1,721,034 research outputs found
West Virginia Community Awareness and Opinion of Water and Hydraulic Fracturing
Get PDFThe need for cleaner energy sources has driven a boom in oil and gas extraction via hydraulic fracturing. However, significant environmental issues that have been raised in response to this rapid expansion of fracking. Most of the scientific research has focused on potential water contamination (methane or toxic chemicals) or seismic activity related to drilling or wastewater injection, but there has been little research on the impacts of fracking on local communities that are directly affected by oil and gas activity. Communities are often without an avenue to voice their opinion or to discuss how they are affected by the rapid rise in fracking with scientists, politicians or industry. Opinion surveys collected from residents in West Virginia who live near hydraulic fracturing operations were analyzed and compared to groundwater drinking well water tests to determine how residents who live in areas impacted by oil and gas drilling feel about hydraulic fracturing and if certain informational inputs (online reports vs. well water data) impact residents’ opinions.
Survey data was collected in Doddridge and Tyler counties of West Virginia from 27 residents whose water was either being tested for the first time or being retested by researchers at Duke University. The participants were asked about their knowledge and opinions of hydraulic fracturing and water quality issues in their community. Their answers were analyzed by qualitative and spatial analyses using STATA and ArcGIS. The survey data results were compared to selected chemical results from the participants’ drinking well water samples.
The results from the project showed that, overall, the residents surveyed disliked fracking, those residents who received information from online reports were more likely to have negative opinions of fracking, residents who had received water testing services for their groundwater before taking the survey were more likely to consider their water quality in their opinion, and residents who had more information about their water supplies were more invested in water issues that could arise in the future due to fracking activities. Although the survey had limited respondents, it gives valuable insight into how scientific data may impact the opinions of water quality issues and hydraulic fracturing for residents in northwestern West Virginia
Recycling Produced Water in the Permian Basin
No full textThe rapid increase of oil exploration through hydraulic fracturing in the Permian Basin in western Texas is associated with production of large volume of wastewater containing potentially hazard chemicals. The wastewater is derived from water that is co-extracted with oil called “produced water.” The management and disposal of the wastewater generated from unconventional oil and gas exploration are the most challenging topics given their low quality and potential environmental and human health risks. Unconventional oil wastewater is even more critical in western Texas where the water availability is limited. Oil wastewater in Western Texas is injected through deep-injection wells to the subsurface as a common disposal practice. Yet local companies are seeking to find ways to recycle oil wastewater for reuse for hydraulic fracturing or possibly other beneficial use.
This Master Project investigates the water quality of produced waters generated from the unconventional oil exploration in the Permian Basin and the treated water generate from a treatment site. As part of this study 15 water samples were collected at the Chiltepin Recycling Plant in Pecos, Texas, prior and after treatment that involved temporary storage of the oil wastewater in open reservoir that is managed with a continuous treatment of aeration to the pit.
