Higher Seismic Activity During Local Night on the Raw Worldwide Earthquake Catalogue   总被引：1，自引：0，他引：1  

L. Knopoff  J. K. Gardner 《Geophysical Journal International》1972,28(3):311-313

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Upper-mantle seismic structure in a region of incipient continental breakup: northern Ethiopian rift   总被引：4，自引：0，他引：4  

Ian D. Bastow  Graham W. Stuart  J-Michael Kendall  Cynthia J. Ebinger 《Geophysical Journal International》2005,162(2):479-493

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Inverse models of gravity data from the Red Sea–Aden–East African rifts triple junction zone     

Christel Tiberi  Cynthia Ebinger  Valérie Ballu  Graham Stuart  Befekadu Oluma 《Geophysical Journal International》2005,163(2):775-787

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Export of Acidity in Drainage Water from Acid Sulphate Soils     

F.J Cook  W Hicks  E.A Gardner  G.D Carlin  D.W Froggatt 《Marine pollution bulletin》2000,41(7-12):319-326

Disturbed acid sulphate soils are potent sources of acidity in coastal waterways. Monitoring studies of the drainage water for sites at East Trinity, Cairns and Pimpama, south-east Queensland indicate that considerable acidity is found in the drainage water from these sites. Hydrogen (H⁺), ferrous (Fe²⁺) and aluminium (Al) ions are the dominant acid cations involved. When drainage water is mixed with fresh or marine waters the effect of H⁺ on acidity generation is immediate. Aluminium can release acidity on hydrolysis, while the oxidation of Fe²⁺ to Fe³⁺ both acidifies and removes dissolved oxygen from the water. Strongly acidic waters with low levels of dissolved oxygen concentration are undesirable for most forms of aquatic life. Export of acidity from acid sulphate soil is likely to have a major effect on inshore fisheries and breeding grounds especially in periods of flood following drought or periods of low rainfall, where large volumes of acidity can be flushed/leached into sensitive aquatic/marine habitats. Impacts may include low dissolved oxygen, fish kills, epizootic ulceration syndrome and damage to oysters. During the processes of oxidation and hydrolysis, iron and aluminium flocs form, that can smother benthic communities. Heavy metals are found in the drainage water at elevated levels and may also be of concern for aquatic organisms. Chronic effects such as habitat degradation, mortality of marine worms, bivalves, invasion of acid tolerant species (both plant and animal) and avoidance of habitat have been documented elsewhere. These areas require further research.  相似文献   

The caldera-forming eruption of Volcán Ceboruco, Mexico   总被引：1，自引：1，他引：0  

James E. Gardner  Steve Tait 《Bulletin of Volcanology》2000,62(1):20-33

3 of magma erupted, ∼95% of which was deposited as fall layers. During most of the deposition of P1, eruptive intensity (mass flux) was almost constant at 4–8×10⁷ kg s⁻¹, producing a Plinian column 25–30 km in height. Size grading at the top of P1 indicates, however, that mass flux waned dramatically, and possibly that there was a brief pause in the eruption. During the post-P1 phase of the eruption, a much smaller volume of magma erupted, although mass flux varied by more than an order of magnitude. We suggest that caldera collapse began at the end of the P1 phase of the eruption, because along with the large differences in mass flux behavior between P1 and post-P1 layers, there were also dramatic changes in lithic content (P1 contains ∼8% lithics; post-P1 layers contain 30–60%) and magma composition (P1 is 98% rhyodacite; post-P1 layers are 60–90% rhyodacite). However, the total volume of magma erupted during the Jala pumice event is close to that estimated for the caldera. These observations appear to conflict with models which envision that, after an eruption is initiated by overpressure in the magma chamber, caldera collapse begins when the reservoir becomes underpressurized as a result of the removal of magma. The conflict arises because firstly, the P1 layer makes up too large a proportion (∼75%) of the total volume erupted to correspond to an overpressurized phase, and secondly, the caldera volume exceeds the post-P1 volume of magma by at least a factor of three. The mismatches between model and observations could be reconciled if collapse began near the beginning of the eruption, but no record of such early collapse is evident in the tephra sequence. The apparent inability to place the Jala pumice eruptive sequence into existing models of caldera collapse, which were constructed to explain the formation of calderas much greater in volume than that at Ceboruco, may indicate that differences in caldera mechanics exist that depend on size or that a more general model for caldera formation is needed. Received: 18 November 1998 / Accepted: 23 October 1999  相似文献   

Spectroscopy and orbital periods of the old novae V533 Herculis, V446 Herculis and X Serpentis     

John R. Thorstensen  Cynthia J. Taylor 《Monthly notices of the Royal Astronomical Society》2000,312(3):629-637

We report spectroscopic orbital periods of 0.147 d (=3.53 h) for V533 Her, 0.207 d (=4.97 h) for V446 Her and 1.478 d for X Ser. V533 Her (Nova Herculis 1963) shows absorption features in its He  i and Balmer lines which appear only in a limited range of orbital phase, suggesting that it is a low-inclination SW Sextantis star. V446 Her is unusual in that it has started normal dwarf nova eruptions after a nova outburst, but we find nothing else unusual about it – in particular, a distance estimate based on its dwarf nova outbursts agrees nicely with another based on the rate of decline of its nova eruption, both giving d ∼1 kpc. In X Ser, unlike in other old novae with long periods, no spectral features of the secondary star are visible. This and its outburst magnitude both suggest that it is quite distant and luminous, and at least 1 kpc from the Galactic plane.  相似文献   

