Measurements of ²¹⁰Pb and ⁷Be in China and their analysis accompanied with global model calculations of ²¹⁰Pb

Abstract

[1] Previous global models generally simulated high concentrations of 210 Pb in the surface air over China. Measured data of 210 Pb are needed in order to examine the accuracy and performance of the models. We collected the first-ever set of surface air radionuclide measurements of 210 Pb and 7 Be at Guiyang (26.57°N, 106.72°E, 1080 m above sea level) on the east of the Himalayas in Guizhou Province and at Mt. Waliguan (36.29°N, 100.90°E, 3816 m above sea level), a Global Atmosphere Watch station for the World Meteorological Organization, on the Qinghai-Tibetan plateau extending from the Himalayas in Qinghai Province, China. These measurements were carefully analyzed for data assurance and quality control and were used for validating models. The patterns for the variations in both measured 210 Pb and 7 Be at the Guiyang site have been shown to be consistent. In this case the increase of 7 Be concentration was the result of the weak subsidence of air developed at the periphery of the high-pressure system. Because of the weak subsidence the boundary layer turbulence could mix the upward transport of 210 Pb, thus increasing 210 Pb concentration. The ratio of 7 Be/ 210 Pb indicated a seasonal variability with rough monthly oscillation. The ratio peaks were in spring and summer when the convective activities were significant. The 210 Pb levels measured at Mt. Waliguan, located at the peak of the mountain, could be attributed to the long-range transport of 222 Rn that decays to 210 Pb, whereas the 7 Be concentration varied directly with the local airflow passing over the site. We found that it was not appropriate to use the ratio of 7 Be/ 210 Pb for analysis of vertical transport exchange processes at the high-altitude Mt. Waliguan site because of the long-range transport of 210 Pb that occurred at the site.

Atmospheric Deposition of 7Be in the Southeast of China: A Case Study in Xiamen

“…Since pollutants cycling in the atmosphere, including residence and dispersal, are closely related to these processes, 7 Be would provide valuable insights into the pollutants cycling on a timescale corresponding to its half-life. In China, a few studies on 7 Be have been reported in several cities, i.e., Shanghai and Guizhou (Lee et al, 2004;Du et al, 2008;Kong, 2012). During the past three years, the construction and auto industry have led to heavy haze in most Chinese cities.…”

Intra-Annual Deposition of Atmospheric 210Pb,210Po and the Residence Times of Aerosol in Xiamen, China

“…Accordingly, the concentrations of atmospheric 222 Rn are controlled by the land-sea distribution pattern (Balkanski et al, 1992). This pattern, to a large degree, decides the longitudinal distributions of its daughters, such as 210 Pb (T 1/2 = 22.3 yr) and 210 Po (T 1/2 = 138.4 d) in the atmosphere and finally their spatial deposition patterns (Turekian et al, 1977;Lee et al, 2004). Apparently, the depositional fluxes of 210 Pb and 210 Po are latitude-dependent on a global scale (Turekian et al, 1977;Kim et al, 1998).…”

“…To date, several models have been established to simulate the atmospheric 210 Pb deposition on global-scales (Turekian et al, 1977;Lee et al, 2004). However, recent researches revealed the significant intra-and inter-annual variability of 210 Pb deposition at a specific station (Su et al, 2003;Huh et al, 2006;Wan et al, 2008).…”

“…Local effects might include several dominating factors. First, land usually benefits the exhalation of 222 Rn into surface air and successive high 210 Pb compared to oceans (Lee et al, 2004), consequently resulting in high 210 Pb deposition on land. For instance, due to the surrounding oceanic settings, Peng-Chia Yu, an island close to Taiwan, has much lower atmospheric 210 Pb deposition fluxes than the almost same latitude site of Nankang (a suburb district of Taipei, Taiwan) (Su et al, 2003).…”

Atmospheric 210Pb changes during monsoon in east and west coast of Peninsular Malaysia

“…210 Pb activity depend on few factors that are (a) aerosol concentration [5], (b) aerosol particle size distribution [6], (c) meteorological condition and atmospheric stability [7][ 8] and (d) altitude [9]. 210 Pb has been widely used as an atmospheric tracer especially in surface air analyses for studying the atmospheric transport processes [7][10] [11]. This is because of 210 Pb characteristic which is easily absorbed onto submicrometer-sized aerosols [12].…”