Natural radionuclides in the water of Narragansett Bay     

Peter Hans Santschi  Yuan-Hui Li  Joy Bell 《Earth and Planetary Science Letters》1979,45(1):201-213

The concentrations of radionuclides of the U-Th series (²³⁸U,²³⁴Th,²³⁴U,²³⁰Th,²²⁶Ra,²¹⁰Pb,²¹⁰Po, and²³²Th,²²⁸Ra,²²⁸Th) in the water of Narragansett Bay are reported. Analysis of the total, particulate, dissolved and colloidal forms of Th isotopes reveal a consistent removal behavior which is controlled mainly by the particulate matter concentration and the sediment resuspension rate. Half-removal times of Th from solution onto particles range from 1.5 to 15 days, and settling velocities of Th containing particles range generally between 1 and 11 m/day.²¹⁰Pb and²¹⁰Po concentrations are seasonally dependent, with higher concentrations and slower removal during the early summer (half-removal times from solution onto particles of 1–5 days in winter and up to 2 months in early summer).  相似文献   

Nature conservation in the Nordic countries: Consensus rather than conflict     

Joy Tivy 《Geoforum》1985,16(3):239-255

This paper presents a comparative analysis of the aims, methods, planning and management, and current problems of countryside conservation in Denmark, Norway, Sweden and Finland. The traditional Nordic common-law of “every man's right of access” to the countryside is of longstanding. In these countries conservation is as much concerned with the protection, for public use, of landscapes of recreational and/or scenic value as with the conservation of ‘wild nature’. In addition, conservation is usually closely integrated with other aspects of physical planning, while responsibility for its management has been devolved, to a greater or lesser extent, from national or regional authorities to local government. The particular aims and methods of conservation, however, vary with the nature of the biophysical resource base, the legislative structure and the stage of conservation planning in the individual countries. In this respect, Denmark has the most sophisticated and developed system, Finland the least. The wider concept of conservation and its close integration with countryside planning in all the Nordic countries contrast with conservation in the U.K. It is suggested that the Nordic approach to the solution of conservation problems might be relevant to a solution of the increasing conflict of ecological, economic and social interests in the British countryside today.  相似文献   

Rates of magma emplacement and volcanic output     

Joy A. Crisp 《Journal of Volcanology and Geothermal Research》1984,20(3-4)

This study includes a compilation of about one hundred estimates of volumetric rates of magma emplacement and volcanic output that are average rates for durations of igneous activity greater than 300 yrs. These data indicate that the rate of volcanic output is about 10⁻¹ km³ yr⁻¹ in regions that are the most active magmatically. Factors that correlate with rates of magma emplacement and volcanic output are: magma composition, crustal thickness, tectonic setting, and regional stress. Of the ninety rates of magma emplacement and volcanic output that were studied, the highest for basaltic magmas are greater than the highest for silicic magmas, regardless of the volumes erupted or areal extent of magmatism. Rates of volcanic output for oceanic areas tend to be greater than rates in continental areas, perhaps because of thinner crust, a predominance of basaltic magma, and higher rates of magma generation. Ratios of intrusive to extrusive volumes are typically about 5 to 1 for oceanic localities and 10 to 1 for continental localities. This difference apparently reflects dissimilar rates of magma ascent related to different crustal thicknesses and magma compositions. The total rate of magma emplacement and volcanic output for the Earth, averaged over the last 180 m.y., is between about 26 and 34 km³ yr⁻¹. About 75% of this total is contributed by ocean-ridge magmatism. Oceanic intraplate magmatism contributes about 5%. Igneous activity in subduction zones, about half of which is continental, adds about 20%. Intracontinental magmatism, more than 95% of which is flood and plains basalts, provides less than 5% of the total global rate of magma emplacement and volcanic output.  相似文献   

Sustained Ability of a Natural Microbial Community to Remove Nitrate from Groundwater     

Charles J. Paradis  John I. Miller  Ji-Won Moon  Sarah J. Spencer  Lauren M. Lui  Joy D. Van Nostrand  Daliang Ning  Andrew D. Steen  Larry D. McKay  Adam P. Arkin  Jizhong Zhou  Eric J. Alm  Terry C. Hazen 《Ground water》2022,60(1):99-111

