Trends in vehicular emissions in China's mega cities from 1995 to 2005

Multiyear inventories of vehicular emissions in Beijing, Shanghai and Guangzhou from 1995 through 2005 have been developed in this paper to study the vehicle emissions trends in China's mega cities during the past decade. The results show that the vehicular emissions of CO, HC, NO_x and PM₁₀ have begun to slow their growth rates and perhaps even to decline in recent years due to the implementation of measures to control vehicular emissions in these cities. However, vehicular CO₂ emissions have substantially increased and still continue to grow due to little fuel economy improvement. Passenger cars and large vehicles (including heavy duty trucks and buses) are the major sources of vehicular CO₂ and CO emissions while large vehicles were responsible for nearly 70% and 80% of the vehicular NO_x and PM₁₀ emissions in these mega cities. Motorcycles are also important contributors to vehicular emissions in Guangzhou and Shanghai.     

Organic Liquids Storage Tanks Volatile Organic Compounds (VOCS) Emissions Dispersion and Risk Assessment in Developing Countries: The Case of Dar-Es-Salaam City, Tanzania

The emission estimation of nine volatile organic compounds (VOCs) from eight organic liquids storage tanks companies in Dar-es-Salaam City Tanzania has been done by using US EPA standard regulatory storage tanks emission model (TANKS 4.9b). Total VOCs atmospheric emission has been established to be 853.20 metric tones/yr. It has been established further that petrol storage tanks contribute about 87% of total VOCs emitted, while tanks for other refined products and crude oil were emitting 10% and 3% of VOCs respectively. Of the eight sources (companies), the highest emission value from a single source was 233,222.94 kg/yr and the lowest single source emission value was 6881.87 kg/yr. The total VOCs emissions estimated for each of the eight sources were found to be higher than the standard level of 40,000 kg/yr per source for minor source according to US EPA except for two sources, which were emitting VOCs below the standard level. The annual emissions per single source for each of the VOCs were found to be below the US EPA emissions standard which is 2,000~kg/yr in all companies except the emission of hexane from company F1 which was slightly higher than the standard. The type of tanks used seems to significantly influence the emission rate. Vertical fixed roof tanks (VFRT) emit a lot more than externally floating roof tanks (EFRT) and internally floating roof tanks (IFRT). The use of IFRT and EFRT should be encouraged especially for storage of petrol which had highest atmospheric emission contribution. Model predicted atmospheric emissions are less than annual losses measured by companies in all the eight sources. It is possible that there are other routes for losses beside atmospheric emissions. It is therefore important that waste reduction efforts in these companies are directed not only to reducing atmospheric emissions, but also prevention of the spillage and leakage of stored liquid and curbing of the frequently reported illegal siphoning of stored products. Emission rates for benzene, toluene, and xylene were used as input to CALPUFF air dispersion model for the calculation of spatial downwind concentrations from area sources. By using global positioning system (GPS) and geographical information system (GIS) the spatial benzene concentration contributed by organic liquid storage tanks has been mapped for Dar-es-Salaam City. Highest concentrations for all the three toxic pollutants were observed at Kigamboni area, possibly because the area is located at the wind prevailing direction from the locations of the storage tanks. The model predicted concentrations downwind from the sources were below tolerable concentrations by WHO and US-OSHA. The highest 24 hrs averaging time benzene concentration was used for risk assessment in order to determine maximum carcinogenic risk amongst the population exposed at downwind. Established risk for adult and children at 2.9×10^-3 and 1.9×10^-3 respectively, are higher than the acceptable US-EPA risk of 1×10^-6. It is very likely that the actual VOCs concentrations in some urban areas in Tanzania including Dar-es-Salaam City are much higher than the levels reported in this study when other sources such as petrol stations and motor vehicles on the roads are considered. Tanzania Government therefore need to put in place: an air quality policy and legislation, establish air quality guidelines and acquire facilities which will enable the implementation of air quality monitoring and management programmes.     

