Comment on Perchlorate Identification in FertilizersŽ and the Subsequent Addition Correction

Edward T. Urbansky, Matthew L. Magnuson, Catherine A. Kelty, Baohua Gu, And Gilbert M. Brown

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• Publié par: Astlio
• Nombre de lectures: 146
• Langue: English

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Correspondence
keep statistics on fertilizer application by N
-P
-K ratio,Comment on “Perchlorate Identification in
butthere is usually not a breakdown into individual com-
Fertilizers” and the Subsequent Addition/ ponents. Therefore, even if some fertilizers contain perchlo-
rate, it is difficult to correlate fertilizer consumption andCorrection
application with exposure risk. For example, the Office of
the Indiana State Chemist (OISC) tracks of the
- top 10 fertilizers semi-annually by N
-P
-K ratio per county.SIR: Perchlorate (ClO ) contamination has been reported4
Some single component formulations are tracked, such asin several fertilizer materials (1, 2) and not just in mined
82
-0
-0 (NH ) and 46
-0
-0 (urea). Multiple componentChile saltpeter, where it is a well-known natural impurity 3
formulations are also tracked, but the compounds providing(3). To survey fertilizers for perchlorate, two analytical
each nutrient are not tracked. The OISC reported that Indianatechniques have been applied to 45 products that span
farmers applied 48 478 tons of urea and 193 347 tons ofagricultural, horticultural, and retail markets, including
anhydrous ammonia in 1998 (7), neither of which isseveral lots for some (see Supporting Information for details).
contaminated with perchlorate. Fertilizer application toOn the basis of the results presented here, it appears that
family gardens and lawns is not monitored at all in Indiana,fertilizers are not significant contributors to perchlorate in
and these products are generally not the same as those usedthe environment.
by production farms.Standard reference materials were purchased from the
National Institute of Standards and Technology. Sealed Some of the most common nitrogen sources are ammonia,
fertilizer packages were obtained from stores in the vicinities urea, and ammonium nitrate. More than 99% of these
of Pittsburgh, PA; Cincinnati, OH; Knoxville, TN; Batesville, materials are synthesized from atmospheric gases (N ,O,2 2
IN; and West Harrison, IN. Bulk agricultural fertilizers were CO)orCH as opposed to being derived from caliche.2 4
sampled from distributors in Cincinnati, OH, and Greensburg, Manufacturing processes for these N sources do not use
IN; random samples (1 kg) were collected. Bulldog Soda chlorine compounds. These N sources are heavily used for
sodium nitrate was provided by Prof. W. P. Robarge, growing corn, wheat, and rice; accordingly, current agricul-
Department of Soil Science, North Carolina State University, tural production of grain crops is unlikely to be implicated
Durham, NC. KMag (langbeinite) was provided by Prof. E. in the polluting of natural waters with perchlorate. At present,
C. Johnson, Department of Chemistry, University of there is insufficient information on uptake of perchlorate by
WisconsinsStevens Point, Stevens Point, WI. Overnight food plants to reasonably assess exposure via ingested
shippers were used to transfer items between ORNL and produce. While there may be a niche for Chile saltpeter in
EPA. Package seals were broken only by EPA or staff. some crops and thus localized perchlorate-tainted runoff,
our results suggest that there is minimal cause for concernProduct samples were combined with water at a ratio of
-1 over water pollution from fertilizers currently used in either10gdL (10% w/w) and dissolved or levigated in a blender
agricultural states or backyard gardens. Prior to the Haberfor 2
-4 min (using 10
-100 g of product). Insoluble materials
process, natural saltpeters were staples in American farming,were leached (post-levigation) by soaking for 24
-48 h with
and so regions that have a history of applying these productsintermittent shaking. The aqueous phase was filtered through
should be prepared to monitor for and possibly encounterglass fiber and 0.45-ím cellulose acetate. No measurable
perchlorate. However, natural saltpeters now constituteanalyte loss was observed in standard solutions subjected to
0.14% of annual U.S. fertilizer consumption. For instance,such filtration. ESI-MS analysis (4) was adapted as follows.
much of the nitrogen used in the Corn Belt is in the form ofThe filtrate was first diluted 10% v/v. A 100-íL aliquot of the
