Black carbon relationships with emissions and meteorology in Xi'an, China   总被引：4，自引：0，他引：4  

Jun-Ji Cao  Chong-Shu Zhu  Judith C. Chow  John G. Watson  Yong-Ming Han  Ge-hui Wang  Zhen-xing Shen  Zhi-Sheng An 《Atmospheric Research》2009,94(2):194-202

Aerosol black carbon (BC) was measured every 5 min at Xi'an, China from September 2003 to August 2005. Daily BC concentrations ranged from 2 to 65 μg m^− 3, averaging 14.7 ± 9.5 μg m^− 3 and displayed clear summer minima and winter maxima. BC typically peaked between 0800 and 1000 LST and again between 2000 and 2200 LST, corresponding with morning and evening traffic combined with nighttime residential cooking and heating. The nocturnal peak was especially evident in winter, when more domestic heating is used and pollutant-trapping surface-inversions form earlier than in summer. BC frequency distributions the most commonly occurring concentrations occurred between 5 and 10 μg m^− 3 in all four seasons. BC ranged from 1.6% and 15.6%, and averaged 8.3% of PM_2.5. A clear inverse relationship between BC and wind speed (WS) was found when WS was below 2.5 to 3.0 m s^− 1, implying a local origin for BC. Mixed layer depths (MLDs) were shallower during BC episodes compared to cleaner conditions.  相似文献   

Size-resolved aerosol chemical concentrations at rural and urban sites in Central California, USA     

Judith C. Chow  John G. Watson  Douglas H. Lowenthal  Karen L. Magliano 《Atmospheric Research》2008,90(2-4):243-ICNAA07

Aerosol size distributions were measured with Micro Orifice Uniform Deposit Impactor (MOUDI) cascade impactors at the rural Angiola and urban Fresno Supersites in California's San Joaquin Valley during the California Regional PM₁₀/PM_2.5 Air Quality Study (CRPAQS) winter campaign from December 15, 2000 to February 3, 2001. PM_2.5 filter samples were collected concurrently at both sites with Sequential Filter Samplers (SFS). MOUDI nitrate (NO₃⁻) concentrations reached 66 μg/m³ on January 6, 2001 during the 1000–1600 PST (GMT-8) period. Pair-wise comparisons between PM_2.5 MOUDI and SFS concentrations revealed high correlations at the Angiola site (r > 0.93) but more variability (r < 0.85) at the Fresno site for NO₃⁻, sulfate (SO₄⁼), and ammonium (NH₄⁺). Correlations were higher at Fresno (r > 0.87) than at Angiola (r < 0.7) for organic carbon (OC), elemental carbon (EC), and total carbon (TC). NO₃⁻ and SO₄⁼ size distributions in Fresno were multi-modal and wider than the uni-modal distributions observed at Angiola. Geometric mean diameters (GMD) were smaller for OC and EC than for NO₃⁻ and SO₄⁼ at both sites. OC and EC were more concentrated on the lowest MOUDI stage (0.056 µm) at Angiola than at Fresno. The NO₃⁻ GMD increased from 0.97 to 1.02 µm as the NO₃⁻ concentration at Angiola increased from 43 to 66 µg m^− 3 during a PM_2.5 episode from January 4–7, 2001. There was a direct relationship between GMD and NO₃⁻ and SO₄⁼ concentrations at Angiola but no such relationships for OC or EC. This demonstrates that secondary aerosol formation increases both concentration and particle size for the rural California environment.  相似文献   

HERE BE DRAGONS: Exploring Fantasy Maps and Settings     

Judith A. Tyner 《Geographical review》2014,104(4):531-533

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Climate change and road freight safety: a multidisciplinary exploration     

David Jaroszweski  Lee Chapman  Judith Petts 《Climatic change》2013,120(4):785-799

