Mercury from Combustion Sources: A Review of the Chemical Species Emitted and Their Transport in the Atmosphere

Different species of mercury have different physical/chemical properties and thus behave quite differently in air pollution control equipment and in the atmosphere. In general, emissions of mercury from coal combustion sources are approximately 20–50% elemental mercury (Hg°) and 50–80% divalent mercury (Hg(II)), which may be predominantly HgCl₂. Emissions of mercury from waste incinerators are approximately 10–20% Hg° and 75–85% Hg(II). The partitioning of mercury in flue gas between the elemental and divalent forms may be dependent on the concentration of particulate carbon, HCl and other pollutants in the stack emissions. The emission of mercury from combustion facilities depends on the species in the exhaust stream and the type of air pollution control equipment used at the source. Air pollution control equipment for mercury removal at combustion facilities includes activated carbon injection, sodium sulfide infection and wet lime/limestone flue gas desulfurization. While Hg(II) is water-soluble and may be removed from the atmosphere by wet and dry deposition close to combustion sources, the combination of a high vapor pressure and low water-solubility facilitate the long-range transport of Hg° in the atmosphere. Background mercury in the atmosphere is predominantly Hg°. Elemental mercury is eventually removed from the atmosphere by dry deposition onto surfaces and by wet deposition after oxidation to water-soluble, divalent mercury.     

An Emissions Inventory for Regional Atmospheric Modeling of Mercury

Estimates of mercury emissions from individual sources and source categories are needed to understand relationships between the emissions and resulting deposition and to evaluate possible approaches to reducing those emissions. We have developed geographically-resolved estimates of annual average mercury emission rates from current anthropogenic sources in the 48 contiguous United States. These estimates were made by applying emission factors to individual facility operating data and to county-wide source activity levels. We apportioned the emissions to an Eulerian modeling grid system using point source coordinates and the fractions of county areas in each grid cell. Point sources account for about 89% of the 48-state total mercury emissions of 146.4 Mg/yr. Most of the emissions in the inventory are from combustion of mercury-containing fossil fuels and municipal waste, located primarily in the mid-Atlantic and Great Lakes states as well as in the Southeast. The major uncertainties in the emission estimates are caused by uncertainties in the emission factors used to develop the estimates. This uncertainty is likely a result of variability in the mercury content of the combusted materials and in the removal of mercury by air pollution control devices. The greatest research need to reduce uncertainties in mercury emission estimates is additional measurements to improve emission factors.     

Substance Flow Analysis of Mercury Affecting Water Quality in the European Union

Knowledge concerning the main flows of priority substances (PSs) and the production systems and consumption structures in the society causing these flows is a prerequisite for any attempt to predict and understand their environmental fate as well as to efficiently minimize future environmental burdens. In this paper, a simple SFA diagram on mercury, including the main European Union (EU-27) source categories, flows and environmental endpoints which in turn affect the mercury concentrations in the EU-27 waters are illustrated. From trend analysis and future projections, it becomes obvious that emissions of mercury as a trace contaminant in fuels and minerals (primary anthropogenic emission sources) are becoming increasingly important to the environmental concentrations compared to emissions from mercury used intentionally (secondary anthropogenic sources). Additional future control strategies should therefore be targeted industrial sources and safe treatment of mercury-containing wastes, wastewater effluents, as well as residues collected from various combustion processes. It was found that knowledge on flows and emission sources on a large geographical scale is limited due to a lack of information on emission factors from various industrial processes and waste systems, especially for the mercury being discharges to water and land.     

Acidifying emissions in The Netherlands

The emission of acidifying compounds to air in the Netherlands, expressed as acidifying equivalents, consisted in 1992 mainly of NO_X (45%), NH₃ (35%) and SO₂ (20%). Transportation, agriculture and large combustion plants each contributed about 30% to the national total emission of acidifying compounds. The emissions from transportation activities mainly consisted of NO_X, while in agriculture NH₃ emission strongly dominated. Combustion processes in large combustion plants resulted both in SO₂ emissions (especially from refineries) and NO_X emissions (especially from public power plants). The total emission of acidifying substances decreases steadily in the Netherlands. The emission in 1992 was 24% lower than in 1985. It is expected to decrease further in future. The emission levels in 1992 and 1993 still are more than twice as high as the emission objective for the year 2000, set by Dutch environmental policy.     

