Community-based responses to climate hazards: typology and global analysis     

Paterson  Barbara  Charles  Anthony 《Climatic change》2019,152(3-4):327-343

Climatic Change - The severity and frequency of climate change hazards are increasing around the world. Because the impacts are most acutely felt in local communities, it is critical to improve...  相似文献   

Prediction of the calcium carbonate budget in a sedimentary basin: A “source-to-sink” approach applied to Great Salt Lake,Utah, USA     

Anthony Bouton  Emmanuelle Vennin  Philippe Amiotte-Suchet  Christophe Thomazo  Jean-Pierre Sizun  Aurélien Virgone  Eric C. Gaucher  Pieter T. Visscher 《Basin Research》2020,32(5):1005-1034

Most source-to-sink studies typically focus on the dynamics of clastic sediments and consider erosion, transport and deposition of sediment particles as the sole contributors. Although often neglected, dissolved solids produced by weathering processes contribute significantly in the sedimentary dynamics of basins, supporting chemical and/or biological precipitation. Calcium ions are usually a major dissolved constituent of water drained through the watershed and may facilitate the precipitation of calcium carbonate when supersaturating conditions are reached. The high mobility of Ca²⁺ ions may cause outflow from an open system and consequently loss. In contrast, in closed basins, all dissolved (i.e. non-volatile) inputs converge at the lowest point of the basin. The endoreic Great Salt Lake basin constitutes an excellent natural laboratory to study the dynamics of calcium on a basin scale, from the erosion and transport through the watershed to the sink, including sedimentation in lake's waterbody. The current investigation focused on the Holocene epoch. Despite successive lake level fluctuations (amplitude around 10 m), the average water level seems to have not been affected by any significant long-term change (i.e. no increasing or decreasing trend, but fairly stable across the Holocene). Weathering of calcium-rich minerals in the watershed mobilizes Ca²⁺ ions that are transported by surface streams and subsurface flow to the Great Salt Lake (GSL). Monitoring data of these flows was corrected for recent anthropogenic activity (river management) and combined with direct precipitation (i.e. rain and snow) and atmospheric dust income into the lake, allowing estimating the amount of calcium delivered to the GSL. These values were then extrapolated through the Holocene period and compared to the estimated amount of calcium stored in GSL water column, porewater and sediments (using hydrochemical, mapping, coring and petrophysical estimates). The similar estimate of calcium delivered (4.88 Gt) and calcium stored (3.94 Gt) is consistent with the premise of the source-to-sink approach: a mass balance between eroded and transported compounds and the sinks. The amount of calcium deposited in the basin can therefore be predicted indirectly from the different inputs, which can be assessed with more confidence. When monitoring is unavailable (e.g. in the fossil record), the geodynamic context, the average lithology of the watershed and the bioclimatic classification of an endoreic basin are alternative properties that may be used to estimate the inputs. We show that this approach is sufficiently accurate to predict the amount of calcium captured in a basin and can be extended to the whole fossil record and inform on the storage of calcium.  相似文献   

A simulation study of the role of raindrop erosion in the formation of desert pavements     

John Wainwright  Anthony J. Parsons  Athol D. Abrahams 《地球表面变化过程与地形》1995,20(3):277-291

A simple model of raindrop erosion—the combined effects of the detachment of sediment by raindrops and its transport by splash or by overland flow—is developed to examine the role of this process in the formation of desert pavements. Application of the model to soils in areas of existing pavement initially simulates the formation of pavements, but the changing sediment size distributions lead to the subsequent destruction of these modelled surfaces. An improved model that accounts for the feedback effects of the changing size distributions on infiltration and microtopography is then developed. Incorporating these effects allows simulated pavements to be maintained over longer periods. The model yields desert pavements whose particle size compositions differ in response to differences in initial soil characteristics, slope and rainfall intensity. This model is tested against empirical data from a site where there is intershrub pavement and associated mounds of fines beneath desert shrubs. The results successfully predict the accumulation of fines under shrubs but underestimate the development of the pavement between shrubs. These findings suggest that the raindrop erosion mechanism on its own cannot account for the development of the pavement and that some other mechanism leading to the surface concentration of coarse particles must also be operating.  相似文献   

