Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots

Abstract Groundwater contaminants that can negatively impact human health, such as nitrate, uranium, arsenic, and manganese, are common in agricultural areas. The mobility and distribution of these contaminants in groundwater are strongly impacted by oxidation‐reduction (redox) processes. Groundwate...

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Main Author: Jeffrey P. Westrop
Format: Article
Language:English
Published: Wiley 2025-06-01
Series:Agrosystems, Geosciences & Environment
Online Access:https://doi.org/10.1002/agg2.70098
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author Jeffrey P. Westrop
author_facet Jeffrey P. Westrop
author_sort Jeffrey P. Westrop
collection DOAJ
description Abstract Groundwater contaminants that can negatively impact human health, such as nitrate, uranium, arsenic, and manganese, are common in agricultural areas. The mobility and distribution of these contaminants in groundwater are strongly impacted by oxidation‐reduction (redox) processes. Groundwater redox, however, is difficult to determine without conducting time‐sensitive geochemical analyses. Prior research demonstrated that areas of low groundwater nitrate concentrations could be identified by the presence of rust on irrigation center pivots. This “rust” is a coating of iron (Fe) oxides formed by the incidental spraying of Fe‐rich groundwater on the surface of pivot. Thus, the pivot rust could be a qualitative indicator of reducing conditions where Fe is soluble in groundwater. Nitrate, arsenic, uranium, iron, and manganese from the irrigation wells associated with 29 pivots (16 rusted and 13 non‐rusted) in central Nebraska. Results indicate significantly higher concentrations of iron and manganese and significantly lower concentrations of nitrate and uranium in areas with rusted pivots, strongly suggesting a link between pivot rust and redox‐sensitive contaminants. Most of the rusted pivots in the study area are along the eastern edge of the subcrop of the Miocene Ogallala Group, where the alluvium overlies the Pierre shale, which could be the source of Fe and other metals in groundwater. These results underscore the utility of pivot rust as a rapid, non‐invasive indicator for redox‐sensitive elements in groundwater.
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spelling doaj-art-9654583e07d7410895e4ffd440d6fb752025-08-20T02:20:38ZengWileyAgrosystems, Geosciences & Environment2639-66962025-06-0182n/an/a10.1002/agg2.70098Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivotsJeffrey P. Westrop0Conservation and Survey Division, School of Natural Resources University of Nebraska‐Lincoln Lincoln Nebraska USAAbstract Groundwater contaminants that can negatively impact human health, such as nitrate, uranium, arsenic, and manganese, are common in agricultural areas. The mobility and distribution of these contaminants in groundwater are strongly impacted by oxidation‐reduction (redox) processes. Groundwater redox, however, is difficult to determine without conducting time‐sensitive geochemical analyses. Prior research demonstrated that areas of low groundwater nitrate concentrations could be identified by the presence of rust on irrigation center pivots. This “rust” is a coating of iron (Fe) oxides formed by the incidental spraying of Fe‐rich groundwater on the surface of pivot. Thus, the pivot rust could be a qualitative indicator of reducing conditions where Fe is soluble in groundwater. Nitrate, arsenic, uranium, iron, and manganese from the irrigation wells associated with 29 pivots (16 rusted and 13 non‐rusted) in central Nebraska. Results indicate significantly higher concentrations of iron and manganese and significantly lower concentrations of nitrate and uranium in areas with rusted pivots, strongly suggesting a link between pivot rust and redox‐sensitive contaminants. Most of the rusted pivots in the study area are along the eastern edge of the subcrop of the Miocene Ogallala Group, where the alluvium overlies the Pierre shale, which could be the source of Fe and other metals in groundwater. These results underscore the utility of pivot rust as a rapid, non‐invasive indicator for redox‐sensitive elements in groundwater.https://doi.org/10.1002/agg2.70098
spellingShingle Jeffrey P. Westrop
Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
Agrosystems, Geosciences & Environment
title Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
title_full Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
title_fullStr Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
title_full_unstemmed Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
title_short Qualitative screening for redox‐sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
title_sort qualitative screening for redox sensitive elements in groundwater using the presence or absence of rust on irrigation center pivots
url https://doi.org/10.1002/agg2.70098
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