Local Pollutant Emissions Research Articles

Does water scarcity shift the electricity generation mix toward fossil fuels? Empirical evidence from the United States

Water withdrawals for the energy sector are the largest use of fresh water in the United States. Using an econometric model of monthly plant-level electricity generation levels between 2001 and 2012, we estimate the effect of water scarcity on the US electricity fuel mix. We find that hydroelectric generation decreases substantially in response to drought, although this baseline generation is offset primarily by natural gas, depending on the geographic region. We provide empirical evidence that drought can increase emissions of CO2 and local pollutants. We quantify the social costs of water scarcity to be $330,000 per month for each plant that experiences a one-standard deviation increase in water scarcity (2015 dollars), a relationship that persists under future projections of water scarcity.

Optimal energy management in series hybrid electric bicycles

Light electric vehicles are a viable way of reducing urban congestion and local pollutant emissions. Electric bicycles combine electrical and human power, hence they represent an appealing class of hybrid vehicles in such a context. Differently from other hybrid vehicles, the energy management of hybrid bicycles is little investigated in the literature. In this work, we study the problem for a series electric-human-powered hybrid architecture, in which there is no direct mechanical link between the pedals and the wheel. We tackle the problem using optimal control principles, aiming to minimize the perceived physical exertion while guaranteeing a predetermined electric range. We build on an approximated solution of the problem and propose a control system that copes with incomplete trip information. In a series of simulation and experimental tests, the proposed strategy approaches the acausal optimum and significantly improves performance if compared to a baseline causal policy; the discussion also encompasses the sensitivity of the results to the requested information.

Impacts of time restriction on heavy truck corridors: The case study of Mexico City

This paper presents a macroscopic analysis of the impact that a time restriction policy for heavy trucks on the main access corridors in Mexico City has on traffic congestion and local pollutant emissions (NOx and CO). The time restriction is a heavy truck ban at the morning rush hour.Four groups of scenarios (15 scenarios) are analyzed, taking into consideration the reactions from carriers, which were obtained from a survey. These reactions are changes to truck paths, truck size and operational schedule (off-peak operations), and the use of consolidation centers. Some scenarios also consider road infrastructure improvement as a complementary policy. This paper describes data collection and statistical analysis, the O-D matrix obtained from each scenario and the traffic assignment process. The comparison of scenarios indicates that: (1) The time restriction policy for heavy trucks on the main access corridors has a negative impact on the whole city’s total congestion and local emissions; and (2) The implementation of consolidation centers beyond the area of restriction to available land without adequate road infrastructure does not reduce the impact of the time restriction policy.

The air quality co-benefit of coal control strategy in China

Coal keeps dominating the primary energy consumption in China, and is highly-related to the carbon emission and air quality challenge. Recently, China has submitted its Intended Nationally Determined Contribution (INDC) and committed to peak the carbon emission around 2030, and reduce the emission intensity by 60%–65% in 2030 compared to the 2005 level. Moreover, severe haze problem blanketed China in recent years and tends to getting worse, which is directly related to fossil fuel combustion, especially coal consumption in China. To address these challenges, this study carried out an analysis on effect of coal control strategy to energy system and local pollutant reduction. A bottom-up model of China-MAPLE is developed, linking the carbon emission and local pollutant emissions to the coal control policy scenarios. Four scenarios are designed for the energy system and co-benefit study. Three main conclusions can be drawn based on the study: first, the deep energy conservation measures including coal control has apparent effect on the energy system optimization, and the coal peaking year is near 2020 which is highly related and consistent with the carbon peaking. Second, the end-of-pipe control measures will significantly reduce the local pollutant emission, however the reduction is not sufficient enough to achieve the air quality standard. Energy conservation measures, especially coal control strategy, are essential for the source control side. Third, for the co-control from both source control and end-of-pipe control, emission of SO2, NOX and PM2.5 in 2030 will be reduced by 78.85%, 77.56% and 83.32% compared to the level of 2010, which fits the air quality targets, together with carbon peaking target achieved. In electricity generation sector, the source control measures will contribute 10%–35% in future and coal control measures contributes 17%–40% to the local pollutant reduction. The strategy of coal control is of high importance for carbon mitigation and also local pollutant control.

