title: Predicting runoff induced mass loads in urban watersheds: Linking land use and pyrethroid contamination.
abstract: Pyrethroid pesticide mass loadings in the Ballona Creek Watershed were calculated using the volume-concentration method with a Geographic Information Systems (GIS) to explore potential relationships between urban land use, impervious surfaces, and pyrethroid runoff flowing into an urban stream. A calibration of the GIS volume-concentration model was performed using 2013 and 2014 wet-weather sampling data. Permethrin and lambda-cyhalothrin were detected as the highest concentrations; deltamethrin, lambda-cyhalothrin, permethrin and cyfluthrin were the most frequently detected synthetic pyrethroids. Eight neighborhoods within the watershed were highlighted as target areas based on a Weighted Overlay Analysis (WOA) in GIS. Water phase concentration of synthetic pyrethroids (SPs) were calculated from the reported usage. The need for stricter BMP and consumer product controls was identified as a possible way of reducing the detections of pyrethroids in Ballona Creek. This model has significant implications for determining mass loadings due to land use influence, and offers a flexible method to extrapolate data for a limited amount of samplings for a larger watershed, particularly for chemicals that are not subject to environmental monitoring. Offered as a simple approach to watershed management, the GIS-volume concentration model has the potential to be applied to other target pesticides and is useful for simulating different watershed scenarios. Further research is needed to compare results against other similar urban watersheds situated in mediterranean climates.
authors.affiliation: UCLA Institute of the Environment and Sustainability, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095-1496, USA. Electronic address: kazuechinen@g.ucla.edu.
authors.forename: Kazue
authors.initials: K
authors.lastname: Chinen
authors.affiliation: UCLA Civil and Environmental Engineering Dept, 5732 Boelter Hall, Los Angeles, CA 90095-1593, USA. Electronic address: simlin@ucla.edu.
authors.forename: Sim-Lin
authors.initials: SL
authors.lastname: Lau
authors.affiliation: UCLA Pub Hlth-Envir Hlth Sci, Envir Sci Engr, Box 951772, 61-295A CHS, Los Angeles, CA 90095-1772, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Nonezyan
authors.affiliation: UCLA Pub Hlth-Envir Hlth Sci, Envir Sci Engr, Box 951772, 61-295A CHS, Los Angeles, CA 90095-1772, USA. Electronic address: emcelroy@ucla.edu.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: McElroy
authors.affiliation: UCLA Pub Hlth-Envir Hlth Sci, Envir Sci Engr, Box 951772, 61-295A CHS, Los Angeles, CA 90095-1772, USA.
authors.forename: Becky
authors.initials: B
authors.lastname: Wolfe
authors.affiliation: UCLA Pub Hlth-Envir Hlth Sci, Envir Sci Engr, Box 951772, 61-295A CHS, Los Angeles, CA 90095-1772, USA. Electronic address: msuffet@ucla.edu.
authors.forename: Irwin H
authors.initials: IH
authors.lastname: Suffet
authors.affiliation: UCLA Civil & Envir Engr, Box 951593, 5714 Boelter Hall, Los Angeles, CA 90095-1593, USA. Electronic address: stenstro@seas.ucla.edu.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Stenstrom
mesh_terms: D004784:Environmental Monitoring; D040362:Geographic Information Systems; D010575:Pesticides; D011722:Pyrethrins; D045483:Rivers
chemical_list: D010575:Pesticides; D011722:Pyrethrins
keywords: Ballona Creek Watershed; GIS; Land use; Policy; Pyrethroids; Stormwater