冬季北京城区大气重污染特征分析

为研究北京市城区大气重污染特征,对2013年12月~2014年2月期间北京市6次大气重污染过程的PM2.5浓度水平、化学组成以及大气氧化性和气象要素特征进行了分析。结果表明,重污染日PM2.5平均质量浓度达到265.0μg/m3,是非重污染日的3.5倍。 PM2.5组分中NO3-,SO42-,NH4+和有机碳(OC)在重污染日的平均浓度分别是非重污染日的6.8,3.4,2.7和2.6倍。前3次过程中SO42-浓度最高,后3次过程中SO42-浓度与NO3-浓度接近。从气象要素来看,重污染期间的基本特征为地面温度升高、相对湿度增大、地面气压降低和风速减小。重污染日的能见度显著降低,平均能见度仅为非重污染日的34.4%。重污染日的大气氧化性明显增强,大气氧化剂OX平均浓度是非重污染日的1.5倍,(OC)/(EC)平均比值是非重污染日的1.6倍。     

我国主要污染物排放强度区域特征分析研究

文章以我国2012年化学需氧量、氨氮、二氧化硫、氮氧化物、烟粉尘和工业固体废物等6种主要污染物的综合排放量与工业排放量数据为依据,应用层次分析赋权方法,测算了不同省份的综合污染值,对我国的污染物综合排放情况进行了评价分析。并与2005年相关研究成果进行了对比分析,找出了我国在污染物排放、治理方面取得的成果与存在的问题,针对我国不同区域的地域、经济、产业等特征要素提出了相应的政策建议。     

Origin of high particle number concentrations reaching the St. Louis, Midwest Supersite

Ultrafine particles are associated with adverse health effects. Total Particle Number Concentration (TNC) of fine particles were measured during 2002 at the St. Louis — Midwest supersite. The time series showed overall low level with frequent large peaks. The time series was analyzed alongside criteria pollutant measurements and meteorological observations. Multiple regression analysis was used to identify further contributing factors and to determine the association of different pollutants with TNC levels. This showed the strong contribution of sulfur dioxide (SO₂) and nitrogen oxides (NO_x) to high TNC levels. The analysis also suggested that increased dispersion resulting from faster winds and higher mixing heights led to higher TNC levels. Overall, the results show that there were intense particle nucleation events in a SO₂ rich plume reaching the site which contributed around 29% of TNC. A further 40% was associated with primary emissions from mobile sources. By separating the remaining TNC by time of day and clear sky conditions, we suggest that most likely 8% of TNC are due to regional nucleation events and 23% are associated with the general urban background.     

Application of the “Climafor” baseline to determine leakage: the case of Scolel Té

The acceptance of forestry-based project activities to mitigate greenhouse gases emissions has been subjected to a number of methodological questions to be answered, of which the most challenging are baseline establishment and identification of and measuring leakage. Here we pose hypotheses for and quantify leakage of the Scolel Té project in Chiapas, Mexico. In this project small-scale farmers are implementing forestry, agroforestry, and forest conservation activities, with carbon sequestration as one of the goals. The main leakage monitoring domain is defined as the area owned by the participating farmers or communities outside the area where the specific project activities take place. The null-hypothesis (no leakage) is that non-project land owned by the farmer or community will experience the same carbon stock changes as predicted by the regional baseline, specifically developed for the project. First we assessed the most likely causes and sources of leakage that may occur in the project. From this analysis, one type of leakage seems to be important, i.e., activity shifting. Second we estimated the leakage of a sample of participating farmers and communities. Actual land use was then compared with expected land use derived from the baseline. The Plan Vivo of each participant, complemented with readily available tools to identify the main sources and drivers of leakage are used to develop simple leakage assessment procedures, as demonstrated in this paper. Negative leakage was estimated to be negligible in this study. Incorporating these procedures already in the project planning stage will reduce the uncertainties related to the actual carbon mitigation potential of any forestry project.