Microbial-mediated nitrate removal from groundwater is widely recognized as the predominant mechanism for nitrate attenuation in contaminated aquifers and is largely dependent on the presence of a carbon-bearing electron donor. The repeated exposure of a natural microbial community to an electron donor can result in the sustained ability of the community to remove nitrate; this phenomenon has been clearly demonstrated at the laboratory scale. However, in situ demonstrations of this ability are lacking. For this study, ethanol (electron donor) was repeatedly injected into a groundwater well (treatment) for six consecutive weeks to establish the sustained ability of a microbial community to remove nitrate. A second well (control) located upgradient was not injected with ethanol during this time. The treatment well demonstrated strong evidence of sustained ability as evident by ethanol, nitrate, and subsequent sulfate removal up to 21, 64, and 68%, respectively, as compared to the conservative tracer (bromide) upon consecutive exposures. Both wells were then monitored for six additional weeks under natural (no injection) conditions. During the final week, ethanol was injected into both treatment and control wells. The treatment well demonstrated sustained ability as evident by ethanol and nitrate removal up to 20 and 21%, respectively, as compared to bromide, whereas the control did not show strong evidence of nitrate removal (5% removal). Surprisingly, the treatment well did not indicate a sustained and selective enrichment of a microbial community. These results suggested that the predominant mechanism(s) of sustained ability likely exist at the enzymatic- and/or genetic-levels. The results of this study demonstrated the in situ ability of a microbial community to remove nitrate can be sustained in the prolonged absence of an electron donor.  相似文献   

Interaction study of clay-bearing amphibolite–crude oil–saline water: Molecular level implications for enhanced oil recovery during low saline water flooding     

Saheli Sanyal  Kumar Abhishek Singh  Harshil Parekh  Vishrut Chokshi  Uttam K Bhui 《Journal of Earth System Science》2018,127(8):112

Low saline water flooding (LSWF) had proved to be an efficient method for enhanced oil recovery in clay-bearing hydrocarbon reservoirs, but the interaction mechanisms among in-situ rocks – fluids and injection fluids within the reservoir – are not yet known properly. Understanding the molecular level interaction among these components is critical for designing and field scale implementation of LSWF in clay-bearing crystalline reservoir rocks, which is very limited in the existing literature. A weathered amphibolite rock and one dead crude oil from the Bakrol field (Cambay basin, India) have been used in this study. The presence of clay minerals in the weathered amphibolite rock was observed using a polarising microscope and characterised by the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques. The crude oil and its fractionated SARA components have been extensively studied by spectroscopic techniques for their characterisation. The interaction study among the rock powder, hydrocarbon crude oil and saline water has been performed in the present work for gaining better insight for designing the injection fluid for LSWF. The weathered amphibolite rock powder was mixed with the dead crude oil and kept for 30 days in room temperature (T) and pressure (P) for proper interaction. The XRD, FTIR and cation exchange capacity results clearly demonstrated the incorporation of crude oil components in the interlayer surfaces of clay minerals. The oil removal efficiency, from the oil-treated rock powder of three saline water samples having NaCl concentration of 3000, 5000 and 8000 ppm, was investigated using the UV–Vis and fluorescence spectroscopies. The low saline NaCl water is capable of removing the maximum amount of polar components from the oil-treated rock powder. These molecular level insights are valuable for designing effective injection fluid for enhancing the oil recovery from the clay-rich crystalline reservoir rock.  相似文献   

Diatom floristic change and lake paleoproduction as evidence of recent eutrophication in shallow lakes of the midwestern USA     

Adam J. Heathcote  Joy M. Ramstack Hobbs  N. John Anderson  Patrick Frings  Daniel R. Engstrom  John A. Downing 《Journal of Paleolimnology》2015,53(1):17-34

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Tracking the relationship between changing skyline and population growth of an Indian megacity using earth observation technology     

