AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Elemental Composition of PM10 and PM2.5 in Windblown Dust in Shiprock and Churchrock, New Mexico
Cristina Gonzalez-Maddux, AURELIE MARCOTTE, Nabin Upadhyay, Pierre Herckes, Yolanda Williams, Gordon Haxel, Marin Robinson, Arizona State University
Abstract Number: 620 Working Group: Remote and Regional Atmospheric Aerosols
Abstract The composition of fine particulate matter (PM2.5) in urban or industrial areas has been shown to be enriched in anthropogenic emissions of toxic metals and other pollutants. In this work, PM2.5 and PM10 samples were collected at two sites on the Navajo Reservation: Diné College in Shiprock, NM and a residential property in Churchrock, NM. Shiprock was selected because of its proximity (<25 km) to more than 500 abandoned uranium mine tailings sites and various industrial facilities including a coal-burning power plant. The Churchrock site was selected because of its close proximity (<1 km) to a partially restored abandoned uranium mining site. A specific goal of the project was to determine if uranium from Shiprock or Churchrock abandoned tailings sites could be detected in the windblown dust. Dust samples from each site were analyzed for concentrations of various elements including those typically associated with uranium mining and coal-burning activities by inductively coupled plasma mass spectrometry (ICP-MS). In addition, samples collected in Churchrock were analyzed for uranium isotope abundances using a multicollector ICP-MS. In Shiprock, six elements were notably enriched (Enrichment Factor (EF) values > 10) including Cu, Zn, Sn, Pb, Sb, and Bi. In Churchrock, four elements were found to be enriched (EF values > 10) including Cu, Pb, Sb, and Bi. Results from principal components analysis (PCA) and HYSPLIT trajectories suggest that sources of PM in Shiprock and Churchrock are both natural (soil) and anthropogenic (combustion) in origin. Uranium isotope ratios suggest that the delta 238/235U values are all within error of one another (2sd) and are typical of crustal rocks, including basalts and granite. The aerosol samples collected were typically less enriched in the 234U as compared to the soil samples, suggesting that the aerosol uranium pool is not entirely derived from local soil dust.