Energy Saving and CO2 Mitigation of Electric Vehicle (EV) Technology in Lao Transport Sector

The high increase in number of vehicles in Lao transport sector in the medium and long-term happens due to continuous growth in transport service demand, which in turn will increase energy consumption in the transport sector. Electric vehicle (EV) technologies can inhibit increment in energy demand growth and energy-related CO 2 emissions in the transport sector; however, cost remains a barrier for the technology diffusion. In this study, a stock vehicle turnover model of the passenger vehicles was developed to assess the potential of EV technology employment for energy saving and CO 2 mitigation in the case of Lao PDR. Three vehicle technologies of EV were chosen to develop countermeasure scenarios. They were the battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). The Long-rang Energy Alternative Planning (LEAP) model was used to forecast sector-wise transport demand until 2050, considering the base year as 2010. Altogether three scenarios were developed namely, the business as usual (BAU) scenario that relies on conventional internal combustion engine vehicles (ICEVs), and two alternative scenarios, namely CM-R and CM-I scenarios, targeting the penetration of (i) BEVs, (ii) HEVs, and (iii) PHEVs. In addition to the analysis of emission mitigation and energy system impacts, co-benefits of CO 2 mitigation are also investigated in terms of emissions of local air pollutants under modelled scenarios. Results show that in the BAU scenario, energy consumption in the transport sector will increase from 548 ktoe in 2010 to 2,823 ktoe in 2050 while CO 2 emission will increase from 1,656 kt-CO 2 in 2010 to 8,511 kt-CO 2 in 2050. However, in countermeasure scenarios, the high penetration of EV technologies will result in reduction of CO 2 emissions when compared with the BAU scenario. In co-benefit analysis, reduction in emissions of other air pollutants was also observed.

Potential Sources and Formations of the PM2.5 Pollution in Urban Hangzhou

Continuous measurements of meteorological parameters, gaseous pollutants, particulate matters, and the major chemical species in PM2.5 were conducted in urban Hangzhou from 1 September to 30 November 2013 to study the potential sources and formations of PM2.5 pollution. The average PM2.5 concentration was 69 µg·m−3, ~97% higher than the annual concentration limit in the national ambient air quality standards (NAAQS) of China. Relative humidity (RH) and wind speed (WS) were two important factors responsible for the increase of PM2.5 concentration, with the highest value observed under RH of 70%–90%. PM2.5 was in good correlation with both NO2 and CO, but not with SO2, and the potential source contribution function (PSCF) results displayed that local emissions were important potential sources contributing to the elevated PM2.5 and NO2 in Hangzhou. Thus, local vehicle emission was suggested as a major contribution to the PM2.5 pollution. Concentrations of NO2 and CO significantly increased in pollution episodes, while the SO2 concentration even decreased, implying local emission rather than region transport was the major source contributing to the formation of pollution episodes. The sum of SO42−, NO3−, and NH4+ accounted for ~50% of PM2.5 in mass in pollution episodes and the NO3−/EC ratios were significantly elevated, revealing that the formation of secondary inorganic species, particularly NO3−, was an important contributor to the PM2.5 pollution in Hangzhou. This study highlights that controlling local pollution emissions was essential to reduce the PM2.5 pollution in Hangzhou, and the control of vehicle emission in particular should be further promoted in the future.

Distribution and Source Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) and Organochlorine Pesticides (OCPs) in Soils from Shergyla Mountain, Southeast Tibetan Plateau

Soils were collected from Shergyla Mountain shade slope and south-facing slope in southeast Tibetan Plateau (TP) in August 2012 and they were measured for polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs)(including HCHs and DDTs). The concentrations of ∑16PAHs ranged from 99.3 to 1984 ng·g-1 dw, with a mean value of 1017 ng·g-1 dw. HCHs and DDTs in soils samples were in the range of 0.37-2.07 ng·g-1 dw (mean 1.15 ng·g-1 dw) and 0.70-43.9 ng·g-1 dw (mean 9.87 ng·g-1 dw), respectively. The concentrations of all measured compounds were much higher than those in central or western TP,and the PAHs concentration was even up to two orders of magnitude. The concentrations of α-HCH and DDTs in south-facing slope increased with altitude, but HCHs and DDTs in shade slope had no significant correlation with altitude. There was no consistent increasing or decreasing trend of PAHs in shade slope with altitude, and the concentrations of PAHs in south-facing slope showed a higher value in lower altitude, indicating the existence of local pollution emissions. The PAHs profile was dominated by lighter constituents (2 & 3-ring accounted for higher than 85%),inferring that the PAHs in the study area were largely influenced by long range atmospheric transport (LRAT) of pollutants. The special diagnostic ratios of PAHs suggested that PAHs were mainly produced by low temperature combustion of biomass and fossil fuels, except that two sampling sites of shade slope had been possibly influenced by oil residue. The relatively low ratios of α/γ-HCH inferred HCHs in the research area was the result of the combined contribution of the historical technical HCHs and Lindan. The ratios of p,p'-DDE/p,p'-DDT and o,p'-DDT/p,p'-DDT indicated DDTs were from the combined contribution of the historical technical DDTs and dicofol. According to the profile of PAHs, HCHs and DDTs and the meteorological conditions of Shergyla Mountain, the transport of PAHs and OCPs in the study area was mainly influenced by the Indian Monsoon.

