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中国农作物秸秆燃烧排放气态、颗粒态污染物排放特征的实验室模拟

A Laboratory Study on Emission Characteristics of Gaseous and Particulate Pollutants Emitted from Agricultural Crop Residue Burning in China

【作者】 张鹤丰

【导师】 陈建民;

【作者基本信息】 复旦大学 , 环境科学, 2009, 博士

【摘要】 生物质燃烧排放的大量气溶胶(气体和颗粒物组分),其对全球大气环境、全球气候系统及生态系统的改变都会产生重要的影响。中国是一个农业大国,农作物秸秆资源拥有量居世界首位。有研究表明在中国农作物秸秆燃烧对生物质燃烧排放的气态污染物、颗粒物污染物贡献最多。本论文针对农作物秸秆燃烧排放气溶胶已经成为我国区域环境和气候影响的重要因素,而且其对我国区域环境和气候的影响方式和影响程度还在不断的变化。很显然,目前要解决农作物秸秆燃烧排放的气溶胶所造成的区域环境效应和气候效应这一难题,须从实验室模拟研究农作物秸秆燃烧排放气溶胶的排放特征开始。基于上述思路,我们自行设计建造了可以模拟农家灶台和田间露天燃烧的燃烧炉,借助于大型气溶胶烟雾箱和先进的表征测量系统手段,深入研究了中国三大主要农作物秸秆-水稻秸秆、小麦秸秆和玉米秸秆-燃烧排放的气态污染物、新鲜颗粒物的排放特征以及排放的新鲜颗粒物的粒径分布特征和粒径成长特征,还分析考察了气体和颗粒物中的多环芳烃和烷基多环芳烃的排放特征。本论文主要包括三大主要部分。第一部分为通过对中国三大农作物秸秆-水稻、玉米和小麦秸秆-进行燃烧实验得到了燃烧排放的气态污染物(CO、CO2、NOx)的排放因子,排放比和燃烧效率。水稻、小麦和玉米秸秆在明火充分燃烧的条件下,气态污染物CO的排放因子分别为64.2,141.2和114.7 gkg-1;CO2排放因子分别为791.3,1557.9和1261.5 g kg-1;NOx排放因子分别为1.81,1.12和1.28 g kg-1。水稻、小麦和玉米秸秆燃烧排放的CO相对于CO2的排放比ERCO/CO2分别为0.081,0.091和0.091,NOx相对于CO2的排放比ERNOx/CO2分别为0.0019,0.0007和0.0010;水稻、小麦和玉米秸秆燃烧所得的改性燃烧效率MCE分别为0.93,0.92和0.92。并且研究确定了中国2004年三种农作物秸秆燃烧排放的气态污染物(CO、CO2、NOx)的排放清单和排放强度地理分布特征。中国2004年因三种农作物秸秆燃烧排放的气态污染物CO,CO2和NOx总量分别为2.3×107,2.5×108和2.8×105t左右。三种气态污染物(一氧化碳、二氧化碳和氮氧化物)排放强度最高的省份分别是山东省、河南省和江苏省。第二部分为通过对中国三大农作物秸秆-水稻、玉米和小麦秸秆-进行燃烧实验得到了燃烧排放的颗粒物的粒径分布特征和粒径成长特征。农作物秸秆燃烧排放的颗粒物的粒径分布呈现出单峰对数正态拟合分布特征,小麦秸秆燃烧排放的颗粒物的初始个数浓度粒径峰值出现在47 nm附近,而水稻和玉米秸秆燃烧排放的颗粒物的初始个数浓度粒径峰值分别出现在102 nm,155 nm附近。在粒径成长过程中考察了粒径成长速率。在4小时老化过程中,水稻秸秆燃烧排放的颗粒物平均成长速率为40 nm h-1,玉米秸秆燃烧排放的颗粒物平均成长速率为38 nm h-1,小麦秸秆燃烧排放的颗粒物平均成长速率为26 nm h-1。此外,还得到了三种农作物秸秆燃烧排放的颗粒物的数目排放因子和质量排放因子,水稻、小麦和玉米秸秆燃烧排放的颗粒物的数目排放因子分别为(1.64±0.1)×1013,(1.4±0.1)×1013和(1.74±0.1)×1013particles kg-1;质量排放因子分别为(2.64±0.5)×105,(1.1±0.3)×105和(3.9±0.6)×105μg kg-1。研究确定了中国2004年三种农作物秸秆燃烧排放的新鲜颗粒物的排放清单和排放强地理分布特征。中国2004年由三种农作物秸秆(水稻、小麦和玉米秸秆)燃烧向大气排放的新鲜颗粒物的总量约1.3吨。排放强度最大的省份是山东省。第三部分为通过对中国三大农作物秸秆-水稻、玉米和小麦秸秆-进行燃烧实验分别得到了燃烧排放的气相中和颗粒物中的多环芳烃和烷基多环芳烃的排放因子,水稻秸秆、玉米秸秆和小麦秸秆燃烧排放的颗粒物中的多环芳烃(PAHs)的排放因子分别为1.64、0.93和0.72 mg kg-1,烷基多环芳烃(APAHs)的排放因子分别为0.24、0.27和0.28 mg kg-1;而水稻秸秆、玉米秸秆和小麦秸秆燃烧排放的气相中的多环芳烃(PAHs)的排放因子分别为3.62、0.81和0.65 mg kg-1,烷基多环芳烃(APAHs)的排放因子分别为1.01、0.35、0.66 mg kg-1。并结合所得的排放因子研究确定了中国2004年三种农作物秸秆燃烧排放的多环芳烃和烷基多环芳烃的排放清单和排放强度地理分布特征。中国2004年因三种农作物秸秆燃烧排放的多环芳烃(PAHs)及烷基多环芳烃(APAHs)的总量分别为1088吨和379吨。多环芳烃(PAHs)及烷基多环芳烃(APAHs)排放强度最高的省份是河南省、山东省和江苏省。以上三大部分研究内容是基于我国三种农作物秸秆燃烧的实际情况,分析考察了其燃烧排放的气态污染物、颗粒物和多环芳烃及烷基多环芳烃的排放特征。详细分析了气态污染物、颗粒物和多环芳烃及烷基多环芳烃的排放因子、排放清单及排放强度地理分布,同时还分析了燃烧排放的颗粒物的粒径分布特征,粒径成长特征。以便可以更好的揭示生物质燃烧源气溶胶的气候效应和环境效应,为研究区域气候模型设计和气候变化模拟提供基础数据,进一步为国家制定相关政策提供科学支撑,为国家的气候和环境外交提供科学依据。