The atmospheric lead record preserved in lagoon sediments at a remote equatorial Pacific location: Palmyra Atoll, northern Line Islands     

Collen JD  Baker JA  Dunbar RB  Rieser U  Gardner JP  Garton DW  Christiansen KJ 《Marine pollution bulletin》2011,62(2):251-257

Anthropogenic lead (Pb) inputs to the atmosphere increased greatly over the past century and now dominate Pb supply to the oceans. However, the Pb content of sediments across the equatorial Pacific region is relatively unknown, and data exist only for deep sea sites where Pb deposition lags surface water inputs by up to a century. Here we present ICP-MS analyses of Pb of a core from a lagoon at Palmyra Atoll, northern Line Islands, that spans approximately the past 160 years. The non-bioturbated sediments of the euxinic lagoon, coupled with rapid rates of deposition, provide a unique fine-scale record of atmospheric Pb supply at a remote Pacific location. These first observations of historic Pb sedimentation in an atoll lagoon reveal a 63-fold increase in Pb flux to sediments during the past century and correlate directly with the North American consumption of leaded gasoline that began in 1926.  相似文献   

Commentary on Palmyra atoll     

Gardner J  Collen J  Dunbar R  Garton D 《Marine pollution bulletin》2011,62(12):2876-2877

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Gas emissions from failed and actual eruptions from Cook Inlet Volcanoes,Alaska, 1989–2006     

Cynthia A. Werner  Mike P. Doukas  Peter J. Kelly 《Bulletin of Volcanology》2011,73(2):155-173

Cook Inlet volcanoes that experienced an eruption between 1989 and 2006 had mean gas emission rates that were roughly an order of magnitude higher than at volcanoes where unrest stalled. For the six events studied, mean emission rates for eruptions were ∼13,000 t/d CO₂ and 5200 t/d SO₂, but only ∼1200 t/d CO₂ and 500 t/d SO₂ for non-eruptive events (‘failed eruptions’). Statistical analysis suggests degassing thresholds for eruption on the order of 1500 and 1000 t/d for CO₂ and SO₂, respectively. Emission rates greater than 4000 and 2000 t/d for CO₂ and SO₂, respectively, almost exclusively resulted during eruptive events (the only exception being two measurements at Fourpeaked). While this analysis could suggest that unerupted magmas have lower pre-eruptive volatile contents, we favor the explanations that either the amount of magma feeding actual eruptions is larger than that driving failed eruptions, or that magmas from failed eruptions experience less decompression such that the majority of H₂O remains dissolved and thus insufficient permeability is produced to release the trapped volatile phase (or both). In the majority of unrest and eruption sequences, increases in CO₂ emission relative to SO₂ emission were observed early in the sequence. With time, all events converged to a common molar value of C/S between 0.5 and 2. These geochemical trends argue for roughly similar decompression histories until shallow levels are reached beneath the edifice (i.e., from 20–35 to ∼4–6 km) and perhaps roughly similar initial volatile contents in all cases. Early elevated CO₂ levels that we find at these high-latitude, andesitic arc volcanoes have also been observed at mid-latitude, relatively snow-free, basaltic volcanoes such as Stromboli and Etna. Typically such patterns are attributed to injection and decompression of deep (CO₂-rich) magma into a shallower chamber and open system degassing prior to eruption. Here we argue that the C/S trends probably represent tapping of vapor-saturated regions with high C/S, and then gradual degassing of remaining dissolved volatiles as the magma progresses toward the surface. At these volcanoes, however, C/S is often accentuated due to early preferential scrubbing of sulfur gases. The range of equilibrium degassing is consistent with the bulk degassing of a magma with initial CO₂ and S of 0.6 and 0.2 wt.%, respectively, similar to what has been suggested for primitive Redoubt magmas.  相似文献   

Solid-phase considerations for the environmental fate of nitrobenzene and triazine munition constituents in soil     

Mark A. Chappell  Cynthia L. Price  Lesley F. Miller 《Applied Geochemistry》2011

This paper focuses on the chemistry of DoD-relevant organic contaminants in soil. Most of the work presented here is based on the author’s experience with the environmental fate of the munition constituents, TNT and RDX, for DoD related issues. The principles and challenges of understanding the transport of nitrobenzene and triazine compounds in the environment are captured. In this work, disparities in the current scientific literature with respect to the construction of sorption experiments are discussed, in terms of soil sample handling, dispersion state of the soil, and sorption hysteresis/equilibrium. Here is discussed the concept of environmentally formulated compounds and its implications toward reduced accuracy of predicting the environmental fate of munition constituents. Also, further research linking simple but oft-forgotten basic concepts of soil fertility to the transport and environmental fate of munition constituents are discussed.  相似文献