The Behaviour of Dissolved Silicon During Estuarine Mixing II. Preliminary Investigations in the Vellar Estuary, Southern India     

Burton  J. D. 《ICES Journal of Marine Science》1970,33(2):141-148

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A comparison of ozone and chlorine toxicity to three life stages of the American oyster Crassostrea virginica     

Leonard B Richardson  Dennis T Burton  Ann M Stavola 《Marine environmental research》1982,6(2):99-113

The effects of ozone-produced oxidants (OPO) on three developmental stages of the American oyster, Crassostrea virginica, were evaluated. Both straight-hinge (48-h post fertilisation) and setting pediveliger larvae were exposed to a series of OPO concentrations ranging from 0·05 to 0·30 mg/litre OPO (as total residual chlorine) at 25°C for 96 h. Mortality was used as the response parameter and results were quantitatively compared with the effects of chlorine-produced oxidants (CPO) obtained from the literature on these same developmental stages. Adult oysters (2- to 4-year class) were exposed to OPO concentrations ranging from 0·01 to 0·50 mg/litre at 15°C for 5 days and to the same concentration range at 25°C for two consecutive 6-day periods. Shell deposition and faecal matter accumulation were used as the response parameters for this stage.Straight-hinge larvae were significantly more sensitive to OPO than setting pediveliger larvae. Both larval stages were significantly more sensitive to CPO than to OPO. Shell deposition was significantly inhibited at all OPO concentrations for both 15°C and 25°C acclimated adult oysters. No significant differences were found between the shell deposition response of oysters at the two acclimation temperatures. Faecal matter accumulation was significantly reduced at OPO concentrations ≥ 0·05 mg/litre at both 15°C and 25°C. It was significantly (p < 0·05) greater for 25°C acclimated oysters than for 15°C acclimated oysters at OPO concentrations < 0·10 mg/litre but not at higher concentrations.  相似文献   

The dust distribution within the inner coma of comet P/Halley 1982i: encounter by Giotto's impact detectors     

McDonnell JA  Alexander WM  Burton WM  Bussoletti E  Evans GC  Evans ST  Firth JG  Grard RJ  Green SF  Grun E  Hanner MS  Hughes DW  Igenbergs E  Kissel J  Kuczera H  Lindblad BA  Langevin Y  Mandeville JC  Nappo S  Pankiewicz GS  Perry CH  Schwehm GH  Sekanina Z  Stevenson TJ  Zarnecki JC et AL 《Astronomy and Astrophysics》1987,187(1-2):719-741

Analysis of the data from Giotto's Dust Impact Detection System experiment (DIDSY) is presented. These data represent measurement of the size of dust grains incident on the Giotto dust shield along its trajectory through the coma of comet P/Halley on 1986 March 13/14. First detection occurred at some 287000 km distance from the nucleus on the inbound leg; the majority of the DIDSY subsystems remained operational after closest approach (604 km) yielding the last detection at about 202000 km from the nucleus. In order to improve the data coverage (and especially for the smallest grains, to approximately 10(-19) kg particle mass), data from the PIA instrument has been combined with DIDSY data. Flux profiles are presented for the various mass channels showing, to a first approximation, a 1/R2 flux dependence, where R is the distance of the detection point from the cometary nucleus, although significant differences are noted. Deviations from this dependence are observed, particularly close to the nucleus. From the flux profiles, mass and geometrical area distributions for the dust grains are derived for the trajectory through the coma. Groundbased CCD imaging of the dust continuum in the inner coma at the time of encounter is also used to derive the area of grains intercepted by Giotto. The results are consistent with the area functions derived by Giotto data and the low albedo of the grains deduced from infrared emission. For the close encounter period (-5 min to +5 min), the cumulative mass distribution function has been investigated, initially in 20 second periods; there is strong evidence from the data for a steepening of the index of the mass distribution for masses greater than 10(-13) kg during passage through dust jets which is not within the error limits of statistical uncertainty. The fluences for dust grains along the entire trajectory is calculated; it is found that extrapolation of the spectrum determined at intermediate masses (cumulative mass index alpha = 0.85) is not able to account for the spacecraft deceleration as observed by the Giotto Radio Science Experiment and by ESOC tracking operations. Data at large masses (>10(-8) kg) recently analysed from the DIDSY data set show clear evidence of a decrease in the mass distribution index at these masses within the coma, and it is shown that such a value of the mass index can provide sufficient mass for consistency with the observed deceleration. The total particulate mass output from the nucleus of comet P/Halley at the time of encounter would be dependent on the maximum mass emitted if this change in slope observed in the coma were also applicable to the emission from the nucleus; this matter is discussed in the text. The flux time profiles have been converted through a simple approach to modeling of the particle trajectories to yield an indication of nucleus surface activity. There is indication of an enhancement in flux at t approximately -29 s corresponding to crossing of the dawn terminator, but the flux detected prior to crossing of the dawn terminator is shown to be higher than predicted by simple modelling. Further enhancements corresponding to jet activity are detected around +190 s and +270 s.  相似文献   

