Numerical model to quantify biogenic volatile organic compound emissions:The Pearl River Delta region as a case study

This article compiles the actual knowledge of the biogenic volatile organic compound（BVOC） emissions estimated using model methods in the Pearl River Delta（PRD） region, one of the most developed regions in China. The developed history of BVOC emission models is presented briefly and three typical emission models are introduced and compared. The results from local studies related to BVOC emissions have been summarized. Based on this analysis, it is recommended that local researchers conduct BVOC emission studies systematically, from the assessment of model inputs, to compiling regional emission inventories to quantifying the uncertainties and evaluating the model results. Beyond that,more basic researches should be conducted in the future to close the gaps in knowledge on BVOC emission mechanisms, to develop the emission models and to refine the inventory results. This paper can provide a perspective on these aspects in the broad field of research associated with BVOC emissions in the PRD region.

Volatile organic compound emissions from straw-amended agricultural soils and their relations to bacterial communities:A laboratory study

A laboratory study was conducted to investigate volatile organic compound（VOC） emissions from agricultural soil amended with wheat straw and their associations with bacterial communities for a period of 66 days under non-flooded and flooded conditions. The results indicated that ethene, propene, ethanol, i-propanol, 2-butanol, acetaldehyde, acetone,2-butanone, 2-pentanone and acetophenone were the 10 most abundant VOCs, making up over 90% of the total VOCs released under the two water conditions. The mean emission of total VOCs from the amended soils under the non-flooded condition（5924 ng C/（kg·hr）） was significantly higher than that under the flooded condition（2211 ng C/（kg·hr））. One ＂peak emission window＂ appeared at days 0–44 or 4–44, and over 95% of the VOC emissions occurred during the first month under the two water conditions. Bacterial community analysis using denaturing gradient gel electrophoresis（DGGE） showed that a relative increase of Actinobacteria, Bacteroidetes, Firmicutes and γ-Proteobacteria but a relative decrease of Acidobacteria with time were observed after straw amendments under the two water conditions. Cluster analysis revealed that the soil bacterial communities changed greatly with incubation time, which was in line with the variation of the VOC emissions over the experimental period. Most of the above top 10 VOCs correlated positively with the predominant bacterial species of Bacteroidetes, Firmicutes and Verrucomicrobia but correlated negatively with the dominant bacterial species of Actinobacteria under the two water conditions. These results suggested that bacterial communities might play an important role in VOC emissions from straw-amended agricultural soils.

Disposal of waste-based fuels and raw materials in cement plants in Germany and Switzerland e What can be learned for global coincineration practice and policy?

The limit value for emissions of total organic carbon(TOC)for incinerators in the European Union(EU)is 10 mg/m3.However,clinker burning is a material conversion process during which TOC emissions from the fuels occur concurrently with the thermal decomposition of organic material from the raw material mixture(limestone,marl,shale,etc.)in the preheater,which alone can emit more than 10 mg/m3.Therefore,the German legislature has created an exemption that allows authorities to set higher limit values for cement kilns if the cause of the higher emissions is the natural raw material mixture and not the co-incinerated waste.Separating the effects requires a test to determine the baseline emission of the natural raw material or waste raw material.Up until now,these tests were only used internally by companies.By applying such tests,the emissions from the fuels,particularly from waste-based fuels,can be determined,restricted and controlled.TOC emissions from natural materials cannot be avoided.In Switzerland and Germany these emissions are on average around 20e35 mg/m3.Switzerland has recently set a high TOC limit value of 80 mg/m3 for cement kilns,independent of the source of organic emissions,and even allows the use of polychlorinated biphenyl(PCB)contaminated soils as raw material(up to 10 mg/kg).This limit is too high and can result in unnecessary emissions of carcinogenic benzene,PCBs and other pollutants.Both the natural raw materials and waste raw materials emit organic carbon.However,there is one major difference.The natural raw materials emit mostly aliphatic compounds at temperatures up to about 600C,whereas the organic compounds originating from waste-based raw material components can include hazardous pollutants like polychlorinated biphenyls(PCBs)and other persistent organic pollutants(POPs),which desorb in the preheater and are released into the environment.Therefore,waste raw materials such as soils contaminated with POPs or other semivolatile toxic chemicals cannot be introduced via the raw mill-(leading to desorption in the preheater)but need to be fed in the kiln inlet.Cement kilns treating POPs or raw materials with problematic semivolatile organics need strict control and possibly continuous monitoring for dioxins and other POPs.

