Methodology of analysis associating survey results by the filter-pack method with those of precipitation- Acid-base balance on acid-related and alkali-related chemical species in urban ambient air and its influence on the acidification of precipitation -     

Masahide Aikawa  Takatoshi Hiraki 《Journal of Atmospheric Chemistry》2008,61(1):21-29

Continuous weekly monitoring on the concentration of gases and aerosols in urban ambient air by a four-stage filter-pack method was carried out for 7 years in order to study not only the acid-base balance of acid-related (HNO₃, NO₃ ⁻, and non-sea-salt-(nss-)SO₄ ²⁻) and alkali-related (NH₃, NH₄ ⁺, and nss-Ca²⁺) chemical species but also its influence on the acidification of precipitation. The concentrations of the total nitrate (= NO₃⁻ + HNO₃) and nss-SO₄²⁻ showed a similar seasonal variation: high in the summer and low in the winter. The total nitrate and nss-SO₄²⁻ accounted for 0.43 and 0.57 of the acid-related species, respectively, on an equivalent basis. The total ammonium (= NH₃ + NH₄⁺) accounted for more than 0.9 of the alkali-related species, except for a springtime nss-Ca²⁺ episodic peak. The alkali-related species were generally overabundant compared with the acid-related species in the HNO₃-NO₃⁻-nss-SO₄²⁻-NH₃-NH₄⁺-nss-Ca²⁺ system. The alkali-rich distribution was especially pronounced in the winter, but the acid-related species was comparable to the alkali-related species in the summer, which was attributed to the larger H⁺ deposition by precipitation in the summer. This study can provide a methodology to associate survey results obtained by a filter-pack method with those of precipitation.  相似文献   

The chemistry of heavy haze over Urumqi,Central Asia   总被引：1，自引：0，他引：1  

Juan Li  Guoshun Zhuang  Kan Huang  Yanfen Lin  Qiongzhen Wang  Yuhong Guo  Jinghua Guo  Shulong Yu  Caixia Cui  Joshua S. Fu 《Journal of Atmospheric Chemistry》2008,61(1):57-72

A sampling campaign of aerosols over Urumqi from 2001–2007 and soil samples in the surrounding areas were carried out to investigate the severe air pollution in Urumqi, a typical inland city, located in the center of Asia. Urumqi is one of the heavy polluted cities in the world, as the days of haze spanned over one third of the year and accounted for 60–80% of the heating period for the past 6 years. High concentration of fine aerosols, frequent occurrence, and rapid formation of heavy haze were the three main characteristics. With comparison of the pollution elements, As, Cd, and S, and the ratio of Ca/Al in aerosols and soils in those sites located on the south of Jungger Basin as tracers, it was found that As, Cd, and S highly enriched in the aerosols over urban Urumqi were not only from the re-suspended road dust but also from the soil transported from south of the Jungger Basin. Different from the most cities in China, the high concentration of sulfate in Urumqi was partially from the primary soil dust transported from the surrounding areas. The mixing of the local anthropogenic aerosols with the soil transported from outside the city was the main source of the high sulfate concentration. Ammonium salts were higher than the summed equivalents of SO₄²⁻, NO₃⁻, and Cl⁻ in Urumqi and much higher than that in other Chinese cities. The total water soluble ions and the total ammonium salts were as high as 57.8% and 51.0% in PM_2.5. The high concentration of soluble salts with high hygroscopicity, especially ammonium and sulfate salts, were the main factors contributing to the heavy haze over Urumqi.  相似文献   

全球低碳化转型与中国的应对战略     

何建坤 《气候变化研究进展》2016,12(5):357-365

《巴黎协定》确立了2020年后全球气候治理新机制,明确了全球应对气候变化长期目标,将加速世界范围内经济发展方式的低碳转型,推进能源体系的革命性变革,促进社会生产方式和消费方式的根本性转变,进而促进人类社会文明形态由工业文明向生态文明演变。全球低碳转型的紧迫形势,将重塑世界范围内经济、贸易、技术的竞争格局。中国以生态文明建设为指引,探索绿色低碳发展路径,确立有雄心、有力度的国家自主决定贡献目标和行动计划,推动能源生产和消费革命,加快经济发展方式的转变,既是顺应世界低碳转型的潮流,又是缓解国内资源环境制约和实现可持续发展的内在需要,是促进经济发展、环境保护和减缓碳排放的多赢战略。中国要以全球长期减排目标为指引,制定中长期低碳发展战略,打造低碳先进技术和发展方式的核心竞争力,同时深度参与全球治理,为建设人类命运共同体,应对全球生态危机体现大国的责任担当。  相似文献   

