Keith D.J.,US Ecology |
Schaeffer B.A.,US Ecology |
Lunetta R.S.,Us Epa National Exposure Research Laboratory |
Gould Jr. R.W.,U.S. Navy |
And 2 more authors.
International Journal of Remote Sensing | Year: 2014
The Hyperspectral Imager for the Coastal Ocean (HICO) offers the coastal environmental monitoring community an unprecedented opportunity to observe changes in coastal and estuarine water quality across a range of spatial scales not feasible with traditional field-based monitoring or existing ocean colour satellites. HICO, an Office of Naval Research-sponsored programme, is the first space-based maritime hyperspectral imaging instrument designed specifically for the coastal ocean. HICO has been operating since September 2009 from the Japanese Experiment Module - Exposed Facility on the International Space Station (ISS). The high pixel resolution (approximately 95 m at nadir) and hyperspectral imaging capability offer a unique opportunity for characterizing a wide range of water colour constituents that could be used to assess environmental condition. In this study, we transform atmospherically corrected ISS/HICO hyperspectral imagery and derive environmental response variables routinely used for evaluating the environmental condition of coastal ecosystem resources. Using atmospherically corrected HICO imagery and a comprehensive field validation programme, three regionally specific algorithms were developed to estimate basic water-quality properties traditionally measured by monitoring agencies. Results indicated that a three-band chlorophyll a algorithm performed best (R2 = 0.62) when compared with in situ measurement data collected 2-4 hours of HICO acquisitions. Coloured dissolved organic matter (CDOM) (R2 = 0.93) and turbidity (R2 = 0.67) were also highly correlated. The distributions of these water-quality indicators were mapped for four estuaries along the northwest coast of Florida from April 2010 to May 2012. However, before the HICO sensor can be transitioned from proof-of-concept to operational status and its data applied to benefit decisions made by coastal managers, problems with vicarious calibration of the sensor need to be resolved and standardized protocols are required for atmospheric correction. Ideally, the sensor should be placed on a polar orbiting platform for greater spatial and temporal coverage as well as for image synchronization with field validation efforts. © 2014 Taylor & Francis.
Cihan A.,Lawrence Berkeley National Laboratory |
Zhou Q.,Lawrence Berkeley National Laboratory |
Birkholzer J.T.,Lawrence Berkeley National Laboratory |
Kraemer S.R.,Us Epa National Exposure Research Laboratory
Water Resources Research | Year: 2014
Flow problems in an anisotropic domain can be transformed into ones in an equivalent isotropic domain by coordinate transformations. Once analytical solutions are obtained for the equivalent isotropic domain, they can be back transformed to the original anisotropic domain. The existing solutions presented by Cihan et al. (2011) for isotropic multilayered aquifer systems with alternating aquitards and multiple injection/pumping wells and leaky wells were modified to account for horizontal anisotropy in aquifers. The modified solutions for pressure buildup distribution and leakage rates through leaky wells can be used when the anisotropy direction and ratio (Kx/Ky) are assumed to be identical for all aquifers alternating with aquitards. However, for multilayered aquifers alternating with aquicludes, both the principal direction of the anisotropic horizontal conductivity and the anisotropy ratio can be different in each aquifer. With coordinate transformation, a circular well with finite radius becomes an ellipse, and thus in the transformed domain the head contours in the immediate vicinity of the well have elliptical shapes. Through a radial flow approximation around the finite radius wells, the elliptical well boundaries in the transformed domain are approximated by an effective well radius expression. The analytical solutions with the effective radius approximations were compared with exact solutions as well as a numerical solution for elliptic flow. The effective well radius approximation is sufficiently accurate to predict the head buildup at the well bore of the injection/pumping wells for moderately anisotropic systems (Kx/Ky≤25). The effective radius approximation gives satisfactory results for predicting head buildup at observation points and leakage through leaky wells away from the injection/pumping wells even for highly anisotropic aquifer systems (Kx/Ky≤1000). Key Points Anisotropic multilayered aquifer systems A new effective radius approximations to well in anisotropic systems Verification with existing solutions and numerical solutions ©2013. American Geophysical Union. All Rights Reserved.
Schaeffer B.A.,US Ecology |
Schaeffer K.G.,Pensacola State College |
Keith D.,US Ecology |
Lunetta R.S.,Us Epa National Exposure Research Laboratory |
And 2 more authors.