On-board measurements of gaseous pollutant emission characteristics under real driving conditions from light-duty diesel vehicles in Chinese cities

A total of 15 light-duty diesel vehicles（LDDVs） were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hydrocarbons（HC） and nitrogen oxides（NOx） at different speeds, chemical species profiles and ozone formation potential（OFP） of volatile organic compounds（VOCs） emitted from diesel vehicles with different emission standards were analyzed. The results demonstrated that emission reductions of HC and NOxhad been achieved as the control technology became more rigorous from Stage I to Stage IV. It was also found that the HC and NOxemissions and percentage of O2 dropped with the increase of speed, while the percentage of CO2 increased. The abundance of alkanes was significantly higher in diesel vehicle emissions, approximately accounting for 41.1%–45.2%, followed by aromatics and alkenes. The most abundant species were propene,ethane, n-decane, n-undecane, and n-dodecane. The maximum incremental reactivity（MIR）method was adopted to evaluate the contributions of individual VOCs to OFP. The results indicated that the largest contributors to O3 production were alkenes and aromatics, which accounted for 87.7%–91.5%. Propene, ethene, 1,2,4-trimethylbenzene, 1-butene, and1,2,3-trimethylbenzene were the top five VOC species based on their OFP, and accounted for 54.0%-64.8% of the total OFP. The threshold dilution factor was applied to analyze the possibility of VOC stench pollution. The majority of stench components emitted from vehicle exhaust were aromatics, especially p-diethylbenzene, propylbenzene, m-ethyltoluene, and p-ethyltoluene.

White phosphorescent organic light-emitting diodes using double emissive layer with three dopants for color stability

We fabricate white phosphorescent organic light-emitting diodes （PHOLEDs） with three dopants and double emissive layer （EML） to achieve color stability. The white PHOLEDs use FIrpic dopant for blue EML （B- EML）, and Ir（ppy）3：Ir（piq）3 dopants for green：red EML （GR-EML） with N,N＇-dicarbazolyl-3, 5-benzene （mCP） as host material. Thicknesses of B-EML and GR-EML are adjusted to form a narrow recombination zone at two EML＇s interface and charge trapping happens in EML according to wide highest occupied molecular orbital and/or lowest unoccupied molecular orbital energy band gap of mCP and smaller energy band gap of dopants. The total thickness of both EMLs is fixed at 30 nm in the device structure of ITO （150 nm）/MoO3 （2 nm）/N,N＇-diphenyl-N,N＇-bis（1-naphthyl-phenyl）-（1,1″-biphenyl）-4, 4＇-diamine （70 nm）/ meP：Firpic-8.0% （12 nm）/mCP：Ir（ppy）3-3.0%：Ir（piq）3-1.5% （18 nm）/2″,2＇,2＂＇-（1,3,5-benzinetriyl）-tris（1- phenyl-l-H-benzimidazole） （30 nm）/8-hydroxyquinolinolato-lithium （2 nm）/A1 （120 nm）. White PHOLED shows 18.25 cd/A of luminous efficiency and white color coordinates of （0.358 and 0.378） at 5000 cd/m2 and color stability with slight CIExy change of （0.028 and 0.002） as increasing luminance from 1000 to 5000 cd/m^2.

Bridging the Energy Benefit and POPs Emission Risk from Waste Incineration

Incineration has been the globally controversial and concerned method of solid waste disposal.Energy recovery and volume reduction are the benefits from waste incineration,but risk due to release of persistent organic pollutants is the major public concern in the world.In this study,the emission of organic pollutants including dioxins and polychlorinated naphthalenes from solid waste incineration in China was comprehensively evaluated,and a relationship between energy benefit and pollutant emission was firstly established.The results show that production of medical and industrial waste was smaller than that of municipal waste but yielded comparable or even higher emission of dioxins.The energy benefit-to-emission index for organic pollutants(EBEIOP)for evaluation of solid waste management on a local or regional scale was proposed.Significant correlations between net energy benefit and pollutant emission for provinces with higher EBEIOP values were found.Furthermore,higher EBEIOP values were associated with economic factors while lower values were influenced by emission from incineration of medical and industrial waste.We suggest that an EBEIOP value of R60 can serve as a reference for“profitable”solid waste management,assisting decision making during energy benefit and environmental risk assessment.