城市机动车尾气中NOx污染的数学模式研究

对城市机动车尾气中NO_x污染物的产生、迁移、转化规律进行了数学分析,提出了城市机动车尾气污染物NO_x随时间和距离变化的数学模式,并运用该模型对长春市内车辆集中路口机动车污染物NO_x进行了模拟与预测。对实验所获得的监测结果与运用数学模式的计算结果进行比较可知：其平均偏差的绝对值小于0.02 mg/m³,相对误差的绝对值均小于0.32,因此城市机动车尾气污染物NO_x的数学模式符合研究区域的实际情况。     

Projected Changes in NO_x Emissions from Lightning as a Result of 2000–2050 Climate Change

Lightning is one of the most important natural sources of atmospheric NOx.The authors investigate the2000–2050 changes in NOx emissions from lightning using the global three-dimensional Goddard Earth Observing System chemical transport model(GEOS-Chem)driven by meteorological fields from the Goddard Institute for Space Studies(GISS)general circulation model(GCM)3.Projected changes in climate over 2000–2050are based on the Intergovernmental Panel on Climate Change(IPCC)A1B scenario.The global NOx emission from lightning is simulated to be 4.8 Tg N in present day and to increase by about 16.7%over 2000–2050 as a result of the future climate change.The largest present-day emissions and climate-induced changes are found in the upper troposphere in the tropics.Regionally in eastern China(20–55 N,98–125 E),NOx emissions from lighting is simulated to be 0.3 Tg N(6.3%of the global total emission)in present day and to increase by 26.7%over2000–2050.The simulated changes in NOx from lightening correspond well with the projected future changes in convective precipitation.     

Mixing Ratios and Photostationary State of NO and NO2 Observed During the POPCORN Field Campaign at a Rural Site in Germany

Ambient mixing ratios of NO, NO2, and O3 were determined together with the photolysis frequency of NO2, JNO2, at a rural, agricultural site in Germany. The data were collected during the POPCORN-campaign from August 1 to August 24, 1994, in a maize field 6 m above ground. The medians of the NO, NO2, and O3 mixing ratios between 10:00 and 14:00 UT were 0.25, 1.09, and 45 ppbv, respectively. The corresponding median of JNO2 was 6.0 · 10–3 s–1. NOx = NO + NO2 showed a strong diurnal variation with maximum mixing ratios at night, suggestive of a strong local surface source of NO, probably by microbial activity in the soil. The estimated average emission rate was 40 ng(N) m–2 s–1 of NOx, the major part of it probably in the form of NO. The available measurements allowed the estimation of the local NOx budget. At night the budget is almost closed and the measured NOx mixing ratios can be explained by the local source, local dry deposition of NO2, formation of NO3 and N2O5, and vertical exchange of air across the nocturnal inversion. During day-time, the local surface source of NO is not sufficient to explain the measured mixing ratios, and horizontal advection of NOx to the site must be included. The NO2/NO ratio during the morning und late afternoon is lower than predicted from the photostationary state owing to the local NO surface source, but is regulary higher during the hours around noon. For noon, August 10, 1994, the NO2/NO ratio was used to derive the momentary lower limit for the concentration of the peroxy-radicals of 2.2 · 109 cm–3 (86 pptv).     

The Tropospheric Gas-Phase Degradation of NH3 and Its Impact on the Formation of N2O and NOx

The gas-phase degradation of NH3 in the atmosphere still has many uncertainties. One of them is the possible isomerisation of NH2O to NHOH, as indicated by kinetic studies. Since NH2O is formed during the gas-phase oxidation of ammonia in the troposphere, this reaction can potentially influence the subsequent production of N2O and NOx. So far, the isomerisation has never been implemented into current chemical schemes describing the atmospheric gas-phase degradation of NH3 and its atmospheric relevance has never been assessed. The N2O yield from NH3 degradation is calculated to be in the range of 10–43 %. It depends on the NO2 and O3 concentrations, but is independent of the NH3 concentration. Compared with the results from recent literature, the N2O yield derived from the new mechanism is 20–80% lower, implying a smaller global N2O source strength of 0.4 Tg yr- 1. The production of NH2SO2 seems to be less important for the atmospheric degradation of NH3. NH3 oxidation is a sink for NOx at NOx mixing ratios of more than about 1 ppb and a source at lower NOx burdens.     

