The fragility of robust social-ecological systems     

John M. Anderies  Marco A. Janssen 《Global Environmental Change》2011,21(4):1153-1156

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Microwave remote sensing of Jupiter's atmosphere from an orbiting spacecraft     

M.A. Janssen  M.D. Hofstadter  A.P. Ingersoll  S.J. Bolton  L.W. Kamp 《Icarus》2005,173(2):447-453

Microwave remote sounding from a spacecraft flying by or in orbit around Jupiter offers new possibilities for retrieving important and presently poorly understood properties of its atmosphere. In particular, we show that precise measurements of relative brightness temperature as a function of off-nadir emission angles, combined with absolute brightness temperature measurements, can allow us to determine the global abundances of water and ammonia and study the dynamics and deep circulations of the atmosphere in the altitude range from the ammonia cloud region to depths greater than 30 bars in a manner which would not be achievable with ground-based telescopes.  相似文献   

Assessment of marine debris on the Belgian Continental Shelf   总被引：2，自引：0，他引：2  

Lisbeth Van Cauwenberghe  Michiel Claessens  Michiel B. Vandegehuchte  Jan Mees  Colin R. Janssen 《Marine pollution bulletin》2013

A comprehensive assessment of marine litter in three environmental compartments of Belgian coastal waters was performed. Abundance, weight and composition of marine debris, including microplastics, was assessed by performing beach, sea surface and seafloor monitoring campaigns during two consecutive years. Plastic items were the dominant type of macrodebris recorded: over 95% of debris present in the three sampled marine compartments were plastic. In general, concentrations of macrodebris were quite high. Especially the number of beached debris reached very high levels: on average 6429 ± 6767 items per 100 m were recorded. Microplastic concentrations were determined to assess overall abundance in the different marine compartments of the Belgian Continental Shelf. In terms of weight, macrodebris still dominates the pollution of beaches, but in the water column and in the seafloor microplastics appear to be of higher importance: here, microplastic weight is approximately 100 times and 400 times higher, respectively, than macrodebris weight.  相似文献   

Effect of irrigation with olive mill wastewater on soil hydraulic and solute transport properties     

O. Mohawesh  M. Mahmoud  M. Janssen  B. Lennartz 《International Journal of Environmental Science and Technology》2014,11(4):927-934

To evaluate the effect of olive mill wastewater (OMW) application on soil hydraulic and transport properties, two treatment sites, which had been irrigated with OMW for 5 and 15 years, and one control site being irrigated with freshwater were compared. The transport and leaching experiment results showed that a portion of the total soil water was available for transport processes while the remaining of the soil water was considered immobile and not readily accessible for solutes. The separation in water fractions of different mobilities was surprisingly consistent among OMW treatments. The bromide recovery rate decreased with the application of OMW showing that tracer molecules became trapped within immobile water phases. The application of OMW increased significantly the soil water-holding capacity, whereas the soil hydraulic conductivity in the near saturation range decreased significantly with long-term OMW application. The soil irrigated with OMW had significantly higher organic matter content, lower bulk density and relatively higher total porosity, but lower macroporosity than that of control sites. We concluded that the soil was increasingly coated with complex organic molecules originating from OMW, as a result, solute exchange between inter- and intrasoil aggregate water was hindered. Although OMW could cause soil and water pollution, its use in agriculture is promoted because of high nutrients and organic matter contents.  相似文献   

Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model   总被引：1，自引：1，他引：0  

Victor Alari  Joanna Staneva  Øyvind Breivik  Jean-Raymond Bidlot  Kristian Mogensen  Peter Janssen 《Ocean Dynamics》2016,66(8):917-930

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Titan's surface from the Cassini RADAR radiometry data during SAR mode     

F. Paganelli  M.A. Janssen  E. Stofan  R.D. Lorenz  R.L. Kirk  C. Elachi  The Cassini Radar Team 《Planetary and Space Science》2008,56(1):100-108

We present initial results on the calibration and interpretation of the high-resolution radiometry data acquired during the Synthetic Aperture Radar (SAR) mode (SAR-radiometry) of the Cassini Radar Mapper during its first five flybys of Saturn's moon Titan.We construct maps of the brightness temperature at the 2-cm wavelength coincident with SAR swath imaging. A preliminary radiometry calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section σ⁰ versus brightness temperature, outlining signatures that characterize various terrains and surface features. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties.  相似文献   

