HR: 08:03h
AN: H41K-01 INVITED    [Abstracts]
TI: Widespread Occurrence of Plant Perchlorate
AU: * Harvey, G
EM: gregory.harvey@wpafb.af.mil
AF: United States Air Force, 1801 10th St Bldg 8 Area B, WPAFB, OH 45433, United States
AU: Orris, G
EM: greta@usgs.gov
AF: USGS, 520 N. Park, Tucson, AZ 85719, United States
AU: Jackson, W A
EM: andrew.jackson@ttu.edu
AF: Texas Tech University, Mail Stop 41023, Lubbock, OH 79409, United States
AU: Rajagopalan, S
EM: srinath.rajagopalan@ttu.edu
AF: Texas Tech University, Mail Stop 41023, Lubbock, OH 79409, United States
AU: Andraski, B
EM: andraski@usgs.gov
AF: USGS, 345 Middlefield Mail Stop 421, Menlo park, CA 94025, United States
AU: Stonestrom, D
EM: dastones@usgs.gov
AF: USGS, 345 Middlefield Mail Stop 421, Menlo park, CA 94025, United States
AB: Perchlorate is a water soluble oxyanion containing four oxygens bonded to a single chlorine atom. High concentration of perchlorate can competitively block the uptake of iodide by the sodium iodide symporter and disrupt thyroid function. Due to this ability to potentially impair thyroid function, perchlorate in environmental exposure pathways has been of concern for more than a decade. Our knowledge of the spatial and temporal aspects of environmental perchlorate has increased dramatically in the past few years. To date, perchlorate has been found in numerous different environmental media, including water, soils and sediments, and plants, from many parts of the world. Perchlorate can be found in marine alage, food and plant samples from Asia, Africa, Europe, North and South America. It is becoming increasingly apparent that perchlorate in low levels is ubiquitous. Perchlorate has been found in several different carbon age-dated water and midden samples that pre-date the industrial age and agricultural use of Chilean nitrate fertilizers by thousands of years. While anthropogenic sources of perchlorate exist, the accumulating spatial and temporal evidence suggests that perchlorate must have a significant natural source. This natural source of perchlorate under the appropriate geochemical and climatic conditions is contributing a natural background level of perchlorate. Concentrations of perchlorate in soils appears to be influenced by soil geochemistry. Soils with low organic content usually have higher levels of perchlorate then soils with abundant organic matter. High levels of perchlorate have been found in remotely located xerophytes growing in aridosols and in deciduous phreatophytes growing in humid densely populated areas. Often the amount of perchlorate in a plant cannot be explained by the amount of perchlorate in either the soil or precipitation. Investigations into the relative source contribution of lithogenic, atmospheric and other sources and mechanisms that lead to plant perchlorate accumulation need to be conducted.
DE: 1829 Groundwater hydrology
DE: 1852 Plant uptake
SC: Hydrology [H]
MN: 2007 Fall Meeting