The effects of migration on <Emphasis Type="Italic">ca.</Emphasis> 100-year-old arsenic-rich mine tailings in Cobalt,Ontario, Canada     

Dale D. Sprague  Frederick A. Michel  Jesse C. Vermaire 《Environmental Earth Sciences》2016,75(5):405

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Jenniferann.com,regional development,and realising the aspirations of mana whenua in Pōkeno     

John Ryks  Jonathan Kilgour  Jesse Whitehead  Amy Whetu  James Whetu 《New Zealand geographer》2019,75(3):152-162

During the 1990s, the township of Pōkeno was held up as an example of a declining rural Aotearoa/New Zealand. By‐passed from the national state highway, it lost its status as a service hub and drastic measures were introduced to revitalise the town, including renaming the town “ Jenniferann.com .” Pōkeno has since undergone an unlikely transformation, with foreign investment and its location within an extended Auckland commuter zone meaning that the township has grown exponentially. This article describes the transformation of Pōkeno and uncovers what has been missing from discussions about Pōkeno's reinvention, namely, the place of mana whenua.  相似文献   

Cool heads for a hot world – Social sciences under a changing sky     

Arun Agrawal  Maria Carmen Lemos  Ben Orlove  Jesse Ribot 《Global Environmental Change》2012,22(2):329-331

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Can 234U–230Th dating be used to date large semi‐arid tufas? Challenges from a study in the Naukluft Mountains,Namibia     

Abigail E.C. Stone  Heather A. Viles  Louise Thomas  Peter Van Calsteren 《第四纪科学杂志》2010,25(8):1360-1372

The large, extensive tufa deposits of the semi‐arid Naukluft Mountains, Namibia are potentially important palaeoenvironmental indicators in an area with few proxy records. Tufas are reliable indicators of increased moisture availability, and have been shown to be amenable to ²³⁴U–²³⁰Th dating, although two challenges are detrital contamination and open‐system behaviour. Densely cemented tufa facies are good candidates for dating, minimising these problems. We report attempts to date five densely‐cemented units, which are only found rarely within the Naukluft deposits. We applied a detailed methodology using multiple subsample analysis, measurement of insoluble residues, application of ‘isochron’ mixing lines, and attempted open‐systems modelling, alongside observations of micromorphology and cathodoluminescence in order to assess the validity of any obtained dates. Surprisingly, densely cemented tufas were found not always to be suitable for dating. Two units contained detrital contamination, which could not be corrected for using a single leachate correction or ‘isochron’ methods. Two units contained ‘excess ²³⁰Th’. This could result under a closed‐system if initial (²³⁴U/²³⁸U) was sufficiently high. Alternatively this may be the result of open‐system behaviour, and loss of uranium, or incorporation of initial unsupported ²³⁰Th, which render samples unsuitable for ²³⁴U–²³⁰Th dating. Micromorphological appearance and cathodoluminescence behaviour are used to explore these possibilities. This study exemplifies the need for careful sample selection, and highlights the importance of analysing multiple subsamples from any tufa sample. The detailed methodology applied proves to be a powerful tool for identifying the range of problems that can be encountered when selecting suitable candidate samples for successful dating. It also shows that semi‐arid tufa sequences may contain very little material suitable for dating. A reliable age of c 80 ka was obtained for a banded unit within a large fluvial barrage, with less reliable dates suggesting tufa deposition during times since >350 ka through to the late Holocene. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Distribution of Fe in the octahedral sheet of trioctahedral micas by polarized EXAFS     

A. Manceau  D. Bonnin  W. E. E. Stone  J. Sanz 《Physics and Chemistry of Minerals》1990,17(4):363-370

The distribution of Fe atoms within the octahedral sheet of a series of trioctahedral micas has been investigated by polarized Fe K-edge EXAFS spectroscopy. Single crystals have been oriented in the X-ray beam with the layer plane at 35° with respect to the electric field vector. At this “magic angle”, contributions to the EXAFS spectrum of nearest cation shells are equal to those recorded on a completely disoriented powder. The average number of Fe and Mg cations surrounding each Fe atom has been determined and compared with those deduced from NMR spectra. It is shown that the distribution of Fe atoms is not random, the deviation from this distribution depending on the fluorine content. The agreement between these independent results proves the reliability of the structural information deduced from EXAFS and NMR spectra as well as the usefulness of these two methods in analyzing the local distribution of cations in minerals.  相似文献   

Carbon dioxide emissions in a methane economy     

Jesse H. Ausubel  Arnulf Grübler  Nebojsa Nakicenovic 《Climatic change》1988,12(3):245-263

Increasing reliance on natural gas (methane) to meet global energy demands holds implications for atmospheric CO₂ concentrations. Analysis of these implications is presented, based on a logistic substitution model viewing energy technologies like biological species invading an econiche and substituting in case of superiority for existing species. This model suggests gas will become the dominant energy source and remain so for 50 years, peaking near 70 percent of world supply. Two scenarios of energy demand are explored, one holding per capita consumption at current levels, the second raising the global average in the year 2100 to the current U.S. level. In the first (efficiency) scenario concentrations peak about 450 ppm, while in the second (long wave) they near 600 ppm. Although projected CO₂ concentrations in a methane economy are low in relation to other scenarios, the projections confirm that global climate warming is likely to be a major planetary concern throughout the twenty-first century. A second finding is that data on past growth of world per capita energy consumption group neatly into two pulses consistent with longwave theories in economics.  相似文献   

Oxygen isotopic variations of snowfall from winter storms in the central Sierra Nevada; Relation to ice growth microphysics and mesoscale structure     