Property rights on genetic resources: economic issues     

Josef Janssen   《Global Environmental Change》1999,9(4):197

Biodiversity loss is one of the major international environmental problems. This paper analyses the question of how the use of genetic and biochemical resources in biotechnological industries might affect biodiversity conservation. It is argued that the answer will significantly depend on the concrete regimes of property rights on genetic resources and related biotechnological knowledge. One of the main conclusions derivable from this analysis is that a tightening of intellectual property rights may either aggravate biodiversity loss or strengthen biodiversity conservation, depending on various conditions. This result has interesting parallels to the results of second best theory. Furthermore it sheds new light on the debate regarding the relationship between the WTO Agreement on trade-related aspects of intellectual property rights (TRIPs) and biodiversity loss.  相似文献   

Compound response of marine and terrestrial ecosystems to varying climate: pre-anthropogenic perspective from bivalve shell growth increments and tree-rings     

Helama S  Schöne BR  Kirchhefer AJ  Nielsen JK  Rodland DL  Janssen R 《Marine environmental research》2007,63(3):185-199

Annual growth increments were examined from shells of the ocean quahog (Arctica islandica L.) from northwest Norway and from tree-ring samples of the Scots pine (Pinus sylvestris L.) from nearby coastal areas. The reconstructed annual growth increments were used to compare growth variability in marine and terrestrial ecosystems. Spatiotemporal comparison of the growth records showed statistically significant correlation during the 19th century A.D., indicative of ecosystem-independent response to pre-anthropogenic climate variations. Geographical correlation between marine and terrestrial records was only observed at the local scale. Years with particularly low winter or high summer North Atlantic Oscillation (NAO) indices showed the best synchronization of marine and terrestrial growth. Despite strong correlation during historical time, our palaeoecological evidence suggests that marine and terrestrial ecosystems may show dissimilar growth reaction to recently observed positive winter-NAO phases.  相似文献   

Nanoscale porosity in SAFOD core samples (San Andreas Fault)     

Christoph Janssen  Richard Wirth  Andreas Reinicke  Erik Rybacki  Rudolf Naumann  Hans-Rudolf Wenk  Georg Dresen 《Earth and Planetary Science Letters》2011,301(1-2):179-189

With transmission electron microscopy (TEM) we observed nanometer-sized pores in four ultracataclastic and fractured core samples recovered from different depths of the main bore hole of the San Andreas Fault Observatory at Depth (SAFOD). Cutting of foils with a focused ion beam technique (FIB) allowed identifying porosity down to the nm scale. Between 40 and 50% of all pores could be identified as in-situ pores without any damage related to sample preparation. The total porosity estimated from TEM micrographs (1–5%) is comparable to the connected fault rock porosity (2.8–6.7%) estimated by pressure-induced injection of mercury. Permeability estimates for cataclastic fault rocks are 10^? 21–10^? 19 m² and 10^? 17 m² for the fractured fault rock. Porosity and permeability are independent of sample depth. TEM images reveal that the porosity is intimately linked to fault rock composition and associated with deformation. The TEM-estimated porosity of the samples increases with increasing clay content. The highest porosity was estimated in the vicinity of an active fault trace. The largest pores with an equivalent radius > 200 nm occur around large quartz and feldspar grains or grain-fragments while the smallest pores (equivalent radius < 50 nm) are typically observed in the extremely fine-grained matrix (grain size < 1 μm). Based on pore morphology we distinguish different pore types varying with fault rock fabric and alteration. The pores were probably filled with formation water and/or hydrothermal fluids at elevated pore fluid pressure, preventing pore collapse. The pore geometry derived from TEM observations and BET (Brunauer, Emmett and Teller) gas adsorption/desorption hysteresis curves indicates pore blocking effects in the fine-grained matrix. Observations of isolated pores in TEM micrographs and high pore body to pore throat ratios inferred from mercury injection suggest elevated pore fluid pressure in the low permeability cataclasites, reducing shear strength of the fault.  相似文献   

Radar-bright channels on Titan     

A. Le Gall  M.A. Janssen  R.D. Lorenz  the Cassini Radar Team 《Icarus》2010,207(2):948-958

During Cassini’s T44 flyby of Titan (May 28, 2008), the Cassini SAR (synthetic aperture radar) revealed sinuous channels in the Southwest of Xanadu. These channels feature very large radar cross-sections, up to 5 dB, whereas the angle of incidence was relatively high, ∼20°. This backscatter is larger than allowed by the coherent backscatter model considered to explain the unusual reflective and polarization properties of the icy satellites and only a few radar scattering mechanisms can be responsible for such high radar returns. The presence of rounded (icy) pebbles with size larger than the radar wavelength (2.18 cm) is proposed to explain the large radar cross-sections measured in these units. The radar-bright channels are thus interpreted as riverbeds, where debris, likely shaped and transported by fluvial activity, have been deposited. Similar debris were observed in the landing site of the Huygens probe. This work may point the way to an explanation for the enhanced brightness of other fluvial regions of Titan.  相似文献