Papers & ReportsCrop Protection2015
Uncertainty Considerations in Calibration and Validation of Hydrologic and Water Quality Models
Hydrologic and water quality (H/WQ) models are widely used to support site-specific environmental assessment, design, planning, and decision making. Calibration and validation (C/V) are fundamental processes used to demonstrate that an H/WQ model can produce suitable results in a particular application. However, the lack of comprehensive guidelines has led to the use of ad hoc, inconsistent, and incomplete C/V processes, which have made it difficult to interpret the myriad of published modeling studies, reduced the utility of many modeling applications, and slowed the advancement of H/WQ modeling. The objective of this article is to provide a generalized structure and process to assist modelers in developing a C/V strategy for H/WQ modeling applications. These best practice recommendations were developed based on an expansive review of the modeling literature, including a special collection of articles on H/WQ model calibration, validation, and use, as well as extensive discussion and debate among the authors. The model C/V recommendations include careful consideration, execution, and documentation of the following elements: (1) goals of model use, (2)Â data and parameters used in C/V, and (3) model C/V processes. Considerations in element 3 include the warm-up period, C/V strategy complexity, C/V process staging, spatiotemporal allocation of C/V comparison data, manual vs. automatic C/V, and additional diagnostics. Notable examples from the literature are provided for each strategy element. The comprehensive C/V strategy described herein will allow for better interpretation of future modeling studies, improved utility of modeling applications, and more systematic advancement of H/WQ models.
Guzman, J.A., A. Shirmohammadi, A. Sadeghi, X. Wang, M.L. Chu, M.K. Jha, P. Parajuli, D. Harmel, Y. Khare, and J. Hernandez. Uncertainty considerations in calibration and validation of hydrologic and water quality models. T. ASABE 58(6): 1745-1762
Papers & ReportsCrop Protection2015
Hydrologic and Water Quality Models: Key Calibration and Validation Topics
As a continuation of efforts to provide a common background and platform for development of calibration and validation (C/V) guidelines for hydrologic and water quality (H/WQ) modeling, ASABE members worked to determine critical topics related to model C/V, perform a synthesis of a previously published special collection of articles and other relevant literature, and provide topic-specific recommendations based on the synthesis as well as personal modeling expertise. This article introduces a special collection of nine research articles covering key topics related to calibration and validation of H/WQ models. The topics include: terminology, hydrologic processes and model representation, spatial and temporal scales, model parameterization, C/V strategies, sensitivity, uncertainty, performance measures and criteria, and documentation and reporting. The main objective of this introductory article is to introduce and summarize key aspects of these topics, including recommendations. Individually, the articles provide model practitioners with detailed topic-specific recommendations related to model calibration, validation, and use. Collectively, the articles present recommendations to enhance H/WQ modeling.
Moriasi, D.N., R.W. Zeckoski, J.G. Arnold, C.B. Baffaut, R.W. Malone, P. Daggupati, J.A. Guzman, D. Saraswat, Y. Yuan, B.W. Wilson, A. Shirmohammadi, and K.R. Douglas-Mankin. Hydrologic and water quality models: key calibration and validation topics. T. ASABE 58(6): 1609-1618
Papers & ReportsWater/Wastewater Assessments2015
Stream Vulnerability to Widespread and Emergent Stressors: A Focus on Unconventional Oil and Gas
Multiple stressors threaten stream physical and biological quality, including elevated nutrients and other contaminants, riparian and in-stream habitat degradation and altered natural flow regime. Unconventional oil and gas (UOG) development is one emerging stressor that spans the U.S. UOG development could alter stream sedimentation, riparian extent and composition, in-stream flow, and water quality. We developed indices to describe the watershed sensitivity and exposure to natural and anthropogenic disturbances and computed a vulnerability index from these two scores across stream catchments in six productive shale plays. We predicted that catchment vulnerability scores would vary across plays due to climatic, geologic and anthropogenic differences. Across-shale averages supported this prediction revealing differences in catchment sensitivity, exposure, and vulnerability scores that resulted from different natural and anthropogenic environmental conditions. For example, semi-arid Western shale play catchments (Mowry, Hilliard, and Bakken) tended to be more sensitive to stressors due to low annual average precipitation and extensive grassland. Catchments in the Barnett and Marcellus-Utica were naturally sensitive from more erosive soils and steeper catchment slopes, but these catchments also experienced areas with greater UOG densities and urbanization. Our analysis suggested Fayetteville and Barnett catchments were vulnerable due to existing anthropogenic exposure. However, all shale plays had catchments that spanned a wide vulnerability gradient. Our results identify vulnerable catchments that can help prioritize stream protection and monitoring efforts. Resource managers can also use these findings to guide local development activities to help reduce possible environmental effects.