Joseph A. Warburton  Belay B. Demoz  Richard H. Stone 《Atmospheric Research》1993,29(3-4)

Observations have been made of the ice-crystal morphology of snow which fell at two sampling sites during a warm front followed by a cold front in the Sierra Nevada of the western United States. The snow sampling and ice crystal observations were conducted at Kingvale (KV) and Hobart Mills (HM), California, which are located at almost identical elevations on the upwind and down wind sides of the Sierra Nevada crest, respectively.These observations and several mesoscale features of one of the storms, have been used to study the substantial changes which occurred in the stable oxygen isotopic composition (δ¹⁸O) of the precipitation at the two sites.At the beginning of the period of observation, a low level warm front lay across the region and its elevation lowered with time from 2.5 km to 1.7 km. This decrease of the frontal surface height was accompanied by a steady increase in the δ¹⁸O values.In the pre-cold frontal passage time periods, the δ¹⁸O values at the upwind site signified warmer origin ice crystal morphology than the downwind site. This is explained by orographic effects and the production of supercooled liquid water at low elevations on the upslope side of the Sierra Nevada.During the passage of the surface cold front, the differences in δ¹⁸O at the two sites were quite small probably because the orography plays a less significant role in the precipitation production process during such events.The δ¹⁸O peaked around −13% which translates to an “equivalent temperature” of −10.7°C for ice phase water capture at the upwind site KV. At site HM downwind of the Sierra crest, and 25 km east of KV, the weighted mean ice phase water capture occurred at elevations some 5 to 6°C colder than at KV, because of subsidence and loss of supercooled liquid water in the lower elevations on the lee side.  相似文献   

Nickeliferous sulfides in xenoliths,olivine megacrysts and basaltic glass   总被引：2，自引：0，他引：2  

Michael E. Fleet  William E. Stone 《Contributions to Mineralogy and Petrology》1990,105(6):629-636

The composition of olivine and nickeliferous sulfide inclusions from a selection of mafic and ultramafre rocks, xenoliths and megacrysts, including picritic basalts from Kilauea Volcano, Hawaii, kimberlite from Fayette County, Pennsylvania, and megacrysts from Mount Shasta, California are compared with the mean experimental value of the distribution coefficient for Ni/Fe exchange (K_D3=32). Only nine of the forty five olivipe/bulk-sulfide pairs investigated have compositions consistent with equilibration at high temperature, yielding calculated K_D3 values in the range 22 to 41. The remaining pairs have calculated K_D3 values which range from 0 to 19. Bulk-sulfides in disequilibrated assem-blages are consistently depleted in nickel and within both indivudual associations and individual petrographic sections they exhibit a wide variation in NiS content. The bulk copper contents of olivine-and groundmass-hosted sulfides from Kilauea Volcano range from 0.5 to 43 at%, and samples from the Kilauea Iki lava lake are more Fe-and Cu-rich and generally have lower K_D3 values than those from the eruption itself. As with magmatic Ni–Cu sulfide deposits, most nickeliferous sulfide inclusions in mantle-related rocks and xenoliths and in volcanic rocks do not have pristine early-magmatic bulk compositions, and it would seem to be premature to attribute these sulfides solely to either a mantle or an early-magnatic origin.  相似文献   

A second World Climate Conference guest editorial     

Jesse H. Ausubel 《Climatic change》1987,11(3):289-290

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Radiocarbon and δ¹³C Values Related to Ground-Water Recharge and Mixing     

James E. Landmeyer  Peter A. Stone 《Ground water》1995,33(2):227-234

Ground-water levels in the Upper Floridan aquifer beneath the southeastern coast of South Carolina have undergone pumpage-induced declines approaching 20 ft below sea level at the southern end of Hilton Head Island. This scenario suggests the potential exists for the inducement of recharge to the Upper Floridan aquifer across the island, which could affect the quality of water being pumped by wells. However, low radiocarbon concentrations in ground-water samples (0.5 to 1.4 ± 0.1 PMC) indicate that most of the water is relict ground water reflecting prepumpage ground-water flow conditions in the Upper Floridan aquifer. The isotopic data indicate long residence times and water-chemistry evolution more characteristic of ground-water recharge occurring farther inland prior to the commencement of pumpage in the late 1800s. Radiocarbon concentrations (as Percent Modern Carbon) and stable carbon isotope ratios (as δ¹³C in dissolved inorganic carbon) determined during this study and reported in other studies on and around Hilton Head Island varied in a systematic manner. Heavier δ¹³C values (–2.8 to –1.6 per mil) in ground water beneath southern Hilton Head Island reflect ground-water discharge from prepumpage flowpaths originating over 100 miles away, hence a depletion in radiocarbon concentration with corrected ground-water ages no younger than 16,000 yrs BP. In contrast, lighter δ¹³C values (–13.9 to –8.67 per mil) beneath the northern part of the island indicate recent recharge as a result of water-level declines, and recharge in areas off the island that have not changed as a result of pumpage (evidenced by enrichment in radiocarbon with corrected ground-water ages no older than 4,000 yrs BP). This suggests that the δ¹³C composition of ground water in the Upper Floridan aquifer is a useful indicator of mixing between ground waters from different sources, and can be used to delineate recharge-discharge patterns. This approach may be applicable to other aquifers of highly evolved ground-water chemistry in regional carbonate aquifer systems that may be receiving recent recharge. Moreover, this approach could prove useful in delineating the contribution of recent water being captured by pumped wells as part of wellhead protection programs designed to assess aquifer vulnerability from surficial contaminant sources.  相似文献