Water samples were analyzed at Vengosh Lab in Duke University for major elements and dissolved organic carbon (DOC). The data show that the Permian produced water is highly saline (chloride up to 27,000 mg/L, 1.4 time the salinity of seawater) with high concentrations of ammonium (175 mg/L), boron (50 mg/L), and DOC (220 mg/L). This water quality infers that disposal or leaking of the Permian wastewater to the environment would cause major damage to the ecological system and contamination of water resources. The data show that the water quality of the treated water is indistinguishable that untreated and thus the recycling process in the site does not reduce the salts and contaminants potential of the Permian produced water
Radium Isotope Geochemistry in Groundwater Systems: The Role of Environmental Factors
No full textPrior studies of groundwater systems have associated increasing salinity and anoxic conditions with increasing radium (Ra) activities in water due to the decreasing effectiveness of Ra removal processes. However, the components of salinity (e.g. Ca vs. Na and SO42- vs. Cl--dominated waters), and the relative importance of salinity-sensitive vs. redox-sensitive processes for Ra mobilization, are less well understood. In this research, the response of Ra to hydrochemical change was examined using a multiple tracer approach to obtain detailed information on divalent cation and Ra mobility. A range of salinity and redox conditions was examined in five field-based studies in the United States and Morocco: (1) fresh waters in fractured crystalline rocks in the Piedmont region of North Carolina; (2) the Willcox Basin, an oxic alluvial basin-fill aquifer in southeastern Arizona; (3) the Jordan sandstone aquifer, a carbonate-cemented quartz sandstone in southeastern Minnesota; (4) an unconfined coastal aquifer undergoing salinization in the city of Agadir, Morocco; and (5) the confined, fresh to saline Cretaceous and Pliocene aquifers of the Atlantic Coastal Plain in North Carolina. In addition to analysis of major element concentrations, trace metal concentrations, and 224Ra, 226Ra, and 228Ra activities, complementary isotope systems were applied to gain insights on the relative stability of chemical processes that remove radium and other alkaline earth metals: (1) strontium isotope ratios (87Sr/86Sr) trace divalent cation release from sources such as clay and carbonate minerals in the aquifer solids and also indicate conditions in which divalent cation release (rather than uptake) is dominant; (2) boron concentrations and isotopes (δ11B) coincide with the opposite condition in freshening conditions of the Atlantic Coastal Plain, in which divalent cations are removed in exchange for Na; and (3) sulfur and oxygen isotopes (δ34S, δ18O) of sulfate trace sulfate sources and provide information on sulfate-reducing conditions, which can inhibit barite (BaSO4) from removing Ra by coprecipitation. In addition, other isotopic and ion measurements trace salinity sources and groundwater residence time, including δ2H, δ18O, 3H, Br-/Cl-, Na/Cl-, and Ca/Na.This dissertation documents correlations between salinity and radium in the brackish to saline North Carolina coastal plain aquifer with total dissolved solids (TDS) up to ~18,000 mg L-1 and to some degree in the Moroccan coastal aquifer, but even the lower-salinity waters (TDS -1) exhibit a range of Ra activities spanning approximately 3 orders of magnitude. Among these low-TDS waters, the highest Ra activities were observed in the anoxic Jordan sandstone aquifer and the lowest were observed in the oxic Willcox Basin aquifer. Although the main control on radium activities in fresh groundwater is the U- and Th-series radionuclide content of the aquifer solids, important secondary controls include the stability of redox-sensitive radium adsorption sites (Mn and Fe oxides), the relative dominance of divalent vs. monovalent cations (e.g. the Ca/Na ratio), formation of the uncharged RaSO40 complex, and/or the saturation state with respect to barite. These processes interact in varied ways in the field-based studies. Increasing radium activities and decreasing 222Rn/226Ra ratios in the North Carolina fractured crystalline rock groundwater system are correlated with increasing Ba, Mn, and Fe concentrations and decreasing dissolved oxygen concentrations, related to weathering and/or organic carbon oxidation. Radium activities in the oxic, neutral to slightly basic