RESEARCH: Optimizing the Mix of Strategies for Control of Vehicular Emissions

/ A number of strategies for the control of vehicular emissions are being considered by the Philippine government to address Metropolitan Manila's air quality problem. An analytical tool is needed for optimizing criteria pollutant reductions given the budgetary constraints. The simplest approach is to take costs and pollutant removals to be linear with each strategy's scale of activity, and this is readily solved as a linear programming problem. Another approach is to use a dynamic system of weights which shift with progressive improvements in pollutant emissions. The two approaches yield somewhat different results, suggesting the sensitivity of the solution to the assumed weights. The study also illustrates the importance of a sound methodology for evaluating priorities given to different air quality goals. One such methodology may involve a polling of expert panels and the public to gain insight into the relative importance given to competing emissions reduction goals. An informal polling of resource agency staff was conducted and discussed in this paper. The authors take the position that proper planning involves tracing intermediate steps to the final outcome and not just focusing on the latter.KEY WORDS: Vehicular emissions; Urban air quality; Emissions control; Optimization; Manila; Environmental systems analysis     

The Clean Development Mechanism and Sustainable Development in China''''s Electricity Sector

1 INTRODUCTIONEnergy and environmental issues in China have receivedsignificant attention in both the peer-reviewed literatureand in international energy and environmental policymaking in the last number of years. China's coal dominatedenergy consumption results in significant regional pollutionproblems, most notably acid rain that affects nearly 1/3rdof China's landmass and air pollution that plagues manyof its major cities. China now ranks as the top emitterof sulphur dioxide (SO2) pol…     

Global and regional abatement costs of Nationally Determined Contributions (NDCs) and of enhanced action to levels well below 2 °C and 1.5 °C

As part of the Paris climate agreement, countries have submitted (Intended) Nationally Determined Contributions (NDCs), which includes greenhouse gas reduction proposals beyond 2020. In this paper, we apply the IMAGE integrated assessment model to estimate the annual abatement costs of achieving the NDC reduction targets, and the additional costs if countries would take targets in line with keeping global warming well below 2 °C and “pursue efforts” towards 1.5 °C. We have found that abatement costs are very sensitive to socio-economic assumptions: under Shared Socioeconomic Pathway 3 (SSP3) assumptions of slow economic growth, rapidly growing population, and high inequality, global abatement costs of achieving the unconditional NDCs are estimated at USD135 billion by 2030, which is more than twice the level as under the more sustainable socio-economic assumptions of SSP1. Furthermore, we project that the additional costs of full implementation of the conditional NDCs are substantial, ranging from 40 to 55 billion USD, depending on socio-economic assumptions. Of the ten major emitting economies, Brazil, Canada and the USA are projected to have the highest cots as share of GDP to implement the conditional NDCs, while the costs for Japan, China, Russia, and India are relatively low. Allowing for emission trading could decrease global costs substantially, by more than half for the unconditional NDCs and almost by half for the conditional NDCs. Finally, the required effort in terms of abatement costs of achieving 2030 emission levels consistent with 2 °C pathways would be at least three times higher than the costs of achieving the conditional NDCs – even though reductions need to be twice as much. For 1.5 °C, the costs would be 5–6 times as high.     

长白山温带森林挥发性有机物的排放通量

2010年夏季,在长白山温带森林开展了挥发性有机物(VOC)排放通量以及气象参数、PAR的综合测量.VOC排放通量采用松弛涡度积累(RelaxedEddyAccumulation)技术在森林冠层上进行测量.初步发现长白山阔叶林主要排放α-蒎烯、β-蒎烯、莰烯、香桧烯、月桂烯、蒈烯、柠檬烯、罗勒烯、松油烯、繖花烃、萜品油烯、三环烯等.研究表明,长白山阔叶混交林VOC排放有明显的日变化——早晚较低和中午前后较高.2010年夏季,单萜烯总排放通量的平均值为0.242mg·m·h-2-1,其变化范围为0.005～1.668mg·m·h-2-1;各成分排放通量的平均值(和最大值)分别为α-蒎烯0.072(0.234)、莰烯0.028(0.356)、月桂烯0.027(0.433)、蒈烯0.023(0.173)、柠檬烯0.037(0.197)、罗勒烯0.016(0.168)、萜品油烯0.053(0.320)、繖花烃0.067(0.755)mg·m·h-2-1.研究还发现VOC排放通量与气温之间存在一定的联系.     

