Voracious planktonic hydroids: unexpected predatory impact on a coastal marine ecosystem     

Laurence P. Madin  Stephen M. Bollens  Erich Horgan  Mari Butler  Jeffrey Runge  Barbara K. Sullivan  Grace Klein-Macphee  Edward Durbin  Ann G. Durbin  Donna Van Keuren  Stphane Plourde  Ann Bucklin  M. Elizabeth Clarke 《Deep Sea Research Part II: Topical Studies in Oceanography》1996,43(7-8)

Hydroids are typically attached, benthic cnidarians that feed on a variety of small prey. During sampling on Georges Bank in spring 1994, we found huge numbers of hydroids suspended in the plankton. They fed on young stages of copepods that are an important prey for fish, as well as on young fish themselves. Two independent methods were used to estimate feeding rates of the hydroids; both indicate that the hydroids are capable of consuming from 50% to over 100% of the daily production of young copepods. These results suggest that hydroids can have a profound effect on the population dynamics of zooplankton and young fish on Georges Bank.  相似文献   

Geochemical and hydrodynamic constraints on the distribution of trace metal concentrations in the lagoon of Nouméa, New Caledonia   总被引：1，自引：0，他引：1  

Christophe Migon  Sylvain Ouillon  Xavier Mari  Emmanuel Nicolas 《Estuarine, Coastal and Shelf Science》2007,74(4):756

Seawater samples were collected in the lagoon of Nouméa (southwest New Caledonia) along two transects from eutrophic coastal bays to the oligotrophic barrier reef. Land-based emissions to the lagoon were measured with dissolved and particulate concentrations of chromium (Cr) and nickel (Ni), used as tracers of both terrigenous and industrial (Ni ore treatment) activities, as well as dissolved and particulate concentrations of zinc (Zn), used as a tracer of urban effluents. The spatial variability of metal concentrations was related to geochemical and hydrodynamic conditions, i.e., respectively: (1) natural and anthropogenic emission sources, and chemical processes occurring in the water column; and (2) water residence times. The parameter used to describe the residence time of water masses was the local e-flushing time, i.e. the time required for a tracer mass contained within a given station to be reduced by a factor 1/e. High metal concentrations were found in coastal areas (up to 9000 ng dissolved Ni L⁻¹), and steeply decreased with distance from the coast (down to 101 ng dissolved Ni L⁻¹ near the barrier reef) to reach levels similar to those found in remote Pacific waters, suggesting a rapid renewal of waters close to the barrier. Distributions of metals in the lagoon are controlled upstream by land-based emission sources and later chemical processes. Then hydrodynamics constrain metal distributions, as shown by the observed relationship between local e-flushing times and the spatial variability of metal concentrations. In addition, a change in the direction of prevailing winds yielded a decrease of dissolved metal concentrations at the same site by a factor of 2.5 (Cr and Ni) and 2.9 (Zn). It is suggested that the residence time is a key parameter in the control of elemental concentrations in the lagoon waters, as much as land-based emission sources.  相似文献   

Doubtful Events Reported in Current Italian Earthquake Catalogues: The Medieval Earthquakes of Subiaco (Central Italy)     

Di Giovambattista  Rita  Tertulliani  Andrea  Zaccaria  Mari 《Natural Hazards》1997,16(1):39-55

Within the framework of a study of the seismicity of the Aniene Valley (Central Italy), we analysed the medieval earthquakes of Subiaco (1216, 1227, 1299), the largest events reported for the area. Our main goal was to investigate some doubtful events reported in earthquake catalogues and, as such, currently utilised for seismic hazard estimates. A careful screening of the oldest available sources and their filiation pattern up to the present pointed out the uncertainty on the date and nature of these phenomena. A multidisciplinary approach based on the joint analysis of archaeological, geomorphologic and historical evidence allowed us to propose new interpretations concerning these events and their significance for the assessment of seismic hazard in the Aniene Valley. The main conclusion is that the dates of the 1216 and 1227 events are fairly unsupported. In particular, the 1216 earthquake could be dated back to between AD 1159 and 1181.  相似文献   

Curvature derived from LiDAR digital elevation models as simple indicators of debris-flow susceptibility     

