Intercomparison of210Pb measurements at GEOSECS station 500 in the northeast Pacific

During reoccupation of the GEOSECS-I test station in May, 1979, more than eighty 30-liter Niskin samples were collected in profile, many as replicates, for²¹⁰Pb intercomparison measurements by the WHOI, SIO and Yale groups. In addition to the inter-laboratory comparisons, the SIO group also carried out extensive experiments to test the effect of sample scavenging method. Pb equilibration time (storage effect), and filtration process on the measured²¹⁰Pb results.The intercomparison measurements indicate that there is a general agreement between the various sets of data. The sample set which allows a direct comparison at the same depth was available in most cases only between two of the three groups. The direct paired comparison shows that (1) the WHOI data are systematically 3% lower than the SIO data; (2) there are no systematic differences observed between the SIO and Yale data although the scatter is rather large; (3) the Yale data are systematically higher than the WHOI data by about 8%.The SIO experiments show that (1) the two scavenging methods employed (Fe(OH)₃ and Co-APDC co-precipitation) yield identical²¹⁰Pb results; (2) variation of Pb carrier equilibration time or of storage time has no discernible effect; (3) the filtration apparatus and procedure employed at this station do not result in²¹⁰Pb loss or contamination.The²¹⁰Pb profile structure and absolute concentration measured earlier at the same location (GOGO-II test station and GEOSECS station 347) agree with those of station 500 within 10%. The present profile shows a minimum²¹⁰Pb concentration around 500 m depth, marking the penetration depth of the flux of excess²¹⁰Pb from the atmosphere. There is a mild mid-depth maximum around 2500–3000 m. The²¹⁰Pb/²²⁶Ra activity ratio decreases monotonically from about 1 at the²¹⁰Pb minimum to about 0.5 near the bottom. The particulate²¹⁰Pb profile shows a systematic increase from the subsurface water to the bottom water by a factor of 5. This feature has been observed in many GEOSECS particulate²¹⁰Pb profiles.     

The dynamics of deep magmas

This study attempts to substantiate a model of magma ascent from deep-seated sources driven by the density difference between magmas and wall rocks in a plastic solid medium via hydraulic fracturing (magma-driven fracturing). The difference between magma and wall rock densities causes overpressure development in the head of a magma column. With increasing height of the column or decreasing magma density, the overpressure can build significantly, which is valid for the case of continuous magma conduit from a deepseated source. The depth of mantle chambers, their vertical extent, and magma densities seem to be the key factors in the formation of volcanoes and intracrustal intrusions. Intermittent (or peripheral) magma chambers under volcanoes and crustal-mantle intrusive bodies may be formed at strength barriers, in the zone of elastoplastic transition and at the mantle-crust boundary.     

http://www.sciencedirect.com/science/article/pii/S1674987111001034

A comprehensive methodology that integrates Revised Universal Soil Loss Equation（RUSLE） model and Geographic Information System（GIS） techniques was adopted to determine the soil erosion vulnerability of a forested mountainous sub-watershed in Kerala,India.The spatial pattern of annual soil erosion rate was obtained by integrating geo-environmental variables in a raster based GIS method.GIS data layers including,rainfall erosivity（R）,soil erodability（K）,slope length and steepness（LS）,cover management （C） and conservation practice（P） factors were computed to determine their effects on average annual soil loss in the area.The resultant map of annual soil erosion shows a maximum soil loss of 17.73 t h^-1 y^-1 with a close relation to grass land areas,degraded forests and deciduous forests on the steep side-slopes（with high LS ）.The spatial erosion maps generated with RUSLE method and GIS can serve as effective inputs in deriving strategies for land planning and management in the environmentally sensitive mountainous areas.     

Increasing prevalence of extreme summer temperatures in the U.S.

Human-caused climate change can affect weather and climate extremes, as well as mean climate properties. Analysis of observations and climate model results shows that previously rare (5th percentile) summertime average temperatures are presently occurring with greatly increased frequency in some regions of the 48 contiguous United States. Broad agreement between observations and a mean of results based upon 16 global climate models suggests that this result is more consistent with the consequences of increasing greenhouse gas concentrations than with the effects of natural climate variability. This conclusion is further supported by a statistical analysis based on resampling of observations and model output. The same climate models project that the prevalence of previously extreme summer temperatures will continue to increase, occurring in well over 50% of summers by mid-century.     

云南天文台三孔较差视宁度监视仪的建立

较详细地讲述了云南天文台三孔较差视宁度监视仪的情况,然而,与一般天文理论和天文技术的专题研究不一样,天文仪器的研制有如说是研究,还不如说是归纳;它不是分析一个具体的尚未解决的难题,而是把许多已知的理论和技术综合起来,构成一台具体的仪器。所以,本文把许多至少是表面上互不相关的理论和技术问题归纳到一篇论文中。仪器是有许多模块组成的,为了看起来逻辑性较强,我们将仪器分模块叙述,全文遵循如下顺序：１在第一篇中,回顾世界各天文台视宁度测量设备的发展史和云南天文台的宁静度测量发展史;２在第二篇中,介绍：１）云南天文台三孔较差视宁度研制任务的来源,仪器的整体状况;２）介绍云南天文台三孔较差视宁度仪的硬件系统;３）介绍云南天文台三孔较差视宁度仪的软件系统;若大模块中有多个小模块,在每一个大模块中,又遵循下述顺序：１）本模块的总体功能;２）构成该模块的基本技术;３）这些基本技术如何构成整体和完成预定功能。３在第三篇中,介绍我们所作的与视宁度测量有关的一些实验和实验结果。     