铵盐在典型大气污染过程中的变化特征及来源分析

为了解铵盐在大气中对重污染天气生成的重要作用,于2020年12月26—29日,利用在线单颗粒飞行时间质谱(SPAMS)和在线离子色谱(MARGA),对上海浦东新区一次典型的重污染天气过程进行分析.结果表明:本次污染过程主要与静稳天气下污染物的积聚,尤其是机动车尾气排放的累计效应,以及气态污染物二次转化过程有关.PM_2.5的高污染时段通常伴随着高浓度的硫酸盐、硝酸盐和铵盐,污染过程中NO^-₃、SO■、NH⁺₄最大小时质量浓度分别达到62.3、19.3和26.0μg·m^-3.对ns-NH⁺₄(过量铵根离子物质的量浓度)-NO^-₃之间的回归分析证明,多数情况下浦东大气中氨是富余的.污染高峰时段的主要污染源为机动车尾气源(36.7%)、扬尘源(24.4%)、二次无机源(15.0%),占比升幅最高的污染源为机动车尾气源.     

鄂州市大气VOCs污染特征及来源解析

2018年3月～2019年2月,在鄂州市主城区采用在线气相色谱仪对102种大气挥发性有机物(VOCs)定量检测,对比分析了VOCs组成、季节变化特征和日变化规律,并利用最大增量反应活性(MIR)估算了VOCs的臭氧生成潜势(OFP).结果表明,鄂州大气VOCs年均体积分数为(30.78±15.89)×10^-9,总体表现为冬季高夏季低,具体表现为烷烃>含氧化合物>卤代烃>烯烃>芳香烃>炔烃.日变化规律表现为夜晚体积分数高于白天,且总体上呈"双峰"分布,芳香烃、卤代烃和OVOCs在00:00至02:00出现"第三峰".对VOCs臭氧生成潜势(OFP)贡献较大的是芳香烃和烯烃,贡献率分别为35.45%和29.5%,其中对OFP贡献率最高的物种为乙烯,达到24.217%.分析VOCs特征物种,发现机动车尾气和溶剂使用是鄂州VOCs的主要来源,其中机动车排放是最主要来源,控制鄂州机动车排放有助于削减大气VOCs活性较大的组分,从而减少臭氧的生成.     

温室气体排放数据库系统设计与实现

以温度升高为主要特征的气候变化越来越影响到人类的可持续发展,温室气体排放系数的收集与整理对于该研究具有重要意义。文章在充分调研IPCC指南及相关排放系数文献的基础上,对温室气体排放系数进行采集与整理,其中对电力行业排放系数的收集细化到不同技术水平、煤质来源水平和区域水平,并在电力行业排放系数收集的基础上,对其他主要工业行业的温室气体排放系数进行收集,完成了数据库设计与建库工作。主要包括四类数据:"温室气体排放系数数据库"、"活动水平数据库"、"电力行业污染物排放数据库"、"元数据库"。在此基础上设计并开发了数据库软件系统,实现了对温室气体排放系数的统一管理与访问。经实际运行,证明该系统能有效管理温室气体排放系数数据,提供数据的分析应用,为温室气体核算和提高环境监管能力提供科学数据和支撑作用。     

Knowledge-based decision-making model for the management of transit system alternative fuel infrastructures

Energy-efficient and environmentally sustainable public transportation systems are within the solution space provided by alternative fuel vehicles. Given the large revenue service potential of alternative fuel buses within the urban space, they are good candidates for emissions reductions when they are employed as part of a comprehensive urban transit planning process. The determination of the most appropriate alternative fuel bus asset for a given application is not necessarily that straightforward. The typical bus fleet is developed over a broad time horizon with each asset being acquired to meet a certain agency need or to close a perceived gap in the delivery of public transportation service. Therefore, as new assets are considered, it is critical for the fleet manager to consider as many factors of the fleet infrastructure to better ensure the positive impact that the newly acquired asset will have on fleet performance relative to the overall service goals and objectives of the fleet. This study investigates a broad range of alternative fuel bus technologies and the associated factors that will inform the decision-making process. Further, this work utilizes the inventory and understanding of the range of technology factors and leverages the perspective knowledge of industry experts on each of these factors to develop an expert systems decision-making philosophy to aid in the adoption of industry standards, best practices, consistency and sustainability in fleet asset management over time.     