A Module to Calculate Primary Particulate Matter Emissions and Abatement Measures in Europe

Primary particulate matter is emitted directly into the atmosphere from various anthropogenic and natural sources such as power plants (combustion of fossil fuels) or forest fires. Secondary particles are formed by transformation of SO₂, NO_x, NH₃, and VOC in the atmosphere. They both contribute to ambient particulate matter concentrations, which may have adverse effects on human health. Health hazards are caused by small particulate size, high number of especially fine (< 2.5 µm) and ultra-fine (< 0.1 µm) particles and/or their chemical composition. As part of an integrated assessment model developed at IIASA, a module on primary particulate matter (PM) emissions has been added to the existing SO₂, NO_x, NH₃ and VOC sections. The module considers so far primary emissions of total suspended particles (TSP), PM₁₀ and PM_2.5 from aggregated stationary and mobile sources. A primary PM emission database has been established. Country specific emission factors for stationary sources have been calculated within the module using the ash content of solid fuels.     

我国NH3-N排放量及空间分布变化初步研究

NH3-N的排放量增加引起了水体富营养化、土壤酸化等一系列环境问题,所以对NH3-N排放情况的研究越来越受到科学家的重视。而有关我国NH3-N排放量历史变化情况,尤其是近20多年来的排放量报道很少。参照已有的各个NH3-N源的排放因子,利用中国农业年鉴统计等数据资料,计算了1980—2005年我国NH3-N排放量。结果表明,1980年,NH3-N排放量为5.50Tg,到2005年达到13.38Tg,增加了143%,年均增长率为5.51%。因使用化学肥料产生的NH3-N排放量最大,约占总排放量的29.4%～47.4%,畜牧业中动物厩舍及其排泄物储存产生的NH3-N排放量居第二位。我国NH3-N排放量空间分布不均匀,主要分布在我国东部河南、山东、江苏、河北以及西南的四川等省,2005年约占总排放量的36.2%。我国NH3-N排放总量的时间变化最大的几个省份分别是黑龙江、天津、河北、河南、山东等,其年均增长在8%以上,而我国的西北和青藏高原地区排放量变化最小,仅为0.44%。     

表面风速和模拟降水对奶牛粪便堆放过程中N2O排放的影响

奶牛场粪便的自然堆放过程中会造成大量的温室气体排放,排放过程和排放量受表面风速和自然降水等环境因素的影响显著。该文针对中国常用的奶牛粪便管理方式,采用动态箱法研究了不同表面风速(0.5、0.8、1.2、1.6 m/s)和模拟降水(降水量9.9 mm)对奶牛粪便自然堆放过程中典型的温室气体氧化亚氮(N2O)排放的影响。结果表明,在0.5~1.2 m/s风速范围内,奶牛粪便自然堆放过程中的N2O排放量随风速升高逐渐增加,1.2 m/s达到最大值,且不同风速下N2O的排放量存在显著差异。模拟降水后N2O排放量在短时间内急剧升高,之后迅速下降至降水前的排放水平,整个过程持续约10 h。由于降低了二氧化碳(CO2)和甲烷(CH4)的排放,与降水前一天相比2次降水分别降低了12.9%和10.9%的温室气体排放量。     

河北省农作物生产投入品碳排放变化特征

基于2010-2018年河北省农资投入、农作物产量、耕地面积和农作物播种面积等统计数据,计算河北省农作物生产投入品碳排放,分析河北省农作物生产投入品碳排放的动态变化和不同投入品碳排放所占比例,为农业生产节能减排,实现低碳农业提供理论依据。结果表明,2010-2018年河北省农作物生产投入品碳排放以2015年为转折点,呈现先上升后下降的趋势。研究期内河北省农作物生产碳排放总量、单位产量碳排放量和单位耕地面积碳排放量分别为2219万～2674万tCO₂eq、0.21～0.30tCO₂eq·t^-1和3.40～4.10tCO₂eq·hm^-2。2018年河北省农作物生产碳排放总量、单位产量碳排放量和单位耕地面积碳排放量最低,分别比最高值降低17.0%、30.0%和17.0%。化肥、农药、农膜、柴油和灌溉用电9a平均碳排放量占比分别为38.6%、2.1%、11.5%、34.7%和13.1%。化肥和柴油是最主要的农业碳排放源,占比均在30%以上。农作物生产投入品碳排放的动态变化受国家政策影响...     