城市居民压力源对幸福感的影响研究——基于乡村旅游休闲参与的角度     

张圆刚  黄业坚  程静静  余向洋  陈希 《地理研究》2019,38(4):971-987

居民幸福感研究日益受到重视,以往研究多是从自然环境、社会人文环境和城市化进程等方面探讨大尺度空间环境因素对城市居民幸福感的影响。结合乡村旅游的角度探讨城市居民幸福感的影响研究,目前还较少。运用SEM分析方法,探究处于多维压力之下的城市居民旅游者如何通过前往乡村进行旅游休闲活动提升幸福感,进行模型构建与分析,结果显示：① 压力源对调适策略有显著正向影响,对休闲参与不显著,但不同群体影响差异显著,压力调适对休闲参与有显著正向影响;② 休闲参与对心流体验和幸福感具有显著正向关系,且心流体验对幸福感具有显著正向影响;③ 心流体验对休闲效益具有正向显著影响,且休闲效益对幸福感具有正向显著影响;④ 心流体验在休闲参与对幸福感、休闲效益在心流体验对幸福感均具有显著中介效应;⑤ 旅游者不同背景变项在压力调适、休闲参与及幸福感等分别呈现不同程度的显著差异。  相似文献   

Petrogenesis of lunar impact melt rock meteorite Oued Awlitis 001     

Axel Wittmann  Randy L. Korotev  Bradley L. Jolliff  Kunihiko Nishiizumi  A. J. Timothy Jull  Marc W. Caffee  Michael Zanetti  Anthony J. Irving 《Meteoritics & planetary science》2019,54(10):2167-2188

Oued Awlitis 001 is a highly feldspathic, moderately equilibrated, clast‐rich, poikilitic impact melt rock lunar meteorite that was recovered in 2014. Its poikilitic texture formed due to moderately slow cooling, which judging from textures of rocks in melt sheets of terrestrial impact structures, is observed in impact melt volumes at least 100 m thick. Such coherent impact melt volumes occur in lunar craters larger than ~50 km in diameter. The composition of Oued Awlitis 001 points toward a crustal origin distant from incompatible‐element‐rich regions. Comparison of the bulk composition of Oued Awlitis 001 with Lunar Prospector 5° γ‐ray spectrometer data indicates a limited region of matches on the lunar farside. After its initial formation in an impact crater larger than ~50 km in diameter, Oued Awlitis 001 was excavated from a depth greater than ~50 m. The cosmogenic nuclide inventory of Oued Awlitis 001 records ejection from the Moon 0.3 Ma ago from a depth of at least 4 m and little mass loss due to ablation during its passage through Earth's atmosphere. The terrestrial residence time must have been very short, probably less than a few hundred years; its exact determination was precluded by a high concentration of solar cosmic ray‐produced ¹⁴C. If the impact that excavated Oued Awlitis 001 also launched it, this event likely produced an impact crater >10 km in diameter. Using petrologic constraints and Lunar Reconnaissance Orbiter Camera and Diviner data, we test Giordano Bruno and Pierazzo as possible launch craters for Oued Awlitis 001.  相似文献   

The chlorine isotope composition of iron meteorites: Evidence for the Cl isotope composition of the solar nebula and implications for extensive devolatilization during planet formation     

Anthony Gargano  Zachary Sharp 《Meteoritics & planetary science》2019,54(7):1619-1631

The bulk chlorine concentrations and isotopic compositions of a suite of non‐carbonaceous (NC) and carbonaceous (CC) iron meteorites were measured using gas source mass spectrometry. The δ³⁷Cl values of magmatic irons range from ?7.2 to 18.0‰ versus standard mean ocean chloride and are unrelated to their chlorine concentrations, which range from 0.3 to 161 ppm. Nonmagmatic IAB irons are comparatively Cl‐rich containing >161 ppm with δ³⁷Cl values ranging from ?6.1 to ?3.2‰. The anomalously high and low δ³⁷Cl values are inconsistent with a terrestrial source, and as Cl contents in magmatic irons are largely consistent with derivation from a chondrite‐like silicate complement, we suggest that Cl is indigenous to iron meteorites. Two NC irons, Cape York and Gibeon, have high cooling rates with anomalously high δ³⁷Cl values of 13.4 and 18.0‰. We interpret these high isotopic compositions to result from Cl degassing during the disruption of their parent bodies, consistent with their low volatile contents (Ga, Ge, Ag). As no relevant mechanisms in iron meteorite parent bodies are expected to decrease δ³⁷Cl values, whereas volatilization is known to increase δ³⁷Cl values by the preferential loss of light isotopes, we interpret the low isotope values of <?5‰ and down to ?7.2‰ to most closely represent the primordial isotopic composition of Cl in the solar nebula. Similar conclusions have been derived from low δ³⁷Cl values down to ?6, and ?3.8‰ measured in Martian and Vestan meteorites, respectively. These low δ³⁷Cl values are in contrast to those of chondrites which average around 0‰ previously explained by the incorporation of isotopically heavy HCl clathrate into chondrite parent bodies. The poor retention of low δ³⁷Cl values in many differentiated planetary materials suggest that extensive devolatilization occurred during planet formation, which can explain Earth's high δ³⁷Cl value by the loss of approximately 60% of the initial Cl content.  相似文献   