Entrekin SA, Maloney KO, Kapo KE, Walters AW, Evans-White MA, Klemow KM (2015) Stream Vulnerability to Widespread and Emergent Stressors: A Focus on Unconventional Oil and Gas. PLoS ONE 10(9): e0137416. doi:10.1371/journal.pone.0137416
Risk Assessment for Mixtures of Agricultural Chemicals in Surface Water; A SETAC Pellston Workshop Update
PRESENTATION ID: 713
PRESENTATION DATE: Thursday, November 5, 2015 at 4:00PM
LOCATION: Ballroom E
In March of 2015, a SETAC Pellston workshop was held to help inform decision making around aquatic mixture risk assessments of chemicals using exposure scenarios and decision trees. The efforts were broadly grouped into three areas of chemical origination: agriculture, domestic, and urban influences (a separate integration group was charged with looking at overarching issues). The agricultural land use combined effect measures with exposure scenarios of chemical mixtures for field and catchment-scale using procedures that are recognized and used in regulatory schemes in the U.S., Europe and other parts of the world. Chemicals modeled were those used in crop protection and livestock production, and were considered to occur as mixtures (in time and space). Two types of scenarios were defined including a single unit that could represent a variety of typical chemical input locations (e.g., feed lot, agricultural field, pasture, aquaculture, biosolids applications, etc). The second scenario was multi-unit, combining several different uses within a single catchment/watershed. These assessments considered inputs from spray drift, surface runoff and erosion, and/or tile drainage systems on a daily basis over an extended period of time (e.g., from one to 30 years). Case studies included a single unit scenario modeled as a wheat field in Eastern UK, consisting of crop protection applications of 13 substances over the course of the year. This scenario used standard FOCUS soil, weather and receiving water body information for consistency. The case study of a multi-unit catchment scenario consisted of a combination of corn fields, pasture, and feedlot inputs based in part on the US EPA Iowa corn scenario used in pesticide registration evaluations. Manure from treated cattle containing two different pharmaceutical substances (a parasiticide and a macrolide antibiotic) was applied to corn fields as fertilizer, and also originated from pastured cattle. Twelve different active substances for crop protection were modeled on the corn field. These applications ranged from a pre-plant herbicide to a late-year fungicide application. A risk assessment decision tree looked at estimated environmental concentrations of all active substances on a daily basis, with subsequent mixture risks evaluated according to methodologies developed under a separate effects workgroup within the same Pellston workshop. A summary of the framework, methodologies and results will be presented.
Christopher Holmes, Waterborne Environmental; Mick J. Hamer, Syngenta; Colin Brown, University of York ; Russell Jones, Bayer CropScience; Lorraine Maltby, The University of Sheffield; Eric Silberhorn, US Food & Drug Administration; Jerold Scott Teeter, Elanco Animal Health; Michael Warne, DSITI; Lennart Weltje, BASF SE.”Risk Assessment for Mixtures of Agricultural Chemicals in Surface Water; A SETAC Pellston Workshop Update”. SETAC Salt Lake City November 2015.
