四川省秸秆露天焚烧污染物排放清单及时空分布特征

根据收集的活动水平数据,采用排放因子法建立了四川省2012年秸秆露天焚烧污染物排放清单,并分析了污染排放的时空分布特征.结果表明,2012年四川省秸秆露天焚烧共排放SO2、NOx、NH3、CH4、NMVOC、CO、PM2.5、EC以及OC分别为1 210、12 185、2 827、20 659、40 463、292 671、39 277、1 984以及10 215 t;水稻、小麦、玉米、油菜是四大主要的焚烧作物秸秆,对污染物的总贡献率约为88%~94%;秸秆露天焚烧受农作收获的影响,全年的排放主要集中在7~8月,而5月是上半年的一个排放小高峰;秸秆焚烧排放的高值地区主要分布在成都平原、川北地区以及川南地区,川西地区排放分布相对较少;本清单的不确定性主要来自排放因子及秸秆焚烧量.     

Fire hazard after prescribed burning in a gorse shrubland: implications for fuel management

Prescribed burning is commonly used to prevent accumulation of biomass in fire-prone shrubland in NW Spain. However, there is a lack of knowledge about the efficacy of the technique in reducing fire hazard in these ecosystems. Fire hazard in burned shrubland areas will depend on the initial capacity of woody vegetation to recover and on the fine ground fuels existing after fire. To explore the effect that time since burning has on fire hazard, experimental tests were performed with two fuel complexes (fine ground fuels and regenerated shrubs) resulting from previous prescribed burnings conducted in a gorse shrubland (Ulex europaeus L.) one, three and five years earlier. A point-ignition source was used in burning experiments to assess ignition and initial propagation success separately for each fuel complex. The effect of wind speed was also studied for shrub fuels, and several flammability parameters were measured. Results showed that both ignition and initial propagation success of fine ground fuels mainly depended on fuel depth and were independent of time since burning, although flammability parameters indicated higher fire hazard three years after burning. In contrast, time since burning increased ignition and initial propagation success of regenerated shrub fuels, as well as the flammability parameters assessed, but wind speed had no significant effect. The combination of results of fire hazard for fine ground fuels and regenerated shrubs according to the variation in relative coverage of each fuel type after prescribed burning enabled an assessment of integrated fire hazard in treated areas. The present results suggest that prescribed burning is a very effective technique to reduce fire hazard in the study area, but that fire hazard will be significantly increased by the third year after burning. These results are valuable for fire prevention and fuel management planning in gorse shrubland areas.     

广西背景大气中生物质燃烧对碳质气溶胶组成和吸光性的影响

碳质气溶胶是大气细颗粒物（PM_2.5）的重要组成部分,对空气质量、人体健康和气候变化均有重要影响.针对生物质燃烧（BB）这一碳质气溶胶的重要来源,于2017年11月至2018年10月在广西壮族自治区背景地区采集了PM_2.5样品,分析了样品中的碳质组成、糖类化合物和水溶性棕色碳（BrC）的吸光系数（b_abs）.使用气团老化指数（AAM）校正LG浓度以消除LG降解带来的影响,进而结合贝叶斯混合模型与分子示踪剂法量化了BB对有机碳（OC）的贡献率,并通过相关性分析法探讨了BrC的可能来源.结果表明,研究期间AAM指数平均值为0.40±0.28,表示LG存在光化学降解过程.农作物秸秆是广西地区最主要的生物质燃料类型,在未考虑LG降解下,全年玉米、水稻和甘蔗秸秆焚烧排放的OC分别占总OC的22%、23%和18%;考虑LG在大气中的降解后,相对贡献率分别降低至16%、21%和17%.LG的降解会导致BB对OC的贡献率评估被低估,经过AAM指数校正后,全年BB对OC的贡献率平均值为49.0%.水溶性BrC的b_abs全年的平均值为（8.7±10.7） Mm^-1,其中BB、化石燃料燃烧以及初级生物气溶胶排放可能是BrC的重要来源.     

