From mimeos to E-copy--a tribute to Professor R B (Bob) Clark,founding editor of the Marine Pollution Bulletin     

Wells P  Baker J  Chapman P  Elliott M  Hutchings P  Mann K  Olive P  Pearce J  Phillips D  Sheppard C 《Marine pollution bulletin》2003,46(9):1051-1054

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Smithsonian Institution's Global Volcanism Network     

Jennifer?FelaEmail author 《Bulletin of Volcanology》2003,65(5):382-383

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Observations of Centaur 8405 Asbolus: Searching for Water Ice     

Jennifer Romon-MartinMaria A. Barucci  Catherine de BerghAlain Doressoundiram  Nuno Peixinho  François Poulet 《Icarus》2002,160(1):59-65

Near-infrared spectra of Centaur 8405 Asbolus have been obtained, covering the whole rotational period. Complementary photometry and visible spectroscopy have also been performed. The aim of this project was to confirm or refute the water ice detection on one side of Asbolus reported by Kern et al. (2000 Astrophys. J.542, L155-L159). We found no absorption feature at any rotational phase of Asbolus. Our study is the first in-depth investigation of a centaur over a complete rotational period. Our results seem also to indicate that a change in the slope from 0.8 to 1.0 μm may occur in Asbolus spectrum.  相似文献   

The published work of U.V. Helava     

David A. Tait 《ISPRS Journal of Photogrammetry and Remote Sensing》1995,50(6)

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Comparative soil CO2 flux measurements and geostatistical estimation methods on Masaya volcano, Nicaragua     

Jennifer L. Lewicki  Deborah Bergfeld  Carlo Cardellini  Giovanni Chiodini  Domenico Granieri  Nick Varley  Cynthia Werner 《Bulletin of Volcanology》2005,68(1):76-90

We present a comparative study of soil CO₂ flux () measured by five groups (Groups 1–5) at the IAVCEI-CCVG Eighth Workshop on Volcanic Gases on Masaya volcano, Nicaragua. Groups 1–5 measured using the accumulation chamber method at 5-m spacing within a 900 m² grid during a morning (AM) period. These measurements were repeated by Groups 1–3 during an afternoon (PM) period. Measured ranged from 218 to 14,719 g m⁻² day⁻¹. The variability of the five measurements made at each grid point ranged from ±5 to 167%. However, the arithmetic means of fluxes measured over the entire grid and associated total CO₂ emission rate estimates varied between groups by only ±22%. All three groups that made PM measurements reported an 8–19% increase in total emissions over the AM results. Based on a comparison of measurements made during AM and PM times, we argue that this change is due in large part to natural temporal variability of gas flow, rather than to measurement error. In order to estimate the mean and associated CO₂ emission rate of one data set and to map the spatial distribution, we compared six geostatistical methods: arithmetic and minimum variance unbiased estimator means of uninterpolated data, and arithmetic means of data interpolated by the multiquadric radial basis function, ordinary kriging, multi-Gaussian kriging, and sequential Gaussian simulation methods. While the total CO₂ emission rates estimated using the different techniques only varied by ±4.4%, the maps showed important differences. We suggest that the sequential Gaussian simulation method yields the most realistic representation of the spatial distribution of , but a variety of geostatistical methods are appropriate to estimate the total CO₂ emission rate from a study area, which is a primary goal in volcano monitoring research.Editorial responsibility: H Shinohara  相似文献   

Smithsonian Institution’s Global Volcanism Network     

Jennifer?FelaEmail author 《Bulletin of Volcanology》2004,66(1):90-91

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Smithsonian Institution’s Global Volcanism Network     

Jennifer?FelaEmail author 《Bulletin of Volcanology》2004,66(3):289-290

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Stable Carbon and Nitrogen Isotopic     

Jennifer Lawson  Peter T Doran  Fabien Kenig  David J Des marais  John C Priscu 《Aquatic Geochemistry》2004,10(3-4):269-301

The perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, are part of the coldest and driest ecosystem on earth. To understand lacustrine carbon and nitrogen cycling in this end-member ecosystem, and to define paleolimnological proxies for ice-covered lakes, we measured the stable carbon and nitrogen isotopic composition of particulate organic matter (POM) and benthic organic matter (BOM) within the lakes of Taylor Valley. The ¹³C compositions of seasonally ice-free edges of the lakes (moats) are enriched relative to under-ice organic matter. Thus, the organic carbon isotopic composition of buried sediments may be a proxy for sample position within the lake. In the moats, ¹³C values are governed by limited CO₂diffusion across benthic cyanobacterial cell membranes. During a high glacial melt (2001–2002) season, both ¹³C_POM and ¹³C_BOM in the moats were more depleted than during previous low melt years. We propose that this occurred in response to higher [CO₂]_(aq) and/or reduced growth rates resulting from turbidity-induced light limitation. Though moats and under-ice environments are usually poorly connected, during the 2001–2002 season, the enrichment of the ¹³C_POM values at 6 m depth in the stream-proximal sites relative to deep-profile sites implies enhanced connectivity between these environments. The ¹³C compositions of BOM and POM profiles in Lake Hoare and Lake Fryxell indicate that these lakes are dominated by benthic productivity. In contrast, in Lake Bonney, the similarity of the ¹³C values of BOM and POM indicates the pelagic component dominance in the carbon cycle.  相似文献   

The pattern and influence of low dissolved oxygen in the Patuxent River,a seasonally hypoxic estuary     

Denise?L.?BreitburgEmail author  Aaron?Adamack  Kenneth?A.?Rose  Sarah?E.?Kolesar  Beth?Decker  Jennifer?E.?Purcell  Julie?E.?Keister  James?H.?Cowan 《Estuaries and Coasts》2003,26(2):280-297

Increased nutrient loadings have resulted in low dissolved oxygen (DO) concentrations in bottom waters of the Patuxent River, a tributary of Chesapeake Bay. We synthesize existing and newly collected data to examine spatial and temporal variation in bottom DO, the prevalence of hypoxia-induced mortality of fishes, the tolerance of Patuxent River biota to low DO, and the influence of bottom DO on the vertical distributions and spatial overlap of larval fish and fish eggs with their gelatinous predators and zooplankton prey. We use this information, as well as output from watershed-quality and water-quality models, to configure a spatially-explicit individual-based model to predict how changing land use within the Patuxent watershed may affect survival of early life stages of summer breeding fishes through its effect on DO. Bottom waters in much of the mesohaline Patuxent River are below 50% DO saturation during summer. The system is characterized by high spatial and temporal variation in DO concentrations, and the current severity and extent of hypoxia are sufficient to alter distributions of organisms and trophic interactions in the river. Gelatinous zooplankton are among the most tolerant species of hypoxia, while several of the ecologically and economically important finfish are among the most sensitive. This variation in DO tolerances may make the Patuxent River, and similar estuaries, particularly susceptible to hypoxia-induced alterations in food web dynamics. Model simulations consistently predict high mortality of planktonic bay anchovy eggs (Anchoa mitchilli) under current DO, and increasing survival of fish eggs with increasing DO. Changes in land use that reduce nutrient loadings may either increase or decrease predation mortality of larval fish depending on the baseline DO conditions at any point in space and time. A precautionary approach towards fisheries and ecosystem management would recommend reducing nutrients to levels at which low oxygen effects on estuarine habitat are reduced and, where possible, eliminated.  相似文献   

Time of day and telephone interviews in Rural‐Urban Australia     

Jennifer M. McKay 《The Australian geographer》1986,17(1):65-71

Private household telephone ownership in Australian capital cities ranges between 91.1 per cent (Canberra) and 81.9 per cent (Brisbane). Consequently, telephone ownership need not be viewed as a major factor distinguishing households. As the characteristics of households without telephones are also known, it is possible to supplement telephone interviews with face to face interviews and thereby ensure that such a sampling frame represents the population. Such techniques, coupled with the ease and relative inexpense of telephone interviews, may promote the use of the medium. Using a letter to forewarn potential respondents and a three call‐back strategy (twice during working hours, once at night), a response rate of 77.4 per cent was achieved; 8.7 per cent of respondents could not be contacted and the balance refused. Reasons for refusals related almost exclusively to the subject matter of the interview — bushfire hazard. The first day time calls yielded 166 interviews out of 378 calls and the second 67 out of 197 calls. No particular time of day or day of week resulted in significantly more interviews; however, 55.4 per cent of respondents were female. Night calls yielded the highest response rates, with 86 interviews from 127 calls, and 63.9 per cent of respondents were male.  相似文献