Tracer Studies in Headwater Watersheds in the Midwestern U.S. to Characterize Stream Flow Dynamics
Stream flow dynamics influences agrochemical exposure timing, duration, and frequency. Tracer studies were conducted in headwater watersheds in Iowa and Missouri to characterize stream hydrological properties to better understand drivers behind the magnitude and duration of crop protection chemical concentrations in stream water and watershed model parameterization. We used chemical tracer chemographs to calculate travel time and stream volume for stream reaches under low-flow conditions. Florescent dye was injected at strategic stream locations and continuously monitored with in-situ fluorometers. Accurate travel times of the chemical tracer were calculated from injection points to corresponding, downstream monitoring points along stream reaches, and were then combined with stream discharge data to estimate stream reach flow volume. Assessing tracer data with observed runoff events indicated that the ratio of rainfall-driven stream flow to initial stream flow volume influenced duration of chemical exposure at the headwater outlet. Results also illustrate that flow in small headwater streams is significantly different from that predicted by NHD+ indicating stream characteristics at this scale require higher resolution data. Finally, tracer study results are being used to inform stream flow numerical simulations toward a better representation of stream hydrodynamic properties at the headwater watershed scale.
Greg Goodwin, Daniel Perkins, Megan Cox, Les Carver, Jennifer Trask (Waterborne Environmental), Sun Mao Chen (Syngenta Crop Protection). Tracer Studies in Headwater Watersheds in the Midwestern U.S. to Characterize Stream Flow Dynamics. Presentation ACS 2017. Washington DC.
Field Study to Determine Runoff and Deposition of an Herbicide in Pasture Conditions
A field-scale runoff study was conducted to evaluate the fate of herbicide residues when applied under field conditions typical to pasture production. The study monitored movement from treated areas through runoff and possible deposition in untreated down gradient areas in Texas and North Carolina. The study included a novel two-part design: 1) a Small Scale Runoff study to verify model parameters following treatment to three different cover conditions and 2) a Large Scale Runoff study to determine the residue pattern and runoff from treated to untreated areas of typical pasture following a significant rainfall event. This study was conducted in accordance with EPA FIFRA Good Laboratory Practice Standards (GLP), 40 CFR 160. The presentation will focus on the complex study goals and novel field study implementation approach including sampling methods, simulated rainfall equipment and monitoring techniques. A general discussion of results including regional differences observed and variations in impact of residue profile based on cover conditions. Discussion of unique sampling methods related to quantifying grass, thatch and soil residues will be included. The complex study provided data for both quantifying movement in the pasture environment as well as parameters useful for environmental fate modeling under different cover conditions.
Les Carver, Jennifer Trask, Nathan Snyder (Waterborne Environmental), Cecilia Mucha Hirata, Aldos Barefoot ( DuPont Crop Protection). Field Study to Determine Runoff and Deposition of an Herbicide in Pasture Conditions. Presentation ACS 2017. Washington DC.
Vegetated Ditches as a Best Management Practice to Filter Pesticides, Sediment, and other Constituents from Agricultural and Urban Runoff Water
Vegetated ditches and bioswales have been promoted and incorporated into the agricultural and urban landscape to reduce the transport of pesticides, nutrients, sediment, and other water quality consitituents in runoff water. Research studies over the past 12 years have examined their utility as best management practices (BMPs) across a range of applications. These results are compiled and compared to predictions from the Vegetated Filter Ditch Model (VFDM) that was developed to design vegated agricultural drainage ditches at a farm level. At the time of development, very little data was available to evaluate the accuracy of model predictions. Now, approximately 10 years later, additional research has become available to verify the applicability of the model to evaluate the water quality benefits of vegetated ditches and swales in both agricultural and urban settings.
Marty Williams, Jennifer Trask (Waterborne Environmental), Debra Denton (EPA). Vegetated Ditches as a Best Management Practice to Filter Pesticides, Sediment, and other Constituents from Agricultural and Urban Runoff Water. Presentation ACS 2017. Washington DC.
