The 1925 meteorite fall near Ellemeet and Serooskerke,the Netherlands          下载免费PDF全文

Sebastiaan J. de Vet 《Meteoritics & planetary science》2015,50(11):E1-E17

Two meteorites impacted in 1925 around the town of Serooskerke on the isle of Schouwen, the Netherlands. The largest mass is widely known as the “Ellemeet” diogenite, while a second mass, heavily weathered due to environmental exposure, also survived until the present day. This work aims to reconstruct the history of the 1925 fall and for the first time documents the second mass, known as the “Serooskerke,” by integrating a historical and experimental approach. The study of historical news archives and cadastral records redefined the 1925 impact site at N 51°42.086′ E 3°49.789′. Environmental exposure experiments reproducing the effects of rainfall and frost weathering identified the latter as the main cause for the second mass' reported disintegration in the field sometime during the 1925–1926 winter. The bulk mineralogy of the second mass was established using XRD powder diffraction for a 2θ range of 3–70° and was found to be identical to an Ellemeet reference sample. UV/VIS/nIR spectroscopy (300–2500 nm) was subsequently used to broadly compare the second mass to HED clan meteorites Bouvante, EET87503, Johnstown and asteroid 4 Vesta in order to corroborate its vestan origin. The historical and geographic relationship of the two masses and the comparable bulk mineralogy supported the pairing of these two meteorites. This makes the Serooskerke a valuable legacy of the 1925 fall, especially as the location of ~50% of the remaining Ellemeet mass is presently unknown.  相似文献   

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   

Numerical Investigation of Gas Scavenging by Weak Precipitation     

Leiming Zhang  Robert Vet  Diane V. Michelangeli 《Journal of Atmospheric Chemistry》2006,54(3):203-231

A one-dimensional cloud model with size-resolved microphysics and size-resolved aqueous-phase chemistry, driven by prescribed dynamics, has been used to study gas scavenging by weak precipitation developed from low-level, warm stratiform clouds. The dependence of the gas removal rate on the physical and chemical properties of precipitation has been explored under controlled initial conditions. It is found that the removal of four gaseous species (SO₂, NH₃, H₂O₂ and HNO₃) strongly depends on the total droplet surface area, regardless the mean size of droplets. The removal rates also correlate positively with the precipitation rate, especially for precipitation having a mean radius larger than 20 μm. The dependence of the scavenging coefficients on the total droplet surface area is stronger than on the precipitation rate. The removal rates of SO₂, NH₃ and H₂O₂ by precipitation strongly depend on the others' initial concentrations. When NH₃ (or H₂O₂) concentration is much lower than that of SO₂, the removal rate of SO₂ is then controlled by the concentration of H₂O₂ (or NH₃). The removal of NH₃ (or H₂O₂) also directly depends on the concentration of SO₂. NH₃ and H₂O₂ can also indirectly affect each other's removal rate through interaction with SO₂. The scavenging coefficient of SO₂ increases with the concentration ratio of NH₃ to SO₂ if the ratio is larger than 0.5, while the scavenging coefficient of NH₃ increases with the concentration ratio of SO₂ to NH₃ when the ratio is smaller than 1. The scavenging coefficient of H₂O₂ generally increases with the concentration ratio of SO₂ to H₂O₂. Although the Henry's law equilibrium approach seems to be able to simulate gas scavenging by cloud droplets, it causes large errors when used for simulating the scavenging of soluble gas species by droplets of precipitating sizes.  相似文献   

Magnetic field structure and distribution of helium on He-peculiar stars     

B. Vetö 《Astrophysics and Space Science》1990,174(1):111-119

The periodic variation of the equivalent width of Hei lines and of the magnetic field in six Bp stars is modeled by the oblique rotator model. The position of the magnetic poles and the structure of the helium distribution has been determined from the magnetic field observations and the line strength measurements of the Hei 4026 line. A comparison between the helium surface distribution and the structure of the magnetic field has been carried out.  相似文献   

The impact of wind-waves and sea level rise on the morphodynamics of a sandy estuarine shoal     

J. Zheng  H. Elmilady  B.R. Röbke  M. Taal  Z.B. Wang  B.C. van Prooijen  P.L.M. de Vet  M. van der Wegen 《地球表面变化过程与地形》2021,46(15):3045-3062

