Periodic density functional theory calculations of bulk and the (010) surface of goethite     

James D Kubicki  Kristian W Paul  Donald L Sparks 《Geochemical transactions》2008,9(1):4

Background  

Goethite is a common and reactive mineral in the environment. The transport of contaminants and anaerobic respiration of microbes are significantly affected by adsorption and reduction reactions involving goethite. An understanding of the mineral-water interface of goethite is critical for determining the molecular-scale mechanisms of adsorption and reduction reactions. In this study, periodic density functional theory (DFT) calculations were performed on the mineral goethite and its (010) surface, using the Vienna Ab Initio Simulation Package (VASP).  相似文献   

Failure to protect beaches under slowly rising sea level     

Alisha Summers  Charles H. Fletcher  Daniele Spirandelli  Kristian McDonald  Jin-Si Over  Tiffany Anderson  Matthew Barbee  Bradley M. Romine 《Climatic change》2018,147(3-4):427-439

The increase in population and the improvement of life standards are stretching the boundaries between water-energy-land management, and demanding innovative and holistic solutions. This article proposes an approach for increasing the water availability of two or more water basins taking into consideration land use and wind patterns, and was named Land, Water, and Wind Watershed Cycle (L3WC). This approach can be applied to one watershed or a combination of watersheds. In the first case, if wind patterns blow mainly in the opposite direction of the main river flow, plantations with high water demand should be focused on the lowest part of the basin. The transpired moisture would then return to the basin with the wind and possibly increase the water availability of the basin. Applying this method to a series of basins, water is transposed from one basin to another, used for irrigated agriculture, returned to the atmosphere with evapotranspiration and pushed back to the basin where the water was extracted by the wind. Case studies of this methodology are presented in the São Francisco basin and between the Tocantins, Amazonas, and Paraná basins and the São Francisco basin in Brazil. The São Francisco basin was selected because it is located in a dry region, its flow has considerably reduced in the past decade and because the trade winds blow constantly from the ocean into the continent all year around. L3WC is a strategy to plan the allocation of water consumption in a watershed, taking into account wind patterns to support the sustainable development of a region. It has the potential of increasing water availability and creating a climate change adaptation mechanism to control the climate and reduce vulnerability to climatic variations.  相似文献   

Atlantic forcing of Pacific decadal variability   总被引：1，自引：0，他引：1  

Fred Kucharski  Farah Ikram  Franco Molteni  Riccardo Farneti  In-Sik Kang  Hyun-Ho No  Martin P. King  Graziano Giuliani  Kristian Mogensen 《Climate Dynamics》2016,46(7-8):2337-2351

  相似文献   

Exploration of the high-redshift universe enabled by THESEUS     

Tanvir  N. R.  Le Floc’h  E.  Christensen  L.  Caruana  J.  Salvaterra  R.  Ghirlanda  G.  Ciardi  B.  Maio  U.  D’Odorico  V.  Piedipalumbo  E.  Campana  S.  Noterdaeme  P.  Graziani  L.  Amati  L.  Bagoly  Z.  Balázs  L. G.  Basa  S.  Behar  E.  De Cia  A.  Valle  M. Della  De Pasquale  M.  Frontera  F.  Gomboc  A.  Götz  D.  Horvath  I.  Hudec  R.  Mereghetti  S.  O’Brien  P. T.  Osborne  J. P.  Paltani  S.  Rosati  P.  Sergijenko  O.  Stanway  E. R.  Szécsi  D.  Tot́h  L. V.  Urata  Y.  Vergani  S.  Zane  S. 《Experimental Astronomy》2021,52(3):219-244

Experimental Astronomy - At peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer...  相似文献   

Persistence and biodegradation of kerosene in high-arctic intertidal sediment     

Røberg S  Stormo SK  Landfald B 《Marine environmental research》2007,64(4):417-428