Effect of the Formulation of Vegetative Filter Strips Pesticide Residue Degradation on Environmental Exposure Assessments
Understanding and being able to simulate the fate and transport of pesticides from the application on a field, through a vegetative filter strip (VFS), and finally to adjacent receiving water bodies is critical for conducting high-tier environmental exposure risk assessments (ERA). Previous research has proposed a modeling framework that links the U.S. Environmental Protection Agency’s (US-EPA) PRZM/EXAMS with a well-tested process-based model for VFS (VFSMOD). This was recently updated to consider pesticide residue trapped in the VFS and degradation prior to subsequent rainfall/runoff events. However, there is disagreement among different ERA regulatory agencies on how different formulations incorporate modifications for temperature and soil water dynamics may affect pesticide loads and the final estimated environmental concentration (EECs) in the aquatic environment. The objective of this research was to update the current modeling approach to consider four formulations for VFS pesticide degradation to accommodate different regulatory environments, and to determine if residues in the VFS and/or aquatic EECs differed among formulations. The importance of the degradation formulations was evaluated for two model pesticides (mobile and rapidly degrading versus less mobile and persistent) for three distinct agroecological scenarios (continental row-crop agriculture, wet maritime extensive agriculture, and dry Mediterranean intensive horticulture) and for receiving water systems lacking VFS, and with VFS of lengths of 1 to 9 m. While the type of degradation equation was important in long-term assessments to predict VFS residues at the beginning of each storm event (statistically different at p<0.01), the degradation formulation was not found important relative to EECs estimation. These results are important since they indicate that the impact of considerations on pesticide residue degradation formulation on EECs estimated is negligible in what it refers to EECs modeled through a VFS. The approach can also inform the relative importance of field degradation processes.
Amy Ritter (Waterborne Environmental), Rafael Munoz-Carpena2, Garey Fox (North Carolina State University), Oscar Perez-Ovilla(Bayer CropScience), Ismael Rodea-Palomares (University of Florida). Effect of the Formulation of Vegetative Filter Strips Pesticide Residue Degradation on Environmental Exposure Assessments. Platform. ACS 2017. Washington DC.
Use of the OECD ENASGIPS Crosswalk Tool
One of the deliverables from the OECD Pesticide Dissipation Project is a GIS-based application to assess the similarity of ecoregions between Europe and North America. The objective of this tool is to find matching ecoregions which enable registrants to demonstrate that foreign test site conditions exist in either Europe or North America. This GIS application has the potential of being used in a variety of manners. Risk assessors can easily determine if e.g. the dissipation results from rice studies conducted in the US are applicable to European registration and vice versa. Although, the tool is easy to use, expert knowledge regarding the underlying data and model help with interpretation? the results. In this presentation, we will explore how the tool and the underlying data can be used to find locations with environmental conditions that match foreign test sites, and the implications of registration of pesticides in Europe from an ecoregion perspective. In addition, we will address issues such as crop data, discuss the implications of using long-term versus short term field data, and account for variability in climate and soil properties and the impact on site selection.
G.Hoogeweg, C.M. Holmes (Waterborne Environmental). Use of the OECD ENASGIPS Crosswalk Tool. SETAC Europe 2017. Poster.