中国南极长城站室内空气微生物状况

空气微生物是空气洁净程度的重要指标、环境污染状况的真实反映[1] .十年来 ,位于南极半岛的中国长城站常年有考察队员居住和工作 ,尤其在南极之夏 ,不时有各国考察、旅游、观光者出入 .这些都给长城站空气微生物的变化带入了外来因素[2 ] .我们于 1994年 2月 ,随机对站上 19个室内测点作空气微生物考察 ,以监测和比较室内空气微生物含量状况 ,为进一步了解空气微生物的卫生学意义 ,并服务于提高南极考察队员的身体素质 ,加深对南极生态系统的理解而提供一些资料 .1　材料与方法1 .1　测点1994年 2月份分 6天对 19个室内空间作了 2 0次测定 …     

Quantification of land use/land cover changes in Pearl River Delta and its impact on regional climate in summer using numerical modeling

This study quantified land use/land cover (LULC) changes in Pearl River Delta (PRD) of South China and its impact on regional climate over the last two decades. The LULC change analyses were accomplished by applying a change detection method to a set of Landsat imagery and ancillary data acquired from 1970s to 2000. The results indicate that the urban expansion is the prevailing LULC change in the PRD. Impact of LULC change on regional climate was simulated by using a mesoscale climate model. Two different land cover datasets circa 1990 and 2000 were input to the model to investigate the impact of urbanization on regional weather and climate condition in summer 2005. The simulation results show that rapid urban expansion can substantially alter regional climate conditions in the PRD region including monthly mean temperature, precipitation, moisture, and surface heat fluxes.     

Atmospheric mercury concentrations and speciation measured from 2004 to 2007 in Reno, Nevada, USA

Atmospheric elemental, reactive and particulate mercury (Hg) concentrations were measured north of downtown Reno, Nevada, USA from November 2004 to November 2007. Three-year mean and median concentrations for gaseous elemental Hg (Hg⁰) were 1.6 and 1.5 ng m⁻³ (respectively), similar to global mean Hg⁰ concentrations. The three-year mean reactive gaseous Hg (RGM) concentration (26 pg m⁻³) was higher than values reported for rural sites across the western United States. Well defined seasonal and daily patterns in Hg⁰ and RGM concentrations were observed, with the highest Hg⁰ concentrations measured in winter and early morning, and RGM concentrations being greatest in the summer and mid-afternoon. Elevated Hg⁰ concentrations in winter were associated with periods of cold, stagnant air; while a regularly observed early morning increase in concentration was due to local source and surface emissions. The observed afternoon increase and high summer values of RGM can be explained by in situ oxidation of gaseous Hg⁰ or mixing of RGM derived from the free troposphere to the surface. Because both of these processes are correlated with the same environmental conditions it is difficult to assess their overall contribution to the observed trends.     

Natural and anthropogenic radionuclides in airborne particulate samples collected in Barcelona (Spain)

Results for naturally occurring ⁷Be, ²¹⁰Pb, ⁴⁰K, ²¹⁴Bi, ²¹⁴Pb, ²¹²Pb, ²²⁸Ac and ²⁰⁸Tl and anthropogenic ¹³⁷Cs in airborne particulate matter in the Barcelona area during the period from January 2001 to December 2005 are presented and discussed. The ²¹²Pb and ²⁰⁸Tl, ²¹⁴Bi and ²¹⁴Pb, ⁷Be and ²¹⁰Pb radionuclide levels showed a significant correlation with each other, with correlation coefficients of 0.99, 0.78 and 0.69, respectively, suggesting similar origin/behaviour of these radionuclides in the air. Caessium-137 and Potassium-40 were transported to the air as resuspended particle from the soil. The ⁷Be and ²¹⁰Pb concentrations showed similar seasonal variations, with a tendency for maximum concentrations during the summer months. An inverse relationship was observed between the ⁷Be, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs concentrations and weekly rainfall, indicating washout of atmospheric aerosols carrying these radionuclides.     

The Bulgarian Emergency Response System for dose assessment in the early stage of accidental releases to the atmosphere

The Bulgarian Emergency Response System (BERS) is being developed in the Bulgarian National Institute of Meteorology and Hydrology since 1994. BERS is based on numerical weather forecast meteorological information and a numerical long-range dispersion model accounting for the transport, dispersion, chemical and radioactive transformations of pollutants. In the present paper, the further development of this system for a mixture of radioactive gaseous and aerosol pollutants is described. The basic module for the BERS, the numerical dispersion model EMAP, is upgraded with a “dose calculation block”. Two scenarios for hypothetical accidental atmospheric releases from two NPPs, one in Western, and the other in Eastern Europe, are numerically simulated. The effective doses from external irradiation, from air submersion and ground shinning, effective dose from inhalation and absorbed dose by thyroid gland formed by 37 different radionuclides, significant for the early stage of a nuclear accident, are calculated as dose fields for both case studies and discussed.