A density-dependent multi-species model to assess groundwater flow and nutrient transport in the coastal Keauhou aquifer,Hawai‘i,USA     

Okuhata  Brytne K.  El-Kadi  Aly I.  Dulai  Henrietta  Lee  Jonghyun  Wada  Christopher A.  Bremer  Leah L.  Burnett  Kimberly M.  Delevaux  Jade M. S.  Shuler  Christopher K. 《Hydrogeology Journal》2022,30(1):231-250

Hydrogeology Journal - Fresh groundwater is a critical resource supporting coastal ecosystems that rely on low-salinity, nutrient-rich groundwater discharge. This resource, however, is subject to...  相似文献   

Geodetic levelling and mean sea level in Great Britain     

Colonel Burnett  Major Carmody 《Journal of Geodesy》1960,34(1):55-58

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Noble gas composition of the solar wind as collected by the Genesis mission     

Veronika S. Heber  Rainer Wieler  Chad Olinger  Donald S. Burnett 《Geochimica et cosmochimica acta》2009,73(24):7414-7432

We present the elemental and isotopic composition of noble gases in the bulk solar wind collected by the NASA Genesis sample return mission. He, Ne, and Ar were analyzed in diamond-like carbon on a silicon substrate (DOS) and ^84,86Kr and ^129,132Xe in silicon targets by UV laser ablation noble gas mass spectrometry. Solar wind noble gases are quantitatively retained in DOS and with exception of He also in Si as shown by a stepwise heating experiment on a flown DOS target and analyses on other bulk solar wind collector materials. Solar wind data presented here are absolutely calibrated and the error of the standard gas composition is included in stated uncertainties. The isotopic composition of the light noble gases in the bulk solar wind is as follows: ³He/⁴He: (4.64 ± 0.09) × 10⁻⁴, ²⁰Ne/²²Ne: 13.78 ± 0.03, ²¹Ne/²²Ne: 0.0329 ± 0.0001, ³⁶Ar/³⁸Ar 5.47 ± 0.01. The elemental composition is: ⁴He/²⁰Ne: 656 ± 5, and ²⁰Ne/³⁶Ar 42.1 ± 0.3. Genesis provided the first Kr and Xe data on the contemporary bulk solar wind. The preliminary isotope and elemental composition is: ⁸⁶Kr/⁸⁴Kr: 0.302 ± 0.003, ¹²⁹Xe/¹³²Xe: 1.05 ± 0.02, ³⁶Ar/⁸⁴Kr 2390 ± 150, and ⁸⁴Kr/¹³²Xe 9.5 ± 1.0. The ³He/⁴He and the ⁴He/²⁰Ne ratios in the Genesis DOS target are the highest solar wind values measured in exposed natural and artificial targets. The isotopic composition of the other noble gases and the Kr/Xe ratio obtained in this work agree with data from lunar samples containing “young” (∼100 Ma) solar wind, indicating that solar wind composition has not changed within at least the last 100 Ma. Genesis could provide in many cases more precise data on solar wind composition than any previous experiment. Because of the controlled exposure conditions, Genesis data are also less prone to unrecognized systematic errors than, e.g., lunar sample analyses. The solar wind is the most authentic sample of the solar composition of noble gases, however, the derivation of solar noble gas abundances and isotopic composition using solar wind data requires a better understanding of fractionation processes acting upon solar wind formation.  相似文献   

Bimodal Transport of a Waste Water Plume Injected into Saline Ground Water of the Florida Keys   总被引：1，自引：0，他引：1  

Kevin S. Dillon  D. Reide Corbett  Jeffrey P. Chanton  William C. Burnett  Lee Kump 《Ground water》2000,38(4):624-634

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Hydrogen fluence in Genesis collectors: Implications for acceleration of solar wind and for solar metallicity     

Gary R. Huss  Elizabeth Koeman‐Shields  Amy J. G. Jurewicz  Donald S. Burnett  Kazuhide Nagashima  Ryan Ogliore  Chad T. Olinger 《Meteoritics & planetary science》2020,55(2):326-351

NASA's Genesis mission was flown to capture samples of the solar wind and return them to the Earth for measurement. The purpose of the mission was to determine the chemical and isotopic composition of the Sun with significantly better precision than known before. Abundance data are now available for noble gases, magnesium, sodium, calcium, potassium, aluminum, chromium, iron, and other elements. Here, we report abundance data for hydrogen in four solar wind regimes collected by the Genesis mission (bulk solar wind, interstream low‐energy wind, coronal hole high‐energy wind, and coronal mass ejections). The mission was not designed to collect hydrogen, and in order to measure it, we had to overcome a variety of technical problems, as described herein. The relative hydrogen fluences among the four regimes should be accurate to better than ±5–6%, and the absolute fluences should be accurate to ±10%. We use the data to investigate elemental fractionations due to the first ionization potential during acceleration of the solar wind. We also use our data, combined with regime data for neon and argon, to estimate the solar neon and argon abundances, elements that cannot be measured spectroscopically in the solar photosphere.  相似文献   

Calibration and use of continuous heat-type automated seepage meters for submarine groundwater discharge measurements     

B.M. Mwashote  W.C. Burnett  J. Chanton  I.R. Santos  N. Dimova  P.W. Swarzenski 《Estuarine, Coastal and Shelf Science》2010

