Erratum to: Segregating gas from melt: an experimental study of the Ostwald ripening of vapor bubbles in magmas     

Nicole C. Lautze  Thomas W. Sisson  Margaret T. Mangan  Timothy L. Grove 《Contributions to Mineralogy and Petrology》2011,161(2):349

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Spring flow,bacterial contamination,and water resources in rural Haiti     

Peter J. Wampler  Andrew J. Sisson 《Environmental Earth Sciences》2011,62(8):1619-1628

Field data from 25 karst springs were collected during the summer of 2008 near Verrettes, Haiti, to gain a better understanding of water quality in fresh water springs used as the primary source of potable water in rural Haiti. Two water samples were taken at each spring for bacterial analysis: one sample was submitted to a local hospital for analysis, while a duplicate sample was cultured using inexpensive and commercially available Coliscan^® Easygel^® Kits. Both capped and uncapped springs were sampled in order to evaluate whether capping improves water quality. Water quality parameters and flow volume estimates were recorded at each spring; however, no correlations between field water parameters and the presence of E. coli or total coliform bacteria were found. Spring flow rates varied from 0.4 to 268.5 L/min. Geologic contacts and regional structures trend in a northwest direction and appear to be exerting a primary control on spring locations. E. coli and total coliform colony counts from the local hospital and Coliscan^® Easygel^® Kits yielded different results for the same springs due to sample handling and analysis complications common in rural Haiti. Water sample analysis and storage problems encountered during this study likely resulted in underprediction, rather than overprediction, of bacterial contamination. Water from 71 to 100% of the springs was unsafe to drink based on the World Health Organization (WHO) drinking water standard. Both capped and uncapped springs had bacterial counts in excess of the WHO standard, suggesting that water treatment from all sources is necessary to ensure clean and safe drinking water. Negatively impacted subterranean microbial ecosystems, poor sanitation practices, shallow karst aquifers with open flow paths, and high spring water temperatures, averaging 26.5°C, may be contributing to the observed bacterial abundance.  相似文献   

Habitat overlap between southern bluefin tuna and yellowfin tuna in the east coast longline fishery - implications for present and future spatial management   总被引：1，自引：0，他引：1  

Jason R. Hartog  Alistair J. HobdayRichard Matear  Ming Feng 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):746-752

Southern bluefin tuna (SBT) are presently a quota-managed species in the multi-species eastern Australian tuna and billfish longline fishery (ETBF). Capture of SBT is regulated by quota, as is access to regions likely to contain SBT. A habitat prediction model combining data from an ocean model and pop-up satellite archival tags is used to define habitat zones based on the probability of SBT occurrence. These habitat zones are used by fishery managers to restrict access by ETBF fishers to SBT habitat during a May-November management season. The zones display a distinct seasonal cycle driven by the seasonal southward expansion and northward contraction of the East Australia Current (EAC) and as a result access by fishers to particular ocean regions changes seasonally. This species also overlaps with the commercially valuable yellowfin tuna (YFT), thus, we modified the SBT model to generate YFT habitat predictions in order to investigate habitat overlap between SBT and YFT. There is seasonal variation in the overlap of the core habitat between these two species, with overlap early (May-Jul) in the management season and habitat separation occurring towards the end (Aug-Nov). The EAC is one of the fastest warming ocean regions in the southern hemisphere. To consider the future change in distribution of these two species compared to the present and to explore the potential impact on fishers and managers of the future, we use future ocean predictions from the CSIRO Bluelink ocean model for the year 2064 to generate habitat predictions. As the ocean warms on the east coast of Australia and the EAC extends southward, our model predicts the suitable habitat for SBT and YFT will move further south. There was an increase in the overlap of SBT and YFT habitat throughout the management season, due to regional variation of each species’ habitat. These results illustrate that a management tradeoff exists between restricting fisher access to SBT habitat and allowing access to YFT habitat. We suggest that some options to address this tradeoff are possible by identifying the seasonal variability of the overlap.  相似文献   

Along-Wind Dispersion In Light Wind Conditions     

David J. Thomson  Alistair J. Manning 《Boundary-Layer Meteorology》2001,98(2):341-358

A new formula for dispersion from continuous sources in light wind conditions is derived, which takes account of along-wind dispersion. Thisis achieved by integrating over puffs released at different times and byassuming that the puffs grow with a size that is proportional totravel time at small travel times, and proportional to the square rootof travel time at large times. The results are compared with theGaussian plume formula and with two previous formulae that assumeeither linear growth or growth proportional to the square root of traveltime throughout the puff evolution. The conditions under which thevarious solutions are good approximations to each other or to anyresults that might be obtained with a more realistic puff growthformula are investigated. Finally the relevance of these idealisedresults to more realistic atmospheric flows is discussed and alternativemodelling approaches are considered.  相似文献   