木质锚杆加固土遗址边坡的稳定性分析          下载免费PDF全文

石玉成  秋仁东 《地震工程学报》2015,37(3):809-815

基于有限元强度折减法,以新疆吐鲁番交河故城的典型工程加固剖面为实例,计算分析木质锚杆加固土遗址坡体在静力、地震作用下的安全系数,同时分析木质锚杆长度、锚固角度等因素对其安全系数的影响,评价木质锚杆加固土遗址坡体的可行性,并在此基础上探讨其相关机理及设计中应注意的问题。研究成果可为木质锚杆加固土遗址坡体的相关工程实践提供参考。  相似文献   

基于宏观地震减灾能力的地震生命损失快速评估方法     

康建红  李智  安俊峰 《东北地震研究》2015,(2)

搜集1999年集集M7.6级地震、2008年汶川M8.0级地震震中高烈度区各乡镇生命损失和当年人口等基础数据,得到不同地震烈度下各乡镇死亡率数据。以评估地震减灾能力的宏观模型为基础,对各乡镇的减灾能力进行评估并划分等级,得到不同等级地震减灾能力与相对应的平均死亡率的统计关系。将此对应关系应用到2010年玉树M7.1级地震中,所得到的生命损失结果与官方公布的结果相近。表明宏观地震减灾能力评估体系可应用于单次地震损失快速评估工作中。  相似文献   

土工袋减振隔振机制分析及试验研究     

刘斯宏  高军军  王艳巧 《岩土力学》2015,36(2):325-332

设置于地基中的土工袋不仅可以提高地基承载力,而且具有减振隔振效果。通过水平循环剪切试验研究了土工袋的动力特性,验证了土工袋具有可变的水平刚度和较大的阻尼比,表明土工袋是一种良好的基础减振隔振材料。土工袋的等效阻尼比随着竖向压力的增大而减小,随着最大剪应变的增大而增大。同时,采用离散单元法进行了土工袋在动力荷载作用下的数值模拟计算,土颗粒间采用弹簧-阻尼器接触模型;而土工袋被看成具有张力的小颗粒薄层,这些小颗粒间的接触与袋内土颗粒间的接触模型相同,但仅设置法向的接触而无切向接触,且只受拉不受压。结果表明,土工袋的减振消能效果主要来自于袋内材料的摩擦耗能、黏滞耗能以及袋子张力引起的耗能。另外,还进行了土工袋沟槽的原位振动测试,验证了土工袋的减振隔振效果。  相似文献   

Spatially-resolved high-resolution spectroscopy of Venus 2. Variations of HDO, OCS, and SO₂ at the cloud tops     

