Study of Meteorological Aspects and Urban Concentration of SO2 in Atmospheric Environment of La Plata, Argentina

This article presents and discusses SO₂ (ppbv) concentration measurements combined with meteorological data (mainly wind speed and direction) for a five-year campaign (1996 to 2000), in a site near an oil refinery plant close to the city of La Plata and surroundings (aprox. 740.000 inh.), considered one of the six most affected cities by air pollution in the country. Since there is no monitoring network in the area, the obtained results should be considered as medium term accumulated data that enables to determine trends by analyzing together gas concentrations and meteorological parameters. Preliminary characterization of the behaviour of the predominant winds of the region in relation with potential atmospheric gas pollutants from seasonal wind roses is possible to carry out from the data. These results are complemented with monthly averaged SO₂ measurements. In particular, for year 2000, pollutant roses were determined which enable predictions about contamination emission sources. As a general result we can state that there is a clear increase in annual SO₂ concentration and that the selected site should be considered as a key site for future survey monitoring network deployment. Annual SO₂ average concentration and prevailing seasonal winds determined in this work, together with the potential health impact of SO₂ reveals the need for a comprehensive and systematic study involving particulate matter an other basic pollutant gases.     

Nonstationary, long memory and anti-persistence in several climatological time series data

In this article we examine the stochastic behaviour of several daily datasets describing sun (total irradiance at the top of the atmosphere and sunspot numbers) and various climatological anomaly series by looking at their orders of integration. We use a testing procedure that permits us to consider fractional degrees of integration. The tests are valid under general forms of serial correlation and deterministic trends and do not require estimation of the fractional differencing parameter. Results show that the series are all nonstationary, with increments that might be stationary for those variables affecting sun, and anti-persistent for those affecting air temperatures.     

Mega-Development Trends in the Amazon: Implications for Global Change

This paper describes four global-change phenomena that are having major impacts on Amazonian forests. The first is accelerating deforestation and logging. Despite recent government initiatives to slow forest loss, deforestation rates in Brazilian Amazonia have increased from 1.1 million ha yr^–1 in the early 1990s, to nearly 1.5 million ha yr^–1 from 1992–1994, and to more than 1.9 million ha yr^–1 from 1995–1998. Deforestation is also occurring rapidly in some other parts of the Amazon Basin, such as in Bolivia and Ecuador, while industrialized logging is increasing dramatically in the Guianas and central Amazonia.The second phenomenon is that patterns of forest loss and fragmentation are rapidly changing. In recent decades, large-scale deforestation has mainly occurred in the southern and eastern portions of the Amazon — in the Brazilian states of Pará, Maranho, Rondônia, Acre, and Mato Grosso, and in northern Bolivia. While rates of forest loss remain very high in these areas, the development of major new highways is providing direct conduits into the heart of the Amazon. If future trends follow past patterns, land-hungry settlers and loggers may largely bisect the forests of the Amazon Basin.The third phenomenon is that climatic variability is interacting with human land uses, creating additional impacts on forest ecosystems. The 1997/98 El Niño drought, for example, led to a major increase in forest burning, with wildfires raging out of control in the northern Amazonian state of Roraima and other locations. Logging operations, which create labyrinths of roads and tracks in forsts, are increasing fuel loads, desiccation and ignition sources in forest interiors. Forest fragmentation also increases fire susceptibility by creating dry, fire-prone forest edges.Finally, recent evidence suggests that intact Amazonian forests are a globally significant carbon sink, quite possibly caused by higher forest growth rates in response to increasing atmospheric CO₂ fertilization. Evidence for a carbon sink comes from long-term forest mensuration plots, from whole-forest studies of carbon flux and from investigations of atmospheric CO₂ and oxygen isotopes. Unfortunately, intact Amazonian forests are rapidly diminishing. Hence, not only is the destruction of these forests a major source of greenhouse gases, but it is reducing their intrinsic capacity to help buffer the rapid anthropogenic rise in CO₂.     