A kerosene type hydrocarbon fraction (equivalent to 7 L m(-2)) was added to enclosures in the surface layer of high-arctic intertidal beach sediment. The experimental spill was repeated in two consecutive years in the period July-September. The rate and extent of hydrocarbon removal and the accompanying bacterial response were monitored for 79 days (2002) and 78 days (2003). The bulk of added kerosene, i.e. 94-98%, was lost from the upper 5 cm layer by putatively abiotic processes within 2 days and a residual fraction in the range 0.6-1.2mg per g dry sediment was stably retained. Concomitant addition of oleophilic fertilizer led to higher initial retention, as 24% of the kerosene remained after 2 days in the presence of a modified, cold-climate adapted version of the well-known Inipol EAP 22 bioremediation agent. In these enclosures, which showed an increase in hydrocarbon-degrader counts from 6.5 x 10(3) to 4.1 x 10(7) per g dry sediment within 8 days, a 17% contribution by biodegradation to subsequent hydrocarbon removal was estimated. Stimulation in hydrocarbon-degrader counts in fertilizer-alone control enclosures was indistinguishable from the stimulation observed with both kerosene and fertilizer present, suggesting that the dynamics in numbers of hydrocarbon-degrading bacteria was primarily impacted by the bioremediation agent.  相似文献   

Failure in accretionary wedges with the maximum strength theorem: numerical algorithm and 2D validation     

Pauline Souloumiac  Kristian Krabbenh?ft  Yves M. Leroy  Bertrand Maillot 《Computational Geosciences》2010,14(4):793-811

The objective is to capture the 3D spatial variation in the failure mode occurring in accretionary wedges and their analog experiments in the laboratory from the sole knowledge of the material strength and the structure geometry. The proposed methodology relies on the maximum strength theorem which is inherited from the kinematic approach of the classical limit analysis. It selects the optimum virtual velocity field which minimizes the tectonic force. These velocity fields are constructed by interpolation thanks to the spatial discretization conducted with ten-noded tetrahedra in 3D and six-noded triangles in 2D. The resulting, discrete optimization problem is first presented emphasizing the dual formalism found most appropriate in the presence of nonlinear strength criteria, such as the Drucker–Prager criterion used in all reported examples. The numerical scheme is first applied to a perfectly triangular 2D wedge. It is known that failure occurs to the back for topographic slope smaller than and to the front for slope larger than a critical slope, defining subcritical and supercritical slope stability conditions, respectively. The failure mode is characterized by the activation of a ramp, its conjugate back thrust, and the partial or complete activation of the décollement. It is shown that the critical slope is captured precisely by the proposed numerical scheme, the ramp, and the back thrust corresponding to regions of localized virtual strain. The influence of the back-wall friction on this critical slope is explored. It is found that the failure mechanism reduces to a thrust rooting at the base of the back wall and the absence of back thrust, for small enough values of the friction angle. This influence is well explained by the Mohr construction and further validated with experimental results with sand, considered as an analog material. 3D applications of the same methodology are presented in a companion paper.  相似文献   

Magnetic properties and heavy metal content of sanitary leachate sludge in two landfill sites near Bandung,Indonesia     

Satria Bijaksana  Estevanus Kristian Huliselan 《Environmental Earth Sciences》2010,60(2):409-419

Magnetic properties and heavy metal content of landfill leachate sludge samples from two municipal solid waste disposal sites near Bandung, West Java, Indonesia, and their correlation with heavy metals are studied in the present work. Leachate was found to be sufficiently magnetic with mass-specific magnetic susceptibility that varies from 64.8 to 349.0 × 10⁻⁸ m³ kg⁻¹. It is, however, less magnetic than the soils around the landfill sites. The magnetic minerals are predominantly pseudo-single domain and multidomain magnetite. Leachate samples from the older but inactive disposal site, Jelekong, are found to be more magnetic than that from Sarimukti, the younger and active site. The enhancement of leachate due to the soil-derived ferrimagnetic particles is possibly the same for both Sarimukti and Jelekong. The fact that strong correlation between magnetic parameters and heavy metals is observed in Jelekong but is absent in Sarimukti suggests that the use of magnetic measurement as a proxy measurement for heavy metal content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Moreover, the accumulation of magnetic minerals and heavy metals in leachate might depend on the activity and the age of landfill site.  相似文献   

