Water quality in Sepetiba Bay,Brazil     

Copeland G  Monteiro T  Couch S  Borthwick A 《Marine environmental research》2003,55(5):385-408

Sepetiba Bay is located at 23 degrees S, 44 degrees W in Rio de Janeiro State, Brazil. Water samples were taken at eight locations adjacent to the north shore of the Bay, near to villages and towns without sewage treatment provision. The samples were analysed and total and faecal coliform concentrations determined. A hydrodynamic model of the Bay was used together with a species dispersion model based on an adaptive quadtree mesh to predict faecal concentrations in the Bay. Effluent sources used in the model were defined using population data from census returns with flow and concentration values estimated using standard values recommended by the World Bank (WB) and the World Health Organisation (WHO). Sufficient agreement was obtained between the measured and predicted concentrations to support the use of WB and WHO summary statistics to estimate sources of sewage.  相似文献   

On the development of ship anti-roll tanks     

Reza Moaleji  Alistair R. Greig   《Ocean Engineering》2007,34(1):103-121

This paper reviews the development of ship anti-roll tanks from the 1880s to the present day including their modelling and control strategies. Mention is also made of other ship roll stabilization systems and the application of the technology to stabilization of other structures. The potential for the use of roll stabilization tanks on modern, high speed multi-hull craft which also have a low speed operational requirement is also discussed.  相似文献   

Ecological impacts of air pollution from road transport on local vegetation     

Keeley L. Bignal  Mike R. Ashmore  Alistair D. Headley  Kirstin Stewart  Katherina Weigert 《Applied Geochemistry》2007

Motor vehicles emit a cocktail of pollutants and are a major contributor to ground-level air pollution, but little is known regarding the ecological impacts of air pollution from roads on the surrounding vegetation. Data are presented on vegetation at three sites adjacent to two major motorways in the UK, comprising two woodland sites and one blanket bog site. Surveys of oak and beech tree health (at the woodland sites) and species composition (at the blanket bog site) were undertaken along transects away from the motorway.  相似文献   

Hybridity emergent: Geo-history, learning, and land restitution in South Africa     

Alistair Fraser 《Geoforum》2007,38(2):299-311

Market-Led Agrarian Reform (MLAR), which is advocated by the World Bank and is being implemented in various contexts around the world, is a more neo-liberal approach to land reform than that we have seen implemented in the past. MLAR principles have underpinned South Africa’s land reform programme, being based on the ‘willing-seller, willing-buyer’ principle, which guarantees market-related prices to sellers. Evidence presented in this paper, however, raises serious questions about the extent to which the South African government has held on to MLAR principles. Specifically, the paper argues that South Africa’s peculiar geo-historical context has in some instances led the government to fuse market-led approaches with more authoritarian interventions that dictate to land reform beneficiaries how the land will be used. A case in point is the government’s approach to the restitution of land rights to communities dispossessed from the Levubu area of Limpopo province. As the paper illustrates, the government has imposed on the intended beneficiaries a so-called ‘strategic partnership’ between them and agribusinesses. Although the government touts the approach as a way to protect the commercial viability of the land and to transfer skills from white farmers to the beneficiaries, the terms of the Levubu solution may turn out to be less than favourable for the beneficiaries.  相似文献   

A Suction Bailer for Sampling Very Thin Saturated Zones     

Joel M. Hubbell  James L. Osiensky  Michael J. Nicholl  James B. Sisson 《Ground Water Monitoring & Remediation》2006,26(2):52-57

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Geomorphology and time: J. B. Thornes and D. Brunsden. Methuen,London, 208 pp     

Alistair F. Pitty 《Quaternary Research》1978,10(1):137-138

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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