轻型柴油机预混合低温燃烧路径优化试验及分析

为探索轻型车用柴油机在中小负荷率工况下实现超低排放的预混合低温燃烧策略,以某四缸轻型车用柴油机为样机,在中小负荷率工况下,进行了喷射正时、废气再循环率(exhaust gas recirculation,EGR)、进气温度、喷射压力、预喷射等不同控制参数对柴油机预混合低温燃烧影响的试验研究。证明适时早喷射可延长预混合期实现预混合燃烧,改善柴油机碳烟排放;采用高比例EGR技术降低进气氧浓度能有效控制预混合燃烧温度,可有效降低NOx排放,同时可推迟由早喷射造成的过早的燃烧相位;在适时早喷射结合高比例EGR的基础上,协同优化喷射压力、进气温度与预喷射参数改善NOx和碳烟排放Trade-off关系,以实现超低排放的预混合低温燃烧;通过预混合低温燃烧路径优化后,10%、25%和50%负荷率工况NOx排放与原机相比分别降低97.8%、80.7%和62.1%,碳烟排放分别降低76%、93.9%和47.1%。3个负荷率工况下优化后的有效燃油消耗率比优化前略有上升。研究结果为轻型柴油机预混合低温燃烧过程的优化及污染物排放控制技术提供了理论基础。     

过量空气系数对柴油/甲醇RCCI发动机非常规排放特性的影响

为探究柴油/甲醇反应活性控制压燃(Reactivity Controlled Compression Ignition,RCCI)发动机非常规排放特性及影响机理,该研究对某高压共轨柴油机进气歧管进行改造,搭建了柴油/甲醇双燃料RCCI发动机专用试验台架,系统研究了不同甲醇替代率、过量空气系数对发动机非常规排放物的影响规...     

An Approach to Temporally Disaggregate Benzo(a)pyrene Emissions and Their Application to a 3D Eulerian Atmospheric Chemistry Transport Model

To simulate the atmospheric fate of air pollutants, it is first necessary to know the emission rates that describe the release of pollutants into ambient air. For benzo(a)pyrene emission data are currently only available as yearly bulk emissions while the simulation models typically require temporally resolved emissions (e.g. hourly). Because residential heating is by far the most important source for benzo(a)pyrene, we developed a method to temporally disaggregate these bulk emission data using the linear dependency of benzo(a)pyrene emission rates stemming from residential combustion on ambient temperature. The resulting time-dependent hourly emission rates have been used in a chemical transport model to simulate concentrations and deposition fluxes of benzo(a)pyrene in the year 2000. The same simulations were repeated with constant emission rates and emission rates that varied only seasonally. By comparing the modeling results of the three emission cases with monthly measurements of air concentrations, the characteristic and the benefit of our disaggregation approach is illustrated. The simulations with disaggregated emissions fitted best to the measurements. At the same time the spatial distribution as well as the yearly total deposition was notably different with each emission case even though the yearly total emissions were kept constant.     

碳中和目标下畜牧业低碳发展路径

推动实现碳中和是可持续发展的关键,减少温室气体排放是推动实现碳中和的根本。作为国际低碳行动的引领者和开拓者,中国承诺将力争于2030年前实现二氧化碳排放达峰,努力争取2060年前实现碳中和。农业生产活动是中国温室气体的第三大排放源,其中畜牧业贡献了农业非二氧化碳温室气体排放的80%,是农业主要温室气体排放源。因此,畜牧业的低碳减排对实现碳中和至关重要。该研究从动物呼吸、动物胃肠道发酵、粪污处理等直接排放源和饲料生产加工、设备设施能源消耗、动物产品加工及运输等间接排放源系统综述了畜牧业的温室气体排放,从源头、过程和末端全方位阐述了畜牧业的低碳减排途径。源头减排包括动物的肠道发酵管控、饲料成分升级、粗粮与精粮比例的调整、使用添加剂以及选育优质畜禽品种,过程减排包括畜舍环境及设备能耗调控、畜禽管理方式优化以及精准畜牧业的应用,末端减排包括粪污处理以及畜产品供应链的优化。该研究对碳中和目标下的畜牧业低碳发展路径进行了综述,以期为推动实现碳中和,促进畜牧业绿色可持续发展提供参考。     

