in the long (about 14 days) and cold Lunar night during which it is non-trivial to keep spacecraft systems alive and sensitive equipment within an acceptable temperature range.The following paper analyzes and compares various concepts to survive Lunar night, both with and without radioisotope heater technology.The latter normally implies the use of highly toxic material (typically plutonium), which is politically problematic and a driver for cost and safety procedures.Concepts without radioisotope heating need to foresee special measures, like extremely efficient thermal insulation or sub-surface positioning of all temperature sensitive components.Special emphasis has been taken on the thermal analysis of a penetrator-type surface station. The relevant issues are discussed and results for day–night cycles are presented, assuming a typical set of engineering parameters. This concept appears to be the easiest to implement from a thermal point of view, if the use of radioisotope heaters has to be avoided.  相似文献   

Eckfeld Maar: Window into an Eocene Terrestrial Habitat in Central Europe   总被引：1，自引：1，他引：0  

Herbert Lutz  Uwe KaulfuSS  Torsten Wappler  Werner L?hnertz  Volker Wilde  Dieter F. Mertz  Jens Mingram  Jens L. Franzen  Herbert Frankenh?user  Martin Koziol 《《地质学报》英文版》2010,84(4):984-1009

<正>To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010,we present a short account of our present knowledge of the Eckfeld Maar after 20 years of continuous research.This paper does not attempt to include all of the detailed results on the geology of the Eckfeld site or its biota.To date,nearly 250 papers and books have been published since the start of our project.An up-to-date list of these publications can be found at www.eckfeldermaar. de.  相似文献   

Reply to comment on “Groundwater monitoring in Denmark: characteristics, perspectives and comparison with other countries”: report published in Hydrogeology Journal (2009) 17:827–842, by Lisbeth Flindt Jørgensen, Jens Stockmarr     

Lisbeth Flindt Jørgensen  Jens Stockmarr 《Hydrogeology Journal》2010,18(3):805-806

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Predicting riverine dissolved silica fluxes to coastal zones from a hyperactive region and analysis of their first-order controls   总被引：2，自引：1，他引：1  

Jens Hartmann  Nils Jansen  Hans H. Dürr  Akira Harashima  Kenji Okubo  Stephan Kempe 《International Journal of Earth Sciences》2010,99(1):207-230

Silicate weathering and resulting transport of dissolved matter influence the global carbon cycle in two ways. First by the uptake of atmospheric/soil CO₂ and second by providing the oceanic ecosystems via the fluvial systems with the nutrient dissolved silica (DSi). Previous work suggests that regions dominated by volcanics are hyperactive or even “hot spots” concerning DSi-mobilization. Here, we present a new approach for predicting DSi-fluxes to coastal zones, emphasizing “first-order” controlling factors (lithology, runoff, relief, land cover and temperature). This approach is applied to the Japanese Archipelago, a region characterized by a high percentage of volcanics (29.1% of surface area). The presented DSi-flux model is based on data of 516 catchments, covering approximately 56.7% of the area of the Japanese Archipelago. The spatial distribution of lithology—one of the most important first order controls—is taken from a new high resolution map of Japan. Results show that the Japanese Archipelago is a hyperactive region with a DSi-yield 6.6 times higher than the world average of 3.3 t SiO₂ km⁻² a⁻¹, but with large regional variations. Approximately 10% of its area exceeds 10 times the world average DSi-yield. Slope constitutes another important controlling factor on DSi-fluxes besides lithology and runoff, and can exceed the influence of runoff on DSi-yields. Even though the monitored area on the Japanese Archipelago stretches from about 31° to 46°N, temperature is not identified as a significant first-order model variable. This may be due to the fact that slope, runoff and lithology are correlated with temperature due to regional settings of the Archipelago, and temperature information is substituted to a certain extent by these factors. Land cover data also do not improve the prediction model. This may partly be attributed to misinterpreted land cover information from satellite images. Implications of results for Earth System and global carbon cycle modeling are discussed.  相似文献