11 research outputs found
Rapid Analysis of Eukaryotic Bioluminescence to Assess Potential Groundwater Contamination Events
Here we present data using a bioluminescent dinoflagellate, Pyrocystis lunula, in a toxicological bioassay to rapidly assess potential instances of groundwater contamination associated with natural gas extraction. P. lunula bioluminescence can be quantified using spectrophotometry as a measurement of organismal viability, with normal bioluminescent output declining with increasing concentration(s) of aqueous toxicants. Glutaraldehyde and hydrochloric acid (HCl), components used in hydraulic fracturing and shale acidization, triggered significant toxicological responses in as little as 4âh. Conversely, P. lunula was not affected by the presence of arsenic, selenium, barium, and strontium, naturally occurring heavy metal ions potentially associated with unconventional drilling activities. If exogenous compounds, such as glutaraldehyde and HCl, are thought to have been introduced into groundwater, quantification of P. lunula bioluminescence after exposure to water samples can serve as a cost-effective detection and risk assessment tool to rapidly assess the impact of putative contamination events attributed to unconventional drilling activity
An Evaluation of Water Quality in Private Drinking Water Wells Near Natural Gas Extraction Sites in the Barnett Shale Formation
Natural gas has become a leading
source of alternative energy with
the advent of techniques to economically extract gas reserves from
deep shale formations. Here, we present an assessment of private well
water quality in aquifers overlying the Barnett Shale formation of
North Texas. We evaluated samples from 100 private drinking water
wells using analytical chemistry techniques. Analyses revealed that
arsenic, selenium, strontium and total dissolved solids (TDS) exceeded
the Environmental Protection Agencyâs Drinking Water Maximum
Contaminant Limit (MCL) in some samples from private water wells located
within 3 km of active natural gas wells. Lower levels of arsenic,
selenium, strontium, and barium were detected at reference sites outside
the Barnett Shale region as well as sites within the Barnett Shale
region located more than 3 km from active natural gas wells. Methanol
and ethanol were also detected in 29% of samples. Samples exceeding
MCL levels were randomly distributed within areas of active natural
gas extraction, and the spatial patterns in our data suggest that
elevated constituent levels could be due to a variety of factors including
mobilization of natural constituents, hydrogeochemical changes from
lowering of the water table, or industrial accidents such as faulty
gas well casings
A Comprehensive Analysis of Groundwater Quality in The Barnett Shale Region
The exploration of unconventional
shale energy reserves and the
extensive use of hydraulic fracturing during well stimulation have
raised concerns about the potential effects of unconventional oil
and gas extraction (UOG) on the environment. Most accounts of groundwater
contamination have focused primarily on the compositional analysis
of dissolved gases to address whether UOG activities have had deleterious
effects on overlying aquifers. Here, we present an analysis of 550
groundwater samples collected from private and public supply water
wells drawing from aquifers overlying the Barnett shale formation
of Texas. We detected multiple volatile organic carbon compounds throughout
the region, including various alcohols, the BTEX family of compounds,
and several chlorinated compounds. These data do not necessarily identify
UOG activities as the source of contamination; however, they do provide
a strong impetus for further monitoring and analysis of groundwater
quality in this region as many of the compounds we detected are known
to be associated with UOG techniques
Grand Challenges in global eye health: a global prioritisation process using Delphi method
Background: We undertook a Grand Challenges in Global Eye Health prioritisation exercise to identify the key issues that must be addressed to improve eye health in the context of an ageing population, to eliminate persistent inequities in health-care access, and to mitigate widespread resource limitations. Methods: Drawing on methods used in previous Grand Challenges studies, we used a multi-step recruitment strategy to assemble a diverse panel of individuals from a range of disciplines relevant to global eye health from all regions globally to participate in a three-round, online, Delphi-like, prioritisation process to nominate and rank challenges in global eye health. Through this process, we developed both global and regional priority lists. Findings: Between Sept 1 and Dec 12, 2019, 470 individuals complete round 1 of the process, of whom 336 completed all three rounds (round 2 between Feb 26 and March 18, 2020, and round 3 between April 2 and April 25, 2020) 156 (46%) of 336 were women, 180 (54%) were men. The proportion of participants who worked in each region ranged from 104 (31%) in sub-Saharan Africa to 21 (6%) in central Europe, eastern Europe, and in central Asia. Of 85 unique challenges identified after round 1, 16 challenges were prioritised at the global level; six focused on detection and treatment of conditions (cataract, refractive error, glaucoma, diabetic retinopathy, services for children and screening for early detection), two focused on addressing shortages in human resource capacity, five on other health service and policy factors (including strengthening policies, integration, health information systems, and budget allocation), and three on improving access to care and promoting equity. Interpretation: This list of Grand Challenges serves as a starting point for immediate action by funders to guide investment in research and innovation in eye health. It challenges researchers, clinicians, and policy makers to build collaborations to address specific challenges. Funding: The Queen Elizabeth Diamond Jubilee Trust, Moorfields Eye Charity, National Institute for Health Research Moorfields Biomedical Research Centre, Wellcome Trust, Sightsavers, The Fred Hollows Foundation, The Seva Foundation, British Council for the Prevention of Blindness, and Christian Blind Mission. Translations: For the French, Spanish, Chinese, Portuguese, Arabic and Persian translations of the abstract see Supplementary Materials section.</p