An Integrative Study Of The Sources And Effects Of Naturally Occurring Contaminants In Private Wells In North Carolina

The purpose of this project is to evaluate the exposure of private well users to natural contaminants of arsenic, radon, and radium. The project investigates the mechanisms in which these natural contaminants are leached into groundwater, the available treatment techniques for removal of natural contaminants, the role of information as an environmental health policy tool that examines how households respond to information regarding inorganic contaminants, and the policy implications for an increasing population that uses groundwater with contaminant levels exceeding EPA regulations

Noble Gases Identify the Mechanisms of Fugitive Gas Contamination in Drinking-Water Wells Overlying the Marcellus and Barnett Shales

Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ13C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., 4He, 20Ne, 36Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, 4He) were significantly higher (P \u3c 0.01) and the proportions of atmospheric gases (air-saturated water; e.g., N2, 36Ar) were significantly lower (P \u3c 0.01) relative to background groundwater. Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing

Groundwater Quality and Its Health Impact: An Assessment of Dental Fluorosis in Rural Inhabitants of the Main Ethiopian Rift

This study aims to assess the link between fluoride content in groundwater and its impact on dental health in rural communities of the Ethiopian Rift. A total of 148 water samples were collected from two drainage basins within the Main Ethiopian Rift (MER). In the Ziway-Shala basin in particular, wells had high fluoride levels (mean: 9.4 ± 10.5 mg/L; range: 1.1 to 68 mg/L), with 48 of 50 exceeding the WHO drinking water guideline limit of 1.5 mg/L. Total average daily intake of fluoride from drinking groundwater (calculated per weight unit) was also found to be six times higher than the No-Observed-Adverse-Effects-Level (NOAEL) value of 0.06 mg/kg/day. The highest fluoride levels were found in highly alkaline (pH of 7 to 8.9) groundwater characterized by high salinity; high concentrations of sodium (Na+), bicarbonate (HCO3−), and silica (SiO2); and low concentrations of calcium (Ca2+). A progressive Ca2+ decrease along the groundwater flow path is associated with an increase of fluoride in the groundwater. The groundwater quality problem is also coupled with the presence of other toxic elements, such as arsenic (As) and uranium (U). The health impact of fluoride was evaluated based on clinical examination of dental fluorosis (DF) among local residents using the Thylstrup and Fejerskov index (TFI). In total, 200 rural inhabitants between the ages of 7 and 40 years old using water from 12 wells of fluoride range of 7.8–18 mg/L were examined. Signs of DF (TF score of ≥ 1) were observed in all individuals. Most of the teeth (52%) recorded TF scores of 5 and 6, followed by TF scores of 3 and 4 (30%), and 8.4% had TF scores of 7 or higher. Sixty percent of the teeth exhibited loss of the outermost enamel. Within the range of fluoride contents, we did not find any correlation between fluoride content and DF. Finally, preliminary data suggest that milk intake has contributed to reducing the severity of DF. The study highlights the apparent positive role of milk on DF and emphasizes the importance of nutrition in management efforts to mitigate DF in the MER and other parts of the world

Fluoride Exposure from Groundwater as Reflected by Urinary Fluoride and Children’s Dental Fluorosis in the Main Ethiopian Rift Valley

This cross-sectional study explores the relationships between children’s F− exposure from drinking groundwater and urinary F− concentrations, combined with dental fluorosis (DF) in the Main Ethiopian Rift (MER) Valley. We examined the DF prevalence and severity among 491 children (10 to 15 This cross-sectional study explores the relationships between children’s F− exposure from drinking groundwater and urinary F− concentrations, combined with dental fluorosis (DF) in the Main Ethiopian Rift (MER) Valley. We examined the DF prevalence and severity among 491 children (10 to 15 years old) who are lifelong residents of 33 rural communities in which groundwater concentrations of F− cover a wide range. A subset of 156 children was selected for urinary F− measurements. Our results showed that the mean F− concentrations in groundwater were 8.5 ± 4.1 mg/L (range: 1.1–18 mg/L), while those in urine were 12.1 ± 7.3 mg/L (range: 1.1–39.8 mg/L). The prevalence of mild, moderate, and severe DF in children’s teeth was 17%, 29%, and 45%, respectively, and the majority (90%; n = 140) of the children had urinary F− concentrations above 3 mg/L. Below this level most of the teeth showed mild forms of DF. The exposure-response relationship between F− and DF was positive and nonlinear, with DF severity tending to level off above a F− threshold of ~6 mg/L, most likely due to the fact that at ~6 mg/L the enamel is damaged as much as it can be clinically observed in most children. We also observed differential prevalence (and severity) of DF and urinary concentration across children exposed to similar F− concentrations in water, which highlights the importance of individual-specific factors in addition to the F− levels in drinking water. Finally, we investigated urinary F− in children from communities where defluoridation remediation was taking place. The lower F− concentration measured in urine of this population demonstrates the capacity of the urinary F−method as an effective monitoring and evaluation tool for assessing the outcome of successful F− mitigation strategy in a relatively short time (months) in areas affected with severe fluorosis