Development of Contributing Factors Influencing the Physical Description of Spray Drift Deposition
PRESENTATION ID: 682
PRESENTATION DATE: Thursday, November 5, 2015 at 3:40PM
LOCATION: Room 251 A-B
Agricultural spray drift management is an important component of risk mitigation in cases where there is potential exposure to non-target organisms in terrestrial and aquatic systems. Within the USEPA ecological risk assessment framework, spray drift characterization is of considerable importance, especially when considering herbicidal effects on non-target plants. Current tools for estimation of spray drift exposure are not consistent with farm equipment technologies and formulation-specific characteristics. These tools, such as AGDRIFT and AGDISP, are based on empirical relationships that are founded on datasets that do not represent current spray drift reduction technologies. By implementing a physically-based model, a risk assessor might be able to pair formulation specific information and a possible range of environmental variables to better characterize potential risk of from spray drift exposure. Unfortunately, a physically-based model that would better represent liquid spray dynamics and associated spray drift and deposition has not yet been developed. Furthermore, there are no clear indications of what parameters of liquid composition and environmental variables would be needed for use in development of a physically-based model. This work explores statistical relationships between liquid properties (e.g. surface tension, particle size spectra, liquid viscosity) and variable wind speed conditions using drift deposition data within a wind tunnel framework. A stepwise regression model was used to rank the importance of variables affecting the outcome from the deposition curves. Results suggest relative importance of measured formulation properties and environmental variables for consideration in the development of a physically-based model that may better represent estimates of spray drift.
Rohith Gali, Daniel Perkins, Farah Abi-Akar, Kevin Wright, Waterborne Environmental; Greg Kruger, University of Nebraska; Lincoln Robert Morriss, FMC Corp Global Regulatory Sciences. “Development of Contributing Factors Influencing the Physical Description of Spray Drift Deposition”. SETAC Salt Lake City November 2015.
Expanding Our Knowledge of Exposure as Part of the Environmental Assessment for a Veterinary Medicine
PRESENTATION ID: 643
PRESENTATION DATE: Thursday, November 5, 2015 at 10:40AM
LOCATION: Ballroom H
The U.S. Food and Drug Administration (FDA), Center for Veterinary Medicine (CVM), evaluates whether significant environmental impacts would occur with the approval of new animal drugs pursuant to the National Environmental Policy Act (NEPA). The approval process may require the preparation of an environmental assessment (EA), which contains sections addressing problem formulation, environmental fate, exposure, effects and risk characterization. Using a recent EA as a framework, this presentation will focus on the refinement of environmental exposure estimates (i.e., Predicted Environmental Concentrations, or PECs) using spatial techniques to identify representative and protective environmental scenarios for the use of this product, and link them to exposure models commonly used in the U.S. Environmental Protection Agency (USEPA) pesticide registration process. A Geographic Information System (GIS) was used to identify regions of high versus low exposure potential across the US based on beef cattle characteristics and climatic conditions. From within each region, a single vulnerable watershed was selected and characterized for watershed-scale modeling. This process of watershed selection places exposure results into national context and promotes confidence that they are representative of realistic intense-use scenarios protective of other U.S. beef regions. Watershed scale exposure modeling for surface water was conducted following the USEPA Tier-2 drinking water pesticide exposure modeling approach. Three potential sources of chemical were modeled: feedlots, agricultural fields applied with manure collected from the feedlots, and pasture. Runoff and erosion inputs to surface water from these sources were modeled over a 30-year timeframe to produce final PECs suitable for use in the effects portion of the EA. The framework, methodology, results and lessons learned will be presented as part of this platform.
Christopher Holmes, Ishadeep Khanijo, Joshua Amos, Amy Ritter, Mark Cheplick, W. Martin Williams, Waterborne Environmental; Joseph Robinson, Zoetis.”Expanding Our Knowledge of Exposure as Part of the Environmental Assessment for a Veterinary Medicine”. SETAC Salt Lake City November 2015.
PresentationsBiocides and Antimicrobials2015
Evaluating the Relative Sensitivity of Endpoints Generated During Midge Life-Cycle Sediment Toxicity Tests
PRESENTATION ID: 606
PRESENTATION DATE: Thursday, November 5, 2015 at 8:20AM
LOCATION: Ballroom D
Midges (Diptera: Chironomidae) are used as model test organisms for evaluating the potential toxicity of chemicals sorbed to sediments. The guidance document “Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates” (EPA 600/R-99/064) released in March 2000 details procedures for conducting life-cycle tests with midges. There are ongoing efforts to revise certain aspects of the guidance document and members of the SETAC Midge Chronic Testing Working Group are providing technical insight with the aim of further advancing the test method. One area of potential revision pertains to the evaluation of appropriate test endpoints. Currently, lethality-based endpoints for the life-cycle test include larval, pupal and adult survival, while sublethal endpoints include larval growth, adult emergence (total/percent, cumulative rate, time to first emergence, and time to death), and reproduction (sex ratio, time to oviposition, mean eggs/female, egg cases/treatment, and egg hatchability). High variability in control response and redundancy of information gained from similar observations prompted scientific inquiry concerning the utility and/or necessity of some endpoints for defining biological effect thresholds. Streamlining the number of measured endpoints could improve the efficiency of the test method and also provide researchers with greater confidence that observed effects are indeed related to contaminant exposure and not manifested merely as a result of natural biological variability. Members of the Crop Life America Sediment Subcommittee team compiled midge toxicity data from studies completed with agrochemicals for retrospective analysis to gain greater understanding of the relative sensitivity of endpoints from the midge life-cycle study. The purpose of this presentation is to briefly review findings of the aforementioned effort and discuss implications for future midge life-cycle testing efforts.