urea or ammonia.dilution was combined with 1.00 mL of 0.20 M C H NMe -10 21 3
Br(aq) and 5.00 mL of methyl isobutyl ketone and diluted to There is a consensus that certain lots of some products
100 mL in a volumetric flask. Duplicates were run with spikes did in fact contain perchlorate when originally sampled and
-1
-of 0, 10, and 20 ng mL ClO to allow the data to be analyzed4 reported (1), but that phenomenon appears to have con-
by the method of standard additions. The flasks were stituted a sporadicsif not singularsevent rather than
stoppered and vigorously shaken; phases separated after 10
- reflecting a recurring problem. In fact, 17 additional products
30 min. The MIBK extracts were drawn off and kept at
-15 analyzed by the same investigators contained no detectable
C other than during instrumental analysis. For IC analysis, perchlorate (2). Nevertheless, this EPA laboratory is coor-
-1the filtrates were diluted until a 100 ng mL spike could be dinating a more comprehensive survey of fertilizers and raw
recovered 100
( 7% (100 íL loop, AG11/AS11 columns, ED40 materials, which aims to resolve the issue completely.
detector) adapted from Jackson et al. (5).
Perchlorate was detected only in sodium nitrate derived Acknowledgments
-1from Chilean caliche (1.2
-1.8 mg g ). None of the other
We appreciate Kova Fertilizer Inc. and CF Industries Inc.
materials showed perchlorate above the detection limits, but
permitting us to sample their products on-site. We thank W.
recovery of fortifications was satisfactory by IC. Detection
P. Robarge, E. C. Johnson, E. J. Urbansky, and C. A. Urbansky
-1limits for ESI-MS and IC are below 100 (0.01%) and 50 ígg
for assistance in sample procurement. We acknowledge
(0.005%), respectively, based on dilution and other factors.
OISC’s M. Hancock and P. F. Kane, who provided information
At present, perchlorate has been confirmed in only two raw
for this report. Mention of specific products and/or manu-
materials, with Chilean sodium nitrate being the well-known
facturers should not be construed as endorsement by the
source. The U.S. Geological Survey and Air Force Research
U.S. Government. ORNL is managed by University of
Laboratories report sporadic detection of perchlorate in
Tennessee
-Battelle LLC for the U.S. Department of Energy.
sylvite (KCl) (6), and the USGS is pursuing further study.
Modern farming practices use a variety of products,
Supporting Information Available
including ammonia, ammonium nitrate, potassium chloride,
and phosphate rock to augment soil nutrients. Some states Four tables showing detailed information on the 45 products
94452 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 34, NO. 20, 2000 10.1021/es0011515 Not subject to U.S. copyright. Publ. 2000 Am. Chem.Soc.
Published on Web 09/09/2000used (6 pages). This material is available free of charge via Edward T. Urbansky,* Matthew L. Magnuson, and
the Internet at http://pubs.acs.org. Catherine A. Kelty
Literature Cited United States Environmental Protection Agency
National Risk Management Research Laboratory(1) Susarla, S.; Collette, T. W.; Garrison, A. W.; Wolfe, N. L.;
McCutcheon, S. C. Environ. Sci. Technol. 1999,33, 3469
-3472. Water Supply and Water Resources Division
(2) Susarla, S.; Collette, T. W.; Garrison, A. W.; Wolfe, N. L.; Cincinnati, Ohio 45268 S. C. Environ. Sci. Technol. 2000,34 , 224.
(3) Schilt, A. A. Perchloric Acid and Perchlorates; GFS Chemicals:
Columbus, OH, 1979; pp 3
-4 and references therein. † ‡Baohua Gu and Gilbert M. Brown
(4) (a) Magnuson, M. L.; Urbansky, E. T.; Kelty, C. A. Anal. Chem.
2000, 72,25
-29. (b) Magnuson, M. L.; Urbansky, E. T.; Kelty,
Oak Ridge National LaboratoryC. A. Talanta 2000, 52, 285
-291.
Environmental Sciences Division and(5) Jackson, P. E.; Laikhtman, M.; Rohrer, J. J. Chromatogr. A 1999,
850, 131
-135. Chemical and Analytical Sciences Division
(6) Harvey, G. J.; Tsui, D. T.; Eldridge, J. E.; Orris, G. J. 20th Annual Oak Ridge, Tennessee 37831
Meeting Abstract Book; Society of Environmental and Toxi-
cological Chemists; Abstract PHA015; p 277. ES0011515
(7) (a) Indiana Fertilizer Tonnage Report By Grades and By
CountiessSpring 1998; Office of the Indiana State Chemist
and Seed Commissioner: West Lafayette, IN, 1998. (b) Indiana * Corresponding author phone: [phone]; fax: [phone];
Fertilizer Tonnage Report By Grades and By Counties
-Fall 1998; e-mail: [e-mail].
†Office of the Indiana State Chemist and Seed Commissioner: Environmental Sciences Division.
‡West Lafayette, IN, 1999. Chemical and Analytical Sciences Division.
9VOL. 34, NO. 20, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 4453