水蚀风蚀交错带小流域生态环境综合治理模式研究

水蚀风蚀交错带是黄土高原侵蚀最严重的地区和黄河下游河床粗泥沙的主要来源区，其生态环境脆弱、治理难度大，加之晋陕蒙能源基地的大规模开发，也带来了新的环境问题。鉴于治黄和煤田开发及生态环境整治的紧迫需要，以水蚀风蚀交错带六道沟小流域为试区，分析研究了该区水蚀风蚀时空分布规律及脆弱生态环境特征，提出以防治水蚀和风蚀为中心，以提高生态经济效益和持续发展为目标，以基本农田优化结构和高效利用及植被建设为重点，建立具有防蚀固沙兼高效生态经济功能的大农业复合生态系统综合治理模式，取得了良好的社会与经济效益。     

风能资源评估系统开发与应用

开发风能资源、利用风力发电在我国虽然只有数十年，但其发展却很快，风能作为可再生的清洁能源也越来越受到重视。风能资源评估作为风电资源开发的前提，是风力机选址的关键。介绍了以Visual Basic为开发工具，利用SQL Server为数据库开发而成的风能资源评估系统的结构和特点。经实践证明，本系统缩短了风能资源评价周期，提高了数据处理可靠性。     

长白山西坡风灾干扰区的恢复和保护

长白山西坡发生的灾害性风灾干扰,一方面给长白山自然保护区的森林资源造成巨大损失,同时也提出了如何加强保护和加速恢复的新课题。文中分析了风灾干扰区的更新格局和过程以及干扰后处理的有关问题,提出了从立地和景观水平促进更新恢复的保护措施     

我国淡水水域光合产物的气候生产力探讨

根据太阳辐射在水体中的有效分布、生长季水温和浮游植物光合生态特性等因子,模拟计算了我国大陆东部淡水水域的光合生产力、气候生产力及其季节变化的地理规律。从中得知,这些水域初级产物的年气候生产力主要呈纬向分布,由南向北递减,各地范围在 1.6-24.4gC/m²·a之间,长江以南是>15.0gC/m²·a的高值区,长城以北和四川盆地为<10.0gC/m²·a的低值区,因此,在气候生产力高值区有可能充分利用气候资源优势,开发低成本的自然淡水水域渔业;而在低生产力区,受自然资源的局限其自然捕鱼量需适量控制,因地制宜。     

京津风沙源区防风固沙功能的时空变化及其区域差异

防风固沙功能是京津风沙源治理成效的关键监测指标。以往研究注重局地防风固沙功能的评估,对全区防风固沙功能的时空变化与内部差异揭示不足。基于京津风沙源区多期遥感数据,采用修正风蚀方程与GIS空间统计技术,评估分析了2000-2015年防风固沙功能的整体变化及其区域差异。结果表明:(1)京津风沙源区年均防风固沙量为28.98亿t,防风固沙能力为68.24 t/hm~2,且均随年份变化波动增加,年均增速分别为1.10%和0.71%;(2)京津风沙源区防风固沙能力呈西北高、东南低趋势,有49.06%的区域防风固沙能力高于70 t/hm~2,评估期内有54%的区域防风固沙能力明显提高;(3)浑善达克沙地亚区、典型草原亚区和荒漠草原亚区的防风固沙量累计为全区防风固沙总量的88%,燕山丘陵山地水源保护亚区和晋北山地丘陵亚区的防风固沙能力提升最显著;(4)锡林郭勒盟、赤峰市和乌兰察布市的防风固沙量合计占全区防风固沙量的77%,朔州市与包头市防风固沙能力较高,北京市与天津市防风固沙能力增速较高。因此,未来应重视分区施策治理与西部和北部防风固沙功能提升。     

砂尘环境试验风洞稳定段和收缩段的数值模拟研究

采用计算流体动力学软件FLUENT,对砂尘环境试验风洞中稳定段和收缩段的气固两相流流场进行数值模拟.给出了计算采用的湍流模型及计算区域的网格划分技术.通过分析稳定段和收缩段的两相流流场的速度梯度分布,得到了反向加砂方式优于正向加砂方式的计算结果.     

反应堆控制棒驱动机构电机温升试验研究

目的 研究电机在不同工况下的温升情况,完成电机散热能力评估,为电机散热优化和工程通风设计提供参考.方法 模拟驱动机构实际运行环境,在断风条件下进行自然散热温升试验,获取电机温升最大工作模式,并在该模式下进行2种风速条件下的通风试验,获取定子绕组的平衡温度.当定子绕组达到热平衡后,切断通风,进行断风试验,获取最大断风时间.结果 电机温升最大时,工作模式为三相通电,增大风速可降低定子外壁温度,提高定子绕组与定子外壁的温差.三相通电工况下,5 m/s和8 m/s风速下最大断风时间分别为15 min和22 min.结论 开展了电机温升试验研究,获得了典型工况下电机的温升状况,为电机散热优化和工程通风设计提供了参考.