Theodore Valenti, Syngenta; Michael Bradley, Smithers Viscient; Jennifer Gates, Mark Cafarella, Waterborne Environmental; Jeffrey Giddings, Compliance Services International; Hank Krueger, Wildlife International; Sean McGee, Bayer CropScience LP; Alan Samel, DuPont Crop Protection; Bibek Sharma, FMC Corp Global Regulatory Sciences; Jane Staveley, Exponent; Jiafan Wang, BASF Agriculture Solutions. “Evaluating the Relative Sensitivity of Endpoints Generated During Midge Life-Cycle Sediment Toxicity Tests”. SETAC Salt Lake City November 2015.
PostersHome and Personal Care Products2015
Development of iSTREEM® 2.0, New Enhancements for Down-The-Drain Model to Support Environmental Exposure Assessments across Multiple Commodity Groups
PRESENTATION ID: RP046
PRESENTATION DATE: Thursday, November 5, 2015
POSTER LOCATION: Exhibit Hall
The iSTREEM® model (“in-stream exposure model”), a free and publically-available web-based model supported by the American Cleaning Institute (istreem.org), provides a means to estimate chemical concentrations in effluent, receiving waters, and drinking water intakes (DWI) across the conterminous U.S. as well a number of watersheds in Canada under mean annual and low-flow (7Q10) conditions. This presentation will discuss recent upgrades made to enhance the model, underlying data, algorithm and presentation of results leading to the release of iSTREEM® 2.0. iSTREEM® 2.0 incorporates geographic locations of over 12,000 wastewater treatment plant (WWTP) facilities along a U.S.-wide river network of effluent-impacted river reaches, providing a framework to integrate geographic data to assess environmental risk for multiple scenarios of interest. WWTP facilities and associated facility level information were derived from the latest available USEPA Clean Watershed Needs Surveys. The river network used by iSTREEM® 2.0 was upgraded from previous iSTREEM® versions to a higher-resolution hydrologic dataset based on the NHDPlus version 2, which includes estimated mean annual and low flow (7Q10) data based on USGS stream gage measurements. The relationship between WWTP facilities and DWI locations to the river network was established applying techniques developed by USEPA. Pre-calculation of certain data and efficiency improvements to model algorithm has enabled simulation runs to complete in significantly less time compared to prior versions of the model. Model results are presented in a standardized manner for consistent results communication across all users, and are provided in a readily usable format (MS Excel) for easy interpretation and further customization of result presentation. Major assumptions used in constructing the model will be discussed. Recent upgrades and developments are geared to expand adoption of the model by a wide variety of users as an environmental risk assessment tool across multiple commodity groups (personal care products, pharmaceuticals, food additives, pesticides, etc.) that require internal or regulatory environmental assessments. The discussion will also include a comparison of model results between the prior version of iSTREEM® and latest iSTREEM® 2.0 to examine the impact of recent upgrades on the national distribution of predicted environmental concentrations (PEC’s) across the U.S.
Raghu Vamshi, Katherine Kapo, Megan Sebasky, Christopher Holmes, Waterborne Environmental; Paul DeLeo, Darci Ferrer,American Cleaning Institute. “Development of iSTREEMÂ® 2.0, New Enhancements for Down-The-Drain Model to Support Environmental Exposure Assessments across Multiple Commodity Groups”. SETAC Salt Lake City November 2015.