【Abstract】 Biomass burning is an important source of gaseous and particulate pollutants in theatmosphere and has a significant impact on global atmospheric chemistry, global climateand global ecosystem change. In China, Agricultural crop residue is abundant and asignificant type of biomass burning. In order to estimate regional environmental impact andclimate effect, the emission characteristics of aerosol emitted from the burning ofagricultural crop residues should be investigated. Based on the above ideas, the gaseous andparticulate emission characteristics, the size distribution and growth characteristics ofemitted particles, the PAHs and APAHs emission characteristics from the burning of rice,wheat and corn straws, which are three major agricultural crop residues in China, are alsoinvestigated, using a self-built burning stove and an aerosol chamber equipped with a set ofanalytical instruments.There are three main contents in this work, as following:The first part investigates the emission factors, emission ratios and combustionefficiency of gaseous pollutants emitted from the burning of three main agricultural cropresidues-rice, wheat and corn straws- in China. The emission inventories and emissionallocations of gaseous pollutants (CO, CO2 and NOx) from rice, wheat and corn strawburnings in China for the year 2004 were also estimated.The second part is to study the size distribution characteristics, growth characteristicsof particles emitted from the burning of three main agricultural crop residues-rice, wheatand corn straws- in China. The size distributions of emitted particles are well characterizedby unimodal lognormal functions, with a remarkable feature of accumulation mode. Thegrowth rate is also determined during smoke age. Moreover, the number emission factors,the mass emission factors, the emission inventories and emission allocations of fresh smokeparticles from rice, wheat and corn straw burnings in China for the year 2004 were alsoestimated.The final part is to investigate the emission factors of PAHs and APAHs in the gas andparticle from the burning of three agricultural crop residues in detail. And the emissioninventories and emission allocations of PAHs and APAHs from rice, wheat and corn strawburnings in China for the year 2004 were also estimated.The emission characteristics of gaseous pollutants, fresh smoke particles and PAHs and APAHs emitted from agricultural crop residue burning are systematically investigated, andthe size distributions and growth characteristics of fresh smoke particles are also estimatedin the above three parts. This work could further reveal regional environmental impact andclimate effect caused by the burning of biomass burning, and provides the basic data for theregional climate modeling and climate change simulation. This study also provides thescientific basis for policy maker and our country’s climate and environment diplomacy.

  • 【网络出版投稿人】 复旦大学
  • 【网络出版年期】2009年 11期
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