Papers & ReportsCrop Protection2012
Development of a Spatial-Temporal Co-occurrence Index To Evaluate Relative Pesticide Risks to Threatened and Endangered Species
A decline in pelagic species has been observed in the San Francisco Bay-Delta, triggering questions as to whether contaminants are contributing to the decline. An index method was developed to evaluate the spatial and temporal co-occurrence of pesticides and threatened and endangered species for this large ecosystem. The co-occurrence index combines monthly species abundance with statistical distributions of pesticide indicator days for 40 widely used pesticides. The frequency of co-occurrence was determined for 12 aquatic and semi-aquatic threatened or endangered species to help guide future research and monitoring priorities, and the placement of best management practices in the study area.
Hoogeweg, C.G., D.L. Denton, R. Breuer, W.M. Williams, and P. TenBrook. 2012. Development of a Spatial-Temporal Co-occurrence Index To Evaluate Relative Pesticide Risks to Threatened and Endangered Species. Pesticide Regulation and the Endangered Species Act. ACS Symposium Series, Vol. 1111, Chapter 22, pp 303–323.
(Chapter reprinted with permission from Pesticide Regulation and the Endangered Species Act. Kenneth D. Racke, Bernalyn D. McGaughey, James L. Cowles, A. Tilghman Hall, Scott H. Jackson, Jeffrey J. Jenkins, John J. Johnston (Editors). Volume 1111. November 6, 2012. DOI: 10.1021/bk-2012-1111. Copyright 2012 American Chemical Society.)
Prioritizing Research Needs for Threatened and Endangered Species in California Watersheds
A decline in pelagic species in the San Francisco Bay Delta region has led to speculation as to whether contaminants may be playing a role. A weight-of-evidence analysis was conducted to rank the relative risk potential for pesticides to impact threatened or endangered species in the Sacramento River, San Joaquin River, and Bay-Delta estuary watersheds. The study utilized monitoring data, simulation modeling, and GIS to address the co-occurrence of 40 widely used herbicides, fungicides, and insecticides to 12 aquatic and semi-aquatic species, including Chinook Salmon (Oncorhynchus tshawytscha), Central Valley steelhead (O. mykiss), southern North American Green Sturgeon (Acipenser medirostris), Delta smelt (Hypomesus transpacificus), Striped Bass (Morone saxatilis), San Francisco Longfin Smelt (Spirinchus thaleichthys), Threadfin Shad (Dorosoma petenense), California Red-legged Frog (Rana draytonii), and the California Freshwater Shrimp (Syncaris pacifica). Pesticide application sites represented in model simulations included fruit, vegetable, grain, nuts, rice, landscape maintenance, and structural applications. Daily pesticide concentrations were predicted at the PLSS section level from runoff, erosion, and drift sources. An co-occurrence matrix approach was developed to evaluate the spatial and temporal co-occurrence of pesticides and species. Areas of highest potential concern were located along the main branch of the Sacramento River, the northern part of the Delta region, and the southern part of the Delta in San Joaquin County. A few small clusters of high co-occurrence values were predicted along the Sacramento River Deep Water Ship Channel and in southern Butte County along the Feather River. Monitoring is sparse in a number of these and lesser areas of potential concern. The results of this study can be used to support current and future monitoring programs by strategic placement of sampling locations and frequency. Ultimately, it is hoped that this project will improve decision making and optimize resource spending of groups seeking to improve the long-term sustainability of these aquatic habitats.
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).