Temporal variations of 7Be and 210Pb activity concentrations in the atmospheric aerosols during 2018-2019 in Beijing, China and their correlations with meteorological parameters.

In order to establish a regional database on natural radioactivity, a series of measurements of 713 atmospheric aerosol samples collected on filters over a two-year period (2018-2019) in center of Beijing, northeastern China have been performed to analyze 7Be and 210Pb activity concentrations. The mean activity concentrations of 7Be and 210Pb were found to be 7.10 ± 2.44 mBq m-3 and 2.93 ± 1.52 mBq m-3, respectively. Both the radionuclides exhibited strong seasonal variations, with maximum concentration of 7Be occurring in the spring and that of 210Pb in the winter. The concentration of both the radionuclides was minimum in the rainy summer. Higher 7Be concentration in the spring was mainly caused by the stratosphere to troposphere exchange. Higher 210Pb concentration during winter was maybe attributed to the combustion processes in heating systems and the ingression of continental air masses resulted from winds originating from northwest. The dependence of the activity concentrations of 7Be and 210Pb with meteorological parameters such as rainfall, temperature, and humidity was studied through linear correlation analysis. Statistically significant negative correlations were observed between 7Be and 210Pb activity concentrations with rainfall, respectively, which suggested that the removal mechanisms of these two radionuclides were similar. Lead-210 showed statistically significant correlations with temperature, humidity and PM10. A comparison of the data obtained in the present study for Beijing with the northern hemisphere literature values of 7Be and 210Pb in the atmospheric aerosols showed that the values were smaller than the ones observed in the present study. Overall, the study provides an improved understanding of the temporal variability and correlation of 7Be and 210Pb concentrations in the atmosphere in center of Beijing, northeastern China.

SHOULD WE BEGIN REGULATING THE RADIATION SAFETY OF CABINET X-RAY SYSTEMS?

Radiation measurements were conducted at 22 cabinet X-ray systems in Beijing, China, between 2015 and 2019. The median dose rates in the closed-drapes position were 0.11, 0.14, 0.12, 0.14, 0.34 and 0.17 µGy h-1 at the operator position and 5 cm from the surface of the left side, right side, top, entrance and exit, respectively. When a scattering object was passed through the entrance/exit (open-drapes position), the dose rates of eight systems ranged from 1.19 to 6.72 µGy h-1 (median: 3.75 µGy h-1). From 2015 to 2019, we monitored the personal dose equivalent Hp (10) 589 times. The personal dose equivalent of three workers exceeded 1 mSv year-1. However, the integrity of equipment shielding needs to be checked regularly to ensure safe operation. The regulation of radiation protection by employers, technician support institutes or government departments is thus warranted to limit the radiation exposure of workers and the public.

Chemical content and source apportionment of 36 heavy metal analysis and health risk assessment in aerosol of Beijing.

The concentration levels of 36 airborne heavy metals and atmospheric radioactivity in total suspended particulate (TSP) samples were measured to investigate the chemical characteristics, potential sources of aerosols, and health risk in Beijing, China, from September 2016 to September 2017. The TSP concentrations varied from 6.93 to 469.18 µg/m3, with a median of 133.97 µg/m3. The order for the mean concentrations of heavy metals, known as hazardous air pollutants (HAPs), was as follows: Mn > Pb > As > Cr > Ni > Se > Cd > Co > Sb > Hg > Be; Non-Designated HAPs Metals: Ca > Fe > Mg > Al > K > Na > Zn > P > Ba > Ti > Cu > Sr > B > Sn > I > V > Rb > Ce > Mo > Cs > Th > Ag > U > Pt. The median concentration of As was higher than China air quality standard (6 ng/m3). The gross α and ß concentration levels in aerosols were (1.84 ± 1.59) mBg/m3 and (1.15 ± 0.85) mBg/m3, respectively. The enrichment factor values of Cu, Ba, B, Ce, Tl, Cs, Pb, As, Cd, Sb, Hg, Fe, Zn, Sn, I, Mo, and Ag were higher than 10, which indicated enriched results from anthropogenic sources. Pb, As, and Cd are considered to originate from multiple sources; fireworks released Ba during China spring festival; Fe, Ce, and Cs may come from stable emissions such as industrial gases. The health risks from anthropogenic metals via inhalation, ingestion, and dermal pathway were estimated on the basis of health quotient as well as the results indicated that children faced the higher risk than adults during the research period. For adults, the health risk posed by heavy metals in atmospheric particles was below the acceptable level.