Joy Sanyal  Koel Roychowdhury 《国际地球制图》2017,32(12):1421-1435

Temporal analysis of Landsat-TM imageries reveals a saturated state of Kolkata (Calcutta) Metropolitan Area. However, the city has witnessed accelerated growth in real estate construction in recent past. This study applies digital photogrammetry to quantify the changes in Kolkata’s skyline. Recently, released SRTM DEM of 1 Arc Second and a digital surface model derived from WorldView-1 stereo images were used to account for the past and recent surface heights, respectively. Consequently, this paper examines whether the sustained addition in housing capacity has been necessarily driven by a growth in the urban population/number of households. Results show that 40.31% of the area experienced vertical growth, majorly by replacing older dwellings with taller apartment blocks. Further analysis reveals that part of these newly added residences has remained unoccupied as they were purchased by non-resident Indians for using as a second home or was never sold due to recent economic slowdown.  相似文献   

Southern California Salt Marsh Dominance Relates to Plant Traits and Plasticity     

Catherine L. Bonin  Joy B. Zedler 《Estuaries and Coasts》2008,31(4):682-693

The three most abundant tidal marsh species at Tijuana Estuary rank Salicornia virginica > Jaumea carnosa > Frankenia salina in occurrences and cover, despite being equally productive in a greenhouse study. The same abundance ranking (Sv>Jc>Fs) developed within 10 years in a restoration site that was planted with near-equal numbers per species. In this paper, we show that resistance to invasion and invasiveness also ranked Sv>Jc>Fs, helping to explain how the restored community lost diversity over time. To explain differential dominance, we assessed 20 traits (including trait ratios), expecting several traits to rank Sv>Jc>Fs, but that was not so. Nor were field abundance ranks explained by the number of superior traits, since Salicornia ranked first in only four traits; Jaumea ranked first in seven, Frankenia in three, and six traits involved ties. Instead, we found explanatory power in two traits (height and runner length) and plasticity (ability to shift trait ratios with changing conditions). We propose that Salicornia becomes dominant by growing tall (height ranked Sv>Jc = Fs) and capturing light first, and that Jaumea co-dominates by extending its runners throughout the understory. Both dominants are more plastic than the subordinate Frankenia, which allocates the greatest proportion of dry weight to roots. Our multi-trait approach explained abundance ranks where focusing on a single trait (potential productivity) could not.  相似文献   

Determination of Zr and Hf in a Flux-Free Fusion of Whole Rock Samples using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) with Isotope Dilution Calibration     

Joy E. Reid  Ingo Horn  Henry P. Longerich  Lance Forsythe  George A. Jenner 《Geostandards and Geoanalytical Research》1999,23(2):149-155

Isotope dilution calibration has been applied to the determination of Zr and Hf in whole rocks by laser ablation (LA)-ICP-MS. Enriched isotopes were added during the preparation of flux-free, synthetic whole rock glasses and homogenised through a combination of grinding and fusion. This method avoids problems, such as solution instability and the chemical resistance of minerals such as zircon, inherent in acid digestion sample preparation. The use of isotope dilution removes the need for external calibration using certified reference material glasses such as NIST SRM 612 for which certified Zr and Hf values are not available. The precision of Zr and Hf determinations were found to be < 1% and 3.5% respectively, limited by Poisson counting statistics which contributed to 50% of the final precision of analysis. Measured values correlate closely with compiled literature values.  相似文献   

A new flow for Canadian young hydrologists: Key scientific challenges addressed by research cultural shifts     

Caroline Aubry-Wake  Lauren D. Somers  Haley Alcock  Aspen M. Anderson  Amin Azarkhish  Samuel Bansah  Nicole M. Bell  Kelly Biagi  Mariana Castaneda-Gonzalez  Olivier Champagne  Anna Chesnokova  Devin Coone  Tasha-Leigh J. Gauthier  Uttam Ghimire  Nathan Glas  Dylan M. Hrach  Oi Yin Lai  Pierrick Lamontagne-Hallé  Nicolas R. Leroux  Laura Lyon  Sohom Mandal  Bouchra R. Nasri  Nataša Popović  Tracy E. Rankin  Kabir Rasouli  Alexis Robinson  Palash Sanyal  Nadine J. Shatilla  Brandon Van Huizen  Sophie Wilkinson  Jessica Williamson  Majid Zaremehrjardy 《水文研究》2020,34(8):2001-2006

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