Willcox Basin are very low (median 226Ra activity 2 mBq L-1), probably due to a combination of effective Ra removal processes including adsorption to Mn and/or Fe oxides and the overall removal of divalent cations during groundwater evolution in this system. These are the same surface charge conditions that release arsenic, of regional water concern, in this pH range. Radium in Jordan aquifer groundwater is dependent on local variations in solid-phase radionuclide levels, probably hosted in the carbonate cement phase. Also, Ra is inefficiently adsorbed to the aquifer solids in the aquifer's anoxic conditions, resulting in the highest radium levels reported in this dissertation (226Ra up to 420 mBq L-1) despite apparent barite precipitation that partially removes Ra. Radium-224 activity in the Moroccan coastal aquifer is associated with salinity, but Ra overall is apparently controlled by barite, indicated by conditions near BaSO4 saturation. Radium activity in the saline waters of the Atlantic Coastal Plain aquifers is associated with TDS concentrations, but the cation exchange properties of the aquifer may provide a major mechanism of Ra removal in the Na-HCO3- and Na-Cl- waters. Overall, the complex interaction between groundwater chemistry and Ra-removing processes implies that in waters with TDS below approximately 3,000 mg L-1, dissolved solids concentration alone does not fully describe radium's response to hydrochemical conditions, but rather that aquifer-specific examination of Ra removal mechanisms is needed.</p
Accumulation and Distribution of Trace Elements and Radionuclides in Agricultural Soils Impacted from Long-term Phosphate Fertilizer Application
No full textExcessive application of phosphate fertilizers can result in the accumulation of both phosphorus (P) and trace metals (U, Cd) in agricultural soils, which could end up in crops and cause chronic harms to the environment. Here we investigate the quality of soils in a long-term trial corn/soybean field at the Tidewater Research Station, North Carolina, where both surface soils (top 20 cm) and subsurface soils (up to 150 cm) were collected from five plots with different application rates of P-fertilizer since 1966. We analyzed a broad range of major nutrients and trace elements with focus on metals and metalloids including Cd, U, V, Cr, As, and Sr, which are notably enriched in the used P-fertilizer relative to local background soil. The study aims to investigate the trace elements accumulation, distribution, and mobilization in the soils. The results show that the impact of long-term P-fertilizer application was mostly manifested in the top layers of the soils compared to deeper soils, with the exception of As showing accumulation in the deeper soils. Among the five plots, bulk soils applied with higher rates of P-fertilizers had higher concentrations of P and trace elements than soils without using P-fertilizers. The concentration of Cd was significantly correlated with that of P (r = 0.97, p = 0.005) in the bulk surface soils, indicative of its direct contribution from P-fertilizer and accumulation in the soil. In contrast, other trace elements exhibited weaker or little correlations with P in the bulk surface soils. The potential bioavailability of elements in soils was assessed via the Mehlich III extraction method, showing that the higher application rate of P-fertilizer, the higher percent of bioavailability was found for Cd (up to 65% of the bulk soil) and P (up to 56%), whereas the other trace elements had much lower bioavailable fractions (0.4 – 12%). Strong correlations (r > 0.9, p < 0.05) were observed between the bioavailable concentrations of P and that of Cd, U, Cr, V, As, Sr in the surface soils. This indicates that the bioavailable form of trace elements is more sensitive in reflecting the impacts from P- fertilizer on surface soils. Four-step sequential leaching tests (i.e., F1: exchangeable, F2: reducible, F3: oxidizable, and F4: residual) conducted for the surface soils indicated differential mobilization of trace elements under different P-fertilizers application rates. Greater portions of Cd were found in the mobile fractions (F1 – F3) of soils with higher P-fertilizer input, while Sr was dominantly present in the residual fraction (F4: 95 – 97%), and redox-sensitive elements were higher in the reducible (As, V) and oxidizable (U, Cr) fractions than Sr, reflecting their redox-dependent mobilization potential. Overall, our systematic data analysis shows the effect of long-term P-fertilizer application on the accumulation of trace elements in soils. Further studies should evaluate the uptake of trace elements by crops and their mobilization to the underlying groundwater resources
