Perchlorate levels in samples of sodium nitrate fertilizer derived from Chilean caliche

• Published in: Environmental pollution (1987) Vol. 112; no. 3; pp. 299 - 302
• Main Authors: Urbansky, E.T., Brown, S.K., Magnuson, M.L., Kelty, C.A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2001; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; Caliche; Chile; Chile saltpeter; Chromatography, Ion Exchange; Drinking water; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; ESI-MS; Exact sciences and technology; Fertilizer; Fertilizers - adverse effects; Fertilizers - analysis; Fundamental and applied biological sciences. Psychology; Groundwater; Groundwaters; Natural water pollution; Nitrates - analysis; Perchlorate; Perchlorates - adverse effects; Perchlorates - analysis; Pollution; Pollution, environment geology; Potable water; Sample Size; Sodium nitrate; Soil and water pollution; Soil science; Spectrometry, Mass, Electrospray Ionization; United States; United States Environmental Protection Agency; Water Pollutants, Chemical - analysis; Water treatment and pollution; South America; Chile; America; United States; USA; Perchlorate; Drinking water; Groundwater; Sodium nitrate; Chile saltpeter; ESI-MS; IC; Potable water; Fertilizer; Caliche; Chemical analysis; Risk analysis; Perchlorates; Electrospray; Ion chromatography; Homogeneity; Water pollution; Nitrogen fertilizer; Mass spectrometry; Quantitative analysis; Ground water
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/S0269-7491(00)00132-9

Sodium nitrate fertilizer, made from refined caliche, also contains perchlorate — a potential environmental contaminant. Paleogeochemical deposits in northern Chile are a rich source of naturally occurring sodium nitrate (Chile saltpeter). These ores are mined to isolate NaNO 3 (16–0–0) for use as fertilizer. Coincidentally, these very same deposits are a natural source of perchlorate anion (ClO 4 −). At sufficiently high concentrations, perchlorate interferes with iodide uptake in the thyroid gland and has been used medicinally for this purpose. In 1997, perchlorate contamination was discovered in a number of US water supplies, including Lake Mead and the Colorado River. Subsequently, the Environmental Protection Agency added this species to the Contaminant Candidate List for drinking water and will begin assessing occurrence via the Unregulated Contaminants Monitoring Rule in 2001. Effective risk assessment requires characterizing possible sources, including fertilizer. Samples were analyzed by ion chromatography and confirmed by complexation electrospray ionization mass spectrometry. Within a lot, distribution of perchlorate is nearly homogeneous, presumably due to the manufacturing process. Two different lots we analyzed differed by 15%, containing an average of either 1.5 or 1.8 mg g −1. Inadequate sample size can lead to incorrect estimations; 100-g samples gave sufficiently consistent and reproducible results. At present, information on natural attenuation, plant uptake, use/application, and dilution is too limited to evaluate the significance of these findings, and further research is needed in these areas.