Highly siderophile element and 187Re‐187Os isotopic systematics of ungrouped achondrite Northwest Africa 7325: Evidence for complex planetary processes     

Gregory J. Archer  Richard J. Walker  Anthony J. Irving 《Meteoritics & planetary science》2019,54(5):1042-1050

The abundances of highly siderophile elements (HSE; including Re, Os, Ir, Ru, Pt, and Pd) and ¹⁸⁷Re‐¹⁸⁷Os isotopic systematics were determined for two fragments from ungrouped achondrite NWA 7325. Rhenium‐Os systematics are consistent with closed‐system behavior since formation or soon after. The abundances of the HSE were therefore largely unaffected by late‐stage secondary processes such as shock or terrestrial weathering. As an olivine gabbro cumulate, this meteorite has a bulk composition consistent with derivation from a body that produced a core, mantle, and crust. Also consistent with derivation from a body that produced a core, both fragments of NWA 7325 have HSE abundances that are highly depleted compared to bulk chondrites. One fragment has ~0.002× CI chondrite Ir and relative HSE abundances similar to bulk chondrites. The other fragment has ~0.0002× CI chondrite Ir and relative HSE abundances that are fractionated compared to bulk chondrites. The chondritic relative HSE abundances of the fragment characterized by higher HSE abundances most likely reflect the addition of exogenous chondritic material during or after crystallization by surface impacts. The HSE in the other fragment is likely more representative of the parent body crust. One formation model that can broadly account for the HSE abundances in this fragment is multiple episodes of low‐pressure metal‐silicate equilibration, followed by limited late accretion and mantle homogenization. Given the different HSE compositions of the two adjoining fragments, this meteorite provides an example of the overprint of global processes (differentiation and late accretion) by localized impact contamination.  相似文献   

Environmental limitations on recruitment from seed in invasive Spartina densiflora on a southern European salt marsh     

Enrique Mateos-Naranjo  Susana Redondo-Gmez  Carlos J. Luque  Eloy M. Castellanos  Anthony J. Davy  M. Enrique Figueroa 《Estuarine, Coastal and Shelf Science》2008,79(4):727-732

The South American cordgrass, Spartina densiflora, has invaded a range of different habitats that can support different native species assemblages on salt marshes in the Gulf of Cadiz, Spain. Little is known about the mechanisms of invasion. We examined the potential for seed germination and recruitment in a field transplant experiment, representing a wide range of environments, on elevational gradients across marshes with muddy and sandy sediments. The biotic resistance of native, perennial vegetation (where present) to recruitment of the alien was also investigated. Spartina densiflora seeds were able to germinate over a greater than 2-m range of elevation in the tidal frame. Germination success on unvegetated muddy sediments was related to sediment redox potential, with poor germination at strongly negative redox potentials on the lower sites. On sandy, well-drained sediments, germination was apparently constrained by water availability at the highest elevations. Comparison of vegetated and cleared plots on the upper marsh showed that there was a negative relationship between the presence of Atriplex portulacoides and germination on the muddy sediments. Recruitment (survival of seedlings for 12 weeks) was seen only on unvegetated muddy sediments at the highest elevation. Hence the invasive success and wide elevational tolerance of S. densiflora on the marshes of the Gulf of Cadiz are not reflected in its short-term ability to become established from its prolific seed production. Colonization of sub-optimal habitats may be largely by vegetative propagules and clonal growth.  相似文献   

OPA 90's impact at reducing oil spills     

Anthony C. Homan  Todd Steiner   《Marine Policy》2008,32(4):711-718

OPA 90 set out stringent requirements and liabilities for tankers operating in US national waters. OPA 90 was in response to the public concern caused by the grounding of the Exxon Valdez in 1989. It made ship owners responsible for the cost of pollution incidents and required all tank ships/barges operating in US waters have double hulls by 2015. We model factors influencing oil spills and test whether OPA 90 helped reduce the number of those spills. After accounting for causal factors, both increased liability and double hulls were statistically significant factors in reducing the number of spills.  相似文献   

Variations in the biomass of Antarctic krill (Euphausia superba) around the South Shetland Islands, 1996-2006   总被引：1，自引：0，他引：1  

Reiss  Christian S.; Cossio  Anthony M.; Loeb  Valerie; Demer  David A. 《ICES Journal of Marine Science》2008,65(4):497-508

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