PostersHome and Personal Care Products2017
A Framework for Dynamic Estimation of Aquatic Environmental Concentrations of Microplastics Via WWTP Discharge
Down-the-drain exposure models provide a valuable screening-level tool for estimating environmental exposure to substances which are treated and discharged at municipal wastewater treatment plants (WWTPs). Microplastics enter WWTPs from a variety of sources. As such, exposure models traditionally used for chemicals may also be utilized for particle emissions into the environment from WWTP discharge. These models often account for removal in WWTP as well as in-river decay processes. However, in light of incomplete and changing knowledge on microplastic fate in surface waters, we developed a framework in which microplastic use rates and general properties can be used to estimate the range of expected environmental concentrations depending on assumptions about removal and decay. We developed a web-based tool incorporating 10 removal rates and 10 decay rates encompassing the typical and extreme ranges of possible values. Each of the 100 model runs produces a distribution of Predicted Environmental Concentration (PECs) representing each effluent impacted stream as described by the iSTREEM® model which estimates spatially-explicit concentrations of chemicals in effluent and receiving waters across the US. Output visualization in the interactive tool includes a broad view of all possible combinations in a matrix format, and a detailed view of the full distribution of PECs for individual model runs. Within the matrix, each of the 100 individual cells correspond to a selected percentile of the PEC distribution (e.g., 95th percentile) for tha combination of removal and decay. We demonstrate the utility of this framework using WWTP influent loadings of polyethylene microbeads from liquid soaps and shower gels estimated using per-capita usage (Gouin et al 2011) and combine with individual facility population served and flow estimates using the iSTREEM model. We can the investigate the question … What kind of environmental concentrations might we estimate using these emissions? This dynamic framework can be used to help inform environmental exposure assessments by readily providing PECs based on varying model inputs on WWTP removal and in-stream decay rates for microplastics, which continues to evolve as more research is conducted. While this framework was applied to the US at a national scale, the framework itself is not geographic-dependent and could function equally well utilizing PEC distributions from Europe or elsewhere.
C.M. Holmes, R. Vamshi, N.Maples-Reynolds (Waterborne Environmental); I.A. Davies, B. Jonas (Personal Care Products Council), S.D. Dyer (The Procter & Gamble
Company / Environmental Stewardship and Sustainability Organization). A Framework for Dynamic Estimation of Aquatic Environmental Concentrations of Microplastics Via WWTP Discharge. SETAC EU 2017. Poster.
PresentationsHome and Personal Care Products2017
Integrating Treatment Facility and River Network Information to Model Spatially-Explicit Environmental Concentrations of Down-The-Drain Substances: ISTREEM
iSTREEM® is a web-based model which estimates spatially-explicit environmental concentrations of down-the-drain chemicals in effluent and receiving waters across the USA. Concentrations are estimated at the discharge points of over 10,000 municipal wastewater treatment plants (WWTPs) and downstream receiving waters covering more than 350,000 km of rivers. The model incorporates WWTP information on population served, treatment type, and facility flow which are linked to a commonly used hydrology framework providing flow and hydrologic connectivity between facilities and downstream sites. As part of the hydrologic routing, a first-order decay is implemented to simulate environmental processes that remove chemical from the water column. The model allows for regional use rates to better simulate potential geographic variability in emissions, as well as differing removal rates to account for different facility treatment types. Given the assumption of temporally constant emission, the model is able to efficiently execute as a single, annual model run. The publicly available web-based model (www.iStreem.org) exemplifies open access to modeling resources, with no software installation required, and computation resources for model runs performed by the iSTREEM server. Users are able to save and retrieve runs, interact with results in a map format, or download source data and model results for more in-depth analysis by the user, including linking to desktop mapping software. The model, sponsored by the American Cleaning Institute (ACI, www.cleaninginstitute.org), is a valuable tool for both promoting product and ingredient stewardship and potential regulatory compliance for chemical suppliers and manufacturers of formulated products. The framework and modular nature of the model allow it to be applied to different geographies beyond the current USA-wide dataset.
C.M. Holmes, R. Vamshi (Waterborne Environmental); P. DeLeo, D. Ferrer (American Cleaning Institute); S.D. Dyer (The Procter & Gamble Company / Environmental Stewardship and Sustainability Organization). Integrating Treatment Facility and River Network Information to Model Spatially-Explicit Environmental Concentrations of Down-The-Drain Substances: ISTREEM. Presentation. SETAC Europe 2017.
