Study Of Aerosol Number Concentration Distribution And Modeled Deposition In Human Airway In Nanjing Northern Suburbs

The particles number concentrations were determined by Wide-range Particle Spectrometer(WPS)in northern suburb of Nanjing in January and April 2015.The aerosol number concentration spectral distribution and the diurnal variation of each particle size mode at different air quality levels were summarized.The synoptic situation and surface meteorological elements were analyzed to discuss the relation between meteorological conditions and the particle concentration of each mode comprehensively,supplementing by backward trajectory.A forecast model for particle number concentrations,which needs inputting meteorological elements and gaseous pollutants concentrations,was established via stepwise regression analysis and examined by predicted experiment independently.The information of size distributions was applied in the multiple-path particle dosimetry model(MPPD)v.3.04 to quantify deposition fractions(DF)and number concentration depositions of fine particles in different regions of human airway,at different air quality levels,at rest and exercise.The result shows that aerosol number spectra are both unimodal in winter and spring.The average total number concentration is about 35.34x 104 cm-3 in winter and 60.85×104 cm-3 in spring.The spectral peak moves to coarser size with a worsen air quality.The number concentrations of nucleation mode and Aitken mode are higher in spring than that in winter,while accumulation mode concentration is opposited.For diurnal variation,peaks of total number concentration emerge in 7:00?10:00 and 17:00?20:00 in winter,with a higher value during bad air quality.Peaks of nucleation mode emerge in 13:00?14:00,besides above-mentioned time.In spring,the total number concentration is higher from 14:00 to midnight continuously above the air quality level 2.The number concentration of nucleation mode has a peak in 12:00?14:00,which of Aitken mode is high in the afternoon,while the air quality is worse,the peak value of accumulation mode is lager.The synoptic situations during observation which promoted pollutants accumulation are high-pressure type and saddle shaped field.The synoptic situations which be beneficial to pollutants diffusion and elimination are quasi-stationary front type and frontside-trough type.The backward trajectory analysis shows that western air mass bring more pollutants,while northern air mass is clean.The surface wind field shows that particle number concentration is high during south wind.Local emission has a great contribution to the number concentrations of Aitken mode and accumulation mode.The number concentration which effected by northwestern wind is high in winter but low in spring.The statistical forecast model of aerosol number concentration exports a fitting curve,which mean absolute error,mean absolute percentage error and root mean squared error is 1.75×105 cm-3,45.40%and 2.42×105 cm-3,respectively.The 3 above-mentioned statistical parameter of prediction experiment is 1.94×105 cm-3,47.82%and 2.97×105 cm-3,respectively.The deposition feature in respiratory system shows that DF of nucleation mode and Aitken mode at rest and exercise are similar,while DF of accumulation mode at exercise is 2.49 times of that at rest.DF of nucleation mode and Aitken mode in pulmonary(PUL)is the highest,about 48.17%of total deposition fractions(TDF)at rest and 54.23%of TDF at exercise.DF of accumulation mode in head is the highest,about 41.23%of TDF at rest and 80.47%of TDF at exercise.The particle NC deposition in human airway in winter is lower than that in spring,and the total NC deposition in 3 regions are PUL>tracheo-bronchial(TB)>head.Compared with resting,nucleation mode deposition in PUL and accumulation mode deposition in TB and head are increase at exercise.The worse air quality,the higher deposition growth rate of exercising to resting in head.