2007—2014年湖北省酸雨变化时空特征分析

本文利用湖北省32个监测站2007—2014年及宜昌、武汉站1990—2014年酸雨逐日监测资料,对湖北省酸雨变化情况进行分析,结果表明：湖北省年均降水pH值为4.68,属于弱酸雨等级;自2008年开始全省酸雨强度不断减弱,2007—2014年期间持续为弱酸雨等级,pH低值区主要位于三峡河谷地区及鄂西部分地区、鄂东南西部及南部;年均酸雨、强酸雨频率分别为69.5%、24.4%,酸雨频率呈波动下降趋势,强酸雨频率自2009年开始呈现明显减少趋势,酸雨频发区主要位于南部大部地区及鄂西北东部;年均电导率为50.3 μs·cm-1,主要呈现中部高、东西低的分布型;湖北省酸雨强度冬强夏弱,发生频率冬多夏少,电导率冬高夏低;武汉2005年以后酸雨强度趋于增加,2006—2012年持续为强酸雨,电导率呈增加趋势,宜昌酸雨强度、降水污染程度均高于武汉;另监测显示,湖北上空NO2含量分布范围呈现扩散加重趋势,武汉地区SO2呈减少趋势,NO2呈增加趋势,这种变化有可能导致湖北省酸雨类型逐渐从硫酸主导型向复合型转变。     

城市NOx 人体健康风险评估的GIS 应用研究

城市大气污染是人类目前及未来面临的主要健康威胁之一， 而随着交通的发展NOx 对 人体健康的影响越来越受到重视。基于GIS 技术进行健康风险评估的研究是目前城市环境健康 问题研究的热点。论文采用环境健康风险评估的基本框架( 浓度、暴露、剂量、效应4 个环节) ， 应 用GIS 栅格数据模型和域面分析技术构建城市空气质量健康风险空间量化评估模型， 模拟了主 要大气污染物NOx 的剂量—效应函数关系； 并根据污染物的分布进行城市局地尺度NOx 健康风 险评估。     

Dry deposition of reactive nitrogen to marine environments: recent advances and remaining uncertainties

Many highly productive marine ecosystems exhibit nitrogen limitation or co-limitation. This article is a status review of research into the exchange of nitrogen between the atmosphere and these ecosystems with a particular focus on reactive nitrogen compounds. A summary of research conducted over the past ten years is presented and a perspective given as to remaining uncertainities and research needs. Looking toward development of coastal management modeling tools, we illustrate the processes that need to be resolved in order to accurately simulate the flux from the atmosphere and provide guidance on the required resolution of such models.     

地面臭氧的变化规律和计算方法的初步研究Ⅰ.紫外波段

通过对广州鼎湖山近地面O3、NOx、太阳辐射、气象参数等项目的观测和理论分析,研究了地面O3与NOx等微量气体及太阳辐射的变化规律,详细讨论了紫外波段、不同天气条件地面O3与NOx,光化学反应、气溶胶、光化辐射等之间复杂的关系.用光能量传输与守恒的观点来考虑大气中与紫外辐射有关的主要过程,并以此来研究大气光化学过程中所遵循的能量规律,建立了一个简单、实用、省时的统计模式,用于计算地面O3浓度.结果表明,不同情况下计算值与观测值均吻合较好.     

潮州市区臭氧污染变化特征及与影响因子关系分析

基于2014—2020年潮州市区空气质量监测数据和气象观测数据,应用统计分析、聚类分析等方法,分析了O₃浓度的时间变化特征,及其与NOx浓度、气象因子的关系。结果表明：潮州市区O₃污染有改善趋势,但是浓度下降速度较缓慢;呈双峰型的月变化特征,主峰在10月份;污染强度呈春季高于秋季的趋势;日变化呈单峰变化,07时出现最低值,随后迅速上升,最大值出现在午后15时,之后浓度又逐渐降低。NO₂、NOx浓度与O₃浓度变化呈反位相关系,早晨峰值比O₃浓度低谷时间推迟1 h;下午低谷比O₃的峰值提前1 h。潮州市区在最高气温>25℃、无降水、光照充足(>8 h)、相对湿度<80%、风速为1.5～2.0 m/s,吹偏西风和偏东风时发生O₃污染的几率较大。O₃超标出现在中午到上半夜,中度以上污染出现在下午。上午时段日出后的日照及积温是影响O₃浓度增长的主要气象因子,到下午时段,日出后的日照和...