Geology and origin of the Chilean nitrate deposits

Ericksen, George E.

doi:10.3133/pp1188

Cited by 242 publications

(277 citation statements)

References 45 publications

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“…Naturally occurring ClO 4 -from the Atacama is widely known (6). The Atacama Desert nitrate deposits of northern Chile also contain naturally occurring ClO4 -and other oxyanions such as IO3 -, CrO4 2-, and Cr2O7 2-.…”

Section: Introductionmentioning

confidence: 99%

Widespread Presence of Naturally Occurring Perchlorate in High Plains of Texas and New Mexico

Rajagopalan

Anderson

Fahlquist

et al. 2006

Environ. Sci. Technol.

145

128

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Perchlorate (ClO 4 -) occurrence in groundwater has previously been linked to industrial releases and the historic use of Chilean nitrate fertilizers. However, recently a number of occurrences have been identified for which there is no obvious anthropogenic source. Groundwater from an area of 155 000 km 2 in 56 counties in northwest Texas and eastern New Mexico is impacted by the presence of ClO 4 -. Concentrations were generally low (<4 ppb), although some areas are impacted by concentrations up to 200 ppb. ClO 4distribution is not related to well type (public water system, domestic, agricultural, or water-table monitoring) or aquifer (Ogallala, Edward Trinity High Plains, Edwards Trinity Plateau, Seymour, or Cenozoic). Results from vertically nested wells strongly indicate a surface source. The source of ClO 4appears to most likely be atmospheric deposition. Evidence supporting this hypothesis primarily relates to the presence of ClO 4in tritium-free older water, the lack of relation between land use and concentration distribution, the inability of potential anthropogenic sources to account for the estimated mass of ClO 4 -, and the positive relationship between conserved anions (e.g., IO 3 -, Cl -, SO 4 -2 ) and ClO 4 -. The ClO 4distribution appears to be mainly related to evaporative concentration and unsaturated transport. This process has led to higher ClO 4and other ion concentrations in groundwater where the water table is relatively shallow, and in areas with lower saturated thickness. Irrigation may have accelerated this process in some areas by increasing the transport of accumulated salts and by increasing the number of evaporative cycles. Results from this study highlight the potential for ClO 4to impact groundwater in arid and semiarid areas through long-term atmospheric deposition.

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Section: Introductionmentioning

confidence: 99%

Widespread Presence of Naturally Occurring Perchlorate in High Plains of Texas and New Mexico

Rajagopalan

Anderson

Fahlquist

et al. 2006

Environ. Sci. Technol.

145

128

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“…In addition, potassium perchlorate is a key ingredient in the production of fireworks, explosives, road flares, and other minor uses (22). Natural sources of perchlorate were generally thought to be restricted to fertilizers mined from Chilean caliche deposits (23). However, recent studies suggest a possible atmospheric origin for background levels of perchlorate, formed from chloride or hypochlorite during atmospheric lightning discharges or from reactions involving ozone, solar energy, and chloride (24)(25)(26).…”

Section: Introductionmentioning

confidence: 99%

Perchlorate Behavior in a Municipal Lake Following Fireworks Displays

Wilkin

Fine

Burnett

2007

Environ. Sci. Technol.

102

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After the fireworks displays, perchlorate concentrations decreased toward the background level within 20 to 80 days, with the rate of attenuation correlating to surface water temperature. Adsorption tests indicate that sediments underlying the water column have limited (<100 nmol/g) capacity to remove perchlorate via chemical adsorption. Microcosms showed comparatively rapid intrinsic perchlorate degradation in the absence of nitrate consistent with the observed disappearance of perchlorate from the study site. This suggests that at sites with appropriate biogeochemical conditions, natural attenuation may be an important factor affecting the fate of perchlorate following fireworks displays.

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“…Chilean nitrate has long been known to be a natural source of perchlorate (20). A recent comprehensive evaluation has shown that, with the exception of fertilizers derived from Chilean nitrate, fertilizers are not a significant source of perchlorate to the environment (21).…”

Section: Introductionmentioning

confidence: 99%

Accumulation and Perchlorate Exposure Potential of Lettuce Produced in the Lower Colorado River Region

Sanchez

Krieger

Khandaker

et al. 2005

J. Agric. Food Chem.

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The Colorado River is contaminated with perchlorate concentrations of 1.5-8 µg/L, an anion linked to thyroid dysfunction. Over 90% of the lettuce (Lactuca sativa L.) consumed during the winter months in the United States is produced in the Lower Colorado River region. Studies were conducted in this region to survey the potential for lettuce perchlorate accumulation and estimate potential human exposure to perchlorate from lettuce. Total uptake of perchlorate in the above-ground plant of iceberg lettuce was approximately 5 g/ha. Exposure estimates ranged from 0.45 to 1.8 µg/day depending on lettuce types and trimming. For all lettuce types, hypothetical exposures were less than 4% of the reference dose recommended by the National Academy of Sciences. Results show the relative iodide uptake inhibition potential because of lettuce nitrate was 2 orders of magnitude greater than that associated with the corresponding trace levels of perchlorate. These data support the conclusion that potential perchlorate exposures from lettuce irrigated with Colorado River water are negligible relative to acute or long-term harmful amounts.

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Geology and origin of the Chilean nitrate deposits

Abstract: ______________________________ 1 Introduction 1 Location _ 2 Acknowledgments ___ 3 Geomorphology _ 3 Climate, vegetation, and soil microorganisms ____ 8 Geology of the nitrate deposits _… Show more

Cited by 242 publications

References 45 publications

Widespread Presence of Naturally Occurring Perchlorate in High Plains of Texas and New Mexico

Widespread Presence of Naturally Occurring Perchlorate in High Plains of Texas and New Mexico

Perchlorate Behavior in a Municipal Lake Following Fireworks Displays

Accumulation and Perchlorate Exposure Potential of Lettuce Produced in the Lower Colorado River Region

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