Submarine groundwater discharge (SGD) assessments were conducted both in the laboratory and at a field site in the northeastern Gulf of Mexico, using a continuous heat-type automated seepage meter (seepmeter). The functioning of the seepmeter is based on measurements of a temperature gradient in the water between downstream and upstream positions in its flow pipe. The device has the potential of providing long-term, high-resolution measurements of SGD. Using a simple inexpensive laboratory set-up, we have shown that connecting an extension cable to the seepmeter has a negligible effect on its measuring capability. Similarly, the observed influence of very low temperature (≤3 °C) on seepmeter measurements can be accounted for by conducting calibrations at such temperatures prior to field deployments. Compared to manual volumetric measurements, calibration experiments showed that at higher water flow rates (>28 cm day⁻¹ or cm³ cm⁻² day⁻¹) an analog flowmeter overestimated flow rates by ≥7%. This was apparently due to flow resistance, turbulence and formation of air bubbles in the seepmeter water flow tubes. Salinity had no significant effect on the performance of the seepmeter. Calibration results from fresh water and sea water showed close agreement at a 95% confidence level significance between the data sets from the two media (R² = 0.98). Comparatively, the seepmeter SGD measurements provided data that are comparable to manually-operated seepage meters, the radon geochemical tracer approach, and an electromagnetic (EM) seepage meter.  相似文献   

GEOGRAPHY AND DEVELOPMENT IN KENYA *     

Isaac Sindiga  G. Wesley Burnett 《The Professional geographer》1988,40(2):232-237

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Experimental determination of U and Th partitioning between clinopyroxene and natural and synthetic basaltic liquid   总被引：2，自引：0，他引：2  

T.Z. LaTourrette  D.S. Burnett 《Earth and Planetary Science Letters》1992,110(1-4):227-244

Clinopyroxene-silicate liquid partition coefficients for U and Th have been determined by particle track radiography from 1 atm crystallization experiments at controlledfO₂. Two natural basaltic and one synthetic composition were studied atfO₂ values from the NiNiO oxygen buffer to 1 log unit more oxidizing than FeFeO (IW+ 1). Over the range offO₂ values and compositions studied,D_U^cpx/liq = 0.0034–0.015,D_Th^cpx/liq = 0.008–0.036, andD_ThD_U= 3.4–1.1. With decreasingfO₂,D_ThD_U can decrease by up to a factor of 3 for a given composition, primarily from an increase inD_U^cpx/liq, which we interpret as resulting from an increase in the proportion of tetravalent U in the system with decreasingfO₂. This demonstrates that crystal-liquid UTh fractionation isfO₂ dependent and that U in terrestrial magmas is not entirely tetravalent.D_Th^cpx/liq appears to decrease in the two basalts at the lowestfO₂, possibly as a result of changes in composition withfO₂.

Our data show the sense of UTh fractionation by clinopyroxene-liquid partitioning is consistent with previous experimental determinations, in thatD_Th^cpxD_U^cpx> 1 in all cases. This indicates that, during partial melting, the liquid will have aTh/U ratio less than the clinopyroxene in the source. The observed²³⁸U²³⁰Th disequilibrium in MORB requires that the partial melt should have aTh/U ratio greater than the bulk source, and, therefore, cannot result from clinopyroxene-liquid partitioning. Further, the magnitudes of the measured partition coefficients are too small to generate significant UTh fractionation in either direction. Assuming that clinopyroxene contains the bulk of the U and Th in MORB source, our results indicate that²³⁸U²³⁰Th disequilibrium in MORB may not be caused by partial melting at all.  相似文献   

Privacy and Ethics in Undergraduate GIS Curricula     

Peter Scull  Adam Burnett  Emmalee Dolfi  Ali Goldfarb  Peter Baum 《The Journal of geography》2016,115(1):24-34

The development of location-aware technologies, such as smartphones, raises serious questions regarding locational privacy and the ethical use of geographic data. The degree to which these concepts are taught in undergraduate geographic information science (GISci) courses is unknown. A survey of GISci educators shows that issues of privacy and ethics are important in a GISci education. However, a large proportion of GISci educators are not concerned about the loss of locational privacy and many do not devote classes to the subject. Those not teaching the subject cite lack of course time and the need for more information.  相似文献   

Energy dispersive X-ray analysis of the surface of a deep-sea ferromanganese nodule     

Bryan R. Burnett  Kenneth H. Nealson 《Marine Geology》1983,53(4):313-329

In an effort to elucidate the mechanism of formation and accretion of ferromanganese nodules, transverse sections of undisturbed botryoid surfaces of nodules from the abyssal central North Pacific were examined by X-ray analyses both by multiple replicate sample transects and mapping. Surface concentrations of Mn and Fe were found of the size and shape of microorganisms. Abundant microorganism-like objects covering the surface and the apparent absence of Si (i.e. no sediment) with the Mn and Fe concentrations suggests microorganisms may be involved either in the selective accretion or removal of these metals. If metal accretion was simply physicochemical, one would expect a more or less even distribution of Mn and Fe on the botryoid surfaces.The replicate X-ray sample transects showed that Mn and Fe have a distribution corresponding to botryoid zonation. Areas of high Mn X-ray intensity were found associated with the cap and equatorial zones of the botryoid. Most of the valley zone of the botryoid show a more or less even Mn distribution and an increase in Fe X-ray intensity. At the base of the botryoid both metals apparently precipitously decrease.  相似文献