Contrasting regional and national mechanisms for predicting elevated arsenic in private wells across the United States using classification and regression trees

Frederick, Logan; VanDerslice, James; Taddie, Marissa; Malecki, Kristen; Gregg, J.; Faust, N.; Johnson, William P.

doi:10.1016/j.watres.2016.01.023

Cited by 21 publications

(36 citation statements)

References 20 publications

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“…Previous studies in Maine and New Jersey have focused on domestic well stewardship and voluntary testing largely among populations living in areas with high risk of exposure to arsenic or nitrates. 4, 10 In contrast, as previously mentioned, SHOW participants were randomly selected to provide both a demographically and geographically representative sample of state residents and not selected based on potential for increased exposure to particular ground water contaminants or concerns.…”

Section: Discussionmentioning

confidence: 99%

“…2–4 A USGS report testing private wells in 48 states found that more than one-fifth of all sampled wells had levels greater than health-based standards, and almost 25% of rural wells located in largely agricultural areas exceeded health based standards, with over 34% testing positive for nitrates. 2 Private well stewardship is a particularly important issue in states like Wisconsin where at least one quarter of the population is served by a private well as their primary drinking water source 5 .…”

Section: Introductionmentioning

confidence: 99%

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Private-well stewardship among a general population based sample of private well-owners

Malecki

Schultz

Severtson

et al. 2017

Science of The Total Environment

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Private well stewardship, including on-going testing and treatment, can ensure private well users are able to maintain source-water quality and prevent exposures to potentially harmful constituents in primary drinking water supplies. Unlike municipal water supplies, private well users are largely responsible for their own testing and treatment and well stewardship is often minimal. The importance of factors influencing regular testing, and treatment behaviors, including knowledge, risk perception, convenience and social norms, can vary by geography and population characteristics. The primary goals of this study were to survey a general statewide population of private well users in Wisconsin in order to quantify testing and treatment patterns and gather data on motivations and barriers to well stewardship. The majority of respondents reported using and drinking well water daily but only about one half of respondents reported testing their wells in the last ten years and of these, only 10% reported testing in the last 12 months. Bacteria and nitrates were contaminants most often tested; and, a private laboratory most often conducted testing. The most commonly reported water treatment was a water softener. Living in a particular geographic region and income were the most significant predictors of water testing and treatment. Iron and hardness, which influence water aesthetics but not always safety, were the most commonly reported water quality problems. Health concerns or perceived lack thereof were, respectively, motivators and barriers to testing and treatment. Limited knowledge of testing and treatment options were also identified as barriers. Results confirm previous findings that well stewardship practices are minimal and often context specific. Understanding the target population’s perceptions of risk and knowledge are important elements to consider in identifying vulnerable populations and developing education and policy efforts to improve well stewardship.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Private-well stewardship among a general population based sample of private well-owners

Malecki

Schultz

Severtson

et al. 2017

Science of The Total Environment

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“…National-scale studies in the United States (US) by the US Geological Survey (USGS; Focazio et al, 2000;Ryker, 2001Ryker, , 2003Welch et al, 2001; Lee and Helsel, 2005;Gronberg, 2011) and others (Lockwood et al, 2004;Frederick et al, 2016) have led to the generation of spatial distribution maps of arsenic in groundwater. To fill the voids as a result of a national-scale assessment approach, regional groundwater studies (especially for areas with insufficient data, e.g., Mid-Atlantic states), have been used to demonstrate arsenic contamination on greater spatial scales (Sanders et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…While the use of geostatistical modeling can be used with success for generating prediction maps, these techniques suffer from limitations including data availability, data quality, and local scale arsenic mobilization variations due to complex groundwater flow paths (Ayotte et al, 2011;Bretzler et al, 2017a). As outlined by Frederick et al (2016), generally when exploring potential relationships between elevated arsenic and various explanatory variables two primary modeling strategies can be used: logistic regression (e.g., Ayotte et al, 2003;Winkel et al, 2008;Gross and Low, 2013;Bretzler et al, 2017b), or decision tree analysis (Hossain and Piantanakulchai, 2013;Tesoriero et al, 2017). However, in this present study, an alternative approach to these modeling techniques, previously applied successfully by McGrory et al (2017) which used similar predictor variables in addition to detailed aqueous geochemistry data that can potentially explain the spatial distribution of arsenic in relation to groundwater controls (e.g., bedrock geology) was utilized.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous approaches have been adopted to overcome these limitations, such as removal of censored data (with resulting loss of information), censored data analysis and/or substitution methods. These substitution methods (i.e., DL * 1/2) are the most commonly used for the assessment of groundwater quality parameters at various spatial scales (Meliker et al, 2008;Homoncik et al, 2010;Sanders et al, 2012;Gong et al, 2014;Frederick et al, 2016;McLeod et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Arsenic in Groundwater in South West Ireland: Occurrence, Controls, and Hydrochemistry

McGrory

Alvarez‐Iglesias

Bargary

et al. 2018

Front. Environ. Sci.

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Globally numerous regions have been identified with elevated arsenic within groundwater which can result in potential adverse health risks. In Ireland, a previous national-scale research assessment of groundwater identified isolated clusters of elevated arsenic and indicated that lithology was a major controlling factor on arsenic in groundwater. Complementary comparisons of national-scale and regional-scale groundwater assessments of arsenic are lacking in Europe when compared to other global regions. The aims of this study were to demonstrate the value of a regional-scale groundwater hydrochemistry dataset with an existing national-scale approach, describe anomalies that can become the focus of attention for public health and economic reasons, and to provide a wider context for arsenic in groundwater within Ireland and Europe. Regional-scale data using 470 locations comprising 1,493 analyses using several hydrochemical parameters (arsenic, pH, conductivity, iron, manganese, sodium, potassium, calcium, magnesium, and total hardness) in south west Ireland were integrated with geological, hydrogeological, and land use datasets. Statistical analysis was performed using a combination of methods including score tests of geological groups using an empirical cumulative distribution function plot in addition to spatial analysis. Results revealed that hydrochemical parameters exhibited different spatial clusters, which was generally associated with lithology. Arsenic was elevated in sandstone derived bedrock. Weak correlation of arsenic with other hydrochemical parameters were observed and redox-sensitive elements like manganese and iron showed a greater diversity in spatial occurrence. This study has shown that the variation of hydrochemical parameters are controlled by regional geology. Finally, the paper focuses on anomalies identified by concentrations of individual ions or statistical associations in the context of, for example, historical mineral exploration and mining in the area and also discusses whether groundwater chemistry sampling on this scale can assist in future mineral exploration, as well as guiding the future development of high quality public and private water supplies.

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Rapid gravity filtration operational performance assessment and diagnosis for preventative maintenance from on-line data

Upton

Jefferson

Moore

et al. 2017

Chemical Engineering Journal

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Contrasting regional and national mechanisms for predicting elevated arsenic in private wells across the United States using classification and regression trees

Cited by 21 publications

References 20 publications

Private-well stewardship among a general population based sample of private well-owners

Private-well stewardship among a general population based sample of private well-owners

Arsenic in Groundwater in South West Ireland: Occurrence, Controls, and Hydrochemistry

Rapid gravity filtration operational performance assessment and diagnosis for preventative maintenance from on-line data

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