Papers & ReportsAgriculture and Food2012
TFA From HFO-1234yf: Accumulation and Aquatic Risk in Terminal Water Bodies
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., 0.01–0.22 µg/L) and 1 to 6 µg/L. After 50 years of continuous emissions, aquatic concentrations of 1 to 15 µg/L are predicted, with extreme concentrations of up to 50 to 200 µg/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. Environ. Toxicol. Chem. 2012; 31: 1957–1965. © 2012 SETAC
Russell, M.H., C.G. Hoogeweg, E.M. Webster, D.A. Ellis, R.L. Waterland, and R.A Hoke.. 2012. TFA from HFO-1234yf: Accumulation and aquatic risk in terminal water bodies. Environmental Toxicology and Chemistry. doi: 10.1002/etc.1925.
Papers & ReportsHome and Personal Care Products2012
Estimating Chemical Emissions From Home and Personal Care Products in China
China’s economy has grown significantly and concomitantly so has the demand for home and personal care (HPC) products. The detection of chemicals used in HPC products is increasing in profile as China strives to improve its environmental management. China is developing robust exposure models for use in regulatory risk-based assessments of chemicals, including those chemicals used in HPC products. Accurate estimates of chemical emissions play an important role within this. A methodology is presented to derive spatially refined emissions from demographic and economic indicators with large variations in emissions calculated, showing product usage being higher in East and South China. The less affordable a product, the greater the influence per capita Gross Domestic Product has on the product distribution. Lastly, more spatially resolved input data highlights greater variation of product use. Linking product sales data with population density increased the observed variability in absolute usage distribution of HPC products at the county > province > regional > country scale.
Using Spatial and Remote Sensing Technologies to Help Interpret Results from Monitoring Studies and Support Stewardship Initiatives
In the October 2003 Atrazine Interim Reregistration Eligibility Decision (IRED), the US EPA required a statistically designed multiple season intensive monitoring program to measure atrazine concentrations in small headwater streams flowing through highly vulnerable watersheds. 40 watersheds (9-100 sq. mi.) were instrumented and monitored for at least two seasons between 2004 and 2006. Atrazine concentrations were measured at least every 4 days at all sites along with flow and weather data. Detailed GIS data were accumulated and analyzed in order to identify potential drivers of runoff in each watershed. Of these 40 potentially highly vulnerable watersheds, only 3 were determined by EPA to require continued monitoring and a watershed management program based upon the monitoring results. Two of these three streams exhibit intermittent flow during the summer. Monitoring continued after 2007 in these three as well as several adjacent watersheds using a daily auto-sampling protocol.
Hendley P., R. Joseph, C.Harbourt and P. Miller. Using Spatial and Remote Sensing Technologies to Help Interpret Results from Monitoring Studies and Support Stewardship Initiatives. Land Grant and Sea Grant National Water Conference, Washington, DC. Jan. 31-Feb. 1, 2011.
Higher Tier Modelling of Groundwater Concentrations from Pesticides Used on Rice
The Med-Rice model is used to determine Predicted Environmental Concentrations in groundwater (PECgw) for pesticides used on rice. Higher tier approaches have not been established under EU guidance to address situations when the Med-Rice model generates a PECgw greater than 0.1 ug/L. This poster compares several options for conducting higher tier modelling of PECgw by linking the RICEWQ (a pesticide fate and transport model developed to simulate the seepage, flooding conditions, overflow, and controlled releases of water associated with rice production) with several leaching and/or groundwater models including VADOFT (Vadose Zone Flow and Transport model) and HYDRUS-1D (unsaturated flow and solute transport model).