Kinetics of the reactions of hydroxyl radicals with aliphatic ethers studied under simulated atmospheric conditions     

Paul J. Bennett  J. Alistair Kerr 《Journal of Atmospheric Chemistry》1989,8(1):87-94

Rate coefficients have been measured for the reactions of hydroxyl radicals with a range of aliphatic ethers by a competitive technique. Mixtures of synthetic air containing a few ppm of nitrous acid, isobutene and an ether were photolyzed in a Teflon-bag smog chamber. From the rates of depletion of the ether and of the isobutene, and based on the value of the rate coefficient k(OH+i-C₄H₈)=5.26×10^-11 cm³ molecule^-1 s^-1, the following rate coefficients were obtained for the hydroxyl radical reactions at 750 Torr and at 294±2K in units of 10^-12 cm³ molecule^-1 s^-1: diethylether = 12.0±1.1, di-n-propylether = 15.3±1.6, di-n-butylether=17.1±0.9, ethyl n-butylether = 13.5±0.4, ethyl t-butyl-ether = 5.6±0.5, and di-isobutylether = 26.1±1.6. The quoted error limits correspond to 2 standard deviations but do not include any contribution from k(OH+i-C₄H₈) for which the error limits are estimated to be about ±10%. The results are discussed in relation to the available literature data and considered in terms of the structure-activity relation for hydroxyl radical reactions with organic molecules.  相似文献   

An application of simple models to Sahelian convective boundary-layer growth     

Alistair D. Culf 《Boundary-Layer Meteorology》1992,58(1-2):1-18

Profiles of temperature were measured in the atmospheric boundary layer (ABL) over the West African Sahel on eleven days at three different times of the year. The final depth of the mixed layer was shown to vary substantially during the year, but it was often greater than 2.5 km. Measured values of the sensible heat flux at the surface are used to force several simple slab models of the ABL. It is found that these simple models can describe the increases of height and temperature of the ABL during the day.  相似文献   

Further studies of the temperature dependence of the rate coefficients for the reactions of OH with a series of ethers under simulated atmospheric conditions     

Marco Semadeni  David W. Stocker  J. Alistair Kerr 《Journal of Atmospheric Chemistry》1993,16(1):79-93

The following temperature-dependent rate coefficients (k/cm³ molecule^–1 s^–1) of the reactions of hydroxyl radicals with aliphatic ethers have been determined over the temperature range 247–373 K by a competitive flow technique: diethyl ether,k _OH=5.2×10^–12 exp[(262±150)/T]; methyln-butyl ether,k _OH=5.4×10^–12 exp[(309±150)/T]; ethyln-butyl ether,k _OH=7.3×10^–12 exp[(335±150)/T]; di-n-butyl ether,k _OH=5.5×10^–12 exp[(502±150)/T] and di-n-pentyl ether,k _OH=8.5×10^–12 exp[(417±150)/T]. The data have been measured relative to the rate coefficientk(OH + 2,3-dimethylbutane)=6.2×10^–12 cm³ molecule^–1 s^–1 independent of temperature.Previous discrepancies in the room-temperature rate coefficients for the OH reactions with ethyln-butyl ether and di-n-butyl ether, obtained in the flow and static experiments of Bennett and Kerr (J. Atmos. Chem. 8, 87–94, 1989;10, 29–38, 1990) compared with those of Wallingtonet al. (Int. J. Chem. Kinet. 20, 541–547, 1988;21, 993–1001, 1989) and of Nelsonet al. (Int. J. Chem. Kinet. 22, 1111–1126, 1990) have been resolved. The results are considered in relation to the available literature data and evaluated rate expressions are deduced where possible. The data are also discussed in terms of structure-activity relationships.  相似文献   

Crystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: implications for andesite genesis   总被引：6，自引：5，他引：1  

Dawnika L. Blatter  Thomas W. Sisson  W. Ben Hankins 《Contributions to Mineralogy and Petrology》2013,166(3):861-886