兰州生物质燃烧VOCs排放特征及其大气环境影响

采用排放因子法建立了2016年兰州市生物质燃烧源挥发性有机物（VOCs）排放清单,并分析了污染物的时空排放特征,利用排放清单对生物质燃烧源的臭氧生成潜势（OFP）和二次有机气溶胶（SOA）生成潜势进行了估算,研究其排放对大气环境的影响.结果表明：2016年兰州市生物质燃烧源排放VOCs总量为6626.2t,排放高值区在榆中东南及东北部、永登中部和七里河南部,经济水平落后、秸秆产量大的地区污染物排放量更大.污染物排放集中在采暖季（11~3月）及农作物收割期（7~8月）;兰州市生物质燃烧源的OFP总量为13880.3t,煨炕为OFP贡献最大的子源,占比46.1%,含氧挥发性有机物（OVOCs）为OFP贡献最大的关键组分,占比51.4%;OFP贡献排名前10的物种有乙酸、丙烯、2-丁酮、甲苯、甲醛、乙醛、间/对-二甲苯、1-丁烯、丙酸和异戊二烯.煨炕是SOA生成潜势贡献最大的子源,占比46.5%,芳香烃为SOA生成潜势贡献最大的关键组分,占比62.2%,SOA生成潜势贡献排名前10的物种有苯酚、甲苯、α-蒎烯、间/对-二甲苯、苯、邻二甲苯、茚、1,2,4-三甲基苯、乙苯和1,2,3-三甲基苯;以降低区域O₃和SOA浓度为目标时,应优先管控煨炕和秸秆露天燃烧（玉米）两类子源.     

聊城市冬季PM2.5中多环芳烃来源解析及健康风险评估

为研究聊城市冬季PM_(2. 5)中多环芳烃(PAHs)的浓度水平、来源及健康效应,于2017年1～2月对聊城市PM_(2. 5)中的14种PAHs进行分析,利用特征比值法和PCA-MLR模型对其来源及贡献率进行解析,并利用Ba P当量浓度(Ba Peq)和呼吸途径暴露PAHs引发癌症的风险(ILCR)模型进行健康风险评估.结果表明,聊城市冬季PM_(2. 5)中PAHs的平均质量浓度为(64. 89±48. 23) ng·m~(-3),其中Fla、Pyr和Chry的浓度最高,占比分别为15. 5%、12. 8%和12. 7%,且4环PAHs总质量浓度占比最高,春节前与烟火Ⅱ期比其他时期污染较重. PCA-MLR模型分析结果表明,聊城市冬季PM_(2. 5)中PAHs来源主要包括煤炭燃烧、生物质燃烧和机动车尾气.聊城市冬季TEQ平均值为(6. 37±4. 92) ng·m~(-3),ILCR模型评估结果表明,成人的ILCR值高于儿童,二者的ILCR值均处于风险阈值内(10-6～10-4),表明聊城市冬季PM_(2. 5)具有潜在致癌风险.     

秸秆产生利用现状调查与禁烧面临难点分析——以江苏省某乡镇为例

以江苏省某乡镇为对象,开展了农作物秸秆产生量、秸秆利用状况、农民处理秸秆方式的调查研究。结果表明,秸秆收集利用量占秸秆产生总量的比例不足25％,50％以上农户产生的秸秆得不到有效利用;农业从业者综合素质相对较低、技术普及不到位、作物收种时间重叠、效益驱动不足、秸秆利用机制不健全是秸秆禁烧和利用面临的主要问题。针对主要问题,从科技支撑、有效组织、政策引导、农机农艺、宣传培训等方面提出了合理的建议。     

