A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models   总被引：1，自引：0，他引：1  

Lee H. Spangler  Laura M. Dobeck  Kevin S. Repasky  Amin R. Nehrir  Seth D. Humphries  Jamie L. Barr  Charlie J. Keith  Joseph A. Shaw  Joshua H. Rouse  Alfred B. Cunningham  Sally M. Benson  Curtis M. Oldenburg  Jennifer L. Lewicki  Arthur W. Wells  J. Rodney Diehl  Brian R. Strazisar  Julianna E. Fessenden  Thom A. Rahn  James E. Amonette  Jon L. Barr  William L. Pickles  James D. Jacobson  Eli A. Silver  Erin J. Male  Henry W. Rauch  Kadie S. Gullickson  Robert Trautz  Yousif Kharaka  Jens Birkholzer  Lucien Wielopolski 《Environmental Earth Sciences》2010,60(2):227-239

A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO₂ transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO₂ release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO₂ transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO₂ from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO₂ through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented.  相似文献   

New Zealand chironomids as proxies for human-induced and natural environmental change: Transfer functions for temperature and lake production (chlorophyll a)     

C. A. Woodward  J. Shulmeister 《Journal of Paleolimnology》2006,36(4):407-429

The analysis of chironomid taxa and environmental datasets from 46 New Zealand lakes identified temperature (February mean air temperature) and lake production (chlorophyll a (Chl a)) as the main drivers of chironomid distribution. Temperature was the strongest driver of chironomid distribution and consequently produced the most robust inference models. We present two possible temperature transfer functions from this dataset. The most robust model (weighted averaging-partial least squares (WA-PLS), n = 36) was based on a dataset with the most productive (Chl a > 10 μg l⁻¹) lakes removed. This model produced a coefficient of determination () of 0.77, and a root mean squared error of prediction (RMSEP_jack) of 1.31°C. The Chl a transfer function (partial least squares (PLS), n = 37) was far less reliable, with an of 0.49 and an RMSEP_jack of 0.46 Log₁₀μg l⁻¹. Both of these transfer functions could be improved by a revision of the taxonomy for the New Zealand chironomid taxa, particularly the genus Chironomus. The Chironomus morphotype was common in high altitude, cool, oligotrophic lakes and lowland, warm, eutrophic lakes. This could reflect the widespread distribution of one eurythermic species, or the collective distribution of a number of different Chironomus species with more limited tolerances. The Chl a transfer function could also be improved by inputting mean Chl a values into the inference model rather than the spot measurements that were available for this study.  相似文献   

Head–tail Galaxies: beacons of high-density regions in clusters     

Minnie Y. Mao  Melanie Johnston-Hollitt  Jamie B. Stevens  Simon J. Wotherspoon 《Monthly notices of the Royal Astronomical Society》2009,392(3):1070-1079

Using radio data at 1.4 GHz from the Australia Telescope Compact Array (ATCA), we identify five head–tail (HT) galaxies in the central region of the Horologium–Reticulum Supercluster (HRS). Physical parameters of the HT galaxies were determined along with substructure in the HRS to probe the relationship between environment and radio properties. Using a density enhancement technique applied to 582 spectroscopic measurements in the  2°× 2°  region about A3125/A3128, we find all five HT galaxies reside in regions of extremely high density (>100 galaxies Mpc⁻³). In fact, the environments surrounding HT galaxies are statistically denser than those environments surrounding non-HT galaxies and among the densest environments in a cluster. Additionally, the HT galaxies are found in regions of enhanced X-ray emission and we show that the enhanced density continues out to substructure groups of 10 members. We propose that it is the high densities that allow ram pressure to bend the HT galaxies as opposed to previously proposed mechanisms relying on exceptionally high peculiar velocities.  相似文献   

Noble gases and nitrogen in Martian meteorites Dar al Gani 476, Sayh al Uhaymir 005 and Lewis Cliff 88516: EFA and extra neon     

Ratan K. Mohapatra  Susanne P. Schwenzer  Siegfried Herrmann  Ulrich Ott  Jamie D. Gilmour 《Geochimica et cosmochimica acta》2009,73(5):1505-1522

