Widespread natural perchlorate in unsaturated zones of the southwest United States

Balaji Rao; Todd A. Anderson; Greta J. Orris; Ken A. Rainwater; Srinath Rajagopalan; Renee M. Sandvig; Bridget R. Scanlon; David A. Stonestrom; Michelle Ann Walvoord; W Andrew Jackson

doi:10.1021/es062853i

USGS · 70029966

Widespread natural perchlorate in unsaturated zones of the southwest United States

Balaji Rao·Todd A. Anderson·Greta J. Orris·Ken A. Rainwater·Srinath Rajagopalan·Renee M. Sandvig·Bridget R. Scanlon·David A. Stonestrom·Michelle Ann Walvoord·W Andrew Jackson

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Abstract

A substantial reservoir (up to 1 kg ha -1 ) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10−15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to the Atacama Desert, now appears widespread in steppe-to-desert ecoregions. The perchlorate reservoir becomes sufficiently large to affect groundwater when recharge from irrigation or climate change flushes accumulated salts from the unsaturated zone. This new source may help explain increasing reports of perchlorate in dry region agricultural products and should be considered when evaluating overall source contributions.

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Environmental Science & Technology Article

Source-reported bounding extent: 30.437852260794457° to 38.32858773159356° latitude; -117.37637060997972° to -100.68431363371681° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Balaji Rao, Todd A. Anderson, Greta J. Orris, Ken A. Rainwater, Srinath Rajagopalan, Renee M. Sandvig, Bridget R. Scanlon, David A. Stonestrom, Michelle Ann Walvoord, W Andrew Jackson. 2007-06-06. Widespread natural perchlorate in unsaturated zones of the southwest United States. https://doi.org/10.1021/es062853i

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