Resolving future fire management conflicts using multicriteria decision making

Management strategies to reduce the risks to human life and property from wildfire commonly involve burning native vegetation. However, planned burning can conflict with other societal objectives such as human health and biodiversity conservation. These conflicts are likely to intensify as fire regimes change under future climates and as growing human populations encroach farther into fire‐prone ecosystems. Decisions about managing fire risks are therefore complex and warrant more sophisticated approaches than are typically used. We applied a multicriteria decision making approach (MCDA) with the potential to improve fire management outcomes to the case of a highly populated, biodiverse, and flammable wildland–urban interface. We considered the effects of 22 planned burning options on 8 objectives: house protection, maximizing water quality, minimizing carbon emissions and impacts on human health, and minimizing declines of 5 distinct species types. The MCDA identified a small number of management options (burning forest adjacent to houses) that performed well for most objectives, but not for one species type (arboreal mammal) or for water quality. Although MCDA made the conflict between objectives explicit, resolution of the problem depended on the weighting assigned to each objective. Additive weighting of criteria traded off the arboreal mammal and water quality objectives for other objectives. Multiplicative weighting identified scenarios that avoided poor outcomes for any objective, which is important for avoiding potentially irreversible biodiversity losses. To distinguish reliably among management options, future work should focus on reducing uncertainty in outcomes across a range of objectives. Considering management actions that have more predictable outcomes than landscape fuel management will be important. We found that, where data were adequate, an MCDA can support decision making in the complex and often conflicted area of fire management.     

Effect of inert species on the laminar burning velocity of hydrogen and ethylene

The maximum laminar burning velocity (LBV) of a fuel-air mixture is an important input parameter to vapor cloud explosion (VCE) blast load prediction methods. In particular, the LBV value has a significant impact on the predicted blast loads for high reactivity fuels with the propensity to undergo a deflagration-to-detonation transition (DDT). Published data are available for the maximum LBV of many pure fuel-air mixtures. However, little test data are available for mixtures of fuels, particularly for mixtures of fuels and inert species. Such mixtures are common in the petroleum refining and chemical processing industries. It is therefore of interest to be able to calculate the maximum LBV of a fuel/inert mixture based on the mixture composition and maximum LBV of each component.This paper presents measured test data for the maximum LBV of H₂/inert and C₂H₄/inert mixtures, with both nitrogen and carbon dioxide as the inert species. The LBV values were determined using a constant-volume vessel and the pressure rise method. This paper also provides a comparison of the measured LBV values with simplified LBV prediction methods.     

Nitro polycyclic aromatic hydrocarbons in atmospheric particulate matter of Athens,Greece

Polycyclic aromatic hydrocarbons (PAHs) and nitro polycyclic aromatic hydrocarbons (N-PAHs) are chemical species of proven mutant and carcinogenic activity. In this study, the concentrations of seven different N-PAHs [2-nitronaphthalene (2N-NAP), 2-nitroflourene (2N-FLU), 2-nitroflouranthene (2N-FLA), 3-nitroflouranthene (3N-FLA), 1-nitropyrene (1N-PYR) and 2-nitropyrene (2N-PYR)] were determined in two fractions of atmospheric particulate matter from the atmosphere of Athens: coarse (2.4 μm?10 μm ) and fine (<2.4 μm ). 3N-FLA was not detected, whereas 1N-PYR, mostly originating from emissions from burning fuel, showed the maximum observed concentrations for both fractions and for the whole experimental period (especially during winter). In addition, 2N-FLA, a secondary nitro-PAH produced by photochemical reactions, showed relatively high values. Analysis of statistical data for N-PAH concentrations, using clustering technique, showed that: (1) 1N-NAP, 2N-FLU and 1N-PYR are mainly produced by direct burning; and (2) photochemical reactions are the dominant sources of 2N-NAP, 2N-PYR and 2N-FLA.     

Continuous monitoring of ambient polycyclic aromatic hydrocarbons near open‐air burning of metal scraps

Airborne concentrations of PAH in the vicinity of the source region with open‐air burning of metal scraps were measured between February, 1992 and November, 1993. The activity of open‐air burning decreased significantly since 1993 due to prohibition regulation. Both gaseous phase and particle‐bound PAH were measured at five sampling sites, which included one reference sampling site far away from the source region. Both values of gaseous and particle‐bound PAH concentrations, which were measured in the vicinity of source region, decreased clearly during the two years monitoring period. It shows that the uncontrolled open‐air burning of metal scraps was a significant emission source of airborne PAH in the study area. The profiles of various species of PAH were also compared. A large decrease in benzo(a)pyrene was observed in the source region.