Atmospheric Emission Inventory for Natural and Anthropogenic Sources and Spatial Emission Mapping for the Greater Athens Area

A spatially, temporally and chemically resolved emission inventory for particulate matter and gaseous species from anthropogenic and natural sources was created for the Greater Athens Area (GAA; base year, 2007). Anthropogenic sources considered in this study include combustion (industrial, non-industrial, commercial and residential), industrial production, transportation, agriculture, waste treatment and solvent use. The annual gaseous pollutants (????x, SOx, non-methane volatile organic compounds (NMVOCs), CO and ????₃) and particulate matter (PM_2.5 and PM_2.5?C10) emissions were derived from the UNECE/EMEP database for most source sectors (SNAP 1?C9; 50?×?50 km²) and their spatial resolution was increased using surrogate spatial datasets (land cover, population density, location and emissions of large point sources, emission weighting factors for the GAA; 1?×?1 km²). The emissions were then temporally disaggregated in order to provide hourly emissions for atmospheric pollution modelling using monthly, daily and hourly disintegration coefficients, and additionally the chemical speciation of size-segregated particles and NMVOCs emissions was performed. Emissions from agriculture (SNAP 10) and natural emissions of particulate matter from the soil (by wind erosion) and the sea surface and of biogenic gaseous pollutants from vegetation were also estimated. During 2007 the anthropogenic emissions of CO, SOx, NOx, NMVOCs, NH₃, PM_2.5 and PM_2.5?C10 from the GAA were 151,150, 57,086, 68,008, 38,270, 2,219, 9,026 and 3,896 Mg, respectively. It was found that road transport was the major source for CO (73.3%), NMVOCs (31.6%) and NOx (35.3%) emissions in the area. Another important source for NOx emissions was other mobile sources and machinery (23.1%). Combustion for energy production and transformation industries was the major source for SOx (38.5%), industrial combustion for anthropogenic PM_2.5?C10 emissions (59.5%), whereas non-industrial combustion was the major source of PM_2.5 emissions (49.6%). Agriculture was the primary NH₃ source in the area (72.1%). Natural vegetation was found to be an important source of VOCs in the area which accounted for approximately the 5% of total VOCs emitted from GAA on a typical winter day. The contribution of sea-salt particles to the emissions of PM_2.5 was rather small, whereas the emissions of resuspended dust particles exceeded by far the emissions of PM_2.5 and PM_2.5?C10 from all anthropogenic sources.     

不同掺混比例生物柴油的非常规污染物排放特性

为了实现柴油机的清洁燃烧,需要系统研究非常规污染物的生成机理与排放特性。根据羰基类、芳香烃类物质的理化性质特点,提出了柴油机非常规污染物高效快速的测量方法,采用不同掺混比例的生物柴油进行了柴油机台架试验,探讨了不同燃料、不同工况下柴油机非常规污染物的排放特性。结果表明,二硝基苯腙采样结合高效液相色谱技术,可以实现柴油机排气中15种羰基类污染物的快速准确测定,活性炭吸附结合气相色谱-质谱联用技术可以实现芳香烃污染物的定性定量分析;中、低负荷时,生物柴油掺混比例对柴油机总羰基排放的影响不大,随着负荷的增加,BD50（生物柴油和市售0#柴油按体积比1:1配制的调合油）和BD0（纯柴油）的总羰基排放呈升高趋势,BD100（以地沟油为原料的生物柴油）的总羰基排放有所降低;BD0的单环芳香烃最大排放浓度最高,3种燃料的气相多环芳香烃排放在低负荷和高负荷工况点存在"双峰"特征,三环菲约占所有环数多环芳香烃总量的44%,燃用生物柴油可降低柴油机约32%的多环芳香烃排放。该研究为柴油机非常规污染物的排放控制提供了参考。     

