A study of the ozone formation by ensemble back trajectory-process analysis using the Eta–CMAQ forecast model over the northeastern U.S. during the 2004 ICARTT period

The integrated process rates (IPRs) estimated by the Eta–CMAQ model at grid cells along the trajectory of the air mass transport path were analyzed to quantitatively investigate the relative importance of physical and chemical processes for O₃ formation and evolution over the northeastern U.S. during the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) period. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model is used to determine the back trajectory of air masses reaching the northeast by linking a downwind receptor to upwind source areas. The process analysis is applied to a high O₃ episode occurring on July 22, 2004 at three selected sites in the northeastern U.S. The process analysis at the location of the site shows that during the daytime, the O₃ concentrations in the surface layer are mainly enhanced by the vertical diffusion of O₃-rich air from aloft, followed by horizontal advection (HADV) and chemical production (CHEM), whereas dry deposition (DDEP) and vertical advection (ZADV) mainly deplete O₃ concentrations at the sites of Valley Central (VC), NY and Castle Spring (CS), NH. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it was found that at the VC site, CHEM and HADV contributed about 53% and 41%, respectively, to O₃ levels within the PBL. This confirms the significance of regional transport of O₃ from the industrialized areas into the Northeast. On the other hand, the process analysis results for O₃ formation in moving air masses indicate that on July 22, large chemical production of O₃ along the transport path over the polluted urban regions leads to significant increase in O₃ in the air mass reaching the VC site, whereas the low chemical production of O₃ along the transport path over the low emission regions leads to the low O₃ concentration at the site of Belleayre Mountain (BM), NY. The dramatic buildup of O₃ concentration from 50 ppb to 102 ppb in the air masses before reaching the VC site after 12:00 EST on 7/22 indicates the significant impact of pollution from the northeastern urban corridor at this site. On the basis of the results at the CS site, it was found that high NO_x emissions along the transport path led to large chemical production of O₃ in the air mass reaching the CS site on July 22. In contrast, the low chemical production of O₃ associated with low emission (relatively clean conditions) along the transport path over the northern portions of the domain is responsible for the low O₃ concentration at the CS site on July 26.     

A PROTOTYPE OF THE MODERN SETTLING -RESERVOIR IN ANCIENT MESOPOTAMIA1

ABSTRACT If one goes to Iraq today, as I did in the summer of 1972 one sees that the area once served by this ancient canal system is presently abandoned to desert. The Ur III texts would indicate that the Sumerian irrigation system allowed them to raise good crops of grain, vegetables and fruits, in an area now completely barren except for an occasional thorn-bush. This paper deals in detail with the Sumerian term nag-ku5, which seems to be a key word in arriving at a more accurate picture of Sumerian canal and irrigation systems. Ur III material indicates that the nag-ku5 may have served a role similar to that of the modern settling-reservoir. The aim of this study is the hope that knowledge of the past could help this desert bloom once more.     

TiO2纳米管光电催化降解酸性橙染料

采用电化学阳极氧化法在金属钛表面制备锐钛矿型TiO2纳米管,并以TiO2纳米管薄膜为阳极,考察溶液pH、外加偏压以及NaC1浓度对酸性橙的光电催化降解反应的影响.实验结果表明:在溶液pH为3.0、外加偏压为2.5V、NaCl浓度为0.05 mol/L的最佳实验条件下反应30 min,酸性橙降解率可达99.99％;TiO2纳米管重复使用25次,酸性橙降解率仍可达94.57％.     

