The arsenic source term for an in-pit uranium mine tailings facility and its long-term impact on the regional groundwater     

Brett J. Moldovan  M. Jim Hendry  Glenn A. Harrington 《Applied Geochemistry》2008

Detailed field sampling and analyses and laboratory-based diffusion-cell experiments were used in conjunction with 3-D reactive transport modeling (MODFLOW and MT3D99) to quantify the fate and long-term (10 ka) transport of As in the Rabbit Lake In-pit Tailings Management Facility (RLITMF), northern Saskatchewan, Canada. The RLITMF (300 m × 425 m × 90 m thick) was engineered to ensure solute transport within the RLITMF is dominated by diffusion. Concentrations of As in the tailings pore fluids ranged from 0.24 to 140 mg/L (n = 43). Arsenic speciation analyses indicate 90% of this arsenic exists as As⁵⁺. This observation is supported by pH–Eh measurements of pore fluids (n = 135). Geochemical analyses yielded a strong inverse correlation between the Fe/As molar ratio in the tailings solids and the corresponding concentration of dissolved As, which is attributed to the adsorption of As to secondary 2-line ferrihydrite present in the tailings. Diffusion-cell testing yielded values for the effective diffusion coefficient, sorption coefficient, and effective porosity of As in the tailings of 4.5 × 10⁻¹⁰ m²/s, 2–4 cm³/g and 0.36, respectively. Reactive transport simulations using the field and laboratory data show adsorption of As to the tailings and diffusive transport of dissolved As in the tailings should reduce the source term concentration of As to between 40% and 70% of the initial concentrations over the 10 ka simulation period. Based on these simulations, the As concentrations in the regional groundwater, 50 m down gradient of the tailings facility, should be maintained at background concentrations of 0.001 mg/L over the 10 ka period. These findings suggest the engineered in-pit disposal of U mine tailings can provide long-term protection for the local groundwater regime from As contamination.  相似文献   

Formation of pockmarks by pore-water escape   总被引：1，自引：1，他引：1  

P. K. Harrington 《Geo-Marine Letters》1985,5(3):193-197

During the course of a North Sea rig site investigation, a number of seabed depressions were observed on side-scan sonar records, some of which may be identified as pockmarks. Others are described as pits. A pockmark evolutionary series is proposed on the basis of all these features with a suggested mechanism which would favor release of pore water, but does not exclude gas escape. Acoustic voids are considered to be a related phenomenon.  相似文献   

The satellites of Neptune and the origin of Pluto     

R.S. Harrington  T.C. Van Flandern 《Icarus》1979,39(1):131-136

Pluto and the chaotic satellite system of Neptune may have originated from a single encounter of Neptune with a massive solar system body. A series of numerical experiments has been carried out to try to set limits on the circumstances of such an encounter. These experiments show that orbits very much like those of Pluto, Triton, and Nereid can result from a single close encounter of such a body with Neptune. The implied mass range and encounter velocities limit the source of the encountering body to a former trans-Neptunian planet in the 2- to 5-Earth-mass range.  相似文献   

Corporate strategy, business strategy and activity location     

James W. Harrington Jr   《Geoforum》1985,16(4):349-356

Analysis of locational patterns and change within an industry may be assisted by division of industry participants into groups based on corporate and business strategies. These strategies reflect the assets of the companies and the characteristics of the industry. They affect the locational needs, behavior and impact of the companies. Hypothesized effects of strategy are explored in a brief study of U.S. semiconductor manufacturers. Of the possible strategic considerations, corporate diversification and integration, and business scale and cost/price position seem to be the most relevant for this industry.  相似文献   

New RAMS cloud microphysics parameterization part I: the single-moment scheme     

R. L. Walko  W. R. Cotton  M. P. Meyers  J. Y. Harrington 《Atmospheric Research》1995,38(1-4)

A new cloud microphysical parameterization is described. Features of this new scheme include: the use of generalized gamma distributions as the basis function for all hydrometeor species; the use of a heat budget equation for hydrometeor classes, allowing heat storage and mixed phase hydrometeors; partitioning hydrometeors into seven classes (including separate graupel and hail categories); the use of stochastic collection rather than continuous accretion approximations and extension of the ice nucleation scheme to include homogeneous nucleation of ice from haze particles and cloud droplets.The versatility and credibility of the new scheme is explored, using sensitivity experiments for a simple two-dimensional convective cloud simulation.  相似文献   

Stability criteria for triple stars     

Robert S. Harrington 《Celestial Mechanics and Dynamical Astronomy》1972,6(3):322-327

A wide variety of equal-mass stellar triple systems has been numerically integrated in order to establish factors pertinent to stability. The significant parameters appear to be whether the relative revolution is direct or retrograde, and the ratio of the periastron distance in the outer orbit to the semi-major axis of the inner orbit. For stability, this ratio must be at least 3.5 for direct orbits and at least 2.75 for retrograde orbits.  相似文献   