Intertidal shoals are pronounced morphological features found in many estuaries worldwide. Apart from maintaining an ecologically unique intertidal environment, shoals also protect adjacent dyke systems by attenuating waves. The fate of sandy shoals under anticipated sea level rise (SLR) scenarios is underexplored. The current research investigates the long-term morphodynamic evolution of estuarine sandy shoals under forcing by short fetch, locally generated wind-waves, tides, and SLR by means of a numerical, process-based model (Delft3D). The focus lies on a sheltered shoal complex in the Western Scheldt, the Netherlands. Starting from the initial, 1963 bathymetry, we model 50-year morphodynamic development with schematized wind-wave forcing. We analyze in detail the impact of locally generated wind-waves on shoal formation. Finally, we impose regional SLR of 1.10 m and 1.95 m for 100 years. Model results show that, on the spatial scale of intertidal flats, small, locally generated wind-waves lower and widen the shoals while the adjacent channels deepen. However, on the estuarine system scale, wind-waves do not lead to fundamentally different channel–shoal patterns and morphodynamic evolution trends. This suggests that channel–shoal formation is mainly due to tide residual sediment transports, with wind-waves playing a secondary role. SLR leads to a notable intertidal area loss, despite a continuous heightening of the shoals, implying that morphodynamic adaptation lags behind SLR. The inclusion of wind-waves does not fundamentally change the reaction of the estuarine shoal to SLR. Future research may focus on exploring the impact of including multiple sediment classes.  相似文献   

‘How dare you say that about my friend’: negotiating disability and identity within Australian high schools     

Eliza de Vet  Gordon Waitt  Andrew Gorman-Murray 《The Australian geographer》2012,43(4):377-391

Australian education policies advocate equal opportunities and non-discrimination through legislation that people with disabilities willing to attend ‘main-stream’ schools must be accommodated for. In this paper, people with mobility disabilities talk about their high school experiences in New South Wales, Australia. We are particularly interested in how these men and women talk about the affirmation of bodily differences within various high school spaces. Adopting narrative analysis and a feminist approach we understand identity as constructed spatially. Our interpretation is focused upon how school spaces helped to shape participants’ sense of self and in turn how participants shaped school spaces. We present a series of vignettes which illustrate how participants with mobility disabilities negotiated their bodily differences in and through school space.  相似文献   

Regional Air Quality Modelling in Canada – Applications for Policy and Real-Time Prediction     

Venkatesh  S.  Gong  W.  Kallaur  A.  Makar  P. A.  Moran  M. D.  Pabla  B.  Ro  C.  Vet  R.  Burrows  W. R.  Montpetit  R. 《Natural Hazards》2000,21(2-3):101-129

Acid rain and photochemical smog are two regionalair-quality issues that have received considerableattention in the last two decades due to their harmfuleffects. Health impacts of particulate matter (PM) inthe atmosphere is another issue of concern.Sulphur dioxide emission controls were introducedin both Canada and the U.S.A. to reduceacid-deposition-related damage. While these emissionreductions have already resulted in reduced sulphatedeposition, based on results from modelling studiesmuch of southeastern Canada is still expected toexperience damaging levels of acid deposition evenafter all currently legislated emission controls arefully implemented. Moreover, there has not been acorresponding reduction in the acidity ofprecipitation. This may be attributable to aconcurrent reduction in base-cation concentration inprecipitation.Models were also developed to understand theformation, transport and diffusion of troposphericozone. The models have been used to provide policyguidance for emission control options to reduceground-level ozone to acceptable limits. In thesummer of 1997 a Canadian pilot project was initiatedto provide real-time forecasts of ground-level ozonein the southeastern part of the province of NewBrunswick in eastern Canada.With the emergence of fine Particulate Matter(PM_2.5) as a health concern, efforts are underwayin Canada to develop a unified' regional air-qualitymodel that will address the combined impacts ofvarious pollutants in the atmosphere. In this effortthe atmosphere is viewed as a single entity where theimpacts of multiple pollutants are considered at thesame time.  相似文献   

Characterization of accumulated precipitates during subsurface iron removal     

Doris van Halem  Weren de Vet  Jasper VerberkGary Amy  Hans van Dijk 《Applied Geochemistry》2011,26(1):116-124