PostersIndustrial and Specialty Chemicals2015
Hepatic Biotransformation of 14C-Decamethylcyclopentasiloxane (D5) and 14C-Decamethyltetrasiloxane (L4) in Fish, Birds and Mammals
POSTER ID: RP028
PRESENTATION DATE: Thursday, November 5, 2015
LOCATION: Exhibit Hall
When considering bioconcentration (BCF), bioaccumulation (BAF) and trophic magnification (TMF) assessments, biotransformation and elimination of a chemical are important processes within an organism to understand. Recent efforts have been made in extrapolating in vitro fish biotransformation data to a whole body BCF value in an effort to better guide the need for an OECD 305 fish bioconcentration study. By integrating biotransformation estimates into BCF models, a more realistic estimation of BCF can be calculated while providing a cost-effective assay that uses less vertebrate animals. Building on this single species extrapolation concept, biotransformation data from multiple species may be used to construct a biomagnification or trophic magnification model for a given chemical. Using 14C radiolabelled compounds and high performance liquid radiochromatography, in vitro metabolism data utilizing liver microsomes were developed for a cyclic siloxane, D5, and a linear siloxane, L4. Of the species investigated, mink demonstrated the greatest potential to biotransform D5 and L4 siloxane. 14C radiochromatograms show the loss of D5 and L4 siloxane, as well as increases in metabolite production over the 60 min incubation period. The percentage loss of D5 was similar with human and rat microsomes and greater then observed with fish. The percentage loss of D5 in birds is low compared to fish and mammals. Similar relationships for loss of parent hold true for L4 (kestrel data not available). These data suggest that D5 and L4 siloxane are biotransformed by a wide array of species, which can influence “B” assessments. In addition, these data can be used to estimate whole-body rates of metabolism for incorporation into predictive environmental assessments.
Duane Huggett, Waterborne Environmental; Mark Cantu, David Hala, University of North Texas; Jeanne Domoradzki, Debra McNett,Dow Corning Corporation.”Hepatic Biotransformation of 14C-Decamethylcyclopentasiloxane (D5) and 14C-Decamethyltetrasiloxane (L4) in Fish, Birds and Mammals”. SETAC Salt Lake City November 2015.
Framework for Addressing Bioaccumulation Potential of Human Pharmaceuticals
POSTER ID: RP027
PRESENTATION DATE: Thursday, November 5, 2015
LOCATION: Exhibit Hall
The potential for human pharmaceuticals to bioaccumulate in aquatic organisms is rapidly becoming an area of scientific and regulatory interest. Historically, bioaccumulation assessments are conducted after consideration of a chemical’s hydrophobicity (e.g. Kow). The current strategy for determining the bioaccumulation potential of a human pharmaceutical is identical in scope in that scientists are required to conduct an OECD 305 fish study if the Kow value of a given pharmaceutical is greater than a prescribed regulatory trigger value (e.g. Log Kow> 4). The physical-chemical knowledge (e.g. pKa) of the compound should be incorporated into this initial Kow assessment to better guide the need for a full “B” assessment. In many instances, the current strategy does not utilize the wealth of non-clinical and clinical data available on the absorption, disposition, metabolism and elimination (ADME) of the pharmaceutical of interest, which could be used to better inform scientists on important characteristics and physiological processes associated with that human pharmaceutical. It is important to recognize that fish have the ability to perform many of the same physiological processes that mammals perform, hence a pharmaceutical’s ADME characteristics could be similar in fish. These data can be used to understand the ability of a fish to absorb, distribute, biotransform and eliminate a human pharmaceutical. If needed, studies can be conducted utilizing methodologies widely used on the drug development process (e.g. in vitro metabolism assays) to understand the similarity between fish and mammals and better guide the testing overall strategy. By utilizing all the available information collected and methodologies employed during the drug development process of a human pharmaceutical, scientists can make a more informed decision regarding the need for bioaccumulation testing (i.e. OECD 305), potentially reduce the number of vertebrate animals used in laboratory studies and achieve an overall cost savings.
Duane Huggett, Nikki Maples-Reynolds, Waterborne Environmental. “Framework for Addressing Bioaccumulation Potential of Human Pharmaceuticals”. SETAC Salt Lake City November 2015.