Implications of 21st century climate change for the hydrology of Washington State   总被引：5，自引：2，他引：3  

Marketa M. Elsner  Lan Cuo  Nathalie Voisin  Jeffrey S. Deems  Alan F. Hamlet  Julie A. Vano  Kristian E. B. Mickelson  Se-Yeun Lee  Dennis P. Lettenmaier 《Climatic change》2010,102(1-2):225-260

Pacific Northwest (PNW) hydrology is particularly sensitive to changes in climate because snowmelt dominates seasonal runoff, and temperature changes impact the rain/snow balance. Based on results from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), we updated previous studies of implications of climate change on PNW hydrology. PNW 21st century hydrology was simulated using 20 Global Climate Models (GCMs) and 2 greenhouse gas emissions scenarios over Washington and the greater Columbia River watershed, with additional focus on the Yakima River watershed and the Puget Sound which are particularly sensitive to climate change. We evaluated projected changes in snow water equivalent (SWE), soil moisture, runoff, and streamflow for A1B and B1 emissions scenarios for the 2020s, 2040s, and 2080s. April 1 SWE is projected to decrease by approximately 38–46% by the 2040s (compared with the mean over water years 1917–2006), based on composite scenarios of B1 and A1B, respectively, which represent average effects of all climate models. In three relatively warm transient watersheds west of the Cascade crest, April 1 SWE is projected to almost completely disappear by the 2080s. By the 2080s, seasonal streamflow timing will shift significantly in both snowmelt dominant and rain–snow mixed watersheds. Annual runoff across the State is projected to increase by 2–3% by the 2040s; these changes are mainly driven by projected increases in winter precipitation.  相似文献   

Atmospheric processes responsible for generation of the 2008 Boothbay meteotsunami     

I. Vilibić  K. Horvath  N. Strelec Mahović  S. Monserrat  M. Marcos  Á. Amores  I. Fine 《Natural Hazards》2014,74(1):25-53

We investigated the atmospheric processes and physics that were active during a tsunami-like event hitting Boothbay Harbor area (Maine, USA) on 28 October 2008. The data collected by tide gauges, ground and sounding stations and meteo–ocean buoys in the area were analyzed, together with satellite and radar images. The atmospheric processes were reproduced by the weather research and forecasting model, verified by in situ and remote sensing data. A cold front moved over the area at the time of the event, with embedded convective clouds detected by satellite and radar data and the internal gravity waves (IGWs) detected by radar and reproduced by the model at the rear of the frontal precipitation band. According to the model, the IGWs that passed over Boothbay Harbor generated strong ground air-pressure oscillations reaching 2.5 hPa/3 min. The IGWs were ducted towards the coast without significant dissipation, propagating in a stable near-surface layer capped by an instability at approximately 3.5 km height and satisfying all conditions for their maintenance over larger areas. The intensity, speed and direction of the IGWs were favourable for generation of a meteotsunami wave along the Gulf of Maine shelf. Operational observation systems were not capable of sufficiently capturing the ground disturbance due to a too coarse sampling rate, while the numerical model was found to be a useful tool in eventual future detection and warning systems.  相似文献   

A combined IR and XRD study of natural well crystalline goethites (α-FeOOH)     

Kaufhold  Stephan  Ufer  Kristian  Hein  Melanie  Götze  Niko  Dohrmann  Reiner 《中国地球化学学报》2022,41(5):794-810

Acta Geochimica - Goethite (α-FeOOH) is one of the most abundant minerals on the Earth surface, occurring in temperate, tropical and equatorial climates. Fe in goethite can be substituted by...  相似文献