Entity

Time filter

Source Type

Leesburg, VA, United States

Russell M.H.,DuPont Company | Hoogeweg G.,Waterborne Environmental | Webster E.M.,Trent University | Ellis D.A.,Trent University | And 2 more authors.
Environmental Toxicology and Chemistry | Year: 2012

A next-generation mobile automobile air-conditioning (MAC) refrigerant, HFO-1234yf (CF3CF=CH2), is being developed with improved environmental characteristics. In the atmosphere, it ultimately forms trifluoroacetic acid (TFA(A); CF3COOH), which is subsequently scavenged by precipitation and deposited on land and water as trifluoroacetate (TFA; CF3COO-). Trifluoroacetate is environmentally stable and has the potential to accumulate in terminal water bodies, that is, aquatic systems receiving inflow but with little or no outflow and with high rates of evaporation. Previous studies have estimated the emission rates of HFO-1234yf and have modeled the deposition concentrations and rates of TFA across North America. The present study uses multimedia modeling and geographic information system (GIS)-based modeling to assess the potential concentrations of TFA in terminal water bodies over extended periods. After 10 years of emissions, predicted concentrations of TFA in terminal water bodies across North America are estimated to range between current background levels (i.e., 0.01-0.22μg/L) and 1 to 6μg/L. After 50 years of continuous emissions, aquatic concentrations of 1 to 15μg/L are predicted, with extreme concentrations of up to 50 to 200μg/L in settings such as the Sonoran Desert along the California/Arizona (USA) border. Based on the relative insensitivity of aquatic organisms to TFA, predicted concentrations of TFA in terminal water bodies are not expected to impair aquatic systems, even considering potential emissions over extended periods. © 2012 SETAC.


Purdy J.R.,Abacus Consulting Services Ltd. | Cheplick M.,Waterborne Environmental
ACS Symposium Series | Year: 2014

The analytical results for a pesticide compound in a set of laboratory soil dissipation studies with a variety of different soil types from North America and Europe show a range of behavior from linear simple first-order to a pronounced biphasic pattern. Using a set of three simple first-order equations, representing reversible movement between two compartments in the soil, and irreversible degradation from one of the two compartments, it was possible to fit the data from all sites. The output was a set of three simultaneously optimized rate constants for each soil type, along with the goodness of fit statistics. The physical interpretation of this model was found to be unrelated to soil physical properties but associated with the movement of residues between a compartment in which the degradation processes occur, and a compartment in which they do not. The former compartment resembles what has been called the bioaccessible compartment in soil. This model, identified as the SFO3 model, is useful for calculation of rate constants for parent compound and intermediate metabolites, comparison of lab and field results, correction for changes in soil temperature or moisture content, identification of outlier data, and development of parameters for modelling input. The utility of the resulting rate constants for predictive modelling for environmental risk assessment depends on the availability of measurable soil properties that can be used to predict them, such as bioaccessibility. © 2014 American Chemical Society.


Diamond J.,Tetra Tech Inc. | Munkittrick K.,Canadas Oil Sands Innovation Alliance | Kapo K.E.,Waterborne Environmental | Flippin J.,Tetra Tech Inc.
Environmental Toxicology and Chemistry | Year: 2015

Trace levels of a variety of currently unregulated organic chemicals have been detected in treated wastewater effluents and surface waters that receive treated effluents. Many of these chemicals of emerging concern (CECs) originate from pharmaceuticals and personal care products that are used widely and that frequently are transported "down the drain" to a wastewater treatment plant (WWTP). Actual effects of CECs on aquatic life have been difficult to document, although biological effects consistent with effects of some CECs have been noted. There is a critical need to find appropriate ways to screen wastewater sites that have the greatest potential of CEC risk to biota. Building on the work of several researchers, the authors present a screening framework, as well as examples based on the framework, designed to identify high-risk versus lower-risk sites that are influenced by WWTP effluent. It is hoped that this framework can help researchers, utilities, and the larger water resource community focus efforts toward improving CEC risk determinations and management of these risks. © 2015 SETAC.


Jones R.L.,Bayer CropScience | Trask J.R.,Waterborne Environmental | Hendley P.,Phasera | Cox M.J.,Waterborne Environmental | And 3 more authors.
Environmental Toxicology and Chemistry | Year: 2016

Washoff of 17 pyrethroid products resulting from a 1-h, 25.4-mm rainfall occurring 24h after application was measured in indoor studies with concrete slabs. These products included different pyrethroid active ingredients and a range of formulation types. Based on this replicated study, 5 product pairs with contrasting washoff behaviors were chosen for an outdoor study using 6 full-scale house fronts in central California. Products in 4 of these pairs were applied once to different rectangular areas on the driveway (1 product in each pair to 3 house lots and the other to the remaining 3 house lots). The products in the fifth pair were applied 3 times at 2-mo intervals to vertical stucco walls above the driveway. All house lots received natural and simulated rainfall over 7 mo. Indoor studies showed differences up to 170-fold between paired products, whereas the maximum difference between paired products in the field was only 5-fold. In the pair applied to the wall, 1 product had 91 times the washoff of the other in the indoor study, whereas in the field the same product had 15% lower washoff. These results show that, although the formulation may influence washoff under actual use conditions, its influence is complex and not always as predicted by indoor experiments. Because the formulation also affects insect control, washoff research needs to be conducted together with efficacy testing. Environ Toxicol Chem 2016;35:340-347. © 2015 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.


Trask J.R.,Waterborne Environmental | Harbourt C.M.,Waterborne Environmental | Miller P.,Waterborne Environmental | Cox M.,Waterborne Environmental | And 3 more authors.
Environmental Toxicology and Chemistry | Year: 2014

The use of pesticides by homeowners or pest-control operators in urban settings is common, yet contributions of washoff from these materials are not easily understood. In the present study, cypermethrin, formulated as Cynoff EC (emulsifiable concentrate) and Cynoff WP (wettable powder) insecticides, was applied at typical rates to 10 different building material surfaces to examine its washoff potential from each surface. Using an indoor rainfall simulator, a 1-h rainfall event was generated and washoff samples were collected from 3 replicates of each surface type. Washoff was analyzed for cypermethrin using gas chromatography-negative chemical ionization mass spectrometry. An analysis of variance for a split-plot design was performed. Many building materials had similar water runoff masses, but asphalt resulted in significantly reduced average water runoff masses (73% less). The Cynoff WP formulation generally produced greater cypermethrin washoff than the Cynoff EC formulation. In addition, results for both the WP and EC formulations indicated that smoother surfaces such as vinyl and aluminum siding had higher washoff (1.0-14.1% mean percentage of applied mass). Cypermethrin washoff from rough absorptive surfaces like concrete and stucco was lower and ranged from 0.1 to 1.3% and from 0 to 0.2%, respectively, mean percentage of applied mass. Both building material surface and formulation play a significant role in cypermethrin washoff. © 2013 The Authors.

Discover hidden collaborations