International Journal of Remote Sensing | Year: 2013
Sustainable practices require a long-term commitment to creating solutions to environmental, social, and economic issues. The most direct way to ensure that management practices achieve sustainability is to monitor the environment. Remote sensing technology has the potential to accelerate the engagement of communities and managers in the implementation and performance of best management practices. Over the last few decades, satellite technology has allowed measurements on a global scale over long time periods, and is now proving useful in coastal waters, estuaries, lakes, and reservoirs, which are relevant to water quality managers. Comprehensive water quality climate data records have the potential to provide rapid water quality assessments, thus providing new and enhanced decision analysis methodologies and improved temporal/spatial diagnostics. To best realize the full application potential of these emerging technologies an open and effective dialogue is needed between scientists, policy makers, environmental managers, and stakeholders at the federal, state, and local levels. Results from an internal US Environmental Protection Agency qualitative survey were used to determine perceptions regarding the use of satellite remote sensing for monitoring water quality. The goal of the survey was to begin understanding why management decisions do not typically rely on satellite-derived water quality products. © 2013 Copyright This work was authored as part of the Contributors' official duties as Employees of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under US Law.
Lu J.,Us Epa National Exposure Research Laboratory |
Struewing I.,Dynamac Inc. |
Yelton S.,Dynamac Inc. |
Ashbolt N.,University of Alberta
Journal of Applied Microbiology | Year: 2015
Aims: To examine the occurrence and quantity of potential pathogens and an indicator of microbial contamination in the sediments of municipal drinking water storage tanks (MDWSTs), given the absence of such data across the United States. Methods and Results: Sediment samples (87 MDWST) from eighteen locations across ten states of the United States were collected and assayed by qPCR for a range of potential enteric and opportunistic microbial pathogens and a sewage-associated Bacteroides marker. Potential opportunistic pathogens dominated, with the highest detection of occurrence (per cent positive detection; average cell equivalence (CE)) being Mycobacterium spp. (88·9%; 6·7 ± 8·5 × 104 CE g-1), followed by Legionella spp. (66·7%; 5·2 ± 5·9 × 103 CE g-1), Pseudomonas aeruginosa (22·2%; 250 ± 880 CE g-1) and Acanthamoeba spp. (38·9%; 53 ± 70 CE g-1), with no detected Naegleria fowleri. Most enteric pathogens (Campylobacter jejuni, Escherichia coli 0157:H7, Salmonella enterica, Cryptosporidium parvum and Giardia duodenalis) were not detected, except for a trace signal for Campylobacter spp. There was significant correlation between the qPCR signals of Legionella spp. and Acanthamoeba spp. (R2 = 0·61, n = 87, P = 0·0001). Diverse Legionella spp. including Leg. pneumophila, Leg. pneumophila sg1 and Leg. anisa were identified, each of which might cause legionellosis. Conclusions: These results imply that potential opportunistic pathogens are common within MDWST sediments and could act as a source of microbial contamination, but need downstream growth to be of potential concern. Significance and Impact of the Study: The results imply that opportunistic pathogen risks may need to be managed by regular tank cleaning or other management practices. © 2015 The Society for Applied Microbiology.
Duncan O.J.,University of Georgia |
Tollner E.W.,University of Georgia |
Ssegane H.,University of Georgia |
McCutcheon S.C.,Us Epa National Exposure Research Laboratory
Applied Engineering in Agriculture | Year: 2013
Estimation of runoff from windrow compost pads is a challenge due to the different hydrologic properties of the compost and pad, and moisture storage in the compost, both of which change with time. The surface of a compost pad is usually crushed rock on top of a compacted layer of clay. The curve number method is widely used for estimating runoff from rainfall, but because the porous layer of gravel promotes greater infiltration and subsurface drainage, this study investigated the effectiveness of this standard approach. Four curve number based methods are assessed for their utility in estimating drainage from a 7284-m2 windrow compost pad in Athens, Georgia, using 16 storm events. The methods estimate drainage using (1) a tabulated curve number, (2) a quasi-dynamic curve number based on the magnitude of the rainfall, antecedent rainfall, and areal coverage of the compost piles, (3) an asymptotic curve number, and (4) an average event-based curve number. Using the tabulated curve number, event runoff (r2 = 0.92) was consistently underestimated. A quasi-dynamic curve number improved the runoff estimation (r2 = 0.98). The asymptotic (r2 = 0.90) and event-based averaged (r 2 = 0.92) curve number methods performed comparable to the tabulated curve number method. Although curve numbers for maturing compost decreased from approximately 95 to 75 over time, this study recommends use of a conservative curve number = 95 for containment of design storms, while curve numbers of 70 to 75 may be appropriate for estimating average annual runoff from mature compost and the area necessary for land application of the pad runoff. © 2013 American Society of Agricultural and Biological Engineers ISSN 0883-8542.