Ozone concentrations in air flowing into New York State

Ozone (O3) concentrations measured at Pinnacle State Park (PSPNY), very close to the southern border of New York State, are used to estimate concentrations in air flowing into New York. On 20% of the ozone season (April–September) afternoons from 2004 to 2015, mid-afternoon 500-m back trajectories calculated from PSPNY cross New York border from the south and spend less than three hours in New York State, in this area of negligible local pollution emissions. One-hour (2p.m.–3p.m.) O3 concentrations during these inflowing conditions were 46 ± 13 ppb, and ranged from a minimum of 15 ppb to a maximum of 84 ppb. On average during 2004–2015, each year experienced 11.8 days with inflowing 1-hr O3 concentrations exceeding 50 ppb, 4.3 days with O3 > 60 ppb, and 1.5 days had O3 > 70 ppb. During the same period, 8-hr average concentrations (10a.m. to 6p.m.) exceeded 50 ppb on 10.0 days per season, while 3.9 days exceeded 60 ppb, and 70 ppb was exceeded 1.2 days per season. Two afternoons of minimal in-state emission influences with high ozone concentrations were analyzed in more detail. Synoptic and back trajectory analysis, including comparison with upwind ozone concentrations, indicated that the two periods were characterized as photo-chemically aged air containing high inflowing O3 concentrations most likely heavily influenced by pollution emissions from states upwind of New York including Pennsylvania, Tennessee, West Virginia, and Ohio. These results suggest that New York state-level attempts to comply with National Ambient Air Quality Standards by regulating in-state O3 precursor NOx and organic emissions would be very difficult, since air frequently enters New York State very close to or in excess of Federal Air Quality Standards.

Effect of typhoon on atmospheric aerosol particle pollutants accumulation over Xiamen, China

Great influence of typhoon on air quality has been confirmed, however, rare data especially high time resolved aerosol particle data could be used to establish the behavior of typhoon on air pollution. A single particle aerosol spectrometer (SPAMS) was employed to characterize the particles with particle number count in high time resolution for two typhoons of Soulik (2013) and Soudelor (2015) with similar tracks. Three periods with five events were classified during the whole observation time, including pre – typhoon (event 1 and event 2), typhoon (event 3 and event 4) and post – typhoon (event 5) based on the meteorological parameters and particle pollutant properties. First pollutant group appeared during pre-typhoon (event 2) with high relative contributions of V – Ni rich particles. Pollution from the ship emissions and accumulated by local processes with stagnant meteorological atmosphere dominated the formation of the pollutant group before typhoon. The second pollutant group was present during typhoon (event 3), while typhoon began to change the local wind direction and increase wind speed. Particle number count reached up to the maximum value. High relative contributions of V – Ni rich and dust particles with low value of NO3−/SO42− was observed during this period, indicating that the pollutant group was governed by the combined effect of local pollutant emissions and long-term transports. The analysis of this study sheds a deep insight into understand the relationship between the air pollution and typhoon.

Linking a transport dynamic model with an emissions model to aid air pollution evaluations of transport policies in Latin America

