Investigating the Possibility of Using Rare Earth Elements as Crustal Elemental Markers in PM 2.5

,; ,; ,; ,

Research article

Journal of the Korean Society for Environmental Analysis 2015;18(1):1-11.

초미세먼지의 지각원소 지시자로서 희토류 원소의 사용 가능성 조사

유근혜, 손세창, 조성용, 박승식

전남대학교

Abstract

In this study 24-hr integrated PM 2.5 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 fluorescenceto 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, wasstrongly 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 PM 2.5 concentration. The Eu and Tb concentrations were on average 24.2 and 12.5 ng/m3, respectively, reaching maximumvalues (89.7 and 73.1 ng/m3) on May 28 when Asian dust storm was observed at the site. Multiple linearregression analysis indicates that crustal material concentration estimated based on Eu and Tb is strongly correlatedwith 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 principalcomponent 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.

Key Words: PM 2.5, Rare earth elements (Eu and Tb), Energy disperse X-ray fluorescence, Crustal elements, Dust storms