The freight and logistics sector is of significant importance as an enabler and driver of the global economy, but it is also inherently vulnerable to hazardous weather. Despite this, there is currently no quantitative assessment of how climate change may affect the sector. This paper applies multidisciplinary climate change impact assessment tools and conceptual frameworks to the road freight sector of Great Britain in order to identify potential future weather-related safety issues. Relationships between weather and freight accidents are determined using road accident data and meteorological observations, which are then used with climate change scenarios to arrive at projections of possible impacts across the regions of Great Britain. Included in the study are industry perceptions of future trends within the sector and wider economy which many affect freight’s exposure and sensitivity to weather. These are elicited through interviews and an iterative expert Delphi study. Hence, unlike many other climate change impact assessments, this innovative study takes into account the potentially significant impact of socio-economic change (including institutional and operational). The results show that summer precipitation and winter ice-related accidents are likely to decrease across most of the country, whereas winter rain-related accidents are projected to increase. However, it is postulated that some of the impacts of climate change will be modified by reflexive behavioural change on the part of the driver and either institutional adaptation or complacency on the part of the road authorities. The paper concludes by framing the study in a range of future scenarios outlining how the socio-economic environment could influence the road transport network and how it is used, modifying the impact of climate change.  相似文献   

Probabilistic discrimination between large-scale environments of intensifying and decaying African Easterly Waves     

Paula A. Agudelo  Carlos D. Hoyos  Judith A. Curry  Peter J. Webster 《Climate Dynamics》2011,36(7-8):1379-1401

About 50?C60% of Atlantic tropical cyclones (TCs) including nearly 85% of intense hurricanes have their origins as African Easterly Waves (AEWs). However, predicting the likelihood of AEW intensification remains a difficult task. We have developed a Bayesian diagnostic methodology to understand genesis of North Atlantic TCs spawned by AEWs through the examination of the characteristics of the AEW itself together with the large-scale environment, resulting in a probabilistic discrimination between large-scale environments associated with intensifying and decaying AEWs. The methodology is based on a new objective and automatic AEW tracking scheme used for the period 1980 to 2001 based on spatio-temporally Fourier-filtered relative vorticity and meridional winds at different levels and outgoing long wave radiation. Using the AEW and Hurricane Best Track Files (HURDAT) data sets, probability density functions of environmental variables that discriminate between AEWs that decay, become TCs or become major hurricanes are determined. Results indicate that the initial amplitude of the AEWs is a major determinant for TC genesis, and that TC genesis risk increases when the wave enters an environment characterized by pre-existing large-scale convergence and moist convection. For the prediction of genesis, the most useful variables are column integrated heating, vertical velocity and specific humidity, and a combined form of divergence and vertical velocity and SST. It is also found that the state of the large-scale environment modulates the annual cycle and interannual variability of the AEW intensification efficiency.  相似文献   

Citation of Maurice E. Tucker for Honorary membership of the International Association of Sedimentologists     

Judith A. McKenzie 《Sedimentology》2011,58(3):829-830

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Petrology, geochemistry and uranium mineralisation of post-collisional magmatism around Goanikontes, southern Central Zone, Damaran Orogen, Namibia     

Paul A.M Nex  Judith A Kinnaird  Grahame J.H Oliver 《Journal of African Earth Sciences》2001,33(3-4)

The Goanikontes area lies within the southern Central Zone of the northeast trending branch of the Damara Orogen. The cover succession around Goanikontes, which comprises Etusis to Chuos Formation metasediments, is in tectonic contact with older pre-Damaran basement rocks. The area can be divided into three structural domains with basement in the east, a northeast-plunging anticline of Damaran metasediments to the west and a high strain zone up to 1 km wide that separates them and truncates the anticline. The high strain zone has provided an important focus for the emplacement of sheeted granites adjacent to the basement-cover contact. Goanikontes is also one of several significant uranium anomalies within the Damaran Orogen, and the excellent 3D exposure of the Swakop river has provided evidence for an interpretation of the tectono-metamorphic setting of magmatism and mineralisation. The granitoids have been divided into equigranular granites and sheeted leucogranites. The sequence of emplacement of the equigranular granites is from red syenogranite (534±7 Ma) to later grey monzogranite (517±7 Ma) with foliated basement-hosted granite of probable time equivalence to the syenogranites. Each type can be distinguished on major- and trace-element geochemistry. The later sheeted leucogranites, which are volumetrically the most important, intrude both basement and cover rocks. These have been divided into six distinct types based on field characteristics and structural setting backed by geochemical data and fluid extraction analyses. The earliest type A are irregular in form, boudinaged and folded by D₃, and geochemically distinct with notably low HFSE; type B's are white, weakly foliated, folded by D₃, garnetiferous and highly peraluminous; type C are tourmaline-bearing, occasionally boudinaged and exhibit the typical sheet-form within the cover rocks. Of the post-D₃ sheets, type D, which is restricted to the high strain zone is characterised by smoky quartz, high radioactivity and often by visible betafite or beta-uranophane; type E, the dominant type within the high strain zone contains prominent oxidation haloes and type F is red in colour, coarsely pegmatitic and has the highest concentration of alkalis. The uranium-mineralised type D sheets have consistently higher fluid and CO₂ content than other sheeted leucogranites. The close correlation between sheet type and uranium abundance, supported by linear trends on LIL plots suggests that the distribution of radiogenic elements is primarily magmatic with more recent meteoric re-distribution, rather than due to substantial hydrothermal modification  相似文献   