ABSTRACTConsidering the key role of the transport sector in the economy and its contribution to greenhouse gas (GHG) and local air pollutant emissions, the development of integrated techniques to evaluate long-term urban trends should be a top priority for creating a more sustainable society. This paper presents an integrated model for reliable estimation of passenger transport emissions of local pollutants and CO2 using an integrated Land-Use and Transport Interaction (LUTI) model in Bogota (Colombia) between 2010 and 2026. Two additional scenarios are modelled to illustrate the use of the model to evaluate the impacts of possible policy interventions. An alternative system dynamics approach is proposed as part of a structured decision-making process. The methodology uses causal loop diagrams (CLD) from systems dynamics to explain cause-and-effect relations, through linking the transport emissions and transport subsystems. The emissions model considers 11 different vehicle categories in total and emission factors for CO2, NOx, THC and PM2.5 were established using local data collected with portable devices and from other available secondary sources. Adjustment factors were established in order to account for ageing of vehicles, technology improvements and changes in category distributions. The development of a general framework based on dynamic systems for assessing long-term emissions estimations according with the particular transport systems is needed for effective sustainable transport planning. The inclusion of adjustment factors for ageing and technology changes provides more reliable projections and helps identify important long-term trends in the emissions inventory. The scenarios proposed are meant to show the results obtained by the model to assist the decision-making process and do not represent current measures in the city or the best practices available. Due to an increase in the use of the private car transport, CO2 emissions will continue to grow in Bogota despite possible technology improvements. Results show that the use of natural gas in the public transport fleet would imply considerable emission reductions in all studied species, being this an alternative technology while electric buses become financially viable.

Current and future prospects for heat recovery from waste in European district heating systems: A literature and data review

Municipal solid waste has seen increasing annual volumes for many decades in contemporary Europe and constitutes, if not properly managed, an environmental problem due to local pollution and greenhouse gas emissions. From an energy perspective, waste is also an alternative fuel for power and heat generation; energy recovery from waste represents an effective measure to reduce landfilling and avoid disposal emissions while simultaneously reducing the equivalent demand for primary energy supply. A key factor for obtaining the full synergetic benefits of this energy recovery is the presence of local heat distribution infrastructures, without which no large-scale recovery and utilisation of excess heat is possible. In this paper, which aims to estimate municipal solid waste volumes available for heat recovery in European district heating systems in 2030, a literature and data review is performed to establish and assess current and future EU (European Union) waste generation and management. Main conclusions are that more heat can be recovered from current Waste-to-Energy facilities operating at low average heat recovery efficiencies, that efficient incineration capacity is geographically concentrated, and that waste available for heat recovery in 2030 is equally determined by total generation volumes by this year as by future EU deployment levels of district heating.

Seasonal Variation of Aerosol Optical Properties in an Urban Site of the Yangtze Delta Region of China

ABSTRACTThe characteristics of aerosol optical properties during 2012 at Hangzhou (30°14′N, 120°10′E), an urban site in the Yangtze Delta Region of China, were analyzed, including aerosol scattering and absorption coefficients, aerosol optical depth (AOD), Angstrom exponent (α), single scattering albedo (SSA), and aerosol size distribution. Both aerosol absorption and scattering coefficients were lowest in summer; the highest absorption coefficient was observed in autumn; while the scattering was highest in winter. There were no significant differences in the seasonal average of AOD, with values of approximately 1.0 in spring, autumn and winter, and 0.72 in summer. The averaged Angstrom exponent was found to be relatively high throughout the year, with a minimum value of 1.14 in spring and a maximum of 1.35 in autumn. The fine modes of the aerosol volume size distributions showed the highest peak around radius 0.15 µm in spring, autumn and winter, and radius 0.25 µm in summer, while the coarse modes showed maximum peaks at radius 2.9 µm in all seasons. The volume concentrations of coarse mode aerosols over Hangzhou were highest in spring compared with other seasons. The mean total SSA values were 0.89, 0.93, 0.89 and 0.88 at 440 nm for spring, summer, autumn and winter, respectively, indicating that the aerosols were mainly composed of scattering particles in Hangzhou. Furthermore, it was found continuous pollution events appeared in East China as a result of biomass burning during June 10–13 in 2012. The main causes of extremely severe air pollution and poor visibility in Hangzhou were related to the long-distance transport of pollutants, local pollution emission and stagnant weather conditions. Aerosol optical properties exhibited high value in absorption AOD and high aerosol volumes, low SSA in coarse mode after biomass burning.

Numerical Investigation of Hybrid Electric Vehicle’s Performance

This paper presents a comparative study about the performance of a classic, hybrid and electric bus by computer simulation using AVL Cruise software. The simulation tasks include main energetic, functional and dynamic parameters, over the usual city bus drive cycle. Based on the simulation results, a comparative analysis was performed for the three models of buses used for urban passenger transport. Hybrid and electric vehicles have been developed with the aim of saving energy, reducing local pollutant emissions and can be considered to offer the best short term to mid-term promise. The impact on the fuel economy generally improves by more than 50 % in urban passenger’s traffic using hybrid buses.

