Wet Deposition of Perchlorate Over the Continental United States

HR: 08:33h
AN: H41K-03 [Abstracts]
TI: Wet Deposition of Perchlorate Over the Continental United States
AU: * Rajagopalan, S
EM: srinath.rajagopalan@ttu.edu
AF: Texas Tech University Department of Civil and Environmental Engineering, MS 41022 10th and Akron, Lubbock, TX 79409, United States
AU: Jackson, A W
EM: andrew.jackson@ttu.edu
AF: Texas Tech University Department of Civil and Environmental Engineering, MS 41022 10th and Akron, Lubbock, TX 79409, United States
AU: Anderson, T A
EM: todd.anderson@tiehh.ttu.edu
AF: The Institute of Environmental and Human Health, The Institute of Environmental and Human Health (TIEHH) Department of Environmental Toxicology Reese Technology Center Building 555 1207 Gilbert Drive, Lubbock, TX 79409, United States
AB: Natural perchlorate (ClO₄^-) has been detected in soil, vegetation, food products, and ground and drinking water supplies at various concentrations across the world. For almost a century natural perchlorate has been known to exist in Chilean nitrate deposits that are up to 16 million years old, and recent isotopic evidence has confirmed its source to be predominantly atmospheric. Although the source of natural perchlorate has been attributed to atmospheric deposition, there is almost no data available concerning the deposition rate of perchlorate from precipitation. This research effort, supported by SERDP, was designed to investigate the range of concentrations, and temporal and spatial variations in perchlorate deposition. Sub-samples of precipitation collected through the National Atmospheric Deposition program over a two year period were analyzed for perchlorate. Sample locations included 14 continental states, and Puerto Rico. Perchlorate has been detected (DL= 5 ng/L) in over 65 % of all samples tested with a mean value of 12.60 ± 13.60 ng/L and ranged from < 5 ng/L to 75 ng/L with higher concentrations predominantly in summer months and inland regions. The Cl^- /ClO₄^- molar ratio varied over three orders of magnitude with few thousands inland to few millions near coastal regions. There were no significant correlations (r > 0.5) between ClO₄^- and other ions (Cl^-, NO₃^-, SO₄^-², Na⁺, K⁺, Ca⁺², Mg⁺², and NH₄⁺). Results from this study will have important implications to the national perchlorate issue and may aid in explaining the occurrence of non-anthropogenic perchlorate being reported in arid and semi-arid areas.
DE: 1854 Precipitation (3354)
DE: 3354 Precipitation (1854)
SC: Hydrology [H]
MN: 2007 Fall Meeting