유근혜 ( Geun Hye Yu ) , 손세창 ( Se Chang Son ) , 조성용 ( Sung Yong Cho ) , 박승식 ( Seung Shik Park )
In this study 24-hr integrated PM2.5 samples were collected between November 5, 2013 and June 30, 2014, at an urban site in Gwangju, Korea, and analyzed for elemental constituents using energy disperse X-ray fluorescence to evaluate possibility of utilizing rare earth elements (REEs) of European (Eu) and Terbium (Tb) as soil dust markers. Over the study period, concentration of Al, i.e., a representative element of soil dusts, was strongly correlated with those of Si (r=0.98), Ca (r=0.97), Ti (r=0.97), Fe (r=0.96), Eu (r=0.76), and Tb (r= 0.90), suggesting their influence from the soil dusts. Over the study period, four dust-storm episodes (Jan. 1, May 26, May 28, and May 29, 2014) occurred, during which crustal material concentration was 9.6, 18.7, 19.7, and 12.3 μg/m3, respectively, which accounts for 23.0, 49.4, 22.6, and 26.7% of the measured PM2.5 concentration. The Eu and Tb concentrations were on average 24.2 and 12.5 ng/m3, respectively, reaching maximum values (89.7 and 73.1 ng/m3) on May 28 when Asian dust storm was observed at the site. Multiple linear regression analysis indicates that crustal material concentration estimated based on Eu and Tb is strongly correlated with that estimated based on concentrations of the typical crustal elements; [Crustal material]estimated = (194.2±15.7)Tb(μg/m3) + (26.1±10.9)Eu(μg/m3) + (-0.53±0.19), r=0.91, p<0.001]. Also results from principal component analysis demonstrate that the elements Eu and Tb were strongly associated with natural elements (Al, Si, Ca, Ti, and Fe), suggesting that crustal dusts could be one of major sources of the Eu and Tb. Finally, results from this study suggest that the Eu and Tb could also be good candidates of soil dust tracers.