大型秸秆沼气集中供气工程温室气体减排估算

发展秸秆沼气工程可有效地减少农业温室气体排放,科学核算温室气体减排量为管理和监督温室气体排放状况提供数据支撑。该文以河北省沧州市耿官屯大型秸秆沼气集中供气工程为研究对象,参考和借鉴了自愿减排项目方法学、CDM方法学,构建了大型秸秆沼气集中供气工程温室气体减排计量方法,包括项目边界、基准线排放量、项目排放量、泄漏量、减排量5个方面,计算了2014年耿官屯大型秸秆沼气集中供气工程温室气体减排量。研究结果表明:项目基准排放量包括秸秆处理产生的温室气体排放、未建秸秆沼气工程情况下农村居民生活用能及农田施用化肥生产耗能产生的温室气体排放。项目排放量包括秸秆与沼肥运输过程耗能排放、工程运行过程耗能排放及沼气处理温室气体排放,项目泄漏量即沼气生产、储存、管网供气和利用过程中产生的因物理泄漏所造成的排放。2014年耿官屯大型秸秆沼气集中供气工程基准线CO2排放量为5 776.15 t,项目排放量为57.53 t,泄漏量为136.59 t,减排量为5 582.03 t,约相当于2 100 t标准煤CO2排放量,每消耗1 t(干质量)秸秆可净减排3.56 t,每利用1 m3沼气可净减排11.50 kg。同时,在工程设计、管道设计、工程管理、工艺技术改良升级等方面提出了提升大型秸秆沼气工程温室气体减排能力的策略。     

保护性耕作对温室效应的影响

农业是非常重要的温室气体排放源,而不合理的农田管理措施强化了农田排放源的特征,同时弱化了吸收汇的作用。保护性耕作对温室效应的影响来自两方面,一方面是免耕减少了农田CO2排放,对CH4和N2O排放的影响不明确;另一方面是秸秆还田以后部分秸秆C以气体形式释放进入大气,增加了农田CO2、CH4排放,但秸秆还田相对其他用途提高了土壤固碳潜力,减少了总的温室气体排放量。通过耕作与秸秆管理对温室气体排放资料的整理分析,指明保护性耕作是一种有利于减少温室效应的农田管理措施,为保护性耕作的温室效应研究提供借鉴。     

陕西省能源消费碳排放及脱钩分析

根据IPCC碳排放计算方法计算了陕西省1980—2010年的能源消费碳排放量,系统分析了陕西省能源消费碳排放总量、碳排放结构以及不同产业和工业不同部门碳排放的变化,并应用脱钩理论探讨陕西省经济增长与能源碳排放的脱钩关系及程度。结果表明:1980—2011年,陕西省碳排放总量及煤炭消费引起的碳排放量呈现波动上升的“N”型曲线特征,石油和天然气消费引起的碳排放呈逐年递增趋势,碳排放主要来自于煤炭消费;工业部门是碳排放的主要部门,工业部门中重工业和电力、燃气及水的生产和供应业排放量最大,比重分别为48%和37%,采掘业次之,所占比重为11%,轻工业所占比重最小,约为4%,通过工业内不同行业的比较发现,电力、热力的生产和供应业、化学原料及化学制品制造业、石油加工、炼焦及核燃料加工业、石油开采和天然气开采业、非金属矿物制品业、黑色金属冶炼及压延加工业、煤炭开采和洗选业和有色金属冶炼及压延加工业是陕西省碳排放主要来源,2005年和2010年8大行业碳排放量占工业碳排放总量的92.56%和95.11%;1980—2011年间除1981年和1997—2000年为强脱钩,1982年和2001—2003年为扩张性负脱钩外,其余时期经济与能源碳排放均呈现弱脱钩状态,能源效率的提高是目前实现弱脱钩的主要原因,但其未能抵消经济发展对能源需求的增长幅度,未来一定时期内弱脱钩发展趋势仍将持续。     

