Development and Use of a Method for the Determination of Polycyclic Aromatic Hydrocarbon and Organochlorine Pesticide Concentrations in Freshly Fallen Snow

摘要

An analytical method was developed and validated for the quantitative analysis of 18 polycyclic aromatic hydrocarbons (PAHs) and 57 organochlorine pesticides (OCPs) and degradation products in 5kg samples of freshly fallen snow, using Oasis HLB solid-phase extraction (SPE) with quantitation by Gas Chromatography/Mass Spectroscopy (GC/MS). The Estimated Detection Limits (EDLs) for PAHs ranged from 53 +/- 1 pg/L-SWE to 222 +/- 3 pg/L-SWE, while the EDLs for pesticides ranged from 5 +/- 0.1 pg/L-SWE to 750 +/- 5 pg/L-SWE, with most relative standard deviations (RSDs) below 8%. Mean analyte recovery for the entire analytical method was 63% +/- 11% for OCPs and 47% +/- 11% for PAHs. The method was applied to samples of freshly fallen, pre-metamorphic snow collected from two remote alpine sites of similar altitude and exposure in the Cascade Mountains of Oregon, USA during the winter of 2012-2013. PAHs were detected in freshly fallen snow at concentrations of 1.3-2.2ng/L of snow water equivalents (SWE). The pesticides dacthal, alpha-HCH and chlorpyrifos were detected at concentrations of 45-220 pg/L SWE. Spatial analysis showed statistically significant between-site differences in alpha-HCH, dacthal, fluorine, and fluoranthene concentrations, indicating variability in persistent organic pollutant (POP) deposition on the 10km scale.