|From:||Lenny Siegel <firstname.lastname@example.org>|
|Date:||4 May 2005 03:46:20 -0000|
|Subject:||[CPEO-MEF] Perchlorate Uses and Environmental Occurrence|
Submitted by Laura Olah <email@example.com>|
Perchlorate Uses and Environmental Occurrence
Perchlorate is an environmental contaminant that seldom occurs naturally except in evaporite deposits in extremely arid regions (Orris et al. 2003). Recent analyses of Chile saltpeter (sodium nitrate) by USEPA and the Department of Energy have found concentrations of approximately 1 g ClO4 –/kg NaNO3 Urbansky and Schock 1999). Chile saltpeter is used as a fertilizer, particularly favored by tobacco farmers, resulting in accumulation of perchlorate in tobacco products (Ellington et al. 2001). Commercial quantities of sodium perchlorate are usually prepared by electrolysis of aqueous solutions of sodium chloride, in which the chloride ion is successively oxidized through hypochlorite (ClO–), chlorite (ClO2–), chlorate (ClO3 –), and finally to perchlorate (ClO4–).
Large commercial quantities of ammonium perchlorate are used in 1.3-inch diameter solid rocket motors and to a limited extent in pyrotechnic and explosive compositions. Potassium perchlorate is used extensively in pyrotechnic compositions and in black-powder-substitute gun propellants. It is used in some spotting charges that enable range control personnel to assess the accuracy of inert (nonexplosive) rounds. Perchlorate salts are also used in nuclear reactors, electronic tubes, as additives in lubricating oils, in tanning and finishing of leather, as mordents for dyed fabrics, in electroplating and electropolishing, aluminum refining, rubber manufacture, and in the production of paints and enamels.
Commercial production of chlorate used for herbicides and bleaching agents is by the incomplete electrolysis of sodium chloride. Analysis of laboratory-grade chlorate found nearly % levels of perchlorate (Burns et al. 1989). It is reasonable to assume that industrial-grade chlorate may contain several % of perchlorate as a result of slight variations in process conditions.
In years past, railroads used sodium chlorate as an ingredient in herbicides to suppress the growth of foliage along rail corridors. Where rainfall is low or intermittent, soils around railbeds may still be contaminated with perchlorate. Another uninvestigated source of perchlorate contamination around railways is from spillage of chlorate salts used for bleaching at paper mills.
SOURCE: Field Screening Method for Perchlorate in Water and Soil (ERDC/CRREL TR-04-8). This report was published by the U.S. Army Corps of Engineers. A reliable and inexpensive colorimetric method for perchlorate in water and soil extracts has been developed and tested with surface water, well water, bioreactor effluent, and soil extracts. The detection limit for water is 1 ug/L and 0.3 ug/g for spiked soils. Results from nearly 100 well water and bioreactor samples show excellent agreement with EPA Method 314 over the range of 1-225 ug/L (slope = 1.11, R2 = 0.913). Some false positives were encountered in some wells. A cleanup method was developed that can eliminate false positives due to humic substances (April 2004, 26 pages). View or download at http://www.crrel.usace.army.mil/techpub/CRREL_Reports/reports/TR04-8.pdf
Laura Olah, Executive Director Citizens for Safe Water Around Badger E12629 Weigands Bay S Merrimac, WI 53561 phone: (608)643-3124 fax: (608)643-0005 email: firstname.lastname@example.org website: www.cswab.org
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