Effects of Natura 2000 on nontarget bird and butterfly species based on citizen science data

The European Union's Natura 2000 (N2000) is among the largest international networks of protected areas. One of its aims is to secure the status of a predetermined set of (targeted) bird and butterfly species. However, nontarget species may also benefit from N2000. We evaluated how the terrestrial component of this network affects the abundance of nontargeted, more common bird and butterfly species based on data from long-term volunteer-based monitoring programs in 9602 sites for birds and 2001 sites for butterflies. In almost half of the 155 bird species assessed, and particularly among woodland specialists, abundance increased (slope estimates ranged from 0.101 [SD 0.042] to 3.51 [SD 1.30]) as the proportion of landscape covered by N2000 sites increased. This positive relationship existed for 27 of the 104 butterfly species (estimates ranged from 0.382 [SD 0.163] to 4.28 [SD 0.768]), although most butterflies were generalists. For most species, when land-cover covariates were accounted for these positive relationships were not evident, meaning land cover may be a determinant of positive effects of the N2000 network. The increase in abundance as N2000 coverage increased correlated with the specialization index for birds, but not for butterflies. Although the N2000 network supports high abundance of a large spectrum of species, the low number of specialist butterflies with a positive association with the N2000 network shows the need to improve the habitat quality of N2000 sites that could harbor open-land butterfly specialists. For a better understanding of the processes involved, we advocate for standardized collection of data at N2000 sites.     

Analysis of the impact of tourism on agricultural carbon emissions-based on the mediating effect of nonagricultural transfer of labor in China

How to control the growth of agricultural carbon emissions while developing tourism has become the primary issue that needs addressing in the development of rural China. This paper explores the impact of tourism on agricultural carbon emissions and further analyses the mediating effect of labor transfer in this relationship. The analysis is evaluated using provincial panel data from 31 provinces in China from 2007 to 2019 with a sequential regression model. The results show that tourism development increases agricultural carbon emissions, which is more pronounced in areas with advanced economies or higher education levels. Second, labor transfer to nonfarming industries suppresses the increase in agricultural carbon emissions caused by tourism. Finally, (i) the impact of tourism on labor transfer in less developed and less educated regions is limited, and (ii) there is the expectation of large-scale use of agricultural machinery due to labor transfer in economically developed or highly educated areas. The heterogeneity test shows these two reasons lead to a mediating effect of labor transfer on agricultural carbon emissions in different regions.     

Modeling manure-borne bromide and fecal coliform transport with runoff and infiltration at a hillslope

Hillslope vegetated buffers are recommended to prevent water pollution from agricultural runoff. However, models to predict the efficacy of different grass buffer designs are lacking. The objective of this work was to develop and test a mechanistic model of coupled surface and subsurface flow and transport of bacteria and a conservative tracer on hillslopes. The testing should indicate what level of complexity and observation density might be needed to capture essential processes in the model. We combined the three-dimensional FEMWATER model of saturated-unsaturated subsurface flow with the Saint-Venant model for runoff. The model was tested with data on rainfall-induced fecal coliforms (FC) and bromide (Br) transport from manure applied at vegetated and bare 6-m long plots. The calibration of water retention parameters was unnecessary, and the same manure release parameters could be used both for simulations of Br and FC. Surface straining rates were similar for Br and bacteria. Simulations of Br and FC concentrations were least successful for the funnels closest to the source. This could be related to the finger-like flow of the manure from the strip along the bare slopes, to the transport of Br and FC with manure colloids that became strained at the grass slope, and to the presence of micro-ponds at the grassed slope. The two-dimensional model abstraction of the actual 3D transport worked well for flux-averaged concentrations. The model developed in this work is suitable to simulate surface and subsurface transport of agricultural contaminants on hillslopes and to evaluate efficiency of grass strip buffers, especially when lateral subsurface flow is important.     

卫星遥感数据在林火排放模型中的应用

火对大气中的温室气体和气溶胶的增加有显著影响,也是植被的一个主要干扰因子.利用精确卫星火产品对中国林火排放量进行量化计算,对于制定正确的减排战略具有参考意义.采用GBA2000的研究结果,分析了不同植被区的过火区分布情况.2000年中国林地上共有8 587个过火斑块,总面积为10 773 212 hm2,其中阔叶落叶林过火面积最大,为3 674 404 hm2;其次为阔叶常绿林,过火面积为1 141 402 hm2.林火排放计算模型采用各植被带平均生物量和燃烧系数估计火烧消耗的生物量和计算森林燃烧释放的温室气体量.我国2000年林火释放CO2 688 Tg,CO和CH4分别为57 Tg和4 Tg.计算精度取决于森林火灾面积、土地类型图、燃烧效率和排放因子.由于采用的卫星火产品没有对中国区域进行精度评估,据此统计的森林过火区有误差.如果采用更精确的卫星遥感数据,将提高林火释放模型的计算精度.