Erratum to: Seismic hazard across Bulgaria and neighbouring areas: regional and site-specific maximum credible magnitudes and earthquake perceptibility     

Thomas J. Bayliss  Paul W. Burton 《Natural Hazards》2013,68(2):1203-1204

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The CM carbonaceous chondrite regolith Diepenveen     

Marco Langbroek  Peter Jenniskens  Leo M. Kriegsman  Henk Nieuwenhuis  Niek De Kort  Jacob Kuiper  Wim Van Westrenen  Michael E. Zolensky  Karen Ziegler  Qing‐Zhu Yin  Matthew E. Sanborn  Josh Wimpenny  Akane Yamakawa  Sebastiaan J. De Vet  Matthias M. M. Meier  Kees C. Welten  Kunihiko Nishiizumi  Marc W. Caffee  Aaron S. Burton  Jason P. Dworkin  Daniel P. Glavin  Qinghao Wu  Richard N. Zare  Alexander Ruf  Mourad Harir  Philippe Schmitt‐Kopplin   《Meteoritics & planetary science》2019,54(7):1431-1461

A carbonaceous chondrite was recovered immediately after the fall near the village of Diepenveen in the Netherlands on October 27, 1873, but came to light only in 2012. Analysis of sodium and poly‐aromatic hydrocarbon content suggests little contamination from handling. Diepenveen is a regolith breccia with an overall petrology consistent with a CM classification. Unlike most other CM chondrites, the bulk oxygen isotopes are extremely ¹⁶O rich, apparently dominated by the signature of anhydrous minerals, distributed on a steep slope pointing to the domain of intrinsic CM water. A small subset plots closer to the normal CM regime, on a parallel line 2 ‰ lower in δ¹⁷O. Different lithologies in Diepenveen experienced varying levels of aqueous alteration processing, being less aqueously altered at places rather than more heated. The presence of an agglutinate grain and the properties of methanol‐soluble organic compounds point to active impact processing of some of the clasts. Diepenveen belongs to a CM clan with ~5 Ma CRE age, longer than most other CM chondrites, and has a relatively young K‐Ar resetting age of ~1.5 Ga. As a CM chondrite, Diepenveen may be representative of samples soon to be returned from the surface of asteroid (162173) Ryugu by the Hayabusa2 spacecraft.  相似文献   

Stormwater plume detection by MODIS imagery in the southern California coastal ocean     

Nikolay P. Nezlin  Paul M. DiGiacomo  Dario W. Diehl  Burton H. Jones  Scott C. Johnson  Michael J. Mengel  Kristen M. Reifel  Jonathan A. Warrick  Menghua Wang 《Estuarine, Coastal and Shelf Science》2008

Stormwater plumes in the southern California coastal ocean were detected by MODIS-Aqua satellite imagery and compared to ship-based data on surface salinity and fecal indicator bacterial (FIB) counts collected during the Bight'03 Regional Water Quality Program surveys in February–March of 2004 and 2005. MODIS imagery was processed using a combined near-infrared/shortwave-infrared (NIR-SWIR) atmospheric correction method, which substantially improved normalized water-leaving radiation (nLw) optical spectra in coastal waters with high turbidity. Plumes were detected using a minimum-distance supervised classification method based on nLw spectra averaged within the training areas, defined as circular zones of 1.5–5.0-km radii around field stations with a surface salinity of S < 32.0 (“plume”) and S > 33.0 (“ocean”). The plume optical signatures (i.e., the nLw differences between “plume” and “ocean”) were most evident during the first 2 days after the rainstorms. To assess the accuracy of plume detection, stations were classified into “plume” and “ocean” using two criteria: (1) “plume” included the stations with salinity below a certain threshold estimated from the maximum accuracy of plume detection; and (2) FIB counts in “plume” exceeded the California State Water Board standards. The salinity threshold between “plume” and “ocean” was estimated as 32.2. The total accuracy of plume detection in terms of surface salinity was not high (68% on average), seemingly because of imperfect correlation between plume salinity and ocean color. The accuracy of plume detection in terms of FIB exceedances was even lower (64% on average), resulting from low correlation between ocean color and bacterial contamination. Nevertheless, satellite imagery was shown to be a useful tool for the estimation of the extent of potentially polluted plumes, which was hardly achievable by direct sampling methods (in particular, because the grids of ship-based stations covered only small parts of the plumes detected via synoptic MODIS imagery). In most southern California coastal areas, the zones of bacterial contamination were much smaller than the areas of turbid plumes; an exception was the plume of the Tijuana River, where the zone of bacterial contamination was comparable with the zone of plume detected by ocean color.  相似文献   

A search for propylene oxide and glycine in Sagittarius B2 (LMH) and Orion     

M. R. Cunningham  P. A. Jones  P. D. Godfrey  D. M. Cragg  I. Bains  M. G. Burton  P. Calisse  N. H. M. Crighton  S. J. Curran  T. M. Davis  J. T. Dempsey  B. Fulton  M. G. Hidas  T. Hill  L. Kedziora-Chudczer  V. Minier  M. B. Pracy  C. Purcell  J. Shobbrook  T. Travouillon 《Monthly notices of the Royal Astronomical Society》2007,376(3):1201-1210