WRF-Chem 모형을 이용한 한반도 대기질 모의: 화학 초기 및 측면 경계 조건의 영향

There is an increasing need to improve the air quality over South Korea to protect public health from local and remote anthropogenic pollutant emissions that are in an increasing trend. Here, we evaluate the performance of the WRF-Chem (Weather Research and Forecasting-Chemistry) model in simulating near-surface air quality of major Korean cities, and investigate the impacts of time-varying chemical initial and lateral boundary conditions (IC/BCs) on the air quality simulation using a chemical downscaling technique. The model domain was configured over the East Asian region and anthropogenic MICS-Asia 2010 emissions and biogenic MEGAN-2 emissions were applied with RACM gaseous chemistry and MADE/SORGAM aerosol mechanism. Two simulations were conducted for a 30-days period on April 2010 with chemical IC/BCs from the WRF-Chem default chemical species profiles ('WRF experiment') and the MOZART-4 (Model for OZone And Related chemical Tracers version 4) ('WRF_MOZART experiment'), respectively. The WRF_MOZART experiment has showed a better performance to predict near-surface CO, , , and mixing ratios at 7 major Korean cities than the WRF experiment, showing lower mean bias error (MBE) and higher index of agreement (IOA). The quantitative impacts of the chemical IC/BCs have depended on atmospheric residence time of the pollutants as well as the relative difference of chemical mixing ratios between the WRF and WRF_MOZART experiments at the lateral boundaries. Specifically, the WRF_MOZART experiment has reduced MBE in CO and O3 mixing ratios by 60~80 ppb and 5~10 ppb over South Korea than those in the WRF-Chem default simulation, while it has a marginal impact on and mixing ratios. Without using MOZART-4 chemical IC, the WRF simulation has required approximately 6-days chemical spin-up time for the East Asian model domain. Overall, the results indicate that realistic chemical IC/BCs are prerequisite in the WRF-Chem simulation to improve a forecast skill of local air quality over South Korea, even in case the model domain is sufficiently large to represent anthropogenic emissions from China, Japan, and South Korea.

Building Beltways To Abate Exposure To Diesel Exhaust In Developing-Country Megacities: Evidence From São Paulo

We examine the inauguration of the Greater São Paulo beltway and argue that investment in certain types of transport infrastructure, though unlikely to relieve congestion, may alter the composition of urban road users and thus of local pollutant emissions, with sizable impacts to public health, particularly in the world's emerging megacities. The beltway diverted diesel-burning heavy-duty vehicles away from roads inside the city, making room for gasoline-ethanol light vehicles that soon filled available road spaces, consistent with the “law of road congestion.” Alongside a transient decline in road congestion, we find evidence of a large and persistent decline in ambient NOx (NOx=NO+NO2) levels, a marker for diesel exhaust and diesel particulate matter, particularly in the high-density areas in close proximity to the original truck routes. We then investigate patient-level hospital admissions and show that the policy-driven shift in ambient air pollution resulted in lower incidence of respiratory and cardiovascular disease, particularly among the young and the elderly, and with no effect on trauma admissions. We use a difference-in-difference design to quantify the beltway's effect on local air, followed by instrumental variables regression to quantify the effect of the beltway-induced change in pollution on health outcomes. Such localized policies have the potential to avert 200,000 hospitalizations and 20,000 deaths across the 20 largest developing cities each year.

Renewable energy scenario in India: Opportunities and challenges

Majority of the power generation in India is carried out by conventional energy sources, coal and fossil fuels being the primary ones, which contribute heavily to greenhouse gas emission and global warming. The Indian power sector is witnessing a revolution as excitement grips the nation about harnessing electricity from various renewable energy sources. Electricity generation from renewable sources is increasingly recognized to play an important role for the achievement of a variety of primary and secondary energy policy goals, such as improved diversity and security of energy supply, reduction of local pollutant and global greenhouse gas emissions, regional and rural development, and exploitation of opportunities for fostering social cohesion, value addition and employment generation at the local and regional level. This focuses the solution of the energy crisis on judicious utilization of abundant the renewable energy resources, such as biomass, solar, wind, geothermal and ocean tidal energy. This paper reviews the renewable energy scenario of India as well as extrapolates the future developments keeping in view the consumption, production and supply of power.Research, development, production and demonstration have been carried out enthusiastically in India to find a feasible solution to the perennial problem of power shortage for the past three decades. India has obtained application of a variety of renewable energy technologies for use in different sectors too. There are ample opportunities with favorable geology and geography with huge customer base and widening gap between demand and supply. Technological advancement, suitable regulatory policies, tax rebates, efficiency improvement in consequence to R&D efforts are the few pathways to energy and environment conservation and it will ensure that these large, clean resource bases are exploited as quickly and cost effectively as possible. This paper gives an overview of the potential renewable energy resources in Indian context while evaluating the present status, the energy demand of the country and forecast consumption and production, with the objective to evaluate and assess whether India can sustain its growth and its society with renewable resources.