Disposal of Produced Water from Oil and Gas Exploration: Environmental Impacts on Waterways in Western Pennsylvania
No full textProduced water is the largest waste stream from oil and natural gas production. The large volume (15 to 20 billion barrels generated annually in the U.S.) and high salinity (5,000 to 270,000 mg/L TDS) of produced water could pose severe environmental impacts upon inadequate disposal. Treatment of produced water through wastewater treatment facilities is a commonly used disposal method in Pennsylvania. This study is based on direct field sampling of effluents released into the streams of the Conemaugh, Alleghany and Monongahela Rivers in Western Pennsylvania. Major and trace element analyses show facility effluent concentrations three times higher than seawater (100,000 mg/L TDS), bromide and trace element levels up to 4,000 times higher than values upstream of facilities. The study reveals a zone up to 500 meters downstream from the facility outfall in which the contamination largely exceeds values upstream of the outfall. High levels of naturally occurring radioactive material (NORM) is retained to stream sediments. Dissolved salts, metals and NORM are potentially contributing to long-term ecological effects on aquatic life. This study provides a systematic assessment of: (1) contaminant releases to the environment from oil and natural gas produced wastewater; (2) the fate of contaminants in surface water; (3) and the concerns regarding the long-term environmental impacts on waterways in Western Pennsylvania
Produced Water Spills Related to Unconventional Oil and Gas Development in North Dakota
No full textBeginning in 2007 unconventional oil production increased dramatically in the region of North Dakota overlying the Bakken shale formation. Since, the North Dakota Department of Health has reported more than 4,000 accidental spills of produced water. Our study seeks to follow up on a 2016 study by Nancy Lauer et al., which characterized the major and trace element chemistry of 29 surface waters in areas impacted by oil and gas wastewater spills. Comparing to background levels and the composition of Bakken produced waters, we used conservative element chemistry characterized 33 surface water samples sites impacted or potentially impacted by produced water spills, including 6 sites sampled the year before. Soil and sediment collected from the sites analyzed for total radium activities (228Ra & 226Ra) showed persistent contamination. One of the most heavily affected sites, an 11 million gallon spill near Blacktail Creek, that was characterized the year before experienced extensive remediation and displayed much lower levels of contaminants in 2016. However, this site was an anomaly; other sites continue to display persistent inorganic contamination up to 5 years after the initial spill
"Mini-Superfund" Site in Kawerau, New Zealand: A Closer Look at Water Quality
No full textIn 1954 New Zealand's government passed the Tasman Pulp and Paper Enabling Act, which gave the Tasman company carte blanche to do everything necessary to create the Pulp and Paper Mill's waste disposal site on Maori Trust land. Consequently, the former Lake Rotooitipaku has become Tasman Pulp and Paper’s primary disposal site. This area has been described as "one of the worst locations one could contrive for a waste disposal site" and previous site assessments have identified groundwater and soil contamination at levels that exceed national and international guidelines for drinking water, agricultural use, and ecological health and protection. An unmet need to fully characterize surface water contamination in the principle surface water bodies neighboring the former Lake Rotooitipaku has shaped the objectives of this Masters Project. One primary objective of this project is to investigate the nature and extent of the inorganic contamination in principle water bodies neighboring Lake Rotooitipaku. Additionally, this project uses chemical and isotopic fingerprinting to distinguish between geothermal and anthropogenic sources of contamination. This project is based on systematic fieldwork and sampling of several key water sources in the area.
