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.     

秸秆焚烧导致南京及周边地区2次空气污染事件的成因比较

从天气形势、卫星遥感火点监测、物理量诊断和后向轨迹模拟等方面分析了2008和2010年秸秆焚烧导致南京及周边地区空气污染事件过程的异同点。结果表明,2008年污染过程受大气底层切变线的控制,2010年污染过程受高压天气形势的控制;2008年火点仅出现在江苏地区,而2010年江苏、安徽和浙江地区均有出现;2008年大气底层气流为弱上升运动,导致高浓度的污染,2010年因受下沉气流控制而导致大范围的污染;2008年污染物来源为江苏地区,2010年则受江苏和安徽地区火点的共同影响,这些差异导致2次污染过程影响的范围和强度有所不同。     

庚烷池火多火源燃烧特性的实验研究

多火源燃烧是森林火灾和城市群发性火灾中重要而又特殊的火灾现象,相关研究很少。通过恒定控制液面高度的实验系统,对直径0.1m、0.2m和0.4m的庚烷池火在单个火源、两火源燃烧和三火源线性排列时的火焰高度、火焰体积和燃烧速率等特性进行了实验研究。研究发现,三火源燃烧时中间火源的火焰高度、火焰体积和燃烧速率明显高于两火源燃烧和单火源燃烧,三火源燃烧时边上火源与两火源的燃烧状况难以区分。这些燃烧特性随着火源间距的减小,呈现增大趋势。热量反馈增强和空气卷吸受限这两种火源相互作用机制相互耦合,且随着火源间距的减小而增强,在S/D（S为火源间距,D为油池直径）为2～4时,两种机制强烈竞争,在其他参数范围内热量反馈增强效应占主导作用。研究还发现火焰体积与热释放速率有较好的线性相关关系,单位火焰体积的热释放速率约为1614kW/m3。     

2,5-二甲基呋喃-空气燃烧过程研究

利用球形发展火焰研究了常温常压下不同当量比,不同相态时2,5-二甲基呋喃-空气的层流燃烧速度和马克斯坦长度,分析了火焰拉伸对火焰传播速度的影响。研究结果表明:随着当量比的增加,2,5-二甲基呋喃-空气混合气的马克斯坦长度减少,火焰的稳定性减弱。并且分别计算出当量比为1.25和1.5的层流燃烧速度,分别为:1.189m/s,1.135m/s.。对于同一当量比1.5的情况下,不同相态的2,5-二甲基呋喃-空气混合物,在相同时刻的气液两相混合物的火焰半径已经拉伸火焰传播速度远远大于纯气相的混合物。     

福建三钢气烧石灰窑烟气除尘技术

总结了气烧石灰窑烟气除尘的3种技术方案及使用效果,并重点推出了一项达到欧洲排放标准的烟气除尘新技术。     

快速密闭时火区热物理参数变化规律的研究

在全尺寸巷道火灾试验中,利用48路全自动数据采集系统,研究了快速密闭条件下火区的燃烧状况及温度和压力变化规律.试验发现,作用在风门上的抽吸力很大,很快降到很小;而燃烧区的温度迅速上升,烟及挥发分的产物迅速增加,氧的相对含量下降,之后燃烧减弱,温度迅速下降;燃烧区高温烟气沿着顶板逆向迁移至密闭墙,使附近的温度迅速上升至293 ℃;快速密闭设施必须要有一定的刚性和耐火特性;对贫氧燃烧,有利于火区的惰化,而对富氧高挥发分燃料火灾,有爆炸的危险;适当减少供风量,截断供风后应及时采取惰化措施.     

2014年10月上旬北京市大气重污染分析

使用垂直观测、地面观测和PM2.5化学组分观测等手段,对2014年10月上旬北京市一次重污染过程进行分析.结果表明,本次大气重污染发生时北京市近地面后散射激光强度变强,气溶胶消光系数升高,说明污染物在近地面层积累.重污染期间气象要素特征为:风场弱,湿度大,地面受弱气压场控制.从PM2.5浓度变化趋势来看,这次重污染过程大体分为四个阶段:“两个台阶”型的浓度爬升阶段(P1和P2)、高浓度维持阶段(P3)和迅速清除阶段(P4).结合地面观测、遥感反演和PM2.5组分分析可发现,区域传输是导致本次重污染的诱因,其中秸秆焚烧是影响因素之一,随后区域传输和本地污染物排放共同维持并加重了重污染过程.大气氧化剂OX与PM2.5浓度、二次离子浓度均表现出显著正相关性,表明较强的大气氧化性能促进PM2.5浓度增长.