污染源、干沉降和气相化学影响硫沉降的数值研究

利用欧拉型区域硫沉降模式对污染源、干沉降和气相化学等物理化学过程在酸沉降中的作用进行了数值分析。结果表明:排放源的强度和高度影响着污染物的分布和输送,其影响是非线性的。在区域酸沉降模式中,干沉降速度和气相化学转化率简单地取为常数对SO#-[2]及SO#+[2-]#-[4]浓度分布引起的误差是不可忽视的。     

欧拉型区域硫沉降模式研究

建立了一个三维硫沉降欧拉模式，模式中比较全面地考虑了硫沉降过程中的物理、化学机制。包括平流、扩散、干湿沉降和积云的垂直输送作用等物理过程，气相化学、液相化学和气溶胶表面的非均相化学等化学过程。其中非均相化学和积云的垂直输送参数化在国内外同类模式中尚不多见。模式结果与实测及其他模式结果的对比表明，该模式能够较好地模拟出SO2的水平和垂直分布及SO2-4在降水中的浓度。     

关于我国和东亚酸性物质的输送研究 I. 三维欧拉污染物输送实用模式

本文发展了一种三维欧拉型污染物长距离输送实用模式，比较详细地考虑了源、输送、干、湿沉降、气、液相化学过程。用分裂解法对气相化学过程进行查表式处理，颇具特色，使用实测气象输入场，节约了大量的计算机资源。通过模式的灵敏度试验，模式具有较高的分辨率和灵敏度。根据与实测资料对比，模式有较好的可信度，能方便的计算长时间（月、季、年）的污染物沉降及远距离输送态势。     

关于我国和东亚酸性物质的输送研究：Ⅰ.三维欧拉污染物输送实用模式

本文发展了一种三维欧拉型污染物距离输送实用模式，比较详细地考虑了源、输送、干、湿沉降、气、液相化学过程。用分裂解法气相化学过程者查表式处理，颅具特色，使用实测气象输入场，节约了大量的计算机资源，通过模式的灵敏度试验，模式具有较高的分辨率和灵敏度，根据与实测资料对比，模式有较好的可信度，能方便的计算长时间（月，季，年）的污染物沉降及远距离输送态势。     

大气污染物SOx输送方程的尺度分析

文中用量纲分析方法分析了控制大气污染物输送方程的动力学特性。提出了 6种反映大气污染物输送过程中各种动力、物理和化学过程相对重要性的动力学参数。并以硫氧化物为例进行了各参数量级大小分析 ,尤其对 3种起汇作用 (去除机理 )的机理 (化学转化、干沉降和湿清除 )在不同尺度大气污染过程中的作用进行了详细分析。结果表明 :在一般情况下 ,SO2 的气相化学作用小于干沉降和湿清除的作用 ;干沉降作用很依赖于模式最底层厚度的选取 ;在有降雨时湿清除作用一般较大。文中还对大气污染物SOx 输送方程各项特征量的量级作了分析对比 ,得出了控制不同尺度大气污染物输送过程的零级近似方程和一级近似方程 ,并指出了这些方程的基本特征     

一个SO2气相化学模式及其敏感性分析

气相化学过程是硫沉降过程中的重要过程。气相化学反应既是ＳＯ２气体的氧化去除过程,也为液相化学过程提供初值条件。首先建立了一个适合于研究硫沉降过程的气相化学数值模式,模式包括了５２个方程、３１个物种。然后利用这个气相化学模式探讨了ＳＯ２的气相氧化过程对大气温度、湿度、太阳光强等条件的敏感性并给出了ＳＯ２气相氧化率的日变化。     

积云对二氧化硫和硫酸盐气溶胶作用的研究

利用一个冰雹云模式与云化学模式耦合而成的二维积云化学模式,研究对流云的输送、微物理转化、云内化学过程、湿清除对SO2及硫酸盐气溶胶的作用。云化学模式的结果表明,由于SO2在向上输送的过程中可溶解于云水和雨水中,从而阻止了SO2向上部的转移,因此对气相SO2来说,云的输送是一个相当无效的过程,而液相清除起主要作用。硫酸盐气溶胶的收支分析表明,降水清除了1.67 mol的SO2-4,占气溶胶总量的64%,其中液态降水清除了0.72 mol,固态降水清除了0.95 mol,说明了冰相过程在硫沉降中的重要性。     

