超细粉尘的扬尘机理研究

针对目前对于一般尘源控制研究较少,而系统研究粉尘的扬尘(尘化)机理的研究就更少这一状况,提出弄清尘化机理、从源头上控制是治理粉尘的首要问题,对粉尘颗粒作用力进行分析,特别就超细粉尘的扬尘机理提出相应的物理模型并进行初步研究.图1,参2.     

用β射线衰减法测定颗粒物的准确性和有效性验证

通过在线监测系统用β射线衰减法测定空气中颗粒物的工作原理、测试数据准确性和有效性。将参比采样器监测数据(重量法)与相应的自动采样器监测数据(β射线衰减法)进行不确定评估和平行性、线性回归分析验证。从而得出,在线监测系统用β射线衰减法测定空气中颗粒物时有较好的线性关系,监测数据准确、可靠,具有一定推广价值。同时,为提高环境监测能力、加强环境执法监管提供可靠依据。     

Monitoring of Daily Integrated Exposure of Outdoor Workers to Respirable Particulate Matter in an Urban Region of India

It is more and more recognised that an estimation of the exposure of the population to air pollutants is more relevant than the ambient air quality, since it gives a better indication of health risk. Outdoor workers in an urban region are generally of low income status and are exposed to higher levels of both indoor and outdoor air pollution. Hence respondents from this population subgroup have been selected for this study. Outdoor workers are divided into two categories, viz. traffic constables and casual outdoor workers like watchmen, roadside shopkeepers etc. Most of the respondents are from the lower income group. Each respondent is monitored for a continuous 48-hour period. The sampling frequency is once a week.The study region is situated in the north-west part of the Greater Mumbai Municipal Corporation. It can be classified as industrial cum residential area. The daily integrated exposure of the outdoor workers consists of two major micro-environments, viz. occupational and indoor residential.A personal air sampler was used along with a cyclone to measure levels of Respirable Particulate Matter (RPM). The cyclone has a 50% removal efficiency for particle diameter of 5 m. Paired samples of PM10 (ambient) and RPM (personal) were collected to establish the correlation between them. The average 24-hour integrated exposure to RPM was 322 g/m3 and exceeded the corresponding PM10 level observed at the nearest Ambient Air Quality Monitoring Station by a factor of 2.25. The 90% confidence interval for this exposure is 283–368 g/m3. This study clearly demonstrates that the daily integrated exposure and therefore the health risk of outdoor workers in an urban area is significantly more serious than that indicated by ambient air quality data.     

ORGANIC MATTER DYNAMICS IN SMALL STREAMS OF THE PACIFIC NORTHWEST1

Small streams in forested landscapes are tightly coupled to the vegetation of the surrounding forest, and one of the key drivers of the stream ecosystem is the nature of organic matter supplied to it. This paper is focussed on three questions related to organic matter dynamics in small, forested streams of the conifer dominated Pacific Northwest: (1) How do small streams differ from large streams? (2) How do small streams of the Pacific Northwest differ from those of other regions? and (3) How do forest practices alter organic matter dynamics of small streams in the Pacific Northwest? The organic matter dynamics of small streams in this region differ from temperate deciduous forests in the nature of the organic matter deposited (protective chemicals, hard epidermis, slower loss rates), the timing of inputs (distributed throughout the year), and the transport rates (smaller, hard needles are more easily transported). The large amount and persistence of wood in these streams provides an additional source of organic matter that can be consumed by particular species and contributes to biofilm and fine particulate organic matter (FPOM) production. Logging is commonly practiced in many forests of the region. This practice has been shown to alter the type, amount, and timing of organic matter delivery to small streams and reduce the amount and size of large wood. Changes in channel complexity and water temperature after logging also can contribute to reduced organic matter storage. Many of the processes controlling organic matter dynamics in small streams are well described in other regions. However, the climate, vegetation, and topography of the Pacific Northwest suggest that the rates and nature of some processes affecting stream organic matter may differ considerably from other regions. Further research on small streams of this area will be required to better understand these differences.     

Source Apportionment in the Town of La Spezia (Italy) by Continuous Aerosol Sampling and PIXE Analysis

We describe the results of an aerosol sampling campaign performedin 1999 in the medium-size industrial town of La Spezia, in theNorthwest of Italy. We used two-stage continuous streakersamplers in three different sites and periods of the year. This kind of samplers allows the separation of the PM₁₀ andPM_2.2 fractions of the particulate matter. Moreover, the hourly resolution in the aerosol collection is particularly useful inan urban environment where, typically, many pollution sourceswith fast variations are present. Up to 1700 samples have beenanalysed by Particle Induced X-ray Emission (PIXE) at the INFNaccelerator facility in Florence, obtaining hourly concentrationfor about 20 elements from Na to Pb, with a sensitivity rangingfrom below 1 to about 10 ng m^-3. The total hourly aerosolmass has been estimated with an optical analysis of the samesamples performed (before the PIXE analysis) by an equipment designed and mounted in Genoa. An extensive statistical analysisof the data included standard and Absolute Principal ComponentFactor Analysis (PCFA and APCFA) to deduce the compositionand the weight of the major aerosol sources in both fractions.Thorough different statistical approaches, we generally resolvedcontributions from vehicle emission, fossil fuel combustion,soil-road dust and sea salt aerosol.     

