Baoshuang Liu

Source apportionment and a novel approach of estimating regional contributions to ambient PM2.5 in Haikou, China ☆

A novel approach was developed to estimate regional contributions to ambient PM2.5 in Haikou, China. In this paper, the investigation was divided into two main steps. The first step: analysing the characteristics of the chemical compositions of ambient PM2.5, as well as the source profiles, and then conducting source apportionments by using the CMB and CMB-Iteration models. The second step: the development of estimation approaches for regional contributions in terms of local features of Haikou and the results of source apportionment, and estimating regional contributions to ambient PM2.5 in Haikou by this new approach. The results indicate that secondary sulphate, resuspended dust and vehicle exhaust were the major sources of ambient PM2.5 in Haikou, contributing 9.9-21.4%, 10.1-19.0% and 10.5-20.2%, respectively. Regional contributions to ambient PM2.5 in Haikou in spring, autumn and winter were 22.5%, 11.6% and 32.5%, respectively. The regional contribution in summer was assumed to be zero according to the better atmospheric quality and assumptions of this new estimation approach. The higher regional contribution in winter might be mainly attributable to the transport of polluted air originating in mainland China, especially from the north, where coal is burned for heating in winter.

Characteristics of Mg2−xTixNi1−yCuy–H2 (0<x<2, 0<y<1) alloys

Abstract The Mg 2− x Ti x Ni 1− y Cu y (0 x y 2 system with and without the treatment of F-solution. A study of the hydrogen desorption process was also carried out. The results show that the main phase of the alloys is an Mg 2 Ni structure. The gas–solid phase reaction can occur without detailed surface treatment and activation. A study on the anti-corrosion properties in alkaline solution of Mg 2− x Ti x Ni 1− y Cu y (0 x y

Insight into the critical factors determining the particle number concentrations during summer at a megacity in China

To identify the critical factors impacting the number concentration of particles with the aerodynamic diameters less than 2.5μm (PNC2.5), the continuous measurement of PNC2.5, chemical components in PM2.5, gaseous pollutants and meteorological conditions were conducted at an urban site in Tianjin in June 2015. Results indicated that the average PNC2.5 was 2839±2430 dN/dlogDp 1/cm3 during the campaign. Compared to other meteorological parameters, the relative humidity (RH) had the strongest relationship with PNC2.5, with a Pearsons correlation coefficient of 0.53, and RH larger than 30% influenced strongly PNC2.5. The important influence of secondary reactions on PNC2.5 was inferred due to higher correlation coefficients between PNC2.5 and SO42-, NO3-, NH4+ (r=0.78-0.89; p<0.01) and between PNC2.5 and ratios that represent the conversion of nitrogen and sulfur oxides to particulate matter (r=0.42-0.49; p<0.01). Under specific RH conditions, there were even stronger correlations between PNC2.5 and NO3-, SO42-, NH4+, while those between PNC2.5 and EC, OC were relatively weak, especially when RH exceeded 50%. Principal component analysis (PCA) and Pearsons correlation analysis indicated that secondary sources, vehicle emission and coal combustion might be major contributors to PNC2.5. Backward trajectory and potential source contribution function (PSCF) analysis suggested that the transport of air masses originated from these regions around Tianjin (Liaoning, Hebei, Shandong and Jiangsu) influenced critically PNC2.5. The north of Jiangsu, the west of Shandong, and the east of Hebei were distinguished as major potential source-areas of PNC2.5 by PSCF model.