This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H₂O and oxidation on differentiation are less well established. Accordingly, we performed crystallization experiments at controlled oxidized fO₂ (Re–ReO₂ ≈ ΔNi–NiO + 2) on a relatively magnesian basalt (8.7 wt% MgO) typical of mafic magmas erupted in the Cascades near Mount Rainier, Washington. The basalt was synthesized with 2 wt% H₂O and run at 900, 700, and 400 MPa and 1,200 to 950 °C. A broadly clinopyroxenitic crystallization interval dominates near the liquidus at 900 and 700 MPa, consisting of augite + olivine + orthopyroxene + Cr-spinel (in decreasing abundance). With decreasing temperature, plagioclase crystallizes, Fe–Ti-oxide replaces spinel, olivine dissolves, and finally amphibole appears, producing gabbroic and then amphibole gabbroic crystallization stages. Enhanced plagioclase stability at lower pressure narrows the clinopyroxenitic interval and brings the gabbroic interval toward the liquidus. Liquids at 900 MPa track along Miyashiro’s (Am J Sci 274(4):321–355, 1974) tholeiitic versus calc-alkaline boundary, whereas those at 700 and 400 MPa become calc-alkaline at silica contents ≥56 wt%. This difference is chiefly due to higher temperature appearance of magnetite (versus spinel) at lower pressures. Although the evolved liquids are similar in many respects to common calc-alkaline andesites, the 900 and 700 MPa liquids differ in having low CaO concentrations due to early and abundant crystallization of augite, with the result that those liquids become peraluminous (ASI: molar Al/(Na + K + 2Ca) > 1) at ≥61 wt% SiO₂, similar to liquids reported in other studies of the high-pressure crystallization of hydrous basalts (Müntener and Ulmer in Geophys Res Lett 33(21):L21308, 2006). The lower-pressure liquids (400 MPa) have this same trait, but to a lesser extent due to more abundant near-liquidus plagioclase crystallization. A compilation of >6,500 analyses of igneous rocks from the Cascades and the Sierra Nevada batholith, representative of convergent margin (arc) magmas, shows that ASI increases continuously and linearly with SiO₂ from basalts to rhyolites or granites and that arc magmas are not commonly peraluminous until SiO₂ exceeds 69 wt%. These relations are consistent with plagioclase accompanying mafic silicates over nearly all the range of crystallization (or remelting). The scarcity of natural peraluminous andesites shows that progressive crystallization–differentiation of primitive basalts in the deep crust, producing early clinopyroxenitic cumulates and evolved liquids, does not dominate the creation of intermediate arc magmas or of the continental crust. Instead, mid- to upper-crustal differentiation and/or open-system processes are critical to the production of intermediate arc magmas. Primary among the open-system processes may be extraction of highly evolved (granitic, rhyolitic) liquids at advanced degrees of basalt solidification (or incipient partial melting of predecessor gabbroic intrusions) and mixing of such liquids into replenishing basalts. Furthermore, if the andesitic-composition continents derived from basaltic sources, the arc ASI–SiO₂ relation shows that the mafic component returned to the mantle was gabbroic in composition, not pyroxenitic.  相似文献   

Exceptional preservation of Upper Carboniferous (lower Westphalian) fossils from Edlington,Doncaster, South Yorkshire,UK     

Dean R. Lomax  Peter Robinson  Christopher J. Cleal  Alistair Bowden  Nigel R. Larkin 《Geological Journal》2016,51(1):42-50

A new fossil‐bearing, Upper Carboniferous (lower Westphalian) locality in Doncaster, South Yorkshire, UK, is reported and an account of the fossils is presented. The diverse flora and fauna consists of plants, bivalves, arthropods (primarily xiphosurans), tentaculitids (microconchids), fish scales, shark egg capsules and coprolites. Fossils are preserved in siderite nodules and shales, and display excellent preservation and detail. Previous collecting of Carboniferous fossils in the Doncaster area has been minimal. The discovery of this locality addresses this deficit and is of further importance as such localities in the UK are diminishing in number with the cessation of coal‐mining and the reclamation of mine dumps, further demonstrating the importance and recognition of the Edlington site. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Linking pollution induced community tolerance (PICT) and microbial community structure in chronically metal polluted estuarine sediments     

Ogilvie LA  Grant A 《Marine environmental research》2008,65(2):187-198

We tested the ability of pollution induced community tolerance (PICT) to detect the effects of chronic metal pollution on estuarine sediment microbial communities, along a gradient spanning two orders of magnitude in metal concentrations. In tandem, we investigated the associated microbial community structure using terminal restriction fragment length polymorphism (T-RFLP). Tolerance of microbes to Cu, measured as IC50 (inhibitory concentration 50%), was strongly correlated with pore water Cu concentration (r(2)=0.842). No strong correlation existed for other metals tested, highlighting the ability of PICT to identify the pollutant causing a toxic effect. There was no correlation between microbial community structure and community tolerance to metals tested, but analysis of community structure did provide some information on reasons for observed PICT response. PICT methodology used here provided a greater strength and consistency of association with pollutant concentration compared to microbial community structure and can be recommended as a sensitive indicator of metal pollution on estuarine sediment microbial communities.  相似文献