The Effect of Non-fluoride Factors on Risk of Dental Fluorosis: Evidence from Rural Populations of the Main Ethiopian Rift

Elevated level of fluoride (F−) in drinking water is a well-recognized risk factor of dental fluorosis (DF). While considering optimization of region-specific standards for F−, it is reasonable, however, to consider how local diet, water sourcing practices, and non-F− elements in water may be related to health outcomes. In this study, we hypothesized that non-F− elements in groundwater and lifestyle and demographic characteristics may be independent predictors or modifiers of the effects of F− on teeth. Dental examinations were conducted among 1094 inhabitants from 399 randomly selected households of 20 rural communities of the Ziway-Shala lake basin of the Main Ethiopian Rift. DF severity was evaluated using the Thylstrup-Fejerskov Index (TFI). Household surveys were performed and water samples were collected from community water sources. To consider interrelations between the teeth within individual (in terms of DF severity) and between F− and non-F− elements in groundwater, the statistical methods of regression analysis, mixed models, and principal component analysis were used. About 90% of study participants consumed water from wells with F− levels above the WHO recommended standard of 1.5 mg/l. More than 62% of the study population had DF. F− levels were a major factor associated with DF. Age, sex, and milk consumption (both cow’s and breastfed) were also statistically significantly (p \u3c 0.05) associated with DF severity; these associations appear both independently and as modifiers of those identified between F− concentration and DF severity. Among 35 examined elements in groundwater, Ca, Al, Cu, and Rb were found to be significantly correlated with dental health outcomes among the residents exposed to water with excessive F− concentrations. Quantitative estimates obtained in our study can be used to explore new water treatment strategies, water safety and quality regulations, and lifestyle recommendations which may be more appropriate for this highly populated region

Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California

Author Posting. © American Chemical Society, 2019. This is an open access article published under an ACS AuthorChoice License. The definitive version was published in Environmental Science and Technology 53(16), (2019): 9398-9406, doi:10.1021/acs.est.9b02395.Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitvale, Lost Hills, South Belridge). 226Ra+228Ra activities (range = 0.010–0.51 Bq/L) exceeded the 0.185 Bq/L drinking-water standard in 18% of the wells (not drinking-water wells). Radium activities were correlated with TDS concentrations (p < 0.001, ρ = 0.90, range = 145–15,900 mg/L), Mn + Fe concentrations (p < 0.001, ρ = 0.82, range = <0.005–18.5 mg/L), and pH (p < 0.001, ρ = −0.67, range = 6.2–9.2), indicating Ra in groundwater was influenced by salinity, redox, and pH. Ra-rich groundwater was mixed with up to 45% oil-field water at some locations, primarily infiltrating through unlined disposal ponds, based on Cl, Li, noble-gas, and other data. Yet 228Ra/226Ra ratios in pond-impacted groundwater (median = 3.1) differed from those in oil-field water (median = 0.51). PHREEQC mixing calculations and spatial geochemical variations suggest that the Ra in the oil-field water was removed by coprecipitation with secondary barite and adsorption on Mn–Fe precipitates in the near-pond environment. The saline, organic-rich oil-field water subsequently mobilized Ra from downgradient aquifer sediments via Ra-desorption and Mn/Fe-reduction processes. This study demonstrates that infiltration of oil-field water may leach Ra into groundwater by changing salinity and redox conditions in the subsurface rather than by mixing with a high-Ra source.This article was improved by the reviews of John Izbicki and anonymous reviewers for the journal. This work was funded by the California State Water Resources Control Board’s Regional Groundwater Monitoring in Areas of Oil and Gas Production Program and the USGS Cooperative Water Program. A.V., A.J.K., and Z.W were supported by USDA-NIFA grant (#2017-68007-26308). Any use of trade, firm, or product names is for description purposes only and does not imply endorsement by the U.S. Government