The principle of subsurface iron removal for drinking water supply is that aerated water is periodically injected into the aquifer through a tube well. On its way into the aquifer, the injected O₂-rich water oxidizes adsorbed Fe²⁺, creating a subsurface oxidation zone. When groundwater abstraction is resumed, the soluble Fe²⁺ is adsorbed and water with reduced Fe concentrations is abstracted for multiple volumes of the injection water. In this article, Fe accumulation deposits in the aquifer near subsurface treatment wells were identified and characterized to assess the sustainability of subsurface iron removal regarding clogging of the aquifer and the potential co-accumulation of other groundwater constituents, such as As. Chemical extraction of soil samples, with Acid-Oxalate and HNO₃, showed that Fe had accumulated at specific depths near subsurface iron removal wells after 12 years of operation. Whether it was due to preferred flow paths or geochemical mineralogy conditions; subsurface iron removal clearly favoured certain soil layers. The total Fe content increased between 11.5 and 390.8 mmol/kg ds in the affected soil layers, and the accumulated Fe was found to be 56-100% crystalline. These results suggest that precipitated amorphous Fe hydroxides have transformed to Fe hydroxides of higher crystallinity. These crystalline, compact Fe hydroxides have not noticeably clogged the investigated well and/or aquifer between 1996 and 2008. The subsurface iron removal wells even need less frequent rehabilitation, as drawdown increases more slowly than in normal production wells. Other groundwater constituents, such as Mn, As and Sr were found to co-accumulate with Fe. Acid extraction and ESEM-EDX showed that Ca occurred together with Fe and by X-ray Powder Diffraction it was identified as calcite.  相似文献   

When insurance and goodwill are not enough: Bushfire Attack Level (BAL) ratings,risk calculations and disaster resilience in Australia     

Eliza de Vet 《The Australian geographer》2020,51(1):35-51

ABSTRACT

Home and contents insurance is integral to household and community resilience against disasters. Yet many households are underinsured. While causes for underinsurance have been widely researched, changes to Australian building regulations in the last decade has established a new source of insurance miscalculations. Bushfire Attack Level (BAL) ratings can inflate rebuilding costs by 20% or more, yet BAL ratings remain obfuscated to homeowners and are notoriously confusing to navigate. After the October 2013 bushfires in New South Wales, the Blue Mountains Local Recovery Steering Group found that ‘information on the BAL process, the guidelines, the expected costs, the consulting experts and a property’s bushfire-prone status is literally all over the place’. This paper aims to provide clarity on the subject, tracing the precise socio-technical means through which disaster risk is perceived and assessed. The paper conceptualises insurance and risk ratings as calculative devices that provide both a technical solution to reduce financial losses and a philosophical tool for risk rationalisation. It then builds on interviews conducted with residents in the Blue Mountains affected by the 2013 bushfires, to ascertain how such calculative devices practically affect communities at risk. The paper concludes by outlining potential solutions to a confusing and costly problem in Australia, highlighting critical public awareness issues surround BAL ratings, which have profound insurance and wellbeing implications for people rebuilding and recovering from bushfire.  相似文献   

Proposing a beneficiary-based shared responsibility approach for calculating national carbon accounts during the post-Kyoto era     

Maria Csutora  Zsófia Vetőné mózner 《Climate Policy》2013,13(5):599-616

Considerable progress has been made in Europe towards cutting GHG emissions during the last decade, but this achievement is partly due to the delocalization of manufacturing industries to emerging countries. Under the United Nations Framework Convention on Climate Change, the current emission accounting method is production-based and cannot fully capture this effect. The use of such a method is clearly unfavourable for emerging countries and could lead to difficulties in engaging them in climate policy negotiations. The consumption-based approach represents the other extreme in apportioning emission responsibilities. This article proposes the beneficiary-based shared responsibility approach, which outperforms previous methods in terms of scientific justification and political acceptability. Consumer countries benefit from enjoying the product itself, while producing countries benefit from the production process, which provides them with employment, government income, and company profit. Thus, emissions related to the material throughput used to produce exported products should be allocated to the final place of consumption. The income of production activities benefits the producer country, so emissions associated with these values should be allocated to them. The main reason for taking this accounting approach is that the responsibility for emissions and the benefits of enjoying a product should not be decoupled.  相似文献