Survey of waste water disposal practices at Antarctic research stations

To inform the future practices to be employed for handling waste water and grey water at the Swedish Antarctic station, Wasa, in Dronning Maud Land, the Swedish Polar Research Secretariat took the initiative to survey the practices of the 28 nations with stations in Antarctica. A questionnaire was sent out to all members of the Antarctic Environment Officers Network during the autumn of 2005. Questions were asked about the handling of waste water and grey water, the type of sewage treatment, and installation and operational costs. The response to the questionnaire was very good (79%), and the results showed that 37% of the permanent stations and 69% of the summer stations lack any form of treatment facility. When waste water and grey water containing microorganisms are released, these microorganisms can remain viable in low-temperature Antarctic conditions for prolonged periods. Microorganisms may also have the potential to infect and cause disease, or become part of the gut flora of local bird and mammal populations, and fish and marine invertebrates. The results from 71 stations show that much can still be done by the 28 nations operating the 82 research stations in Antarctica. The technology exists for effective waste water treatment in the challenging Antarctic conditions. The use of efficient technology at all permanent Antarctic research stations would greatly reduce the human impact on the pristine Antarctic environment. In order to protect the Antarctic environment from infectious agents introduced by humans, consideration should also be given to preventing the release of untreated waste water and grey water from the smaller summer stations.     

大气CO2富集对根际NaCl盐渍的人参果植株干物质生产和水分利用的影响

对单株砂培盆栽的半木质化枝条扦插生根的一月龄人生果(Solanum muricatum Ait.)栽培品种"Xotus",每周浇两次200mL NaCl质量浓度分别为0mg·L^-1和25mg·L^-1的Hoagland营养液处理2个月,第二个月在控制空气CO₂体积分数为(350±10)×10^-6、(700±10)×10^-6和(1050±10)×10^-6的植物生长箱内试验。结果表明,人参果植株干物质生产量和耗水量受根际NaCl盐渍而下降,又随大气CO₂升高而增加。根际NaCl盐渍能增大植株叶片蒸腾系数、根/冠比和干物质向枝干和根部分配的比例及积累量,降低根系吸收水分的效率和耗水量。升高大气CO₂能促进叶片发育及干物质向地上部其他器官和地下部组织分配,增加总叶面积、比叶干重和各种器官中干物质增长量,提高干物质生产率和水分利用率。根际经25mg·L^-1NaCl盐渍处理的植株,总干物质增长量和水分利用率相应下降50%～54%和24%～37%;与350×10^-6CO₂的处理的植株相比,700×10^-6及1050×10^-6CO₂的处理分别使这两项指标提高到79%～106%和61%～88%以及133%～189%和99%～142%。大气CO₂富集能改善受NaCl盐渍的植株干物质生产力、提高水分利用率。根际NaCl盐渍和大气CO₂富集对人参果植株干物质生产和水分利用有生物互作效应。它们的共同作用会促进植株干物质的增长及叶片中合成的干物质向其他器官分配,提高干物质生产率和水分利用率,同时减少总叶面积、枝条和根系干重、根系吸水效率、植株耗水量和叶片蒸腾系数。因此,全球大气CO₂富集将有利于该作物的干物质生产和水分利用。     

海底地形测量成果的质量检核评估(二):深远海海域声速剖面的获取

声速改正是海底地形探测资料处理的关键技术环节之一,而声速剖面的质量则将从源头上影响声速改正的精度。针对当前深远海海域海底地形探测中在何时、何地布放何种声速仪器获取声速剖面性价比更高的技术难题,提出将海底地形和温盐场作为在深度方向和时空间布放声剖站的设计依据,开展了基于WOA13温盐场提高XBT计算声速剖面精度试验。结果表明,基于已有的海底地形和温盐场可提高深远海海域声速剖面站布设的性价比。     

CI-Miner: semantically enhancing scientific processes

The realization of an international cyberinfrastructure of shared resources to overcome time and space limitations is challenging scientists to rethink how to document their processes. Many known scientific process requirements that would normally be considered impossible to implement a few years ago are close to becoming a reality for scientists, such as large scale integration and data reuse, data sharing across distinct scientific domains, comprehensive support for explaining process results, and full search capability for scientific products across domains. This article introduces the CI-Miner approach that can be used to aggregate knowledge about scientific processes and their products through the use of semantic annotations. The article shows how this aggregated knowledge is used to benefit scientists during the development of their research activities. The discussion is grounded on lessons learned through the use of CI-Miner to semantically annotate scientific processes in the areas of geo-sciences, environmental sciences and solar physics: A use case in the field of geo-science illustrates the CI-Miner approach in action.     

Using SPIRAL (Single Pollen Isotope Ratio AnaLysis) to estimate C3- and C4-grass abundance in the paleorecord

C₃ and C₄ grasses differ greatly in their responses to environmental controls and influences on biogeochemical processes (e.g. water, carbon, and nutrient cycling). Difficulties in distinguishing between these two functional groups of grasses have hindered paleoecological studies of grass-dominated ecosystems. Stable carbon isotopic analysis of individual grains of grass pollen using a spooling-wire microcombustion device interfaced with an isotope-ratio mass spectrometer holds promise for improving C₃ and C₄ grass reconstructions. This technique, SPIRAL (Single Pollen Isotope Ratio AnaLysis), has only been evaluated using pollen of known C₃ and C₄ grasses. To test the ability of SPIRAL to reproduce the abundance of C₃ and C₄ grasses on the landscape, we measured δ¹³C values of > 1500 individual grains of grass pollen isolated from the surface sediments of ten lakes in areas that span a large gradient of C₃- and C₄-grass abundance, as determined from vegetation surveys. Results indicate a strong positive correlation between the δ¹³C-based estimates of % C₄-grass pollen and the abundance of C₄ grasses on the landscape. The % C₄-grass pollen slightly underestimates the actual abundance of C₄ grasses at sites with high proportions of C₄ grasses, which can be corrected using regression analysis. Comparison of the % C₄-grass pollen with C/N and δ¹³C measurements of bulk organic matter illustrates the distinct advantages of grass-pollen δ¹³C as a proxy for distinguishing C₃ and C₄ shifts within the grass family. Thus SPIRAL promises to advance our understanding of grassland ecology and evolution.     

