EBTAG Annual Workshop and Field Trip
May 16-17, 2012

¹Los Alamos National Laboratory, groffman@lanl.gov

²Adelante Consulting Group

Polychlorinated biphenyls (PCBs) are persistent organic compounds and are ubiquitous on a global scale. The development of a low-level analytical method (1668A) resolves PCB concentrations on the order of 10 pg/L, revealing PCBs in remote locations far from PCB sources including high-latitude arctic and remote marine environments. In 2009, the Laboratory, in cooperation with the New Mexico Environment Department–Department of Energy Oversight Bureau (NMED-DOE OB), initiated a baseline PCB study to estimate the range of PCBs in stormwater runoff in areas not affected by historical Los Alamos National Laboratory (LANL) operations or activities in the Los Alamos townsite. Reference watersheds were identified north of the LANL and Los Alamos townsite in similar terrain at roughly the same altitude and climatic regime. Locations were also sampled upstream of the western boundary of LANL. Stormwater monitoring was conducted from 2009 to 2010. Thirty-seven samples were collected using automated stormwater samplers and analyzed for PCBs by Method 1668A. PCB concentrations for all samples collected from the reference watersheds range from 23 pg/L to 23,999 pg/L, with a median of 489 pg/L and standard deviation of 6186 pg/L. PCB concentrations from all samples collected from the western boundary locations ranged from 33 pg/L to 16,754 pg/L, with a median of 1885 pg/L and standard deviation of 4423 pg/L. These results are important for identifying baseline concentrations and may affect regulatory actions. Final results, including a statistical analysis and a conceptual model, will be presented to account for the variability within the landscape. Results from other surveys will be presented as well to provide perspective on the PCB distribution in northern New Mexico.