Atmospheric deterioration of Qin brick in an environmental chamber at Emperor Qin's Terracotta Museum, China

Potential mechanisms for the changing appearance of Qin terracotta was evaluated on simulated bricks with, SO₂, NH₃, O₃, and a NH₃/O₃ mixture for total dosages of 2.2–5.4 ppm-years. Changes in the surface composition and appearance were evaluated with scanning electron microscopy/energy dispersive X-ray analysis (SEM–EDX) and X-ray photoelectron spectroscopy (XPS). No observable changes with O₃ exposure were found. Sulfate as sulfur and ammonium as nitrogen increased by 1.2 at% and 0.8 at% of the surface deposit as determined by XPS. O₃ did not have a detectable effect by itself, but when combined with NH₃, NO₃ as nitrogen increased by 1.5 at%, indicating a strong oxidation of NH₃ to nitric acid. The combination of outdoor O₃ infiltration with indoor NH₃, presumably from the visitors, appears to have a greater potential for damage than either pollutant by itself. SEM–EDX mapping of the surface showed sulfur associated with calcium and magnesium compounds after SO₂ exposure, but not before. More detailed microscopic examination showed this primarily in the form of gypsum, especially near cracks and pits in the surface. Both of these mechanisms are probably among the causes of changes in terracotta appearances since they were unearthed in 1974.     

降雨和空气污染对城市居民公共自行车使用的影响研究——以西安市为例

公共自行车交通（以下简称公自）作为近年来快速发展的新型公共交通模式,逐渐成为国内外相关学科的研究热点。国内外大量学者探索了公自的使用特征及影响因素,但关注天气条件对公自使用影响的研究不足,来自中国城市的实证证据更是缺乏。本文以西安市为案例,利用西安市公自系统运营数据,探索降雨和空气污染对城市居民公自使用的影响。研究结果表明：①降雨和空气污染条件下公自使用规模减少,但降雨带来的影响大于空气污染。②降雨和空气污染条件下公自站点中平衡站点比例减少,且公自借出和归还为主站点的冷热点区域空间分布发生显著差异。③降雨和空气污染对公自使用强度有显著影响,一级站点数量明显减少,且降雨的影响大于空气污染。降雨条件下公自使用高强度站点中心化和沿走廊分布的空间特征弱化。但空气污染条件下,无显著变化。研究结果有助于准确评估降雨和空气污染对于城市居民社会经济活动的影响程度,也能为更准确的研究城市居民公自使用的影响机制提供参考依据。     

Monitoring the Near‐surface Urban Heat Island in Beijing,China by Satellite Remote Sensing

Urban heat island (UHI) effect is an important impact factor of the regional climate and ecological environment. How to observe and analyse the spatial distribution of UHI has become an important issue of urban environmental research. In this paper, the near‐surface air temperature of Beijing was derived based on the Landsat/TM satellite imagery on 26 July 2011 to study the near‐surface UHI. A statistical model at 195‐m window size was established to estimate the air temperature, using land surface temperature, normalized difference vegetation index, altitude, and surface albedo as independent variables. The mean absolute error (MAE) of the model was 0.87°C, and the R² was 0.66, indicating that the method can be used to effectively estimate the air temperature. The air temperature distribution obtained from remote sensing revealed that the UHI effect in Beijing was very significant and showed a concentrated pattern. The heat island intensity was stronger in the southern part than in the northern part of the city. In addition, the relationship between the air temperature and impervious surfaces was analysed. The air temperature increased with increasing impervious surface coverage, and the rate of change depended on the impervious surface coverage. When the impervious surface coverage was below 40 per cent, the temperature increased rapidly with increasing impervious surface coverage, and when the impervious surface coverage was above 40 per cent, the temperature increased slowly. This study provides a new approach to monitor near‐surface UHI and reveals its relationship with impervious surface, providing a scientific reference for urban planning and environmental assessment.     

文物保存微环境中的氮氧化物集成净化

氮氧化物(NOx)是环境中的重要污染物,是文物保存环境的重大威胁,不仅其本身会对文物产生严重危害,而且与其他污染物如硫氧化物和有机酸耦合会加剧侵蚀。为此,本研究采用光催化预处理与生物质吸附集成技术净化文物保存微环境空气中低浓度的氮氧化物。实验结果表明:直接使用竹屑、杉木屑、落叶松、稻壳和稻糠生物质可去除NOx;在520℃下炭化的竹炭对NOx去除率可达75%。NOx的光催化效率随流速升高而降低,当NOx中混有有机酸时集成净化效率会出现波动。对光催化和吸附的不同组合进行了比较,最优组合可使NO和NO2浓度分别降至1.98μg/m3和1.80μg/m3。     

