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Calderon R.,Catholic University of Temuco | Palma P.,Laboratorio Sanitario Ambiental | Parker D.,University of California at Riverside | Escudey M.,University of Santiago de Chile | Escudey M.,Chilean Center of Nanosciences and Nanotechnology
Chemosphere | Year: 2014

Various studies have evaluated the accumulation of ClO4 - in lettuce (Lactuca sativa), but very few have dealt with the variables that can interfere with its capture. The present study evaluates the transfer of ClO4 - in two L. sativa varieties: butter head (L. sativa var. capitata) and cos lettuce (L. sativa var. crispa) under hydroponic conditions. The ClO4 - concentrations used correspond to levels (1 and 2mgL-1), measured in irrigation water in the Iquique region in the north of Chile. Results indicate that the capture of ClO4 - is dependent on its concentration, lettuce genotype, and temperature. The butter head variety accumulates the highest perchlorate concentrations. Anion competition involving NO3 - (16 and 48mM), Cl- (23 and 56mM), and SO4 2- (10 and 20mM) was evaluated, being NO3 - (48mM), the most significant competition reducing the concentration of ClO4 - in tissues of L. sativa varieties. © 2014 Elsevier Ltd.

Calderon R.,University of Santiago de Chile | Palma P.,Laboratorio Sanitario Ambiental | Parker D.,University of California at Riverside | Molina M.,Federico Santa Maria Technical University | And 3 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2014

Perchlorate is an anion that originates as a contaminant in ground and surface waters. The presence of perchlorate in soil and water samples from northern Chile (Atacama Desert) was investigated by ion chromatography- electrospray mass spectrometry. Results indicated that perchlorate was found in five of seven soils (cultivated and uncultivated) ranging from 290 ± 1 to 2,565 ± 2 μg/kg. The greatest concentration of perchlorate was detected in Humberstone soil (2,565 ± 2 lg/kg) associated with nitrate deposits. Perchlorate levels in Chilean soils are greater than those reported for uncultivated soils in the United States. Perchlorate was also found in superficial running water ranging from 744 ± 0.01 to 1,480 ± 0.02 lg/L. Perchlorate water concentration is 30-60 times greater than levels established by the United States Environmental Protection Agency (24.5 μg/L) for drinking. © Springer Science+Business Media 2013.

Calderon R.,Catholic University of Temuco | Palma P.,Laboratorio Sanitario Ambiental | Godoy F.,University of Los Lagos | Escudey M.,University of Santiago de Chile
Archives of Agronomy and Soil Science | Year: 2016

The mobility of perchlorate in soils depends on several factors, including soil mineralogy and the presence of other oxyanions that compete with perchlorate for the retention sites. Currently, there are no studies that evaluate the mobility of perchlorate in arid soils. The present study evaluated the mobility of ClO4 – in three arid soils, Canchones, Humberstone and Pica, exposed to two ClO4 – concentration ranges and different ionic strengths. In Humberstone (non-agricultural) and Pica (agricultural) soils, the sorption processes were not important for both concentration ranges, while Canchones soil (agricultural) showed a decrease in perchlorate concentration associated with microbial degradation processes. The increase of medium ionic strength by addition of Ca(NO3)2 only had an important effect on Humberstone soil, associated with the presence of kaolinite and muscovite (variable charge). A competition effect was observed between perchlorate, nitrate and other anions presents in solution by absorption sites generated from variable charge mineral and calcium. Considering the quite low sorption capacity of the soils and the high solubility, perchlorate can be absorbed by fruit and vegetables of export in concentrations over the healthy levels established by international organization. © 2016 Taylor & Francis

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