Atsuko NONOMURA  Shuichi HASEGAWA  Hideo MATSUMOTO  Mari TAKAHASHI  Mina MASUMOTO  Kazuhito FUJISAWA 《山地科学学报》2019,(1)

To mitigate the damage caused by debris flows resulting from heavy precipitation and to aid in evacuation plan preparation, areas at risk should be mapped on a scale appropriate for affected individuals and communities. We tested the effectiveness of simply identifying debris-flow hazards through automated derivation of surface curvatures using LiDAR digital elevation models. We achieved useful correspondence between plan curvatures and areas of existing debris-flow damage in two localities in Japan using the analysis of digital elevation models(DEMs). We found that plan curvatures derived from 10 m DEMs may be useful to indicate areas that are susceptible to debris flow in mountainous areas. In residential areas located on gentle sloping debris flow fans, the greatest damage to houses was found to be located in the elongated depressions that are connected to mountain stream valleys. Plan curvaturederived from 5 m DEM was the most sensitive indicators for susceptibility to debris flows.  相似文献   

Changing human-environment interactions in medium mountains: the Apuseni Mts (Romania) as a case study     

Tamás Telbisz  Zoltán Imecs  László Mari  Zsolt Bottlik 《山地科学学报》2016,13(9):1675-1687

The study of human-environment relationships in mountain areas is important for both theoretical and practical reasons, as many mountain areas suffer similar problems, such as depopulation, unemployment and natural hazards. Medium mountains constitute a special case within mountains, because they are more populated but less attractive as tourist destinations than high mountains. In this context, the Apuseni Mts (Romania) are considered as a case study. In this paper, we apply GIS-based, quantitative methods to characterize the strength and dynamics of human-environment interactions, taking into consideration some environmental factors (elevation, relative height, slope, river distance, lithology, land cover, natural attractions) as well as historical population and recent tourism data. We found that population density has strong (r ²>0.8) relationships with all relief factors (elevation, relative height, slope, river distance), and that best-fit functions are nonlinear. We outlined the varying demographic scenarios by elevation zones and interpreted the historically switching sign of population change versus elevation relationship. We demonstrated that lithology also has an impact on the spatial distribution of population, although it is not independent from the relief effect. The land cover of the mainly cultural landscape is very strongly correlated with relief parameters (especially slope), which suggests good adaptation. We pointed out the dominance of karst objects in the natural tourism potential of the Apuseni Mts and also explored further components of real tourism (spas, heritage, towns). Finally, we concluded that the environmental settings investigated do in fact constrain the spatial framework of society, but socio-economic changes in history can be explained from the side of society, which conforms to the theory of cultural possibilism.  相似文献   

Potential of mosques to serve as evacuation shelters for foreign Muslims during disasters: a case study in Gunma,Japan     

Kotani  Hitomu  Tamura  Mari  Li  Jiayue  Yamaji  Eiji 《Natural Hazards》2021,109(2):1407-1423

Natural Hazards - Foreigners tend to be vulnerable to disasters due to religious and cultural differences. In Japan, Muslim foreign residents, who are minorities, likely face difficulties in terms...  相似文献   

Persistent organochlorine residues in sediments from the Chukchi Sea, Bering Sea and Gulf of Alaska   总被引：14，自引：0，他引：14  

Hisato Iwata  Shinsuke Tanabe  Mari Aramoto  Norio Sakai  Ryo Tatsukawa 《Marine pollution bulletin》1994,28(12):746-753

Three surface sediments and two sediment cores were collected from the Gulf of Alaska, Bering Sea and Chukchi Sea, and analysed for persistent organochlorines (OCs). The geographical distributions of OCs showed different patterns according to their physicochemical properties. The concentrations of HCHs and HCB revealed rather uniform distribution, suggesting their more transportable nature in long-range atmospheric transport. On the other hand, DDTs and PCBs were predicted to be less transportable via the atmosphere due to the decreasing trends of residue levels in sediments from south to north. The OC profiles in the sediment core from the Gulf of Alaska which seemed to be preserved without turbation revealed the elevated residue levels from bottom to surface layers. This implies that the aerial inputs of OCs in the cold ocean are still continuing significantly. The accumulation rates of OCs into sediments were rather smaller than the atmospheric inputs, indicating that the residue levels in water bodies are unlikely to decrease rapidly in the near future.  相似文献   

