Event Title

Arsenic contamination of domestic wells in the Cache Valley Basin: potential role of arsenic mineralogy in surface soils

Presenter Information

William Fullmer

Location

USU Eccles Conference Center

Event Website

http://water.usu.edu

Start Date

4-5-2016 4:30 PM

End Date

4-5-2016 4:33 PM

Description

Arsenic (As) is one of the most frequently detected contaminants in domestic private wells used for household drinking water and irrigation in the U.S. Arsenic in groundwater is influenced by biogeochemical factors rather than anthropogenic sources. Basin-fill aquifers in the western US, including the Cache Valley Basin (CVB), UT have elevated As levels. Arsenic contamination in the CVB is associated with carbonate minerals related to Utah’s calcareous and semi-arid environment rather than the often-reported association with iron oxides. This study examines the spatial and temporal distribution of As in domestic wells in CVB and explores As mineralogy in surface soils as a potential source of As in groundwater. Spatial distribution of As in wells was evaluated using published literature. Additional domestic wells were sampled in fall 2014 and spring 2015 to examine seasonal changes of chemical constituents influencing As solubilization throughout the CVB. Surface soils were collected from seven sites and characterized for As mineralogy using chemical extraction methods. Twenty-three out of 157 of domestic wells in CVB have As concentrations exceeding the drinking water maximum contamination level (10 ?g/L). Well samples collected in the spring had lower As concentrations than fall sampling. The majority of the As in the surface soils was associated with insoluble iron oxides but 10 to 45% was in pools considered to be labile, including carbonate minerals. This finding is significant since weakly held As is more likely to leach and lead to As contamination in groundwater. It is important to understand the interactions between calcareous soils and arsenic within the CVB with application for basin-fill aquifers in the western US. The knowledge could provide engineers and private well owners with better understanding of drilling locations and land management practices that could prevent further leaching of arsenic into the groundwater.

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Apr 5th, 4:30 PM Apr 5th, 4:33 PM

Arsenic contamination of domestic wells in the Cache Valley Basin: potential role of arsenic mineralogy in surface soils

USU Eccles Conference Center

Arsenic (As) is one of the most frequently detected contaminants in domestic private wells used for household drinking water and irrigation in the U.S. Arsenic in groundwater is influenced by biogeochemical factors rather than anthropogenic sources. Basin-fill aquifers in the western US, including the Cache Valley Basin (CVB), UT have elevated As levels. Arsenic contamination in the CVB is associated with carbonate minerals related to Utah’s calcareous and semi-arid environment rather than the often-reported association with iron oxides. This study examines the spatial and temporal distribution of As in domestic wells in CVB and explores As mineralogy in surface soils as a potential source of As in groundwater. Spatial distribution of As in wells was evaluated using published literature. Additional domestic wells were sampled in fall 2014 and spring 2015 to examine seasonal changes of chemical constituents influencing As solubilization throughout the CVB. Surface soils were collected from seven sites and characterized for As mineralogy using chemical extraction methods. Twenty-three out of 157 of domestic wells in CVB have As concentrations exceeding the drinking water maximum contamination level (10 ?g/L). Well samples collected in the spring had lower As concentrations than fall sampling. The majority of the As in the surface soils was associated with insoluble iron oxides but 10 to 45% was in pools considered to be labile, including carbonate minerals. This finding is significant since weakly held As is more likely to leach and lead to As contamination in groundwater. It is important to understand the interactions between calcareous soils and arsenic within the CVB with application for basin-fill aquifers in the western US. The knowledge could provide engineers and private well owners with better understanding of drilling locations and land management practices that could prevent further leaching of arsenic into the groundwater.

https://digitalcommons.usu.edu/runoff/2016/2016Posters/1