Using urban man-made ponds to reconstruct a 150-year history of air pollution in northwest England

A regional pollution history has been reconstructed for the borough of Halton (northwest England) from four urban ponds in north Cheshire and south Merseyside, using environmental analyses of lake sediment stratigraphies. Mineral magnetism, geochemistry and radiometric dating have produced profiles of pollution characteristics dating from the mid-nineteenth century to present day. These pollution profiles reflect the atmospheric deposition of a range of pollutants over 150 years of intensified industry. Distinct phases of pollution deposition and characteristics are identified reflecting: (1) intensification of industry in the nineteenth century; (2) expansion of industry during the twentieth century; (3) post 1956 Clean Air Acts. This work promotes the potential use of these pollution archives for use in epidemiology to better understand links between human health and environmental pollution, especially for diseases with long latency times, where retrospective pollution exposure assessments are important.     

Assessment of heavy metals among suspended particulates and dissolved phases in Suez Canal water

The concentrations and distribution of particulate and dissolved heavy metals, viz: Cu, Zn, Pb, Cd, Fe and Mn have been determined seasonally during 2003 in water samples collected from the Suez Canal. The presented data clarifies that the metals exhibited clear differences in their distribution between particulate and dissolved forms. The concentrations of particulate metals viz: Zn, Pb, Cd, Fe and Mn were high as compared to the dissolved form. Dissolved copper showed the highest percentage of total copper rather than particulate. The particulate forms of Pb, Cd, Fe and Mn had always-higher concentrations than the dissolved forms during the course of study except at summer season. The northern part of the Suez Canal at Port Said showed mean concentrations of particulate and dissolved Cu = 1.43 and 2.10, Zn = 8.61 and 3.17, Pb = 1.72 and 1.23, Cd = 0.35 and 0.35, Fe = 23.49 and 15.83 and Mn = 2.09 and 1.82 μg/L. These high concentrations may be attributed to the high activities, particularly, loading and unloading operations at Port Said harbour, industrial effluents and domestic drainage of Port Said city. On the other hand, Sinai side could be considered as reference site, as it is almost clean without harmful outfalls, where Cu = 0.16 and 0.56, Zn = 2.14 and 0.94, Pb = 6.29 and 3.44, Cd = 0.055 and 0.088, Fe = 6.29 and 3.44 and Mn = 0.56 and 0.26 μg/L for particulate and dissolved metals respectively.     

长沙市冬季某商场建筑室内外细颗粒物浓度的实测与分析

对长沙市冬季某商场建筑室内餐饮区、化妆品区、鞋包区、服饰区和室外同步进行了细颗粒物(PM2.5)质量浓度的实测.分析了室内不同功能区、室外PM2.5质量浓度随时间的变化特征,并分析了温度、相对湿度、风速、大气压力对PM2.5质量浓度的影响.结果表明:室外PM2.5质量浓度高于室内;室内餐饮区PM2.5质量浓度最高,其次是化妆品区和服装区,鞋包区最低;室内人为活动和室外污染共同影响着室内颗粒物质量浓度;风速与PM2.5质量浓度相关性较弱,温度、相对湿度、大气压力与PM2.5质量浓度具有较强的相关性.     

清洁空气行动计划实施对长三角地区PM_(2.5)污染改善效果模拟评估

为了解长三角地区清洁空气行动计划实施后区域PM2.5的改善效果,在建立2012年长三角地区大气污染物排放清单的基础上,依据上海、江苏、浙江和安徽三省一市行动计划细则,对2013—2017年各省、直辖市主要大气污染物减排量进行测算.利用WRF(天气研究和预报模式)-CMAQ(通用多尺度空气质量模型)系统,模拟研究了清洁空气行动计划实施后可能带来的区域PM2.5改善效果.结果表明:清洁空气行动计划涉及到的能源、工业、交通等六大领域减排任务,按照减排力度强、中、弱3种方案测算,预计长三角地区SO2减排总量分别为74.5×104、53.8×104和34.4×104t;NOx减排总量分别为108.7×104、83.9×104和61.1×104t;一次PM2.5减排总量分别为40.3×104、26.1×104和14.6×104t;挥发性有机污染物(VOCs)的减排总量分别为98.2×104、57.0×104和23.5×104t.模拟评估结果表明,在弱、中、强3种减排方案下,长三角地区国控点ρ(PM2.5)年均值预计比基准年(2013年)分别降低(4.4±1.1)、(8.1±2.4)和(12.5±3.9)μg/m3,降幅分别达到8.7%±2.2%、15.9%±4.7%和24.3%±7.7%.长三角地区须在清洁空气行动计划实施细则指导下,控制新增量,并稳步严格推进前体物强力减排,才能实现2017年预期空气质量改善目标.     

昆明湖水体悬浮颗粒物与有色可溶性有机物光谱吸收特性研究

基于2011年9月23日在北京颐和园昆明湖测量的10个采样点的水体各组分吸收系数光谱,分析了秋季昆明湖悬浮颗粒物、非藻类颗粒物、藻类颗粒物及有色可溶性有机物(CDOM)的光谱吸收特性.结果表明,水体总吸收当中,藻类颗粒物贡献率最大,CDOM次之,非藻类颗粒物贡献率最低,这表明藻类颗粒物是秋季昆明湖水体中最主要的水体组分.秋季昆明湖南部藻类颗粒物吸收系数与叶绿素a浓度均大于北部,这可能是因为昆明湖水由北侧流入从南侧流出,且北京秋季盛行北风导致的.未发现CDOM与叶绿素a浓度间具有显著的相关关系,可能与藻类空间分布不均匀、并且受CDOM外源影响有关系.