Characterization of ammonia emissions from light-duty gasoline vehicles based on real-world driving and dynamometer measurements.

Ammonia (NH3) contributes significantly to the formation of particulate matter, and vehicles represent a major source of NH3 in urban areas. However, there remains a lack of comprehensive understanding regarding the emission characteristics of NH3 from vehicles. This study conducted real-world driving emission (RDE) measurements and dynamometer measurements on 33 light-duty gasoline vehicles (LDGVs) to investigate their emission characteristics and impact factors. The tested vehicles include China 3 to China 6 emission standards. The results show that the average NH3 emission factors of LDGVs decreased by >80 % from China 3 to China 6 emission standards. The results obtained from dynamometer measurements reveal that independent from other conventional pollutants (such as HCHO and NOx), NH3 emissions do not exhibit significant emission peaks during the hot- or cold-start phase. The RDE measurement covers a more comprehensive range of the vehicle's real-world driving conditions, resulting in higher NH3 emission factors compared with dynamometer measurements. The analysis of RDE measurements revealed that NH3 emissions are influenced by vehicle speeds and accelerations. Acceleration processes contribute approximately 50 % of total NH3 emissions over a driving period. Finally, using real driving speed, acceleration, and road gradient as input parameters, an NH3 emission rate model based on vehicle specific power was developed. This emission rate model enables a more precise reflection of LDGVs' NH3 emissions of LDGVs across diverse driving conditions and provides valuable data support for high-resolution inventories of vehicle NH3 emissions.

Atmospheric concentrations and sources of black carbon over tropical Australian waters.

Black carbon (BC) aerosols significantly contribute to radiative budgets globally, however their actual contributions remain poorly constrained in many under-sampled ocean regions. The tropical waters north of Australia are a part of the Indo-Pacific warm pool, regarded as a heat engine of global climate, and are in proximity to large terrestrial sources of BC aerosols such as fossil fuel emissions, and biomass burning emissions from northern Australia. Despite this, measurements of marine aerosols, especially BC remain elusive, leading to large uncertainties and discrepancies in current chemistry-climate models for this region. Here, we report the first comprehensive measurements of aerosol properties collected over the tropical warm pool in Australian waters during a voyage in late 2019. The non-marine related aerosol emissions observed in the Arafura Sea region were more intense than in the Timor Sea marine region, as the Arafura Sea was subject to greater continental outflows. The median equivalent BC (eBC) concentration in the Arafura Sea (0.66 µg m-3) was slightly higher than that in the Timor Sea (0.49 µg m-3). Source apportionment modelling and back trajectory analysis and tracer studies consistently suggest fossil fuel combustion eBC (eBCff) was the dominant contributor to eBC across the entire voyage region, with biomass burning eBC (eBCbb) making significant additional contributions to eBC in the Arafura Sea. eBCff (possibly from ship emissions or oil and gas rigs and their associated activities) and cloud condensation nuclei (CCN) were robustly correlated in the Timor Sea data, whereas eBCbb positively correlated to CCN in the Arafura Sea, suggesting different sources and atmospheric processing pathways occurred in these two regions. This work demonstrates the substantial impact that fossil fuel and biomass burning emissions can have on the composition of aerosols and cloud processes in the remote tropical marine atmosphere, and their potentially significant contribution to the radiative balance of the rapidly warming Indo-Pacific warm pool.

Relationship between Atmospheric PM-Bound Reactive Oxygen Species, Their Half-Lives, and Regulated Pollutants: Investigation and Preliminary Model.

The concentration, nature, and persistence of particulate matter (PM)-bound reactive oxygen species (ROS) are of significant interest in understanding how atmospheric pollution affects health. However, the inherent difficulties in their measurement, particularly regarding the so-called "short-lived" ROS, have limited our understanding of their persistence and concentrations in the atmosphere. This paper aims to address this limitation through the analysis of PM-bound ROS measurements from the Particle Into Nitroxide Quencher (PINQ) system at an atmospheric monitoring site in the city of Heshan, Guangdong Province, China. The measured daily average and standard deviation for the measurement period was 0.050 ± 0.017 nmol·m-3. The averaged measured concentration of ROS per mass of PM and standard deviation was 0.0012 ± nmol·mg. The dataset was also correlated with standard pollutants, and a simplified model was constructed to separate the contributions of short-lived (t1/2 = 5 min) and long-lived (t1/2 ∼ infinity) ROS to total concentration using ozone, carbon monoxide, and PM mass. This showed that the short-lived ROS contribute an average of 33% of the daily PM-bound ROS burden over the measurement period, up to 52% of daily average on elevated days, and up to 71% for hourly averages. These results highlight the need for accurate measurements of short-lived ROS and provide the starting point for a general model to predict PM-bound ROS concentrations using widely available standard pollutants for future epidemiological research.

[Characteristics of Volatile Organic Compounds Emitted from Biomass-pellets-fired Boilers].

A pre-concentrator-GC-MS/FID was used to investigate the characteristics of volatile organic compounds (VOCs) based on the flue gases emitted from five biomass-pellets-fired boilers in this study. And the concentrations of particle matter, nitrogen oxides (NOx), sulfur dioxides (SO2) and mercury and its compounds were also measured. Results demonstrated that the concentrations of SO2 and mercury and its compounds emitted from all five boilers were relatively low, which were lower than the national emission standard, while NOx and particles from some boilers were higher than the standard. The mass concentration of 56 VOC species was in the range of (872.43±293.80)-(6929.66±1137.25) µg·m-3, and the analysis of influencing factors implied that the furnace temperatures and loads havd strong negative correlations with the concentration of total VOCs. The emission components of VOCs were mainly composed of alkenes (41%-59%) including ethylene, 1-butene, cis-2-butene and 1-hexene; alkanes (27%-49%) including hexane, isopentane and cyclopentane; and aromatics (6%-18%) including benzene and toluene. Moreover, the maximum incremental reactivity (MIR) method was applied to analyze ozone formation potential (OFP) of VOCs. The contribution of OFP of five boilers was mainly from alkenes, occupying a relatively high percentage of 76%-90%, and that of alkanes was in the range of 6% to 19%.

Preparation of ZnS:Ni/ZnS quantum dots with core/shell structure and application for detecting cefoperazone-sulbactam.

ZnS:Ni quantum dots (QDs) have been synthesized via a water-soluble route, which were coated by ZnS shell through surface modification to give ZnS:Ni/ZnS QDs. The QDs were characterized by atomic force microscope, X-ray diffraction, infrared spectrometry and fluorescent spectrometry. Then, a novel method for the determination of cefoperazone-sulbactam (CPZ-SBT) in aqueous solutions has been developed based on the enhancement of fluorescence of ZnS:Ni/ZnS QDs in the presence of CPZ-SBT. Under the optimal conditions, the enhanced fluorescence intensity (ΔF) was proportional to CPZ-SBT concentration in the range of 8.0×10(-6)-1.0×10(-4) g/L with a detection limit of 1.0×10(-7) g/L. The method was employed for the determination of CPZ-SBT in sample to give satisfactory result. Compared with others, this method was more sensitive, fast and simple with low limit detection.