The nitrogen load to the Baltic sea — Present situation,acceptable future load and suggested source reduction

The Baltic Sea is one of the most polluted sea areas in the world. Except for different local pollution sources, the overall environmental problem is eutrophication. The eutrophic situation is caused by increased external load of nutrients during decades. Since nitrogen (N) is generally considered the main limiting nutrient for primary production in the Baltic Sea, the countries within the Baltic Sea drainage basin have agreed to reduce the anthropogenic waterborne input of N by 50% between 1987 and 1995. Furthermore, N emissions to the atmosphere are to be frozen at the level that existed at the end of the 1980s. A number of countries have also declared their intention to reduce N emissions to the atmosphere by 30% between 1980 and 1998. Presently, the annual N load to the Baltic Sea totals 1,409,000 tonnes, of which 980,000 tonnes (69%) are waterborne discharges (rivers, point and non-point sources), and 134,000 tonnes (10%) are caused by N₂ fixation. The rest, 296,000 tonnes (21%) is atmospheric deposition on the sea surface. Some 60% of the atmospheric deposition is caused by emissions from sources in the drainage area and the rest is emissions from areas outside the drainage area. The highest acceptable future N load to the Baltic Sea is estimated at 600,000 tonnes/year. This means a necessary reduction of 57%, compared to the present load. Therefore, comprehensive load reductions must be conducted from anthropogenic sources, e.g. agriculture, forest and forestry, industry, and municipal sewage treatment plants and rural living. The atmospheric N deposition must be reduced by almost 40%, and the measures must focus on emission reductions in traffic, combustion, and agriculture.     

生物质炉具现场测试污染物排放特征及减排效果评估

目前对于生物质成型燃料替代散煤减排效果的现场评估还非常缺乏,且均为基于短时间测试方法,无法反映炉具全天实际排放情况。该研究以黑龙江省某生物质成型燃料及配套炉具推广示范村为例,采用全天24 h实地测试的方法,研究了该地区的燃煤炉具以及推广的自动进料和手动进料生物质炉具的污染排放情况。结果表明：自动/手动进料生物质炉具相比燃煤炉具的PM2.5、CO、SO2排放因子分别降低41.2%、54.3%、40.0%和35.3%、22.1%、20.0%,NOx的排放因子没有降低。对不同取暖方式的户均排放总量核算发现：自动/手动进料生物质炉具排放的PM2.5、CO、SO2分别减排39.79%、52.77%、41.35%和33.41%、19.38%、27.01%;NOx分别升高46.14%和6.69%。此外,调研发现经济性和便利性是生物质炉具推广的重要影响因素。     

Freshwater Fish Mercury Concentrations in a Regionally High Mercury Deposition Area

We sampled and analyzed individually, edible dorsal muscle from largemouth bass (LMB), Micropterus salmoides (n?=?138) and yellow perch (YP), Perca flavescens (n?=?97) from 15 lakes to investigate potential local impacts of mercury emission point sources in northeastern Massachusetts (MA), USA. This area was identified in three separate modeling exercises as a mercury deposition hotspot. In 1995, 55% of mercury emissions to the environment from all MA sources came from three municipal solid waste combustors (trash incinerators) and one large regional medical waste incinerator in the study area. We determined the mercury accumulation history in sediments of a lake centrally located in the study area. Recent maximum mercury accumulation rates in the sediment of the lake of ~ 88 μg/m²/year were highly elevated on a watershed area adjusted basis compared to other lakes in the Northeast and Minnesota. Fish from the study area lakes had significantly (p?=?0.05) greater total mercury concentrations than fish from 24 more rural, non-source-impacted lakes in other regions of the state (LMB n?=?238, YP n?=?381) (LMB: 1.5–2.5 x; YP: 1.5 x). The integration of this extensive fish tissue data set, depositional modeling projections, historical record of mercury accumulation in sediments of a lake in the area, and knowledge of substantial mercury emissions to the atmosphere in the area support designation of this area as a mercury depositional and biological concentration hotspot in the late 1990s, and provides further evidence that major mercury point sources may be associated with significant local impacts on fisheries resources.