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Drones to help in microbial water quality monitoring
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Papers by Yakov Pachepsky
Vadose Zone Journal, Dec 1, 2014
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AGUFM, Dec 1, 2012
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Journal of Hydrology, Sep 1, 2013
ABSTRACT Improving understanding of chemical transport in the subsurface commonly employs evolvin... more ABSTRACT Improving understanding of chemical transport in the subsurface commonly employs evolving groundwater monitoring networks. The objective of this work was to apply the information theory to propose an objective algorithm for augmenting a subsurface monitoring network (SMN) with the purpose of discrimination of conceptually different subsurface flow and transport models. This method determines new monitoring locations where the Kullback-Leibler total information gain is maximized. The latter is computed based on estimates of the uncertainty in modeling results and uncertainty in observations. The method was applied to discriminate models in (1) a synthetic case of groundwater contamination from a point source; (2) the tracer experiment conducted at the USDA-ARS OPE3 research site where a pulse of KCL solution was applied with irrigation water and CL- concentrations were subsequently monitored. Models were compared that included or ignored the effect of subsurface soil lenses on chemical transport. Pedotransfer functions were used to develop the ensemble of models for estimating the uncertainty in modeling results obtained with the numerical 3D flow and transport model. Peak tracer breakthrough concentrations were used to define the information gains. The determination of the new locations to augment existing ones was conducted on a 2-D grid. The information gain peaked in small area, and additional observation locations were very well spatially defined. Well-calibrated models provided a single optimal location, whereas, if models were not calibrated well, the Bayesian estimates of the new observation location depended on the activation sequence assumed for existing locations. The information gain maximization can suggest data collection locations to reduce uncertainties in the conceptual models of subsurface flow and transport. Published by Elsevier B.V.
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Critical Reviews in Environmental Science and Technology, Apr 28, 2011
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Soil Science, Oct 1, 2005
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Geoderma, Feb 1, 2017
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EGUGA, Apr 1, 2016
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Letters in Applied Microbiology, Sep 7, 2012
Aims: The focus of this work was to compare the survival of Escherichia coli introduced into str... more Aims: The focus of this work was to compare the survival of Escherichia coli introduced into streambed sediments from goose, deer and bovine faeces vs indigenous E. coli. Methods and Results: The survival experiments were conducted in flow-through chambers for 32 days using two sediments (mineral and organic) obtained from a first-order creek in Maryland. Bovine, goose and deer faeces were collected fresh and diluted or enriched so that added E. coli and indigenous populations were equivalent. Escherichia coli and total coliforms were enumerated using the Colilert-18 Quanti-Tray system. Patterns of E. coli survival and inactivation rates were virtually identical for indigenous strains in both mineral and organic sediments. The addition of E. coli strains from bovine, goose or deer faeces had relatively little impact on final E. coli concentrations, with the exception of deer-borne E. coli populations in the organic sediment. Conclusion: These results indicate that indigenous sediment-borne E. coli strains are generally, or more, persistent than those deposited into sediments, including wildlife. Significance and Impact of the Study: This is the first study on the survival of E. coli originating from wildlife faeces, in sediments, as opposed to bovine faeces or laboratory-cultured strains. As wildlife are likely to be the primary source of E. coli in most non agricultural watersheds, an understanding of the persistence of these strains is important to understanding microbial water quality.
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Ecological Modelling, Mar 1, 2005
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Journal of Environmental Quality, 2020
Fecal indicator organisms (FIOs), such as Escherichia coli and enterococci, are often used as sur... more Fecal indicator organisms (FIOs), such as Escherichia coli and enterococci, are often used as surrogates of contamination in the context of beach management; however, bacteriophages may be more reliable indicators than FIO due to their similarity to viral pathogens in terms of size and persistence in the environment. In the past, mechanistic modeling of environmental contamination has focused on FIOs, with virus and bacteriophage modeling efforts remaining limited. In this paper, we describe the development and application of a fate and transport model of somatic and F‐specific coliphages for the Washington Park beach in Lake Michigan, which is affected by riverine outputs from the nearby Trail Creek. A three‐dimensional model of coliphage transport and photoinactivation was tested and compared with a previously reported E. coli fate and transport model. The light‐based inactivation of the phages was modeled using organism‐specific action spectra. Results indicate that the coliphage...
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Water, Air, & Soil Pollution, 2018
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Critical Reviews in Environmental Science and Technology, 2017
ABSTRACT This review outlines major directions of simpler model development in environmental mode... more ABSTRACT This review outlines major directions of simpler model development in environmental modeling, metamodeling, statistical-regression- and machine-learning-based empirical models, and mechanistic models with reduced structures. Simpler models may be favored due to limited observational data, uncertainty in the complex model predictions, and intent of using a model as a component of a multimedia or multicompartmental model. Decision-making often relies on simple models. Model simplification can be useful in understanding the behavior of complex models. Understanding the role of models of different complexity as affected by intended uses and problem statements is an important part of the modern ontology of environmental science and technology.
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Journal of Environmental Management, 2017
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