Submarine groundwater discharge and benthic biogeochemical zonation in the Huanghe River Estuary     

Guangquan Chen  Bochao Xu  Shibin Zhao  Disong Yang  William C.Burnett  Shaobo Diao  Maosheng Gao  Xingyong Xu  Lisha Wang 《海洋学报(英文版)》2022,41(1):11-20

Submarine groundwater discharge(SGD) has received increasing attention by studies on coastal areas; however,its effects on biogeochemical zonation have not been investigated to date. The Huanghe River Estuary(HRE) is a world class river estuary with high turbidity, and heavy human regulation. This study investigated how SGD is related to the benthic biogeochemistry of the HRE. Based on the distribution of several parameters(e.g., salinity,temperature, dissolved oxygen(DO) levels, p H, radium iso...  相似文献   

A record of Lateglacial/Holocene environmental change from a high‐elevation site in the Intermountain West,USA     

Andrea Brunelle  Thomas A. Minckley  Elliott Lips  Paul Burnett 《第四纪科学杂志》2013,28(1):103-112

Records of past vegetation and fire history can be complicated by changes in the depositional environment of a sampling location. However, these changes can alternatively be used as a measure of climate variability. Our study site, ca. 18.0 cal. ka BP record from Little Brooklyn Lake, Wyoming, located near the crest of the Snowy Range, records three moisture states. Initially, the lake was likely a glacier‐fed pond indicated by the presence of Pediastrum algae colonies. Around 13.0 cal. ka BP this pond transitioned to a meadow environment, suggested by the loss of Pediastrum algae colonies and slow sedimentation rates. Meadow conditions were maintained until ca. 5.0 cal. ka BP when Pediastrum algae colony abundance increased,indicating the formation of a shallow lake. From 18.0 to ca. 5.0 cal. ka BP, the pollen record is suggestive of alpine vegetation conditions with relatively high spruce and herbaceous taxa. Low charcoal influx also characterizes the period between 18.0 and 5.0 cal. ka BP. After 5.0 cal. ka BP, the coincidence of the formation of shallow lake and pollen data, indicating a shift to a spruce and fir forest, suggests an increase in effective moisture. Fire remained rare in this basin over the entire record, however, once the lake established sedimentation rates and charcoal influx increased. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

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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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