A new microsplitter for unconsolidated sediments     

John T. Guptill  Yvonne Herman  Sam C. Saunders 《Marine Geology》1976,20(2):15-23

Unrepresentative subsamples can be obtained from a sedimentary sample through repeated subdivision when using a mechanical microsplitter. Physical biases are often compounded by repetition and can result in wide variations among the estimates computed from the relative proportion of foraminifera of a given species. A new microsplitter, designed on a new principle, has been built to separate small representative subsamples. The device is based on the uniform distribution of unconsolidated sediments suspended in water. A subsample of the desired size is obtained by collecting sediment from an appropriate sedimentation area. Operation of this sampler is rapid and convenient and requires only one step, thus eliminating sampling biases introduced by repeated operations with other splitters. This new device was tested and found to be superior to the Otto Microsplitter according to some statistical goodness-of-fit tests conducted on the series.  相似文献   

The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) phase 2(c) Red-Arkansas River basin experiment:: 2. Spatial and temporal analysis of energy fluxes   总被引：3，自引：0，他引：3  

Xu Liang  Eric F. Wood  Dennis P. Lettenmaier  Dag Lohmann  Aaron Boone  Sam Chang  Fei Chen  Yongjiu Dai  Carl Desborough  Robert E. Dickinson  Qingyun Duan  Michael Ek  Yeugeniy M. Gusev  Florence Habets  Parviz Irannejad  Randy Koster  Kenneth E. Mitchell  Olga N. Nasonova  Joel Noilhan  John Schaake  Adam Schlosser  Yaping Shao  Andrey B. Shmakin  Diana Verseghy  Kirsten Warrach  Peter Wetzel  Yongkang Xue  Zong-Liang Yang  Qing-cun Zeng 《Global and Planetary Change》1998,19(1-4)

The energy components of sixteen Soil-Vegetation Atmospheric Transfer (SVAT) schemes were analyzed and intercompared using 10 years of surface meteorological and radiative forcing data from the Red-Arkansas River basin in the Southern Great Plains of the United States. Comparisons of simulated surface energy fluxes among models showed that the net radiation and surface temperature generally had the best agreement among the schemes. On an average (annual and monthly) basis, the estimated latent heat fluxes agreed (to within approximate estimation errors) with the latent heat fluxes derived from a radiosonde-based atmospheric budget method for slightly more than half of the schemes. The sensible heat fluxes had larger differences among the schemes than did the latent heat fluxes, and the model-simulated ground heat fluxes had large variations among the schemes. The spatial patterns of the model-computed net radiation and surface temperature were generally similar among the schemes, and appear reasonable and consistent with observations of related variables, such as surface air temperature. The spatial mean patterns of latent and sensible heat fluxes were less similar than for net radiation, and the spatial patterns of the ground heat flux vary greatly among the 16 schemes. Generally, there is less similarity among the models in the temporal (interannual) variability of surface fluxes and temperature than there is in the mean fields, even for schemes with similar mean fields.  相似文献   

Multimethod (K–Ar, Rb–Sr, Sm–Nd) dating of bentonite minerals from the eastern United States     

Theofilos Toulkeridis  Norbert Clauer  Sam Chaudhuri  & Steve L. Goldstein 《Basin Research》1998,10(2):261-270

Isotopic determinations (K–Ar, Rb–Sr and Sm–Nd), and trace and rare-earth elemental analyses were made on a few biotite and clay fractions of Palaeozoic bentonite units from the eastern United States. The clay fractions were gently leached with dilute hydrochloric acid to study separately the acid-soluble minerals intimately associated with the extracted clay particles. The data highlight interesting potentials for this integrated approach to decipher complex tectonothermal evolutions of sedimentary basins. Biotite K–Ar ages are consistent with a Middle Ordovician stratigraphic age for the bentonite units with a mean age of 459±10 Ma. The clay residues give a Sm–Nd isochron age of 397±44 Ma, indicative of their crystallization during Acadian tectonothermal activity at about 200 °C. The clay leachates, which are considered to represent mineral phases different from clay material, yield a distinct Sm–Nd isochron age of 285±18 Ma which is indistinguishable from K–Ar ages obtained previously on the clays, suggesting a thermally induced diffusion of radiogenic ⁴⁰Ar from clay particles during Alleghenian–Ouachita orogenic activity. The Rb–Sr system of the clay material seems to have been variably disturbed, except for the sample taken near the Allegheny Front for which an age of 179±4 Ma suggests a further localized activity of the thrust system at about 130–150 °C. Clearly the limited number of samples does not allow us to perfectly constrain an evolutionary model. However, analysis of the soluble minerals for their contents in metal and rare-earth elements suggests that metal-carrying fluids migrated during the Alleghenian–Ouachita orogenic activity in the eastern North American continent. Consequently, they could have contributed to the concentration of ore deposits in the region, but this possibility needs to be tested with a larger data base.  相似文献   