掺甲醇汽油对国III汽油机排放性能影响

在一台整车试验满足国III排放法规要求的多点电喷汽油机上,采用甲醇掺入汽油的混合燃料（甲醇的体积分数分别为0%、15%和50%）进行台架试验,使用傅里叶变换红外光谱分析仪（FTIR）在线检测了常规车用三效催化转化器前后的常规和非常规排放.研究结果表明：怠速工况下,掺醇燃料对NOx排放基本没有影响,但CO和HC随掺醇比增加而普遍降低,非常规排放中乙醛排放有所降低,甲醇和甲醛则随掺醇比的增加有较大幅度升高,热怠速时经催化后掺醇燃料对各种排放均无影响,可被控制在极低的水平;其它工况下,随掺醇比增加,CO和HC减少,NOx在高掺醇比下低速低负荷和高速高负荷时有较为明显的改善,非常规排放甲醛和甲醇排放随掺醇比增大而急剧增加,乙醛排放则随之减少.经三效催化转化器作用,无论常规排放NOx、CO和HC,还是非常规排放甲醛、甲醇和乙醛基本上能够实现零排放.     

杂质对废塑料裂解产物及污染物排放的影响

从垃圾中分选出的废塑料混有大量杂质,杂质对现有废塑料裂解工艺有直接的影响.针对这一问题,对混有厨余、纸、织物和渣土等杂质的废塑料裂解产物和污染物排放进行了研究.同时检测和分析了厨余、纸、织物和沙土等常见杂质所含N、Cl、S元素向裂解油、裂解气中的迁移规律.研究表明,厨余的混入将对裂解油的产物产生严重不利影响,如热值降低至27 MJ/kg,油品的含水率高达25%以及多环芳烃含量大大提高,因而应在分选过程中除去.厨余、织物和纸张等杂质的混入导致裂解气体中污染物浓度的显著上升.渣土的混入对气体产物有有利影响,对油品无明显不利影响.     

生物质炭对华北平原4种典型土壤N2O排放的影响

生物质炭作为一种新型的土壤改良剂,在降低土壤温室气体排放方面发挥着重要作用.为明确生物质炭对冬小麦苗期土壤N_2O排放的影响,以华北平原的4种典型土壤(水稻土、砂姜黑土、褐土和潮土)为研究对象,进行田间试验,设置了4个处理:对照(CK)、单施化肥(NPK)、单施生物质炭(BC)和化肥与生物质炭配施(NPK+BC).结果表明,单施化肥显著增加了4种土壤N_2O排放,与对照相比,水稻土、砂姜黑土、褐土和潮土N_2O排放分别增加了314%、116%、240%和282%.添加生物质炭对华北平原4种土壤N_2O排放影响存在差异,与CK相比,单施生物质炭水稻土、褐土N_2O排放显著增加了72. 4%和50. 9%,而砂姜黑土和潮土BC与CK处理无显著差异.与NPK相比,生物质炭与化肥配施显著降低了4种土壤N_2O排放.添加生物质炭提高了4种土壤pH,其中,初始pH最低的水稻土,受生物质炭影响较显著,施肥则降低了4种土壤pH.砂姜黑土、褐土和潮土施肥处理N_2O排放通量均与铵态氮含量呈显著正相关,水稻土和砂姜黑土单施生物质炭处理N_2O排放通量与硝态氮含量呈显著正相关.     