We have used the Mopra Telescope to search for glycine and the simple chiral molecule propylene oxide in the Sgr B2 (LMH) and Orion KL, in the 3-mm band. We have not detected either species, but have been able to put sensitive upper limits on the abundances of both molecules. The 3σ upper limits derived for glycine conformer I are  3.7 × 10¹⁴ cm⁻²  in both Orion-KL and Sgr B2 (LMH), comparable to the reported detections of conformer I by Kuan et al. However, as our values are 3σ upper limits rather than detections we conclude that this weighs against confirming the detection of Kuan et al. We find upper limits for the glycine II column density of  7.7 × 10¹² cm⁻²  in both Orion-KL and Sgr B2 (LMH), in agreement with the results of Combes et al. The results presented here show that glycine conformer II is not present in the extended gas at the levels detected by Kuan et al. for conformer I. Our ATCA results have ruled out the detection of glycine (both conformers I and II) in the compact hot core of the LMH at the levels reported, so we conclude that it is unlikely that Kuan et al. have detected glycine in either Sgr B2 or Orion-KL. We find upper limits for propylene oxide abundance of  3.0 × 10¹⁴ cm⁻²  in Orion-KL and  6.7 × 10¹⁴ cm⁻²  in Sgr B2 (LMH). We have detected fourteen features in Sgr B2 and four features in Orion-KL which have not previously been reported in the interstellar medium, but have not been able to plausibly assign these transitions to any carrier.  相似文献   

Spatiotemporal development of physical,chemical, and biological characteristics of stormwater plumes in Santa Monica Bay,California (USA)     

Alina A. Corcoran  Kristen M. Reifel  Burton H. Jones  Rebecca F. Shipe 《Journal of Sea Research》2010,63(2):129-142

This study characterized stormwater plume development and associated phytoplankton dynamics in a coastal marine ecosystem through shipboard monitoring. We focused on plumes within Santa Monica Bay, California (USA), a coastal system that is subject to rapid pulses of untreated runoff from the urbanized watershed of Los Angeles during the winter rainy season. The physical, chemical, and biological signatures of stormwater plumes were tracked over time after each of 4 precipitation events ranging in magnitude from 1.5 cm to 9 cm. Low salinity surface plumes persisted in Santa Monica Bay for at least 2 to 5 days over spatial scales of up to 15 km. This is consistent with a 6-day residence time for surface water plume parcels, which was estimated from a drifter trajectory in the bay. Shipboard sampling and salinity measurements in the surf zone showed that plumes often persisted even longer nearshore. Plume waters were generally characterized by higher concentrations of dissolved nitrogen, colored dissolved organic matter, and higher light attenuation than non-plume waters. The magnitude of the effect of stormwater runoff on phytoplankton dynamics was dependent on the size of each storm and subsequent residence time of runoff within the bay. Rain events led to increases in primary productivity, phytoplankton biomass, and specifically, increases in diatom biomass, as measured by concentrations of biogenic silica.  相似文献   

Spatial Discontinuities in Support for Hydraulic Fracturing: Searching for a “Goldilocks Zone”     

Chad Zanocco  Hilary Boudet  Christopher E. Clarke  Peter D. Howe 《社会与自然资源》2019,32(9):1065-1072

Recent research suggests that those located closer to energy development are, on average, more supportive of this development. However, case studies in specific locations reveal additional nuance. In a case study of Bakken Shale residents, Junod et al. identified a “Goldilocks Zone” of unconventional oil and gas development (UOGD) acceptance—an area on the periphery of development that is “just right” because residents feel close enough to receive economic benefits but far enough away to avoid negative impacts. We explore whether this Goldilocks Zone extends nationally by combining geocoded public opinion data (N?=?23,154) with UOGD locations. Using multilevel regression modeling, we find that respondents located within 115?km of newly active UOGD are more supportive of hydraulic fracturing while those located within 115–305?km are comparatively less supportive. While we do not uncover a national-level Goldilocks Zone, our work highlights innovative approaches for examining spatial relationships in energy development opinion.  相似文献   

Survey evaluations to assess marine bioinvasions     

Campbell ML  Gould B  Hewitt CL 《Marine pollution bulletin》2007,55(7-9):360-378

Countries need to know what species are present within their waters to effectively manage the issue of non-indigenous marine species. Five survey methods are currently employed to detect introduced marine species: the Hewitt and Martin protocols (66% of effort; 73 ports, 12 countries); Rapid Assessment Surveys (7% of effort; 8 regions, 4 countries); the Bishop Museum protocols (7% of effort; 8 ports, 3 countries); the Chilean aquaculture surveys (1% of effort; numerous regions; 1 country); and Passive Sampling protocols (18% of effort; 20 ports, 2 countries). These methods use either quantitative, qualitative, or a mixture of the two sampling techniques and tend to target locations that are potential inoculation sites (i.e., such as ports, marinas and aquaculture facilities). To date, introduced marine species surveys have been implemented in 19 countries and have detected more than 1185 non-indigenous, 735 cryptogenic and 15,315 native species.  相似文献