气象因子对臭氧的影响及其在空气质量预报中的应用

为提高重庆市臭氧(O_3)预报准确率,利用2013—2015年5—10月O_3监测数据和气象数据,通过主成分分析、逐步回归分析等方法,确定了影响重庆O_3浓度的主要气象因素为最高温度、温差、太阳辐射、降水量、相对湿度、水气压和压差;通过基于O_3污染水平相似的主要气象控制因子筛选和最优组合的预报结果优化方法,提高了O_3预报准确率,使2016年5—8月O_3的AQI类别预报准确率由57.7%增至72.4%,O_3超标的预报准确率由38%增至46%。     

Seasonal Differences in the Levels of Gaseous Air Pollutants in the Vicinity of a Waste Dump

Hydrogen sulphide, ammonia, nitrogen dioxide, mercaptans and sulphur dioxide (H₂S, NH₃, NO₂, R-SH, SO₂) concentrations were measured at the location in the vicinity of the waste dump to determine the air pollution level of these pollutants prior to the operation of the Mobile Thermal Treatment Plant. Samples were collected over one year period. Seasonal differences, and the influence of meteorological parameters (temperature, relative humidity, pressure and wind direction) on the air pollution levels were studied. Results show relatively low concentrations of H₂S, NO₂, R-SH and SO₂, while NH₃ levels were higher compared to the guideline values. Good weather conditions (high air pressure and low relative humidity) are connected to long range transport of NO₂, while higher temperatures result in elevated NH₃ and R-SH concentrations. Because of the predominant northeast wind direction (the same as the waste dump direction), the contribution of air pollution from the direction of the waste dump at the measuring site is significant, but that does not necessarily mean that the pollutants originated from that source.     

华东森林及高山背景区域SO2、NOx、CO本底特征

国家大气背景监测福建武夷山站是中国华东区域背景站点之一,可代表华东森林及高山区域背景状况。为了解该区域的大气背景状况,评估区域污染现状以及污染物输送在区域污染中的作用,选取福建武夷山背景站2011年3月至2012年2月主要气体污染物（SO₂、NO_x、CO）为期1年的监测数据,研究各污染物在不同时间尺度的浓度变化特征和相关关系,以及与气象因子的相关关系,并利用后向轨迹模式探讨区域输送对华东森林及高山背景区域各气体污染物质量浓度的影响。结果表明,武夷山背景点监测期间SO₂、NO_x、CO的平均质量浓度分别为3.9、5.1、409.8 μg/m³,且具有明显的季节变化特征,春、冬季明显高于夏、秋季;三者日变化幅度均很小,呈现出单谷型分布型态,说明武夷山背景点受人为活动的影响很小,主要受气象条件影响;相关性分析结果显示,SO₂与NO_x浓度相关性较好,与湿度有较好的负相关,与风速在冬季具有一定的正相关,NO_x与CO浓度在秋季和冬季的相关性较好,且二者与温度的负相关性较好。后向轨迹分析结果表明,SO₂全年最大浓度峰值主要来自北方采暖季燃煤排放的远距离输送影响,NO_x、CO全年最大值则源于生物质燃烧的远距离输送影响。     

广州PM2.5污染特征及影响因素分析

对广州市2008—2010年PM_2.5质量浓度、影响因素数据资料进行整理统计,通过定性分析、定量计算以及对各物理量之间的相互作用过程研究,得出PM_2.5质量浓度变化特征和各影响因素之间的关系。结果表明,PM_2.5质量浓度变化呈现夏季和非夏季2种典型的季节性特征,夏季月平均值0.049 mg/m³,主要分布在0.03～0.05 mg/m³,非夏季月均值为0.063 mg/m³,分布于0.05～0.08 mg/m³之间;夏季、非夏季PM_2.5质量浓度超标率(采用美国EPA标准)分别为70.7%、77.8%,质量标准2倍、3倍以上出现的概率都表现出明显的季节性差异;PM_2.5与温度正相关,和其他因素负相关,其中与能见度相关性最大,其次是温度、风速,与降雨量相关性最差,与气压、相对湿度相关系数季节性特征显著。     

兰州市气象要素对大气质量影响力的模拟分析

为了弄清气象要素对大气质量的影响以及大气污染反弹的原因,通过对兰州市冬春之际气象要素对大气质量影响力的模拟分析,建立了气象要素与大气质量间的模拟模型,并应用该模型对兰州市大气污染指数进行预测分析。结果表明,该模型计算精度高,预测结果真实可信,方法可行性好,可用来模拟分析兰州市冬春之际空气污染的成因和动态变化。     