Measurements of N2O photolysis coefficients in the stratosphere: Comparison with model calculations     

D. Marić  W. Hans  U. Schurath 《Journal of Atmospheric Chemistry》1989,8(1):19-40

A balloon-borne continuous actinometer has been developed which measures stratospheric N₂O photolysis coefficients, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOAamaaBa% aaleaacaGGobWaaSbaaWqaaiaaikdaaeqaaSGaci4taiabg2da9iab% gkHiTiGacsgaciGGSbGaaiOBaiaacIcaciGGobWaaSbaaWqaaiaaik% daaeqaaSGaci4taiGacMcacaGGVaGaciizaiaadshaaeqaaaaa!44F2!\[j_{N_2 \operatorname{O} = - \operatorname{d} \ln (\operatorname{N} _2 \operatorname{O} )/\operatorname{d} t} \], with a time resolution of approximately 100 s, and a lower detection limit approaching 10^-10 s^-1. The instrument performed successfully, or was at least partially successful, on five stratospheric balloon flights between October 1982 and September 1986. The experimental profiles are compared with model calculations of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOAamaaBa% aaleaacaGGobWaaSbaaWqaaiaaikdaaeqaaSGaci4taaqabaaaaa!39A3!\[j_{N_2 \operatorname{O} } \]. The model takes full account of the sphericity of the atmosphere and of the specific flight conditions, but neglects scattering, which should have a negligible effect on % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOAamaaBa% aaleaacaGGobWaaSbaaWqaaiaaikdaaeqaaSGaci4taaqabaaaaa!39A3!\[j_{N_2 \operatorname{O} } \]. The quantitative results, particularly the altitude and solar zenith angle dependences under extreme conditions, support the low absorption cross-sections of oxygen in the Herzberg continuum as recommended by WMO in 1986 and are inconsistent with Ackerman's tabulations of 1971. It is shown that the altitude dependence of Brewer and Wilson's historical irradiance measurements in the stratospheric window region is well reproduced by our model, but should be multiplied by a factor of 1.75.  相似文献   

Prediction of the abiotic degradability of organic compounds in the troposphere     

Hans Güsten  Leo Klasinc  Dubravko Marić 《Journal of Atmospheric Chemistry》1984,2(1):83-93

A statistically relevant correlation between the reaction rate coefficient, k _OH, for the OH radical reaction with 161 organic compounds in the gas phase at 300 K, and the corresponding vertical ionisation energies E _i,v, reveals two classes of compounds: aromatics where –log(k _OH/cm³s^-1)3/2E _i,v(eV)–2 and aliphatics where –log(k _OH/cm³s^-1)4/5E _i,v(eV)+3. The prediction of the rate coefficient, k _OH, for the reaction of OH with organic molecules from the above equations has a probability of about 90%. Assuming a global diurnal mean of the OH radical concentration of 5×10⁵ cm³, the upper limit of the tropospheric half-life of organic compounds and their persistence can be estimated.  相似文献   

Kriging of water levels in the Souss aquifer,Morocco   总被引：2，自引：0，他引：2  

Mohamed Aboufirassi  Miguel A. Mariño 《Mathematical Geosciences》1983,15(4):537-551

Universal kriging is applied to water table data from the Souss aquifer in central Morocco. The procedure accounts for the spatial variability of the phenomenon to be mapped. With the use of measured elevations of the water table, an experimental variogram is constructed that characterizes the spatial variability of the measured water levels. Spherical and Gaussian variogram models are alternatively used to fit the experimental variogram. The models are used to develop contour maps of water table elevations and corresponding estimation variances. The estimation variances express the reliability of the kriged water table elevation maps. Universal kriging also provides a contour map of the expected elevation of the water table (drift). The differences between the expected and measured water table elevations are called residuals from the drift. Residuals from the drift are compared with residuals obtained by more traditional least-squares analysis.  相似文献