柑橘/大球盖菇套作下土壤CO2排放及其效率对秸秆还田量的响应

以柑橘/大球盖菇套作模式为研究对象,利用秸秆作为大球盖菇的培养基原料,通过原位试验,连续监测大球盖菇生长期内,不同秸秆还田量(半量、全量和倍量)下土壤CO_2排放规律,并进一步对比栽培大球盖菇(HSM、ASM和DSM)和未栽培大球盖菇(HS、AS和DS)处理下土壤CO_2排放量变化及其影响因素,结合大球盖菇产量及土壤碳排放效率,分析不同秸秆还田量所产生的环境及经济效益,为合理利用柑橘园林下土地提供理论依据.结果表明:①秸秆还田处理的土壤CO_2累积排放量均高于常规种植(CK),随着秸秆还田量的增加呈增加趋势;且栽培大球盖菇处理的土壤CO_2累积排放量大于未栽培大球盖菇,表现为:DSM(52. 09 t·hm-2) ASM(41. 10 t·hm-2) HSM(33. 20 t·hm-2) DS(27. 15 t·hm-2) AS(25. 34t·hm-2) HS(18. 94 t·hm-2) CK(12. 16 t·hm-2);其中,倍量秸秆填埋还田+栽培大球盖菇(DSM)处理的土壤CO_2累积排放量增加最为显著,较CK增加了328. 37%;②对于栽培了大球盖菇的处理,土壤CO_2排放量最大时段均集中在大球盖菇菌丝生长期,其次为出菇后和出菇期;其中DSM处理在菌丝生长期的土壤CO_2累积排放量占其总累积排放量的43. 27%,其次为全量秸秆填埋还田+栽培大球盖菇(ASM,42. 63%)和半量秸秆填埋还田+栽培大球盖菇(HSM,40. 57%);③栽培大球盖菇处理降低了温度敏感系数Q10; 5cm土壤温度能解释27%～71%的土壤CO_2排放速率变化(P 0. 01),而土壤体积含水量单因子对土壤CO_2排放速率不存在显著影响;但双因子拟合发现,5 cm土壤温度和体积含水量可以解释土壤CO_2排放速率变化的36%～82%;④对于栽培了大球盖菇的处理,各处理产量分别为:DSM(49. 7 t·hm-2) ASM(47. 0 t·hm-2) HSM(23. 3 t·hm-2),其中ASM的土壤碳排放效率最高(CEE=1. 14).综上,柑橘/大球盖菇套作模式短期内会显著促进土壤CO_2排放,但同时也提高了柑橘园综合经济效益,其中全量秸秆还田能较好地协调其产生的经济及环境效益.     

南京地区一次臭氧污染过程的行业排放贡献研究

采用WRF-CHEM模式对南京地区春季一次臭氧(O_3)污染过程进行了模拟及行业排放贡献分析.此次O_3污染过程发生在2015年5月22—26日,南京地区一直处于地面高压控制的晴好天气之下,并于25日达到O_3污染的峰值.模拟与观测的一致性指数IOA达到0.89,表征本次O_3污染过程的模拟与观测结果的一致性较高.通过5类排放源(工业源、农业源、居住源、交通源、生物源)的敏感性试验,探究各行业排放源中O_3前体物对近地面O_3浓度的相对贡献.结果表明工业源在白天为持续正贡献,且在午后16:00时达到峰值,而交通源、居住源和农业源的贡献随气温的升高在白天由负贡献转为正贡献,并在18:00时左右达到峰值.在夜晚,O_3则主要通过交通源排放的大量NO进行滴定消耗.在高O_3浓度(≥200μg·m~(-3))时,各人为排放源均为正贡献,工业源的贡献最大,达到50μg·m~(-3),在低O_3浓度(200μg·m~(-3))时,交通源、居住源和农业源呈负贡献.生物源在人为排放源主导的南京城区O_3污染过程中的贡献几乎为零.考虑到O_3生成机制的复杂性,对于南京地区,减少工业源排放是控制O_3污染的关键.     

基于数据挖掘算法和数值模拟技术的大气污染减排效果评估

近年来,京津冀地区采取了大量污染减排措施进行大气污染治理,如何客观评估减排效果是目前大气环境领域的研究难点.为准确评估大气污染过程的减排效果,本文利用北京地区常规气象资料、国控站PM_(2.5)浓度资料,遴选了北京地区2018年3月11—14日和2013年3月14—17日两次空气污染过程,计算了大气容量系数、静稳指数,并利用KNN数据挖掘算法和WRF-Chem模式,对比分析了有无减排条件下的PM_(2.5)日均浓度.结果表明:两次空气污染过程的天气形势和局地气象条件较相似,就大气热力和动力的垂直结构来看,2018年空气污染过程比2013年空气污染过程的大气稳定性更强、边界层高度更低、环境容量更小,但PM_(2.5)峰值浓度却显著下降,平均浓度明显降低,PM_(2.5)小时浓度的增长趋势相对平缓,重污染持续时间缩短.KNN数据挖掘算法减排评估结果显示,该方法能够较好地预测PM_(2.5)日均浓度的变化趋势,2018年3月11—14日,在减排和不减排情景下PM_(2.5)日均值分别为171和229μg·m~(-3),减排使得污染过程PM_(2.5)平均浓度下降了25.3%.数值模拟结果与KNN数据分析结论吻合,进一步验证了减排措施的有效性.综合看来,2018年空气污染过程中PM_(2.5)浓度相比历史相似气象条件下的污染过程显著降低,这是长期大力度减排效果的体现.