The absorption of sound in seawater in relation to the estimation of deep-water fish biomass   总被引：1，自引：1，他引：1  

Doonan  Ian J; Coombs  Roger F; McClatchie  Sam 《ICES Journal of Marine Science》2003,60(5):1047-1055

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A re-evaluation of relationships between fish size, acoustic frequency, and target strength   总被引：1，自引：6，他引：1  

McClatchie  Sam; Alsop  Jon; Coombs  Roger F. 《ICES Journal of Marine Science》1996,53(5):780-791

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Water demand management and the quest for sustainability          下载免费PDF全文

Sam Trowsdale  Caitlin Golder  Karen Fisher  Gary Brierley 《New Zealand geographer》2017,73(3):192-204

This paper problematises positivist framings of water demand management (WDM) that define the average‐water‐user. Through a situated, case‐study account undertaken in suburban Auckland, we highlight variable social and cultural underpinnings of domestic water use. Activities that are commonly the focus of WDM are shown to be embedded elements of life around which relationships, affects and futures are woven. As a consequence, myopically focusing on the technical–managerial mediation of what are socionatural relations reduces prospects to achieve intended policy outcomes. Reframing WDM as a hydrosocial process provides a basis for water providers to develop more culturally appropriate water management.  相似文献   

Rejoinder     

Sam Schramksi  Zhuojie Huang 《The Professional geographer》2016,68(2)

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Biological soil crust development and its topsoil properties in the process of dune stabilization, Inner Mongolia, China   总被引：4，自引：0，他引：4  

Yirui Guo  Halin Zhao  Xiaoan Zuo  Sam Drake  Xueyong Zhao 《Environmental Geology》2008,54(3):653-662

This study was undertaken at Horqin Sand Land, Inner Mongolia, Northern China. Field samples of biological soil crusts (BSCs) and underlying topsoil (0–5 cm under BSC) were taken in areas of different dune stabilization stages, and their physicochemical properties were analyzed, including particle size distribution, bulk density, organic matter, nitrogen, phosphorus, electrical conductivity (EC), pH, and CaCO₃ content. The results revealed that semi-mobile dunes, semi-fixed dunes and fixed dunes had developed a physical crust, algae crust and moss crust, respectively. The thickness, hardness, water content, fine fraction and nutrient contents of BSCs were gradually increasing along the dune stabilization gradient. Meanwhile, BSC establishment and development enhanced the bulk density, silt and clay content, and nutrients of the topsoil under it, in an increasing tend from semi-mobile dune to fixed dune. Organic matter concentrations and other nutrients in the 0–5 cm topsoil layer under BSCs were significantly higher compared to unconsolidated soil (control). Moreover, there were strong significant positive correlations between topsoil and BSCs’ organic matter, total nitrogen, available nitrogen, available phosphorus, CaCO₃, and <0.05 mm particle content, suggesting that BSCs have an influence on some of the properties of the underlying topsoil.  相似文献   

Climate-Change Journalism and “Edgeball” Politics in Contemporary China     

Sam Geall 《社会与自然资源》2018,31(5):541-555

ABSTRACT

Climate change is a complex and uncertain phenomenon, requiring political approaches that can find compromise and incorporate feedback from experience, as well as harness the role of civil society in holding governments to account. It thus presents an unusual challenge for China, the world’s largest greenhouse-gas emitter and an authoritarian regime, which tends to avoid the inclusion of non-state actors in governance. Drawing on ethnographic research among contemporary Chinese environmental journalists, this article suggests that climate change, as a destabilizing phenomenon with nonlinear and uncertain dynamics, can be drawn upon to develop a pluralistic political position that may run counter to such authoritarian approaches. It shows that Chinese journalists can create in climate reporting a space where outcomes are not known in advance, and where people therefore might generate political positions that challenge dominant narratives around science, technology, and the environment.  相似文献   

Seeing the Fields and Forests: Application of Surface-Layer Theory and Flux-Tower Data to Calculating Vegetation Canopy Height   总被引：1，自引：0，他引：1  

Sam Pennypacker  Dennis Baldocchi 《Boundary-Layer Meteorology》2016,158(2):165-182

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