Meteorite “finds” from the terrestrial hot deserts have become a major contributor to the inventory of Martian meteorites. In order to understand their nitrogen and noble gas components, we have carried out stepped heating experiments on samples from two Martian meteorites collected from hot deserts. We measured interior and surface bulk samples, glassy and non-glassy portions of Dar al Gani 476 and Sayh al Uhaymir 005. We have also analyzed noble gases released from the Antarctic shergottite Lewis Cliff 88516 by crushing and stepped heating. For the hot desert meteorites significant terrestrial Ar, Kr, Xe contamination is observed, with an elementally fractionated air (EFA) component dominating the low temperature releases. The extremely low Ar/Kr/Xe ratios of EFA may be the result of multiple episodes of trapping/loss during terrestrial alteration involving aqueous fluids. We suggest fractionation processes similar to those in hot deserts to have acted on Mars, with acidic weathering on the latter possibly even more effective in producing elementally fractionated components. Addition from fission xenon is apparent in DaG 476 and SaU 005. The Ar-Kr-Xe patterns for LEW 88516 show trends as typically observed in shergottites - including evidence for a crush-released component similar to that observed in EETA 79001. A trapped Ne component most prominent in the surface sample of DaG 476 may represent air contamination. It is accompanied by little trapped Ar (²⁰Ne/³⁶Ar > 50) and literature data suggest its presence also in some Antarctic finds. Data for LEW 88516 and literature data, on the other hand, suggest the presence of two trapped Ne components of Martian origin characterized by different ²⁰Ne/²²Ne, possibly related to the atmosphere and the interior. Caution is recommended in interpreting nitrogen and noble gas isotopic signatures of Martian meteorites from hot deserts in terms of extraterrestrial sources and processes. Nevertheless our results provide hope that vice-versa, via noble gases and nitrogen in meteorites and other relevant samples from terrestrial deserts, Martian secondary processes can be studied.  相似文献   

Recombinant workfare, across the Americas: Transnationalizing “fast” social policy   总被引：1，自引：0，他引：1  

Jamie Peck  Nik Theodore 《Geoforum》2010,41(2):195-1109

The paper presents a genealogy of the Bloomberg administration’s Opportunity NYC program, launched in 2007 as part of New York City’s explicitly experimental anti-poverty strategy. Opportunity NYC was modeled on “conditional cash transfer” programs, currently operating in more than thirty countries across the Global South, drawing direct inspiration from Mexico’s widely touted Oportunidades program. This striking case of South-North policy emulation calls attention to some distinctive features of what is characterized here as a transnationalizing “fast-policy” regime, based on technocratic forms of program evaluation and development, dense expert networks, and orchestrated communities of practice, within which a range of policy intermediaries—particularly those connected with multilateral agencies—are assuming significant new roles. What appears to be a pragmatic form of policy learning in fact operates in the context of narrow ideological parameters, within which there is a concerted technocratic “push” toward favored solutions.  相似文献   

Simulating low flows over a heterogeneous landscape in southeastern Poland     

Krzysztof Raczyński  Jamie Dyer 《水文研究》2021,35(8):e14322

This paper presents a scheme describing low flow formation processes in areas with different environmental conditions, including the impact of the selection and explanatory power of predictors for a probabilistic model based on the Logit model. The research was carried out using 29 daily streamflow gauges located in the Lublin region of southeastern Poland for the hydrological period 1976–2018. Analysis resulted in two distinct low flow schemes. In the lowland rivers, low flows occur during the warm season and are related to evaporation exceeding precipitation. In the upland rivers, hydrogeological factors related to water levels in the local Cretaceous aquifers determine the occurrence of low flows. This differentiation affects the quality of the predictive models. For lowland rivers, models based on the climatic water balance with a monthly shift have a better fit, while these models used for upland rivers are characterized by an approximately 10% decrease in accuracy. For upland rivers, the combined C_tH_t models without shifts produce the best model fit. The generalized precision of the Logit models is around 80%–90%.  相似文献   

Wetland soil moisture complicates the use of Sporormiella to trace past herbivore populations     