Rapid recharge of fresh water to the halite‐hosted brine aquifer of Salar de Atacama,Chile

We document, analyse, and interpret direct and rapid infiltration of precipitation to the southern margin of the Salar de Atacama halite‐hosted brine aquifer during two intense precipitation events in 2012–2013. We present physical, geochemical, and stable and radioactive isotope data to detail this influx of water. The two events differ distinctly in the mechanisms of recharge. The 2012 event did not produce direct precipitation onto the salar surface, while the 2013 event did. Both events are recorded by abrupt changes in head in observation wells along the halite aquifer margin. Spatially distributed water levels rose by over 30 cm during the larger 2013 event consistent with remotely sensed observations of surface water extent. The lithium concentration and stable isotopic composition of water indicate dilution of brine and dissolution of salt with fresh water. Tritium measurements of precipitation, surface water, and groundwater all indicate modern influx of water to the halite aquifer along the southern margin. We extend these observations by examining the response of the halite aquifer as a whole to precipitation events during the period of 2000–2010. This study suggests that local recharge to the aquifer during sporadic precipitation onto the halite nucleus is an important component of the modern water budget in this hyper‐arid environment. The rapid dissolution and salinization along the southern margin of the salar halite nucleus are aided by such precipitation events contributing a modern fresh water component to the water budget of the economically valuable lithium‐rich brine. Copyright © 2016 John Wiley & Sons, Ltd.     

THE INTERNATIONAL MOBILITY OF LABOR: NORTH AFRICAN MIGRANT WORKERS IN FRANCE*

Since World War II, migrant labor has contributed significantly to Western Europe's economic growth. Initially, industries recruited and hired migrant workers to overcome labor shortages and downward demographic trends within the domestic work force. Since the recession of the mid-1970s, however, migrant labor has faced increasing job loss and restricted entry to many Western European countries. Throughout the postwar period, state immigration policy has supported industry, initially by assisting in the recruitment, and more recently, facilitating the repatriation of migrant workers. Economic and social disparities between developed core and underdeveloped peripheral countries are linked to international labor mobility. Certain sectors in the core benefit from the reserve labor force while emigration from peripheral countries partially contributes to these countries' economic problems. These issues are explored through a case study of the employment of North Africans in the French automobile industry.     

Sub-grid scale precipitation in ALCMs: re-assessing the land surface sensitivity using a single column model

The sensitivity of a land surface scheme to the distribution of precipitation within a general circulation model's grid element is investigated. Earlier experiments which showed considerable sensitivity of the runoff and evaporation simulation to the distribution of precipitation are repeated in the light of other results which show no sensitivity of evaporation to the distribution of precipitation. Results show that while the earlier results over-estimated the sensitivity of the surface hydrology to the precipitation distribution, the general conclusion that the system is sensitive is supported. It is found that changing the distribution of precipitation from falling over 100% of the grid square to falling over 10% leads to a reduction in evaporation from 1578 mm y^–1 to 1195 mm y ^–1 while runoff increases from 278 mm y^–1 to 602 mm y^–1. The sensitivity is explained in terms of evaporation being dominated by available energy when precipitation falls over nearly the entire grid square, but by moisture availability (mainly intercepted water) when it falls over little of the grid square. These results also indicate that earlier work using stand-alone forcing to drive land surface schemes off-line, and to investigate the sensitivity of land surface codes to various parameters, leads to results which are non-repeatable in single column simulations.     

The origin of SNC meteorites: An alternative to Mars

Shergottites, Nakhlites, and Chassignites (SNC) are a small group of achondrites with crystallization ages of approximately 1.3 AE. Although it has recently been postulated the these meteorites came from Mars, the dynamical difficulties of ejecting large meteorites from a major planet have caused us to examine the alternative possibility that they crystallized from an impact melt formed on a large asteroid. The kinetic energy necessary to produce a crater of a given size is estimated; it is postulated that 25% of this energy is partitioned into heat, and the heat is distributed in this model in a pattern suggested by the impact melt distribution in Brent Crater and the radioactivity distribution in Cactus nucelear explosion crater. The time evolution of the temperature by heat conduction for several locations around the crater is computed. Crystallization times for the more deeply buried impact melts are form 5 × 10⁴ years for 60-km-diameter craters and increase for larger craters. These times are long enough for the observed cumulate textures to develop. Once solidified, these rocks may be ejected from the asteroid by subsequent cratering events. Since asteroidal escape velocities are low, ejection may be accomplished by shock pressures too low to produce petrologically detectable shock features. The SNC meteorites could thus have originated in the asteroid belt, their young crystallization ages being due to melting induced by impacts occurring on asteroids long after condensation from the solar nebula. This scenario avoids the dynamical difficulties of a major planet origin, but raises questions of how the SNC's acquired their chemical and REE characteristics. To date, there seems to be no internally consistent model for the origin of these strange meteorites. The impact melt hypothesis is offered as a rational alternative to a Martian origin. Neither hypothesis explains all the problems.