Polychlorinated Biphenyls in Whole-Body Field Mice Collected Upgradient and Downgradient of a Sediment Retention Structure in Los Alamos Canyon, Los Alamos National Laboratory, New Mexico, USA

Abstract

Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos Canyon (LAC), Los Alamos National Laboratory (LANL), New Mexico, USA, from 2007 through 2013. Samples were also collected approximately 8 km downgradient of the retention structure in 2009 and 2013. LAC, a major drainage that crosses LANL lands, contains legacy waste, including PCBs, and occasionally discharges storm water and snowmelt flows to the Rio Grande approximately 8.8 km away from the weir. The Rio Grande is the major waterway that flows southward across the state. The weir was constructed across the channel on the northeastern boundary of LANL in late 2000 to help contain sediments mobilized by floodwaters as a result of a large wildfire in early 2000 that burned forest lands west and adjacent to LANL. Total PCBs in field mice directly upgradient of the sediment retention structure from 2007 through 2012 were significantly greater (p < 0.05) than in field mice collected from background locations but decreased in concentration over time; by 2013 the levels were statistically similar (p > 0.05) to background. The highest mean total PCB concentration in field mice was below the levels that may negatively impact field mice population attributes. Total PCBs in field mice collected 8 km below the sediment retention structure in 2009 were lower than field mice collected from behind the weir and decreased over time; also by 2013, the amount of PCBs in field mice 8 km below the sediment retention structure were not significantly different (p > 0.05) from background. The rank order of concentrations of ICES 7 PCB congeners in upgradient and downgradient field mice were: No. 153 > 180 > 138 > 118 > 28 > 101 > 52 and No. 153 > 180 > 138 > 118 > 28 > 52 > 101, respectively. Based on the PCB homolog distribution, the major formulation detected in field mice was Aroclor-1260. Overall, the reduction of PCBs in whole-body field mice from both sites over time was attributed, in part, to sediment control practices.

The concentrations of radionuclides, heavy metals, and poloychlorinated biphenyls in field mice collected from regional background areas. Revision 3

“…Field mice are effective indicators of contaminant presence because of their feeding (e.g., omnivore) and activity (e.g., burrowing) habits (Arthur et al 1987, Talmage andWalton 1991), and at LANL they are used as the biota (radionuclide) dose (McNaughton 2006) and (chemical) uptake (Fresquez et al 2013, Fresquez 2014) models for terrestrial mammals because they have the smallest home range (0.089 to 1.5 acres) (Wood et al 2010). The three objectives of the biota monitoring program are as follows:…”