A dynamical investigation of the conjecture that Mercury is an escaped satellite of Venus     

Thomas C. Van Flandern  Robert S. Harrington 《Icarus》1976,28(4):435-440

The possibility that Mercury might once have been satellite of a Venus, suggested by a number of anomalies, is investigated by a series of numerical computer experiments. Tidal interaction between Mercury and Venus would result in the escape of Mercury into a solar orbit. Only two escape orbits are possible, one exterior and one interior to the Venus orbit. For the interior orbit, subsequent encounters are sufficiently distant to avoid recapture or large perturbations. The perihelion distance of Mercury tends to decrease, while the orientation of perihelion librates for the first few thousand revolutions. If dynamical evolution or nonconservative forces were large enough in the early solar system, the present semimajor axes could have resulted. The theoretical minimum quadrupole moment of the inclined rotating Sun would rotate the orbital planes out of coplanarity. Secular perturbations by the other planets would evolve the eccentricity and inclination of Mercury's orbit through a range of possible configurations, including the present orbit. Thus the conjecture that Mercury is an escaped satellite of Venus remains viable, and is rendered more attractive by our failure to disprove it dynamically.  相似文献   

Spatial and temporal variability of ground water recharge in central Australia: a tracer approach   总被引：7，自引：0，他引：7  

Harrington GA  Cook PG  Herczeg AL 《Ground water》2002,40(5):518-527

Two environmental tracer methods are applied to the Ti-Tree Basin in central Australia to shed light on the importance of recharge from floodouts of ephemeral rivers in this arid environment. Ground water carbon-14 concentrations from boreholes are used to estimate the average recharge rate over the interval between where the ground water sample first entered the saturated zone and the bore. Environmental chloride concentrations in ground water samples provide estimates of the recharge rate at the exact point in the landscape where the sample entered the saturated zone. The results of the two tracer approaches indicate that recharge rates around one of the rivers and an extensive floodplain are generally higher than rates of diffuse recharge that occurs in areas of lower topographic relief. Ground water 2H/1H and 18O/16O compositions are all depleted in the heavier isotopes (delta2H = -67 per thousand to -50 per thousand; delta18O = -9.2 per thousand to -5.7%o) compared with the long-term, amount-weighted mean isotopic composition of rainfall in the area (delta2H = -33.8 per thousand; delta18O = -6.3 per thousand). This indicates that recharge throughout the basin occurs only after intense rainfall events of at least 150 to 200 mm/month. Finally, a recharge map is developed to highlight the spatial extent of the two recharge mechanisms. Floodout recharge to the freshest ground water (TDS <1,000 mg/L) is approximately 1.9 mm/year compared with a mean recharge rate of approximately 0.2 mm/year to the remainder of the basin. These findings have important implications for management of the ground water resource.  相似文献   

RURAL ADDRESSING AND COMPUTER MAPPING IN NEW MEXICO     

William J. Gribb  Robert J. Czerniak  John A. Harrington 《The Professional geographer》1990,42(4):471-480

Specifying the location of a rural residence is a common geographic problem. Most addressing systems are designed for urban areas and are not applicable to rural areas. The mile marker addressing system meets all of the requirements for a rural addressing system. With the addition of computer mapping techniques, rural addressing can be done efficiently and can provide the basis for a county's computer mapping system. Projects in New Mexico provide several examples of computerized rural addressing projects.  相似文献   

Geochemical processes controlling arsenic mobility in groundwater: A case study of arsenic mobilization and natural attenuation     

Y. Thomas He  Arthur G. Fitzmaurice  Azra Bilgin  Sunkyung Choi  Peggy O’Day  John Horst  James Harrington  H. James Reisinger  David R. Burris  Janet G. Hering 《Applied Geochemistry》2010

The behavior of As in the subsurface environment was examined along a transect of groundwater monitoring wells at a Superfund site, where enhanced reductive dechlorination (ERD) is being used for the remediation of groundwater contaminated with chlorinated solvents. The transect was installed parallel to the groundwater flow direction through the treatment area. The ERD technology involves the injection of organic C (OC) to stimulate in situ microbial dechlorination processes. A secondary effect of the ERD treatment at this site, however, is the mobilization of As, as well as Fe and Mn. The concentrations of these elements are low in groundwater collected upgradient of the ERD treatment area, indicating that, in the absence of the injected OC, the As that occurs naturally in the sediment is relatively immobile. Batch experiments conducted using sediments from the site inoculated with an Fe(III)- and As(V)-reducing bacterium and amended with lactate resulted in mobilization of As, Fe and Mn, suggesting that As mobilization in the field is due to microbial processes.  相似文献