基于腾讯位置数据的中国城市居民航空出行时空特征

随着中国经济社会的快速发展,航空出行成为居民出行方式的重要组成部分,并影响着城市格局。本文基于2019年4月28日—5月10日国内215个机场的腾讯定位请求数据,分析中国城市居民在工作日和五一假日两个场景下的航空出行时空特征,进而探究其与城市格局的关系。结果表明：①中国城市居民航空出行在空间上,总体呈现东部沿海高于内陆地区,且中部地区相对较低的特点;②在时间上,多集中在工作日,且京津冀、长三角、粤港澳大湾区、成渝等经济发达地区的中心城市更偏向“工作日优势型”,而中部地区及西南部地区的非区域中心城市更偏向“假日优势型”,并呈现以24小时为周期的下降、上升和波动的日变化,与工作日相比,五一假日提前2小时进入波动期,且居民假日航班时间选择更偏向在下午3点和晚上8点前后;③在工作日和假日两类场景下,所呈现的聚类等级分化与其所在城市规模之间关联性较强,在一定程度上接近城市金字塔的规模等级分布特征。     

Air Services at Australian Cities: Change and Inertia 2005–2010

This research analyses international and domestic air services in Australia during a six year period, 2005–2010. We place air services into their urban context by relating them to city‐based measures such as population, tourism, and producer services employment among other measures. The research takes a supply‐side approach in an assessment of international and domestic capacity at major Australian airports from the perspective of the number of seats, the nature of links, and competition. Multiple linkage analysis and the concept of effective competitors allow us to explore this perspective at greater depth. Our findings show substantial changes in international patterns, specifically favouring Melbourne, Perth, and Gold Coast. In contrast, the domestic scene is characterised by little change, an outcome we link to the underlying stability in the settlement system and the location of some major economic activities. While the results are related to our measures of urban characteristics, some special region‐specific aspects are also at work. Finally, in both the international and domestic cases we find evidence of greater airline diversity which may benefit consumers.     

The new Siberia

This paper assesses relationships between Scottish ice climbing and daily weather conditions between 1961 and 1990. Synoptic air flow and instrumental climate data from Braemar and Fort Augustus were analysed in relation to first ascents of ice climbs in the Cairngorms, and on Ben Nevis and Creag Meagaidh. Lagged weather variables were calculated and stepwise logistic regression was used to estimate optimum models for both areas. Significant variables are anticyclonicity, low minimum air temperature and northerly or easterly airflow (Cairngorms, P = 0.0006); and northerly or easterly airflow, low minimum air temperature and low precipitation (Ben Nevis and Creag Meagaidh, P < 0.0001). A five‐day cold spell is optimum for Ben Nevis and Creag Meagaidh. A week with relatively little precipitation is beneficial in both areas. Air flow direction is more influential than vorticity, the optimum predictors of ice conditions using synoptic data alone are a persistent easterly component (beneficial), and a persistent southerly and westerly component (detrimental), P < 0.0001.     

Smoggy with a Chance of Altruism: The Effects of Ozone Alerts on Outdoor Recreation and Driving in Atlanta

Metropolitan smog alerts are prominent public information campaigns designed to enhance public health and to curb driving and other emissions. Unlike many other voluntary information‐based environmental policies, air quality alerts target household behavior via forecast information about ambient concentrations rather than firm or product characteristics. This paper explores behaviors with high emissions (driving) and with high exposure (outdoor recreation) and underscores the difference between altruistic and risk aversion motivations. Behavioral impacts are identified using the threshold nature of daily air quality forecasts. A regression discontinuity (RD) design finds elderly users and exercisers tend to curtail their use of a major park following smog alerts. The RD design also reveals that households do not drive less on smog alert days. Juxtaposing high emissions behavior with high exposure behavior in the same study highlights how public forecast information may better trigger some responses and struggle to trigger others.     

Breathless: Schools, Air Toxics, and Environmental Justice in California

The exposure of children to environmental disamenities has emerged as a key policy concern in recent years, with some analysts and activists suggesting that minority children are disproportionately impacted. Utilizing a dataset that combines air toxics at the census tract level with school-based demographic and other information, this article indicates disparate exposures for students of color in California schools and suggests that there may be negative impacts on one measure of academic performance, even after controlling for other factors usually associated with test scores. Policy implications include a special focus on school remediation and strengthening overall efforts to reduce emissions "hot spots."     

Aerostatic spacing: on things becoming lighter than air

The development of practical aerostatic or lighter than air balloon flight in 1783 marked the emergence of a new way of being and becoming mobile, one that also involved an important technical and experiential transformation in earth–atmosphere relations. This paper narrates an account of the distinctive kinds of spaces of which aerostatic flight is generative. At the centre of this account is the claim that the affective materiality of aerostatic flight is simultaneously processual and possessing of what political theorist Jane Bennett calls 'thing-power'. In developing this claim, the paper draws from a range of historical and contemporary accounts of aerostatic flight in order to elaborate upon three aspects of the spaces of things becoming aerostatic: the distinctive kinds of sensing of which aerostatic flight is generative; the differential qualities of affectivity in which the movement and materiality of aerostatic things participates; and the kinds of vertiginous events in which the felt movement – actual or anticipated – of aerostatic things is implicated. The paper concludes by speculating upon how attending to the distinctive and sometimes disquieting materiality of aerostatic things might contribute to geographical engagements with the spaces of air and atmosphere.