高梯度磁除尘的实验研究

对磁性粉尘和非磁性粉尘进行了磁分离实验研究。结果表明,对磁性粉尘,磁除尘效率可达99％以上,而对非磁性粉尘,通过粉尘上磁,磁除尘效率可达90％以上。     

The New England Air Quality Forecasting Pilot Program: Development of an Evaluation Protocol and Performance Benchmark

Abstract

The National Oceanic and Atmospheric Administration recently sponsored the New England Forecasting Pilot Program to serve as a “test bed” for chemical forecasting by providing all of the elements of a National Air Quality Forecasting System, including the development and implementation of an evaluation protocol. This Pilot Program enlisted three regional-scale air quality models, serving as prototypes, to forecast ozone (O₃) concentrations across the northeastern United States during the summer of 2002. A suite of statistical metrics was identified as part of the protocol that facilitated evaluation of both discrete forecasts (observed versus modeled concentrations) and categorical forecasts (observed versus modeled exceedances/nonexceedances) for both the maximum 1-hr (125 ppb) and 8-hr (85 ppb) forecasts produced by each of the models. Implementation of the evaluation protocol took place during a 25-day period (August 5–29), utilizing hourly O₃ concentration data obtained from over 450 monitors from the U.S. Environment Protection Agency’s Air Quality System network.     

Motor vehicle fatalities among Gulf War era veterans: characteristics, mechanisms, and circumstances

OBJECTIVES: Our objective was to describe fatal motor vehicle crashes (MVC) among veterans of the 1991 Gulf War era and to compare the distribution of crash and individual characteristics between those deployed to the Gulf War (GWV) and those not deployed (NDV). METHODS: We compared individual characteristics, crash mechanisms, and crash circumstances between 765 GWV and 553 NDV who died from MVC within the first five years of the war, between May 1991 and December 1995. RESULTS: Overall, GWV and NDV who died from a MVC were more likely to be enlisted males (97%), 21-30 years old (72%), have a high school education or less (91%), drive a passenger car (52%), and not use restraints (60%). The overall annual rate of motor vehicle fatalities for GWV (23.6 per 100,000; 95% confidence interval: 21.9-25.3) was significantly greater than the rate for NDV (15.9, 95% CI: 14.6-17.3). GWV with the highest motor vehicle fatality rates include males (24.8, 95% CI: 23.0-26.6), 17-20 year olds (105.0, 95% CI: 78.2-138.1), and those not married (27.3, 95% CI: 25.1-30.1). Adjusting for differences in age distribution across GWV and NDV did not account for the difference in rates. Characteristics of MVC fatalities that were over-represented among GWV include serving as regular active duty (p = 0.001), having a high school education or less (p = 0.01), being involved in a single-vehicle crash (p = 0.008), and dying within the first hour following the crash (p = 0.004). Also, we identified a greater proportion of alcohol-related crashes among GWV during the late night and early morning hours. CONCLUSIONS: The highest rates of motor vehicle fatality among young, single males in the military mirror the experience of the general population. Further research is necessary to determine modifiable risk factors that can be targeted for specific interventions and whether the elevated late night alcohol-related crash rate among GWV is an effect of deployment or an inherent population bias among those selected for operational deployments.     

Enhancing forest carbon sequestration in China: toward an integration of scientific and socio-economic perspectives

This article serves as an introduction to this special issue, "China's Forest Carbon Sequestration", representing major results of a project sponsored by the Canadian International Development Agency and the Chinese Academy of Sciences. China occupies a pivotal position globally as a principle emitter of carbon dioxide, as host to some of the world's largest reforestation efforts, and as a key player in international negotiations aimed at reducing global greenhouse gas emission. The goals of this project are to develop remote sensing approaches for quantifying forest carbon balance in China in a transparent manner, and information and tools to support land-use decisions for enhanced carbon sequestration (CS) that are science based and economically and socially viable. The project consists of three components: (i) remote sensing and carbon modeling, (ii) forest and soil assessment, and (iii) integrated assessment of the socio-economic implications of CS via forest management. Articles included in this special issue are highlights of the results of each of these components.     

煤矿工人个体安全防护装备的创新与改进

本文从井下工作人员所需穿戴的安全防护装备入手,结合矿井环境特点．探讨如何在现有装备的基础上进行改进,以提高工作时的安全系数,更好保护井下工作人员的身体健康．以及在事故发生时起到更好的救护作用。