Hydrogeologic assessment of escalating groundwater exploitation in the Indus Basin, Pakistan

Groundwater development has contributed significantly to food security and reduction in poverty in Pakistan. Due to rapid population growth there has been a dramatic increase in the intensity of groundwater exploitation leading to declining water tables and deteriorating groundwater quality. In such prevailing conditions, the hydrogeological appraisal of escalating groundwater exploitation has become of paramount importance. Keeping this in view, a surface water–groundwater quantity and quality model was developed to assess future groundwater trends in the Rechna Doab (RD), a sub-catchment of the Indus River Basin. Scenario analysis shows that if dry conditions persist, there will be an overall decline in groundwater levels of around 10 m for the whole of RD during the next 25 years. The lower parts of RD with limited surface water supplies will undergo the highest decline in groundwater levels (10 to 20 m), which will make groundwater pumping very expensive for farmers. There is a high risk of groundwater salinization due to vertical upconing and lateral movement of highly saline groundwater into the fresh shallow aquifers in the upper parts of RD. If groundwater pumping is allowed to increase at the current rate, there will be an overall decline in groundwater salinity for the lower and middle parts of RD because of enhanced river leakage.     

A search for soft X-ray emission from stellar sources

With the soft X-ray detector (0.2–0.284 keV) aboard the Astronomical Netherlands Satellite (ANS) we have searched for X-ray emission from hot star coronae and peculiar stars. On Sirius ( CMa) and Capella ( Aur) X-ray emission has been measured at 6 and 5 level, respectively, above background. In all other cases the search revealed no evidence for soft X-ray emission. Upper limits to the luminosities of about 25 star coronae (main-sequence stars, (sub)giants, and supergiants) and of 4 peculiar stars ( Sco, Lyr, P Cyg, and Car) have been obtained.Paper presented at the COSPAR/IAU Symposium on Fast Transients in X-and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.     

Towards urbanisation of the non-hydrostatic numerical weather prediction model Lokalmodell (LM)

Numerical weather prediction models are increasingly employed for providing meteorological data for urban air quality applications. Model resolution, physiographic parameters and surface-layer parameterisations need to be adapted to the requirements of the urban boundary layer. The Lokalmodell of the German Weather Service was triple-nested down to a horizontal grid resolution of 1.1 km, urbanised physiographic parameters were implemented, and an additional anthropogenic heat source was introduced. Results of a sensitivity study for a spring dust episode in Helsinki show a clear urbanisation effect of these measures on temperature, humidity and the partitioning of surface fluxes, leading to an increased Bowen ratio and heat storage and an urban heat island effect.     

Cyclic degradation and non-coaxiality of soft clay subjected to pure rotation of principal stress directions

Foundation soils are often under non-proportional cyclic loadings. The deformation behaviour and the mechanism of non-coaxiality under continuous pure principal stress rotation for clays are not clearly investigated up to now. In order to study the effect of pure principal stress rotation, a series of cyclic undrained tests on Shanghai soft clay subjected to cyclic rotation of principal stress directions keeping the deviatoric stress constant under the pure rotation condition were conducted using hollow cylinder apparatus. Based on this, the evolutions of excess pore pressure and strains during cyclic loading were investigated, together with the effects of the intermediate principal stress parameter and the deviatoric stress level on stress–strain stiffness and non-coaxiality. The result can provide an experimental basis for constitutive modelling of clays describing the behaviour under non-proportional loadings.     

Eruption episodes and magma recharge events in andesitic systems: Mt Taranaki,New Zealand

Eruption episodes, where a series of eruption events are generically related, can include the eruption of a wide spectrum of volcanic activity over decadal periods. This paper concentrates on the opening phases of an eruption episode which occurred approximately 1800 yrs BP from Mt Taranaki, New Zealand. These events spanned the eruption of differing bulk compositions and styles from two distinct vent locations; an andesitic sub-plinian eruption from the summit vent and a scoria cone-building eruption of basaltic magma from a satellite vent. Compositional profiles and zoning textures of plagioclase, amphibole and clinopyroxene phenocrysts from the opening andesitic event show evidence of magma mixing and subsequent crystallisation just prior to the initiation of the eruption episode. Titanomagnetite grain morphology and Ti variation suggest that the magma mixing event occurred within a few days to weeks before the eruption acting as a trigger for it. We present a magmatic model which is constrained by the petrological observations and eruptions of the episode. In this model magma differentiation at depth causes its rise and recharging of a mid-crustal magma storage area at 5–7 km. Although the recharging magma differed slightly in oxygen fugacity and temperature, it was compositionally and physically similar enough to the residing andesitic magma to allow efficient mixing. The petrological characteristics described here can be readily observed and enable identification of mixing events in other recent eruption episodes.