The atmospheric PM 2.5 , PM 2.5 /PM 10 , PCDD/Fs-WHO 2005 -TEQ, and PCDD/F (polychlorinated dibenzo-p-dioxins and dibenzofuran) phase distributions of 23 cities in southern China, during 2014-2016, were investigated in this study. In general, the cities with higher latitudes had higher PM 2.5 concentrations than those with lower latitudes. During 2014-2016, the lowest three-year average concentrations of PM 2.5 occurred at Sanya and Haikou and were 16.4 and 21.7 µg m -3 , respectively; while the highest concentrations of PM 2.5 was occurred at Wuhan and Luzhou and were 68.8 and 63.1 µg m -3 , respectively. During 2015-2016, the PM 2.5 concentrations 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 R M values of the 23 cities were 5.20, 4.49 and 4.13 in 2014, 2015 and 2016, respectively, which revealed that the PM 2.5 concentrations in the cities of southern China slowly decreased, although they were still far above the WHO air quality regulated standard (10 µg m -3). In general, a city with a higher PM 2.5 concentration was also had a higher PM 2.5 /PM 10 ratio. Among the 23 cities, the six highest three-year averages of total-PCDD/Fs-WHO 2005 -TEQ concentrations were 0.0665, 0.0633, 0.0625, 0.0600, 0.0528 and 0.0526 pg-WHO 2005 -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-WHO 2005 -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-WHO 2005 -TEQ that were approximately 61%, 42%, 57% and 81% in the spring, summer, fall and winter, respectively. The results of this study provide information showing the trends of both atmospheric PM 2.5 and PCDD/Fs in the cities of southern China. In addition, this study provided the overview relating to the PM 2.5 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.

Monitoring atmospheric deposition fluxes (dry and wet deposition) is of great importance in tracing the environmental fate and behavior of PCDD/Fs. To further understand the characteristics of both dry and wet PCDD/F deposition in Northern China, two cities, namely Harbin and Shijiazhuang were investigated. . The results indicated that the dry deposition flux was the major mechanism for removal of PCDD/Fs from the atmosphere in Northern China. By examining both the PM 2.5 level and total-PCDD/Fs-WHO 2005 -TEQ deposition in Northern China, and comparing the values with those found in other places, it is clear that there is an urgent need to control the particulate emissions in this area.

Atmospheric deposition is an important pathway for air pollutants entering the environment. In order to better understand both dry and wet deposition of PCDD/Fs in ambient air, two cities -Guangzhou and Nanjing in Southern China, were investigated.

No abstract

No abstract