Jamie R. Wood  Janet M. Wilmshurst 《第四纪科学杂志》2012,27(3):254-259

Spores of the dung‐fungi Sporormiella provide a proxy for assessing past changes in herbivore abundance, and for temporally linking these with shifts in vegetation communities (pollen) and fire frequency (charcoal). Although the proxy is now widely used, potential influences of local environmental conditions are poorly understood. Here we assess the reliability of Sporormiella as a proxy of herbivores by presenting five new spore records from the South Island of New Zealand; a land where the herbivore extinction/introduction chronology is well established, and where extinctions occurred independently of major climate change. We show that Sporormiella spores from relatively dry soils provide a good proxy for herbivore extinctions and introductions. However, spore abundances from saturated soil sites appear to fluctuate in close correlation with changes in local hydrology (represented by wetland herb pollen, testate amoebae and moisture sensitive mosses). Our results suggest Sporormiella records derived from wetlands require cautious interpretation, and that proxies for hydrological conditions should also be considered when interpreting such records. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Assessing stand water use in four coastal wetland forests using sapflow techniques: annual estimates,errors and associated uncertainties          下载免费PDF全文

Ken W. Krauss  Jamie A. Duberstein  William H. Conner 《水文研究》2015,29(1):112-127

Forests comprise approximately 37% of the terrestrial land surface and influence global water cycling. However, very little attention has been directed towards understanding environmental impacts on stand water use (S) or in identifying rates of S from specific forested wetlands. Here, we use sapflow techniques to address two separate but linked objectives: (1) determine S in four, hydrologically distinctive South Carolina (USA) wetland forests from 2009–2010 and (2) describe potential error, uncertainty and stand‐level variation associated with these assessments. Sapflow measurements were made from a number of tree species for approximately 2–8 months over 2 years to initiate the model, which was applied to canopy trees (DBH > 10–20 cm). We determined that S in three healthy forested wetlands varied from 1.97–3.97 mm day^?1 or 355–687 mm year^?1 when scaled. In contrast, saltwater intrusion impacted individual tree physiology and size class distributions on a fourth site, which decreased S to 0.61–1.13 mm day^?1 or 110–196 mm year^?1. The primary sources of error in estimations using sapflow probes would relate to calibration of probes and standardization relative to no flow periods and accounting for accurate sapflow attenuation with radial depth into the sapwood by species and site. Such inherent variation in water use among wetland forest stands makes small differences in S (<200 mm year^?1) difficult to detect statistically through modelling, even though small differences may be important to local water cycling. These data also represent some of the first assessments of S from temperate, coastal forested wetlands along the Atlantic coast of the USA. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

The distribution and climatic implications of periglacial landforms in eastern Australia          下载免费PDF全文

Adrian Slee  James Shulmeister 《第四纪科学杂志》2015,30(8):848-858

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The Campanian Ignimbrite (Y5) tephra at Crvena Stijena Rockshelter, Montenegro     

Mike W. Morley  Jamie C. Woodward 《Quaternary Research》2011,75(3):683-696

Clearly defined distal tephras are rare in rockshelter sediment records. Crvena Stijena, a Palaeolithic site in Montenegro, contains one of the longest (> 20 m) rockshelter sediment records in Europe with deposits ranging in age from Middle Pleistocene to mid-Holocene. A distinctive tephra is clearly exposed within the well stratified record approximately 6.5 m below the present land surface. We present geochemical data to confirm that this tephra is a distal equivalent of the Campanian Ignimbrite deposits and a product of the largest Late Pleistocene eruption in Europe. Originating in the Campanian volcanic province of southwest Italy, this tephra has been independently dated to 39.3 ka. It is a highly significant chronostratigraphic marker for southern Europe. Macrostratigraphic and microstratigraphic observations, allied with detailed particle size data, show that the tephra layer is in a primary depositional context and was transported into the rockshelter by aeolian processes. This site is unique because the tephra forms an abrupt boundary between the Middle and Upper Palaeolithic records. Before they can be used as chronostratigraphic markers in rockshelter and cave-mouth environments, it is essential to establish the stratigraphic integrity of distal tephras and the mechanisms and pathways involved in their transport and deposition.  相似文献