Vladimir A. Krasnopolsky 《Icarus》2010,209(2):314-322

While CO, HCl, and HF, that were considered in the first part of this work, have distinct absorption lines in high-resolution spectra and were detected four decades ago, the lines of HDO, OCS, and SO₂ are either very weak or blended by the telluric lines and have not been observed previously by ground-based infrared spectroscopy at the Venus cloud tops. The H₂O abundance above the Venus clouds is typically below the detection limit of ground-based IR spectroscopy. However, the large D/H ratio on Venus facilitates observations of HDO. Converted to H₂O with D/H ≈ 200, our observations at 2722 cm⁻¹ in the Venus afternoon show a H₂O mixing ratio of ∼1.2 ppm at latitudes between ±40° increasing to ±60° by a factor of 2. The observations in the early morning reveal the H₂O mixing ratio that is almost constant at 2.9 ppm within latitudes of ±75°. The measured H₂O mixing ratios refer to 74 km. The observed increase in H₂O is explained by the lack of photochemical production of sulfuric acid in the night time. The recent observations at the P-branch of OCS at 4094 cm⁻¹ confirm our detection of OCS. Four distributions of OCS along the disk of Venus at various latitudes and local times have been retrieved. Both regular and irregular components are present in the variations of OCS. The observed OCS mixing ratio at 65 km varies from ∼0.3 to 9 ppb with the mean value of ∼3 ppb. The OCS scale height is retrieved from the observed limb darkening and varies from 1 to 4 km with a mean value of half the atmospheric scale height. SO₂ at the cloud tops has been detected for the first time by means of ground-based infrared spectroscopy. The SO₂ lines look irregular in the observed spectra at 2476 cm⁻¹. The SO₂ abundances are retrieved by fitting by synthetic spectra, and two methods have been applied to determine uncertainties and detection limits in this fitting. The retrieved mean SO₂ mixing ratio of 350 ± 50 ppb at 72 km favors a significant increase in SO₂ above the clouds since the period of 1980-1995 that was observed by the SOIR occultations at Venus Express. Scale heights of OCS and SO₂ may be similar, and the SO₂/OCS ratio is ∼500 and may be rather stable at 65-70 km under varying conditions on Venus.  相似文献   

Tidal Reduction Method Based on Temporal Tidal Time-Difference Variations     

Ju Liu  Jingyang Bao  Wei Zhou  Jun Xu  Xianghong Zhao 《Marine Geodesy》2013,36(5):407-421

Abstract

Technical developments in the positioning and depth detection fields have allowed for vast improvements in sounding results, but the effects of tidal reduction (TR) yet merit improvement; today, TR is the main factor that limits bathymetry precision. It is crucial to determine tidal time difference (TTD) between tidal gauges to conduct effective TTD-based TR. The influence of temporal TTD variations is usually ignored, and the temporal observation window to determine TTD is generally freely selected. In this study, temporal TTD variations were analyzed under the tidal constituent merging theory. Daily and hourly TTDs were compared and utilized to reduce the TR error during time difference method operation. At-sea experiments were conducted to contrast the effects of daily versus hourly TTDs on TR; the results indicate that hourly TTD is more precise and thus better suited to TR.  相似文献   

Robust Automatic Reduction of Multibeam Bathymetric Data Based on M-estimators     

Mohammad-Hadi Rezvani  Abbas Sabbagh  Alireza A. Ardalan 《Marine Geodesy》2013,36(4):327-344

Multibeam echosounders have commonly been employed for a wide range of applications including offshore survey, navigation, hydrogeology, and oceanography. Because the tremendous volume of the bathymetric data is demanding for some purposes and requires significant storage space, the data reduction plays a prominent role in practice. Additionally, the multibeam soundings are inevitably contaminated with sporadic outliers, and as such, the data cleaning can be challenging especially in shallow waters. We present a speedily robust method for reliably reducing the volume of the bathymetric data within grid cells. In this respect, robust M-estimators are recursively applied to the data in a patch-wise manner to alleviate the undesirable effects of the outlying observations. Accordingly, the reduced bathymetry is automatically made unaffected by the possible outliers once their equivalent weights have been downweighted. The performance of the presented method has been demonstrated by synthetic datasets and an experimental dataset collected by an ATLAS FS 20/100 kHz shallow-water multibeam echosounder in the offshore waters of Kish wharf. The reliability, efficiency, and capability of the proposed method have been verified, which makes it quite possible to meet the IHO requirements for special-order seafloor mapping.  相似文献   

土地利用图综合流程研究     

王晓妍  朱明骥  郭庆胜  翁杰  刘鹏  杨志龙 《测绘信息与工程》2012,37(6):10-13

土地利用图作为一种典型的专题地图,其综合是目前我国正在进行的第二轮土地利用总体规划工作的一部分,所以研究土地利用图综合具有重要的意义。土地利用图空间上全覆盖、无重叠以及语义上层次化的特点决定了土地利用图的综合是一个复杂的过程。土地利用图的综合过程大致可以分为预处理、图形简化、狭长图斑线化、小图斑综合（聚合和融合）以及综合质量评价等几个步骤,结合实际工作对各个步骤进行详细的阐述,结果证明文中采用的方法基本能够实现土地利用图的自动综合,并且综合结果能够满足用户需求。  相似文献