The Ground Water Management Zone — An Alternative to Costly Remediation     

Michael A. Apgar  P. G.  Philip J. Cherry  P. G.  Judith H. Jordan  Stephen N. Williams 《Ground Water Monitoring & Remediation》1989,9(1):70-73

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Mineralogical and geochemical analysis of shallow overburden as an aid to gold exploration in southwestern Gaspésie, Quebec, Canada     

M. A. Bernier  G. R. Webber 《Journal of Geochemical Exploration》1989,34(2)

Mineralogical and geochemical data from shallow overburden surveys are examined to ascertain parameters which govern the distribution of gold in overburden in a 2400-km² area of southwestern Gaspésie, Quebec, Canada.The area is a deeply dissected plateau underlain by faulted and gently folded Siluro-Devonian strata. Complex geomorphic and glacial histories are reflected in the non-glacial character of the landscape, the preservation of very old erosional landforms and extensive variation in the composition and distribution of overburden.Total sample analysis and heavy-mineral studies show that the composition of overburden changes across the area in approximate correspondence with changes in underlying bedrock. Three broad zones related to bedrock and overburden types are delimited. Gold analyses of <250 μm overburden are insensitive to regional variations, with only 15 samples out of 300 registering above the detection limit of 2 ppb. Better contrasts of gold concentrations are obtained from chemical analyses of nonmagnetic heavy-mineral concentrates (NM HMC). Although sample density is low, NM HMC data show anomalies which can be related to particular bedrock and structural settings. Particulate gold was not observed in any of the NM HMC. Gold is associated with secondary iron-oxide phases replacing primary sulphide minerals. High concentrations of gold in NM HMC of overburden collected north of the mouth of the Assemetquagan River support the hypothesis of a local source to the north or northwest for the alluvial gold in the lower 2 km segment of the river.Dilution by far-travelled, shield-derived heavy minerals is by far the most important cause of regional mineral variation. Conversion of gold concentrations in NM HMC to concentrations in total size fraction eliminates some of the erratic behavior of NM HMC data caused by variations in heavy-mineral abundance and corrects for the dilution effect where the proportion of heavy minerals in the far-travelled component of overburden is much greater than in the local component. These calculations suggest a contribution of gold to the background in the fine sand fraction of overburden of 0.07 ppb. Where the diluting component is local, conversion of NM HMC data to total size fraction may or may not correct for differences in heavy-mineral contributions of underlying bedrock, depending on local conditions. Where dilution by far-travelled components is excessive, NM HMC analyses are inadequate to reflect conditions in underlying bedrock.  相似文献   

The Australian clothing industry: competition,productivity and scale     

Bing Qing Zhang  Michael Webber 《The Australian geographer》1992,23(1):50-65

There has been substantial change in the Australian clothing industry over the last 20 years. Forms of restructuring in the industry include both the re‐emergence of outworking and subcontracting, and locational changes (decline in inner metropolitan areas, perhaps offset by outworking, but relative growth in other regions). The total turnover has slightly increased whereas employment has declined sharply. The changes in employment and output have led to major growth in labour productivity and in capital intensity. Yet labour productivity growth may not be the outcome of significant technical change: productivity growth is sometimes the result of plant closure; the formal social relations of outworking may permit plants to capture some of the profits produced by subcontractors. In any event, there is no evidence of improvements in total factor productivity in the clothing industry. Despite popular conceptions, the clothing industry has been able to achieve high rates of profit. Thus, the prices charged by the clothing industry have exceeded those needed to earn an average rate of return. But that rate of profit produces only small quantities of profit in its typical small plants. The general problem of the clothing industry is the very small scale of the most plants, resulting in lack of income for enterprises and of funds for new investment. The issue, then, is more complex than simply costs and international competition: it is more a question of investment dynamics and scale.  相似文献