中国地区硫酸盐气溶胶的分布特征

建立了一个三维欧拉型排放/输送/转化/沉降模式,其主要特点是采用独立的气相化学子模式计算各种不同条件下SO2的转化速率,建立转化率的数据库,直接为欧拉模式调用,并对液相化学和湿清除过程进行了参数化处理。这样使模式既考虑了大气化学过程的非线性,又具有较高的计算效率,能够方便地计算年（季）尺度的硫酸盐气溶胶SO2-4的浓度分布。利用中尺度气象模式MM4和欧拉输送模式模拟了中国地区硫酸盐气溶胶的时空分布,其结果可以方便地应用到考虑硫酸盐气溶胶气候效应的气候模式中去。     

区域酸沉降模式

本文提出一个区域的欧拉酸雨模式,包括了大气中污染物质的输送、扩散、非线性化学转化和干湿沉降等物理和化学过程.气相化学反应有18种化学物质,包含了二氧化硫气相氧化的主要化学方程.液相氧化反应包含了H_2O_2,O_3及催化剂对二氧化硫的氧化过程.水平方向有35×35个网格点,垂直方向分15层.选用了四川、贵州地区1988年的8次降水过程对模式作了检验,结果证明模式能较好地模拟这个地区的二氧化硫、硫酸根及降水pH的分布状况.     

修正的拉格朗日K模式敏感性分析

本文分析修正的拉格朗日Ｋ模式分别对于混合层高度、风速、化学转化率、湿沉积清除速率、沉积速率、地面粗糙度、温度垂直递减率等参数的敏感性，得出的结果有利于保证对敏感因子的资料搜集和参数化方案的合理设计。     

华东典型地区大气硫沉降通量的观测和模拟研究

本文使用中国科学院常熟和鹰潭生态实验站和气象站的观测资料，应用区域酸沉降模式系统（RegADMS）和大叶阻力相似模型来研究华东地区不同下垫面条件上的大气硫沉降问题，定量估计了农田下垫面上大气硫化物的沉降通量。SO2和硫酸盐的干沉降速率使用大叶阻力相似模型来估计，使用与降水量有关的参数化方案来确定湿沉降系数。结果表明，常熟地区农田下垫面的大气硫沉降通量为19．0gm^-2 a^-1，其中干沉降占42％；而位于江西红壤地区的鹰潭站的大气硫沉降通量为10．4gm^-2a^-1，其中干沉降占83％。比较发现，两地硫干沉降通量绝对值相差不大，但其在总沉降通量中所占的份额有较大差异；常熟站的硫湿沉降通量比鹰潭站要大9．23gm^-2a^-1，该差异是由两地污染状况和气象条件的不同造成。华东地区的年硫沉降总量为1．88Mt（1Mt=10^6t），其中72．8％沉降在农田下垫面上。硫沉降中43％是干沉降，57％是湿沉降。     

Wet deposition of sulfate in the Inland Sea region of Japan

Precipitation chemistry data derived from a sampling network operated in the Inland Sea model region (June 1984–May 1985) are used as a basis for discussing the wet deposition of sulfate on a regional scale in Japan. Horizontal distribution, seasonal variation, relationship between wet deposition and precipitation amount, sulfate/nitrate ratio, and transport of sulfate from the ocean are discussed. Temporal trends in concentrations of atmospheric sulfur compounds and sulfate wet deposition in the model region are also covered.     

An evaluation of the ADOM cloud module

Abstract

The Acid Deposition and Oxidant Model (ADOM) is an Eulerian long‐range transport and deposition model. One of the most highly parametrized and least well established parts of the model is the scavenging module that describes cloud formation, pollutant scavenging, aqueous‐phase chemistry and wet deposition. As a means of gaining insight into the scavenging module, results from simulations with the module are compared with the results from simulations for equivalent conditions with a three‐dimensional dynamic cloud chemistry model.

Comparisons of results for a variety of initial conditions show that wet deposition of sulphate, nitrate and ammonium ions tend to be underpredicted by the scavenging module and that the pH of the rain is overpredicted. Although the differences are for the most part not large, they are sensitive to cloud top height. The amount of hydrogen peroxide deposited at the surface is significantly smaller in the ADOM module than in the cloud chemistry model. For the particular conditions that are considered, oxidation is limited by the hydrogen peroxide concentration for the cloud chemistry model, but by the sulphur dioxide concentration for the ADOM module.     