苏州市区灰霾现象形成的气象条件分析

随着社会和经济的快速发展,灰霾现象的发生有逐渐上升趋势,严重影响城市形象和群众的身心健康。苏州市的灰霾现象发生频率1—2月最高,7—8月最低。通过寻找形成灰霾现象的主要气象控制因子,有助于判别不同气象条件在灰霾天气形成中的作用。采用基于因子分析的主成分提取方法,将6个气象因子观测资料整合为3个主成分,并逐一揭示4个典型季节各主成分的支配因子在灰霾天气形成中的作用。结果表明,热量条件是影响1—2月、4—5月和7—8月霾日形成的主要气象条件。动力条件是10—11月霾日形成的主要气象条件,水分条件影响相对较弱,仅起辅助作用。     

2015—2019年保定市O3变化及其周边源区分析

利用保定市2015—2019年近地面O₃和气象观测数据,统计分析了该地区O₃变化特征及其与地面气温、相对湿度、风速和风向的关系,并确定了O₃的周边源区.结果表明,2015—2019年保定市O₃污染呈加重趋势,O₃污染超标天数从2015年的63 d增加至2019年的95 d.由于秋冬季昼夜温差较大,导致其O₃日变化相对扰动高于春夏季节.O₃浓度与近地面气温呈非线性正相关关系,随相对湿度(RH)的增加呈阶段性的先增后减的变化趋势,其中当RH为40%～50%时,O₃浓度及其污染超标率均达到最大.此外,风场对O₃分布有重要影响,盛行偏南风时易发生O₃重污染,表明影响该地区O₃污染源区主要位于保定南部.潜在源贡献因子分析方法(PSCF)和浓度权重轨迹分析法(CWT)的分析结果表明,保定市春夏O₃源区分布范围最大,其中贡献高值区主要分布在...     

气象因素对输变电线路电磁环境的影响

不考虑气象因素的输变电线路的电磁环境预测值与实际值之间有差距,探讨了温度、湿度、风等气象因素对输变电线路电磁环境的影响,并提出减缓措施。结果表明:温度上升,则电磁场强度及无线电干扰强度都会增强;高相对湿度下电磁场强度与湿度成正比,低湿度则无明显影响,湿度对无线电干扰的影响与线路电压有关;风使输电线发生偏移,改变空间电磁场强度。     

Nutritionally relevant elements in staple foods: influence of arable site versus choice of variety

Eighteen representative sites for the Austrian grain-growing and eight for the potato-growing zones (soils and crops) were investigated. On each site, total element contents (B, Ba, Ca, Cd, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, P, Sr and Zn) were determined in 4–12 varieties of winter wheat (n = 136), 6 varieties of spring durum wheat (n = 30), 5 varieties of winter durum wheat (n = 15), 7 varieties of rye (n = 49), 5 varieties of spring barley (n = 30) and 5 varieties of potatoes (n = 40). Element accumulations in grain species and potato tubers varied significantly with site conditions, with the main exceptions for B in potatoes and wheat as well as for Zn, Cu and Co in durum wheat. On average, across all investigated sites, differences in varieties occurred concerning the elements Ca, Cd, Ba, Sr and Zn (except Zn in potatoes and winter durum). A rough estimation revealed that an average Austrian consumer of wheat, rye and potatoes meets more than 50% of the needs of daily element intake for K, P and Mg, between 36 and 72% for Fe, Zn and Cu, and more than 100% for Co, Mo and Mn. In particular, the elements Ca and Na have to be added from other sources.     

MODEL FOR PREDICTING TRANSPORT OF PESTICIDES AND THEIR METABOLITES IN THE UNSATURATED ZONE1

ABSTRACT: A finite element model based on Galerkin's upstream weighted residual technique was developed to predict the simultaneous convective-dispersion transport and transformations of pesticides and their metabolites in the unsaturated zone. Transformations of the parent compound and its metabolites were assumed to be first-order reactions for oxidation and hydrolysis, while adsorption of the pesticide species (parent compound and metabolites) to the soil components was assumed to be represented by a linear equilibrium (Freundlich type) isotherm. Volatilization and plant root uptake of pesticides in the solution phase were neglected in the analysis. The proposed model was used to simulate the transport and transformation of aldicarb and its metabolites, aldicarb sulfoxide and aldicarb sulfone, in the soil profile. Several examples are used to demonstrate the accuracy, validity, and applicability of the proposed model. Simulated results indicate that the proposed model can potentially be used to estimate the mass flux of water, and pesticide and pesticide metabolite concentrations in the subsurface environment. However, further verification of the model against actual field data is needed to fully demonstrate the model's potential.