Atmospheric gaseous aromatic hydrocarbons in eastern China based on mobile measurements:Spatial distribution,secondary formation potential and source apportionment

Monocyclic aromatic hydrocarbons(MAHs)and polycyclic aromatic hydrocarbons(PAHs)are both well known as hazardous air pollutants and also important anthropogenic precursors of tropospheric ozone(O3)and secondary organic aerosols(SOA).In recent years,there have been intensive studies covering MAHs emission from various sources and their behavior under stimulated photochemical conditions.Yet in-situ measurements of PAHs presence and variations in ambient air are sparse.Herein we conducted large geometrical scale mobile measurements for 16 aromatic hydrocarbons(AHs,including 7 MAHs and 9 PAHs)in eastern China between October 27 and November 8,2019.This unique dataset has allowed for some insights in terms of AHs concentration variations,accompanying chemical composition,source contributions and spatial distributions in eastern China.In general,AHs showed a clear concentration variability between the south and the north of the Yangtze River Delta(YRD).The concentrations of PAHs were approximately 9%of AHs,but contributed 23%of SOA formation potential.Source apportionment via positive matrix factorization(PMF)model revealed that industrial processes as the largest source(44%)of observed AHs,followed by solvent usage(21%),vehicle exhaust(19%),coal combustion(11%)and coking processes(6%).In the perspective of PAHs sources,coal combustion emissions were identified as the dominating factor of a share of 41%–52%in eastern China.Our findings complemented the simultaneously monitoring information of PAHs and MAHs in eastern China,revealed the importance of PAHs to SOA formation and highlighted the necessity of formulating strategies to reduce emissions from anthropogenic sources and reduce risks to human health.

Measurement of Ion Mobilities of Selected Amines by Ion Mobility Spectrometry

The ion mobilities of selected amines were measured by IMS. The minimum detection limits and linear ranges of selected amines were detected.

A new portable open-path instrument for ambient NH_(3) and on-road emission measurements

Increased attentions to vehicle emission of NH_(3)have been paid since it is generally regarded as an important source in urban areas.Here,we developed a movable instrument based on Differential Optical Absorption Spectroscopy(DOAS)principle for detecting on-road NH_(3),which can avoid the losses in the sampling process attributed to the non-sampling methods.For this mobile DOAS,the temporal resolution,detection limit and relative error for NH_(3)were 1 min,2.29 ppbv and 4.57%±2.44%,respectively.By employed to the on-road measurements along the arterial highway in Shanghai,the spatial distributions of NH_(3)and NO were obtained,and their dependence of traffic and road conditions were studied.The slopes of linear regression between NH_(3)and NO were 0.40,0.02 and 0.07 on the Middle Ring Road,Outer Ring Road and Chongming Island Ring Road.It indicates that light gasoline vehicles(LGVs)were found to be the main contributor to NH_(3)emissions,while heavy-duty diesel vehicles(HDVs)mainly emitted NO.Based on the measured NH_(3)in the tunnel,the mileagebased NH_(3)emission factor per vehicle was estimated to be 17.9±6.3 mg/km.The reported open-path instrument can be broadly used in on-road pollutant monitoring or vehicle emissions,and the measurements can reveal the real situation of emission characteristics,even find the abnormal operations of vehicle catalyst system.

Distribution and transport characteristics of fine particulate matter in beijing with mobile lidar measurements from 2015 to 2018

Accurately quantifying the concentration and transport flux of atmospheric fine particu-late matter(PM_(2.5))is vital when attempting to thoroughly identify the pollution formation mechanism.In this study,the mobile lidar measurements in Beijing on heavily polluted days in December from 2015 to 2018 are presented.The lidar was mounted on a vehicle,which could perform measurements along designated routes.On the basis of mobile lidar mea-surements along closed circuits of the 6th Ring Road around Beijing,the spatial distribution and transport flux of PM_(2.5) in Beijing were determined with information of wind field.In the spatial distribution,both the concentration and transport of PM_(2.5) were revealed to be more significant in the southern section of Beijing.The regional transport layer at heights<1.3 km plays an important role in pollution formation.The maximum transport flux reached 1600μg/(m^(2)*sec)on 11 December 2016.With the aerosol boundary layer height determined from the image edge detection(IED)method,the inter-annual variations of the aerosol boundary layer height(ABLH)were also analysed.The ABLH decreased from 0.73 to 0.46 km during the same heavy pollution period from 2015 to 2018.Increasingly adverse aerosol boundary layer(ABL)meteorological factors,including lower ABLH,light winds,temperature inversions,and accumulated moisture,have become necessary for pollution formation in Beijing.

Measurement of rectangular surface mobility of an infinite plate

A measuring method of surface mobility for an infinite plate subject to a uniform conphase velocity excitation is investigated. In the measurement, a finite plate is employed to simulate an infinite plate and a rigid cone is used to make a uniform conphase velocity excitation. A method to deduct the affect of additional mass is derived. The results of the measurement agree with that calculated theoretically.

Urban Heat Island Investigations in Arctic Cities of Northwestern Russia

Urban microclimate peculiarities in two Arctic cities in northwestern Russia--Kirovsk （67.62°N, 33.67°E） and Apatity （67.57°N, 33.38°E）-were investigated by using mobile temperature records. The experiment was carried out in and around Apatity and Kirovsk in February 2014 and December 2016. The DS 18B20 digital thermometer was in- stalled on the roof of a car （height： approximately 1.2 m） to measure and record temperature variations automatically. In addition to the digital thermometer, the car was also equipped with an onboard global positioning system, allow- ing every temperature measurement to be referenced with an altitude and a latitude/longitude position. The possibility of urban heat island formation in these polar cities, above the Arctic Circle, was studied. Our analysis indicated that on 11 February 2014, the temperature varied in accordance with the background environmental lapse rate （-0.0045℃ m^-1）, and nearly corresponded to it （-0.0165℃ m^-1） on 12 February 2014. On 6 December 2016, a strong local temperature inversion with a positive value of 0.032℃ m^-1 was detected, seemingly caused by the formation of a cold air pool in the valley near Kirovsk. It was found that the temperature variations within and outside these cities are strongly influenced by local topographic effects and the physical conditions of the atmospheric boundary layer.