Fig 1.
Map of Antarctica showing the site of the snow pit at Dome A (pentagram), as well as the sites of the previous studies about Uranium concentration, including DP-07-01 [15], Coat lands [16], IC-6 [17], LGB [18], Law Dome [19] and a series of snow pits along the US ITASE traverses (shown by brown dots) [20].
The topographic data were extracted using ETOPO1 elevations global data, available from National Oceanic and Atmospheric Administration at http://www.ngdc.noaa.gov/mgg/global/global.html (Last access: 4 October 2018).
Fig 2.
Profiles of the non-sea salt sulfur (nss-SO42-) concentration (black solid line) and the β-activity (red solid line) of the snow pit.
Fig 3.
Profiles of Uranium concentrations and EFc.
(A) Uranium concentrations at Dome A. (B) EFc of Uranium at Dome A. (C) Uranium concentrations at IC-6. (D) EFc of Uranium at IC-6 (solid red lines represent five-year running averages).The Uranium concentrations data at IC-6 was obtained from Carlos (2012)[17].
Table 1.
Uranium concentration ranges and mean values at Dome A and other Antarctic sites.
Fig 4.
Sea salt contribution and Excess U.
(A) Sea salt contribution to Uranium deposition. (B) Excess U. (C) Excess U accounts for % of total U.
Fig 5.
Uranium production and correlation.
(A) The Uranium production of Australian, South Africa, South America from 1970 to 2010 (data from minerals UK at http://www.bgs.ac.uk/mineralsuk/statistics/wms.cfc?method=searchWMS). (B) The correlation between the annual U concentration and the annual production of Australia (T-test).
Fig 6.
Frequency plot of 15-day back trajectories at 500 m (A) and 1000 m (B) height levels above the ground representing the airflow trajectories at the middle and high altitudes respectively for daily simulation during the period 2000–2009. The Back trajectory data obtained using the NOAA (National Oceanic and Atmospheric Administration, USA) HYSPLIT model (at ftp://arlftp.arlhq.noaa.gov/pub/archives/reanalysis).