| Atmospheric PM2.5 and dioxins were the most prominent problem in air pollution at present.PM2.5 had drawn more and more attention because it reduces the visibility of the atmosphere and endangers human health.However,the harm of dioxins could not be underestimated,which are extremely toxic,easily accumulate in organisms and pose a potential hazard to the people.The international community?including China?is paying more and more attention to the pollution concentration,pollution characteristics and the harm to the human body of PM2.5 and dioxins in typical areas.Due to its large population,the rapid development of social economy and industry in southern China,the cities of South China had become the focus of this study.The atmospheric PM2.5,PM2.5/PM10,PCDD/Fs-WHO2005-TEQ,and PCDD/F?polychlorinated dibenzo-p-dioxins and dibenzofuran?phase distributions,dry and wet deposition and health risks of 23 cities in southern China,during 2014–2016,were investigated in this study.Through the simulation of the model and the serious collection and integration of the data,the research results obtained were as follows:?1?In general,the cities with higher latitudes had higher PM2.5 concentrations than those with lower latitudes.During 2014–2016,the lowest three-year average concentrations of PM2.5.5 occurred at Sanya and Haikou and were 16.4 and 21.7?g m–3,respectively;while the highest concentrations of PM2.5 was occurred at Wuhan and Luzhou and were 68.8 and 63.1?g m–3,respectively.During 2015–2016,the PM2.5concentrations of most of cities decreased,but those of five cities?Chengdu,Luzhou,Nanchang,Qujing and Quanzhou?increased,indicting that the air quality of these five cities was still not well controlled.The average RM values of the 23 cities were 5.20,4.49 and 4.13 in 2014,2015 and 2016,respectively,which revealed that the PM2.5concentrations in the cities of southern China slowly decreased,although they were still far above the WHO air quality regulated standard(10?g m–3).In general,a city with a higher PM2.5.5 concentration was also had a higher PM2.5/PM10 ratio.?2?Among the 23 cities,the six highest three-year averages of total-PCDD/Fs-WHO2005-TEQ concentrations were 0.0665,0.0633,0.0625,0.0600,0.0528 and 0.0526pg-WHO2005-TEQ m–3 in Chengdu,Wuhan,Nanjing,Hefei,Luzhou and Hangzhou,respectively.During 2014,the six cities?Hefei,Nanjing,Wuhan,Guiyang,Shanghai and Chengdu?with the lowest temperatures in winter?an average of 5.4°C?,their average particle phase fractions of total-PCDD/Fs-WHO2005-TEQ that were approximately 76%,53%,71%and 93%in the spring,summer,fall and winter,respectively;while,the six cities?Haikou,Fuzhou,Guangzhou,Nanning,Nanchang and Changsha?with the highest temperatures in summer?an average of 16.5°C?,had average particle phase fractions of total-PCDD/Fs-WHO2005-TEQ that were approximately 61%,42%,57%and 81%in the spring,summer,fall and winter,respectively.The PM2.5-bound total PCDD/Fs-WHO2005-TEQ content of six cities with higher PM2.5 concentration?Wuhan,Hefei,Changsha,Nanjing,Chengdu and Shanghai?and six with lower PM2.5 concentration?Sanya,Fuzhou,Guiyang,Guangzhou,Nanning and Nanchang?,during 2014,ranged between 0.3980-0.6751 and 0.3961-0.5750ng-WHO2005-TEQ g–1,respectively.And,during 2014,dry and wet deposition fluxs of total-PCDD/Fs-WHO2005-TEQ in Hefei were higher than Shanghai.The monthly dry and wet deposition fluxes of total-PCDD/Fs-WHO2005-TEQ in Hefei were in the range of 167-935 and 3.44-224 pg WHO2005-TEQ m–2 month–1,while in Shanghai,the corresponding value were 78.4-626 and 13.0-153 pg WHO2005-TEQ m–2 month–1.?3?The diurnal respiratory exposure and health risks in the central cities of southern China were higher than those in the south.During 2014-2016,the respiratory exposure of dioxin decreased year by year,with the lowest occurring in Sanya and Haikou,the highest in Nanjing,Wuhan and Chengdu,respectively.And the adult respiratory exposure in these three years were 0.0025-0.0117 pgTEQ/?kg·d?,and the non-oncogenic and carcinogenicity index were 0.0007-0.0033 and 4.24*10-7-1.97*10-6,respectively.The corresponding values for children were 0.0057-0.0267 pgTEQ/?kg·d?,0.0015-0.0072 and 9.25*10-7-4.30*10-6,respectively.However,the population respira-tive exposure and health risk values in these 23 cities were lower than the standard values,so the risks were all within acceptable limits.The results of this study provide information showing the trends of both atmospheric PM2.5 and PCDD/Fs in the cities of southern China.In addition,this study provided the overview relating to the PM2.5 and PCDD/Fs in ambient air of southern China,which was not reported in previous studies.The results of this study were of great importance to present the trends of air quality in China.It is also useful for the establishment of control strategies in the future. |
PDF Full Text Request