Approximately 80% of Virginians with private drinking water (PDW) sources are unaware of the quality of their drinking water. Strontium is a water quality contaminant gaining recognition at the federal level. At concentrations >1.5 mg/L, strontium substitutes calcium in the bones leading to bone density disorders (e.g. rickets). This is particularly problematic for children and individuals with low calcium and low protein diets. Because most Virginians do not know the quality of their PDW and since strontium poses a public health risk, this study investigates the sources of strontium in PDW in Virginia and identifies the areas and populations most vulnerable. Physical factors such as rock type, rock age, and fertilizer use have been linked to elevated strontium concentrations in drinking water. Meanwhile, social factors such as poverty, poor diet, and adolescence also increase social vulnerability to health impacts of strontium. Thus, this study identifies both physically and socially vulnerable regions in Virginia using water quality data from the Virginia Household Water Quality Program and statistical and spatial analyses conducted in RStudio 1.0.153 and ArcMap 10.5.1. Physical vulnerabilities were highest in the Ridge and Valley province where geologic formations with high strontium concentrations (e.g., limestone, dolomite, sandstone, and shale) are the dominant the aquifer rocks. The complex relationship between agricultural land use and strontium concentrations made it difficult to determine the impact of fertilizer use on strontium concentrations in PDW in Virginia. In general, the spatial distribution of social vulnerability factors was distinct from physical factors with the exception of food deserts. This study provides information and analysis to help residents of Virginia understand their risk of strontium exposure in PDW. / Master of Science / There are 1.7 million residents in Virginia that rely on private drinking water supplies in their homes. Those individuals are responsible for knowing how often to test their water, what to test their water for, and how to treat their water, if needed, to achieve safe drinking standards. Unfortunately, approximately 80% of Virginians with private drinking water sources (e.g., wells, cisterns, and springs) do not know if their water is safe to drink. Strontium, an element closely related to calcium, is a contaminant that the federal government recognizes as dangerous because in high quantities (>1.5 mg/L of water) it can replace calcium in bones making them brittle (e.g. rickets). These health impacts are more extreme in children and individuals with low calcium and low protein diets. Since strontium poses a public health risk, this study identified areas and populations in Virginia that have higher chances of being exposed to strontium and higher chances of their health being impacted by high levels of strontium. Physical factors such as rock type, rock age, and fertilizer use have been linked to elevated strontium concentrations in drinking water, indicating various physical vulnerabilities. Meanwhile, social factors such as poverty, poor diet, and adolescence also increase social vulnerability to the health impacts of strontium. This paper investigates regions in Virginia that are likely to contain high strontium levels and thus potential health impacts from strontium. Statistical and spatial analyses of water quality data from Virginia Cooperative Extension’s Virginia Household Water Quality Program combined with risk factor data identified vulnerable areas in Virginia. The highest chance of exposure was in counties near the western border of the state (e.g., Augusta, Fredrick, Highland, Montgomery, Shenandoah, and Wythe) due to the presence of limestone, dolomite, sandstone, and shale, all of which naturally contain high amounts of strontium. The land use data indicated that there were no strong patterns of strontium occurrence relative to fertilizer use. In general, the spatial distribution of social vulnerability factors was distinct from physical factors with the exception of food deserts occurring at high rates in the same areas as the samples with high strontium levels (e.g., Augusta, Fredrick, Highland, Montgomery, Shenandoah, and Wythe). The presence of food deserts prevents individuals from obtaining a high calcium and high protein diet, which makes them more vulnerable to the impacts of strontium. Overall, this study can help people in Virginia who are not on public water systems understand their risk of from being exposed to strontium.