PresentationsHome and Personal Care Products2017
Estimating Sewer Residence Time at the National Scale to Enable Probabilistic Risk Assessment of Down-The-Drain Household Consumer Product Ingredients
Many household consumer product ingredients disposed of down-the-drain can undergo significant degradation in the sewer system prior to being treated and discharged from a wastewater treatment facility. Understanding the distribution of sewer residence times for wastewater at the national scale, in combination with in-sewer biodegradation data for specific chemicals, can provide a more realistic assessment of environmental exposure and risk. However, the availability of data for sewer residence times at the national or regional scale is currently limited. We overview how commonly-available data resources such as road networks, land use and population data, and wastewater treatment facility data can be analyzed spatially to estimate the distribution of sewer residence times at a national or regional scale. This approach was developed using case study sewer system data and extrapolated to a national dataset of over 3,400 wastewater treatment facilities across the U.S., yielding a national median residence time of 3.3 hours. We demonstrate how sewer residence time distributions derived by this spatial approach can be used as a tool to enable probabilistic risk assessment of down-the-drain household consumer product ingredients for a given country or region.
K.E. Kapo, R. Vamshi, M. Sebasky, C.M. Holmes (Waterborne Environmental), M. Paschka, K. McDonough (P&G). “Estimating Sewer Residence Time at the National Scale to Enable Probabilistic Risk Assessment of Down-The-Drain Household Consumer Product Ingredients”. Presentation. SETAC EU 2017.
Comparison of Aquatic Exposure Assessment Models for Pesticide Use on Rice
An evaluation of six modeling approaches for predicting environmental concentrations associated with the use of crop protection chemicals on rice was conducted. A comparison of predicted environmental concentrations (PECs) computed with all six approaches (EPA Tier 1, MED-RICE, Japanese regulatory spreadsheet “Aquatic PEC”, SWAGW, RICEWQ-EXAMS, and PFAM) is presented along with the status of their regulatory acceptance for pesticide registration in the United States, European Union, China, and Japan. RICEWQ-EXAMS is used in the Pesticide Risk Assessment Exposure Simulation Shell (PRAESS) for China Scenarios and for higher tier in Europe. Of the six models, RICEWQ and PFAM models have the capability to simulate multiple pesticide applications,metabolites, and the flooding, overflow, and controlled releases of water associated with rice production. Each country has different guidance on which model, input parameters and ecological environments are used for computing PECs. A description of each model/scenario will be presented a long with a comparison of PECs from two pesticides using each model.
A. Ritter, M. Cheplick, G. Hoogeweg, C.M. Holmes (Waterborne Environmental). Comparison of aquatic exposure assessment models for pesticide use on rice. SETAC BRUSSELS. Presentation. April 2017.
PostersHome and Personal Care Products2016
A Spatial Approach for Estimating the National Distribution of Sewer Residence Times for Wastewaters in the U.S.
Sewer residence time can have a significant influence on the environmental fate and transport of wastewater constituents, including down-the-drain household consumer product ingredients. In this study, best-available data resources and geoprocessing tools were used to develop a spatial approach for estimating the national distribution of sewer residence times for wastewaters in the U.S. Case studies estimating sewer residence times for two municipalities demonstrated that road networks could be used as a spatial proxy for sewer networks when the latter data is not available. The approach was then extrapolated to a national dataset of >3,400 wastewater treatment plant (WWTP) facilities across the U.S. to estimate the national distribution of sewer residence times, with an estimated national median sewer residence time of 3.3 hours. Sewer residence times for smaller WWTP facilities (< 1 million gallons per day) were comparatively shorter than larger facilities, however the latter comprised a greater proportion of the overall national wastewater volume. The sewer residence time distributions derived in this study can be combined with in-sewer biodegradation data to estimate WWTP influent concentrations of down-the-drain household consumer product ingredients as part of a national-scale probabilistic risk assessment.
Katherine Kapo, Raghu Vamshi, Megan Sebasky (Waterborne), Michael Paschka, Kathleen McDonough (P&G). “A Spatial Approach for Estimating the National Distribution of Sewer Residence Times for Wastewaters in the U.S.” Poster. SETAC NA 2016.