NUMERICAL MODELING OF AIR POLLUTANT AND RAINFALL EFFECT ON ACID WET DEPOSITION

It is helpful to go deep into understanding the acid rainfall through studying the relation of two centers between aciddeposition and rainfall and the relation of intensity between them.We adopt a three-dimensional Eulerian regional aciddeposition model,or NCAR-RADM,to calculate regional chemical concentrations and dry and wet depositions ofacids.The temporally and spatially varied meteorological field is provided by a mesoscale meteorological model,vertion4.We calculate dry and wet depositions of acids in eight kinds of different rainfall distributions.The results show thatthe wet depositions of acids near pollutant source is very sensitive to rainfall intensity in initial stage.The distribution ofacid wet deposition will tend to that of rainfall intensity when rainfall intensity is small in source.And it will tend to thatof initial pollutant concentration when rainfall intensity is large in source.     

Rainwater Chemistry and Wet Deposition over the Wet Savanna Ecosystem of Lamto (Côte d'Ivoire)

From the IGAC-DEBITS Africa network (IDAF), data sets on precipitation chemistry collected from the ‘wet savanna ecosystem’ site of Lamto (Côte d'Ivoire), are analyzed (1995–2002). Inorganic (Ca^{2 +}, Mg^{2 +}, Na⁺, K⁺, NH₄ ⁺, Cl^?, SO₄ ^{2 ?}, NO₃ ^?) and organic (HCOO^?, CH₃COO^?) ions content were determined using Ion Chromatography. The analyzed 631 rainfall events represent 8420.9 mm of rainfall from a 9631.1 mm total. The precipitation chemistry at Lamto is influenced by four main sources: natural biogenic emissions from savanna soils (NO _x and NH₃), biomass burning (savanna and domestic fires), terrigeneous particles emissions from dry savanna soils, and marine compounds embedded in the summer monsoon. The inter-annual variability of the weighted volume mean concentration of chemical species linked with wet deposition fluctuates by ～ 20% over the period. Ammonium concentration is found to be the highest (17.6 μ eq.l^{? 1}) from all IDAF sites belonging to the West Africa ecosystems. Ammonia sources are from domestic animals, fertilizers and biomass burning. In spite of the high potential acidity of 30.5 μ eq.l^{? 1} from NO₃ ^?, SO₄ ^{2 ?}, HCOO^? and CH₃COO^?, a relatively weak acidity is measured: 6.9 μ eq.l^{? 1}. The 40% acid neutralization is explained by the acid gas – alkaline soil particles interaction. The remaining neutralization is from inclusion of gaseous ammonia. When results from Lamto, are compared with those from Banizoumbou (dry savanna) and Zoetele (equatorial forest), a regional view for wet tropospheric chemistry processes is obtained. The high concentration of the particulate phase in precipitation emphasizes the importance of multiphases processes between gases and particles in the atmospheric chemistry of the West Africa ecosystems. For example, the nss Ca^{2 +} precipitation content, main indicator of terrigeneous particles, goes from 30.8 μ eq.l^{? 1} in dry savanna to 9.2 μ eq.l^{? 1} at Lamto and 8.9 μ eq.l^{? 1} in the Cameroon forest. A similar gradient is obtained for rainfall mineral particles precipitation content with contribution of 80% in dry savanna, 40% in wet savanna, and 20% in the equatorial forest.     

Determination of Sulfur Balance Between the Atmosphere and a Norway Spruce Forest Ecosystem: Comparison of Gradient Dry + Wet and Throughfall Deposition Measurements

Total sulfur deposition was determined above a Norway spruce forest, in Hungary. Two methods were applied, on one hand dry + wet deposition measurements and on the other, throughfall and stemflow deposition estimations have been carried out. Results show: total depositions are 3.3 and 3.2 g S m^–2 yr^–1 determined by dry + wet and throughfall deposition methods, respectively. The share of the dry deposition in the total S-load is 73%. The agreement between the results of the two different methods is good and suggests the needlessness of complicated dry + wet flux measurements, i.e. the total and dry deposition of sulfur compounds to forests can be determined by simple throughfall and wet deposition measurements.