In Virginia, over one million households rely on private water supplies (e.g. well, spring, cistern). Previous literature acknowledges bacterial contamination in private water supplies as a significant public health concern in the United States. The present study tested private wells and springs in 20 Virginia counties for total coliforms (TC) and E. coli (EC) along with a suite of chemical contaminants. Sample collection was organized by the Virginia Household Water Quality Program (VAHWQP), a Virginia Cooperative Extension effort managed by faculty in the Biological Systems Engineering Department. Microbial and chemical source tracking were used to identify possible sources of contamination. A logistic regression was employed to investigate potential correlations between TC contamination and chemical parameters (e.g. NO3-, turbidity) as well as homeowner provided survey data describing system characteristics and perceived water quality. TC and EC contamination were quantified via the Colilert (www.idexx.com) defined substrate method for most probable number (MPN) of EC and TC per 100 mL of water. Of the 538 samples collected, 41% (n=221) were positive for TC and 10% (n=53) for EC. Chemical parameters were not statistically predictive of microbial contamination. Well depth, water treatment, and farm location proximate to the water supply were factors in a regression model that predicted presence/absence of TC with 74% accuracy. Microbial and chemical source tracking techniques (Polymerase Chain Reaction (PCR) and fluorometry, respectively) identified 4 of 26 samples as likely contaminated with human wastewater. Application of these source-tracking analyses on a larger scale will prove useful in defining remediation strategies. / Master of Science

Per- and polyfluoroalkyl substances (PFAS) are a class of man-made contaminants of increasing human health concern due to their resistance to degradation, widespread occurrence in the environment, bioaccumulation in human and animal organ tissue, and potential negative health impacts. Drinking water is suspected to be a primary source of human PFAS exposure, so the US Environmental Protection Agency (US EPA) has set interim and final health advisories for several PFAS species that are applicable to municipal water supplies. However, private drinking water supplies may be uniquely vulnerable to PFAS contamination, as these systems are not subject to EPA regulation and often include limited treatment prior to use for drinking or cooking. The goal of this study was to determine the incidence of PFAS contamination in private drinking water supplies in two counties in Southwest Virginia (Floyd and Roanoke), and to examine the potential for reliance on citizen-science based strategies for sample collection in subsequent broader sampling efforts. Samples for inorganic ions, bacteria, and PFAS analysis were collected on separate occasions by homeowners and experts at the home drinking water point of use (POU) in 10 Roanoke and 10 Floyd County homes for comparison. Experts also collected an outside tap PFAS sample. At least one PFAS compound was detected in 76% of POU samples collected (n=60), with an average total PFAS concentration of 23.5 parts per trillion (ppt). PFOA and PFOS, which are currently included in EPA health advisories, were detected in 13% and 22% of POU samples, respectively. Of the 31 PFAS species targeted, 15 were detected in at least one sample. On average, a single POU sample contained approximately 3 PFAS, and one sample contained as many as 8 different species, indicating that exposure to PFAS in complex mixtures is worth noting. Although there were significant differences in total PFAS concentrations between expert and homeowner collected samples (Wilcoxon, alpha = 0.05), it is unclear whether this difference was due to contamination by the collector or the water usage and time of day of sampling (i.e. morning, afternoon). It is worth noting that there was no significant difference in the number of PFAS species in the samples collected by homeowners and experts. Given the considerable variation in PFAS detections between homes, future studies reliant on homeowner collection of samples appears possible given proper training and instruction to collect at the same time of day (i.e. first thing in the morning). / Master of Science / Per- and polyfluoroalkyl substances (PFAS) belong to a large family of manmade compounds that are commonly used in a variety of household and consumer products due to their unique water and stain resistant properties. PFAS compounds are not easily broken down in the environment and have been detected globally in air, soil, and water samples. In addition to their environmental detections, PFAS are slow to be removed from the body after ingestion and known to cause negative health effects in concentrations less than one part per trillion. Drinking water is considered to a main source of PFAS consumption for humans; as such, the US Environmental Protection Agency (US EPA) has set strict, but not legally binding, interim and final health advisories (HA) for four types of PFAS. However, these health advisories only apply to public water services and do not cover private drinking water systems, such as wells or springs, which are the full responsibility of the well owner. Private drinking water system users often do not treat their water before drinking which may make these systems uniquely vulnerable to PFAS contamination. This study focused on 20 total homes, 10 in Roanoke County and 10 in Floyd County to see if PFAS was present and to determine whether or not homeowners would be able to collect their own samples for PFAS analysis at home as accurately as researchers or experts with proper instructions. Homeowners and experts collected drinking water samples inside at a point of use (POU), usually at a kitchen faucet, and outside of the home, usually from a tap. PFAS were present in 76% (n=60) of POU samples, with an average combined concentration of 23.5 parts per trillion (ppt). The two most well studied PFAS, PFOA and PFOS were detected in 13% and 22% of POU samples, respectively. It was also common to detect at least 3 PFAS in a single sample. Although there were differences in total average concentrations of PFAS in samples collected by homeowners and experts, variation could be caused by several factors indicating that with proper training and instruction it is likely future studies could still rely on homeowners to collect samples for PFAS analysis.