None of the inorganic constituents measured in A8 pond, Urupa pond, or Tarawera River exceed the ANZECC guideline values for recreational water use. Therefore we conclude that the water quality is acceptable, with regard to inorganic contamination, for recreational purposes. Hydrogen and oxygen isotopic fingerprints and conservative mixing calculations suggest that geothermal waters have mixed only with the Tarawera River, but not with A8 and Urupa ponds. Furthermore, the evidence suggests that there is no source of inorganic anthropogenic contamination in the principle surface water bodies. Further research is necessary to explore potential sources of organic contaminants in A8 pond, Urupa pond, and the Tarawera River
Arsenic exposure from groundwater in Union County, North Carolina
No full textArsenic contamination of groundwater is a global problem affecting human health. The highest concentrations occur overseas in areas such as Bangladesh, India, Vietnam, and Thailand. The United States is not immune and also has hotspots of arsenic in dangerously high concentrations. The focus of this project was to evaluate the extent and concentration of arsenic in one such area, Union County, North Carolina, and to attempt to use arsenic in toenails as a biomarker of exposure. Arsenic concentration above the EPA’s maximum contaminant level (MCL) of 10ppb was found in 22 out of 64 households tested (34%). The measurement of arsenic in toenails was successfully used as a biomarker of exposure. Data showed that men had a greater sensitivity to arsenic and their nail data had better correlation. Children also showed a greater sensitivity. Out of 69 participants in the toenail-biomarker study, 4 had arsenic concentrations in their toenails above a level deemed safe. Based on these results it is evident that arsenic contamination of drinking water in Union County is an issue of concern
Biomarkers of Exposure: Arsenic Concentrations in Keratin in Populations Exposed to Arsenic in Drinking Water
Get PDFArsenic (As) exposure via groundwater consumption is a global health problem affecting millions. Monitoring exposure is a key step in understanding and predicating future health outcomes. This thesis explores the relationships between arsenic concentrations in toenails and arsenic in water. Three case studies were investigated, with residents from: North Carolina, USA (n=103); the Rift Valley, Ethiopia (n=60); and the Mekong Delta, Vietnam (n=65). Arsenic concentrations above the WHO's recommended 10ppb limit were found in groundwater from the three research sites. Arsenic in toenails was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). In the Rift Valley of Ethiopia, 53% of the tested drinking wells (n=34) had As above the WHO's limit. Arsenic concentrations in toenails (n=60) were significantly correlated to As concentrations in groundwater (r=0.72; pIn the Mekong Delta of Vietnam (Dong Thap Province), 36 out of the 68 tested wells had As content above the WHO's recommended limit of 10ppb, with levels as high as 981 ppb. Arsenic contents in nails collected from local residents (n=62) were significantly correlated to As in drinking water (r=0.49, pSixty-one wells were tested from Union County, North Carolina, with 15 out of 61 wells exceeded the WHO's 10 ppb limit. Arsenic values ranged from below the limit of detection (0.07) to 130ppb, with a mean of 11ppb (median=1.5ppb). Nails were collected from county residents (n=103) and were statistically correlated with As-water concentrations (r=0.48, pIntegration of the data from the three cases studies across different populations and ethnicities show high correlation between As concentrations in groundwater and As in nails in all the three locations (r(Union County)= 0.48, p<0.001; r(Ethiopia)=0.72 p<0.001; r(Vietnam)=0.49, p<0.001). For As-nail to As-water pairs in which As in water was above 1ppb, these three locations are statistically indistinguishable from one another (r=0.62, p<0.001, n=176). These results support the hypothesis that nails can be used as a biomarker of exposure regardless of geographic or ethnic differences in populations considered. Nutrition (meat, seafood, and milk consumption) rather than gender, ethnicity, or dose is suggested to be the major confounding issue affecting the magnitude of As exposure in the human body.</p
Origin and Scope of Hexavalent Chromium in North Carolina Groundwater
No full textPotential groundwater contamination from coal ash ponds is a current public health concern in North Carolina. One of the suspected contaminants is chromium, particularly the toxic hexavalent chromium form. A recent study on chromium in groundwater from the Piedmont Aquifers of NC finds that chromium is more prevalent than previously thought due to geogenic sources from water-rock interactions in naturally enriched ultramafic rock formations. To expand on the prior work, this project generates a dataset of domestic, community, and monitoring wells across the mountain, Piedmont, and coastal regions of NC to investigate the scope and origin of hexavalent chromium in groundwater. Geospatial and statistical analyses show increasing hexavalent and total chromium concentrations as aquifer lithology characterization by mafic material increases non-mafic formations to major mafic formations. Correlation tests show a strong, positive correlation between hexavalent and total chromium concentrations in groundwater. These new results support previous findings and provide additional evidence that hexavalent chromium is the predominant species of total dissolved chromium, and that groundwater in aquifers with lithology containing mafic constituents will have elevated levels of chromium when compared to aquifers in non-mafic lithology
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