Sowing the Wind and Reaping the Whirlwind? The Effect of Wind Turbines on Residential Well-Being

We investigate the effect of the physical presence of wind turbines on residential well-being in Germany, using panel data from the German Socio-Economic Panel (SOEP) and a unique novel panel data set on more than 20,000 wind turbines for the time period between 2000 and 2012. Using a Geographical Information System (GIS), we calculate the proximity between households and the nearest wind turbine as the most important determinant of their disamenities, e.g. visual interference into landscape aesthetics. Our unique novel panel data set on wind turbines, which was collected at the regional level, includes their exact geographical coordinates and construction dates. This allows estimating the causal effect of the physical presence of wind turbines on residential well-being, using a difference-in-differences design. To ensure comparability of the treatment and control group, we apply propensity-score and novel spatial matching techniques based on exogenous weather data and geographical locations of residence, respectively. We show that the construction of a wind turbine within a treatment radius of 4,000 metres around households has a significantly negative effect on life satisfaction. For larger treatment radii, no negative externalities can be detected. Moreover, the effect is transitory, vanishing after five years at the latest. As wind turbines are addressed at avoiding negative externalities of local pollutant and global greenhouse gas emissions, they fulfill an important role in the de-carbonization of electricity systems world-wide. Comparing the imposed spatially and temporally limited externalities with the avoided externalities from emissions, the positive impact of wind turbines is by several magnitudes higher than the negative.

Evolution of aerosol vertical distribution during particulate pollution events in Shanghai

A set of micro pulse lidar (MPL) systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011. Three typical particulate pollution events (e.g., haze) were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer (PBL) during these pollution episodes. The aerosol vertical extinction coefficient (VEC) at any given measured altitude was prominently larger during haze periods than that before or after the associated event. Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering, leading to different aerosol vertical distribution structures. Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions. Several peaks in aerosol VECs were found at altitudes above 1 km during the dust- and bioburning-influenced haze events. Aerosol VECs decreased with increasing altitude during the local-polluted haze event, with a single maximum in the surface atmosphere. PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events; subsequently, PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages. The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.

Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China

Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients (σsc), absorption coefficients (σab), Angström exponent (α), single scattering albedo (ω), backscattering ratio (βsc), aerosol mass scattering proficiency (Qsc) and aerosol surface scattering proficiency (Qsc′) were obtained. The mean statistical values of σsc were 77.45Mm−1 (at 450nm), 50.72Mm−1 (at 550nm), and 32.02Mm−1 (at 700nm). The mean value of σab was 7.62Mm−1 (at 550nm). The mean values of α, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters (ED) of aerosols were less than 0.8μm. The vertical profiles of σsc,, α, βsc, Qsc and Qsc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Qsc, Qsc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions.

Assessment of energy-saving and emission reduction potentials in China’s ammonia industry

As one of the most energy-, emission- and pollution-intensive industries, the production of ammonia is responsible for significant emissions of greenhouse gases (GHGs) and local air pollutants. Although many energy efficiency measures have been proposed by Chinese government to mitigate GHG emissions and improve air quality, a less than full understanding of the costs and potentials have been barrier to promoting and implementing these measures. Assessing the costs, benefits, and cost-effectiveness of different energy efficiency measures is essential to advancing this understanding. In this study, a bottom-up energy conservation supply curve was used to estimate the potential of 26 energy efficiency measures in China’s ammonia industry. Their cost-effective implementation results in a potential saving of 271.5 PJ/year for fuels and 5.44 TWh/year for electricity, which equals to 14 % and 14 % of fuel and electricity consumed in the ammonia industry in 2012, and would be responsible for mitigating emissions of annual 26.7 Mt CO2. In addition, the co-benefits of air pollutants emission reductions that result from energy savings were quantified. The results advance the understanding of the cost-effectiveness of energy efficiency measures and can be used to augment the efforts in reducing energy use and environmental impacts.