Elevated levels of diesel range organic compounds in groundwater near Marcellus gas operations are derived from surface activities

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of American 112 (2015): 13184-13189, doi: 10.1073/pnas.1511474112 .Hundreds of organic chemicals are utilized during natural gas extraction via high volume hydraulic fracturing (HVHF). However, it is unclear if these chemicals, injected into deep shale horizons, reach shallow groundwater aquifers and impact local water quality, either from deep underground injection sites or from the surface or shallow subsurface. Here, we report detectable levels of organic compounds in shallow groundwater samples from private residential wells overlying the Marcellus Shale in northeastern Pennsylvania. Analyses of purgeable and extractable organic compounds from 64 groundwater samples revealed trace levels of volatile organic compounds, well below the Environmental Protection Agency’s maximum contaminant levels, and low levels of both gasoline range (GRO; 0-8 ppb) and diesel range organic compounds (DRO; 0-157 ppb). A compound-specific analysis revealed the presence of bis(2-ethylhexyl)phthalate, which is a disclosed HVHF additive, that was notably absent in a representative geogenic water sample and field blanks. Pairing these analyses with 1) inorganic chemical fingerprinting of deep saline groundwater, 2) characteristic noble gas isotopes, and 3) spatial relationships between active shale gas extraction wells and wells with disclosed environmental health and safety (EHS) violations, we differentiate between a chemical signature associated with naturally occurring saline groundwater and a one associated with alternative anthropogenic routes from the surface (e.g., accidental spills or leaks). The data support a transport mechanism of DRO to groundwater via accidental release of fracturing fluid chemicals derived from the surface rather than subsurface flow of these fluids from the underlying shale formation.The authors thank Duke University’s Pratt School of Engineering and the National Science Foundation’s CBET Grant Number 1336702 and NSF EAGER (EAR-1249255) for financial support.2016-04-1

Thank You to Our 2020 Peer Reviewers

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Maternal blood cadmium, lead and arsenic levels, nutrient combinations, and offspring birthweight

Abstract Background Cadmium (Cd), lead (Pb) and arsenic (As) are common environmental contaminants that have been associated with lower birthweight. Although some essential metals may mitigate exposure, data are inconsistent. This study sought to evaluate the relationship between toxic metals, nutrient combinations and birthweight among 275 mother-child pairs. Methods Non-essential metals, Cd, Pb, As, and essential metals, iron (Fe), zinc (Zn), selenium (Se), copper (Cu), calcium (Ca), magnesium (Mg), and manganese (Mn) were measured in maternal whole blood obtained during the first trimester using inductively coupled plasma mass spectrometry. Folate concentrations were measured by microbial assay. Birthweight was obtained from medical records. We used quantile regression to evaluate the association between toxic metals and nutrients due to their underlying wedge-shaped relationship. Ordinary linear regression was used to evaluate associations between birth weight and toxic metals. Results After multivariate adjustment, the negative association between Pb or Cd and a combination of Fe, Se, Ca and folate was robust, persistent and dose-dependent (p < 0.05). However, a combination of Zn, Cu, Mn and Mg was positively associated with Pb and Cd levels. While prenatal blood Cd and Pb were also associated with lower birthweight. Fe, Se, Ca and folate did not modify these associations. Conclusion Small sample size and cross-sectional design notwithstanding, the robust and persistent negative associations between some, but not all, nutrient combinations with these ubiquitous environmental contaminants suggest that only some recommended nutrient combinations may mitigate toxic metal exposure in chronically exposed populations. Larger longitudinal studies are required to confirm these findings