Accumulation of persistent organic pollutants in terrestrial vegetation from the Canadian Rocky Mountains.

Abstract

This thesis examines the accumulation of persistent organochlorine compounds in Canadian mountain environments through the sampling of air and coniferous vegetation along a 1430-meter elevation gradient in the Canadian Rocky Mountains. Results showed that lower temperatures encountered in high altitudes favor the accumulation of chemicals with higher volatility in vegetation. Air concentrations further suggest that the reason for this accumulation in elevated areas is increased atmospheric deposition from distant sources and not from temperature-induced revolatilization from local terrestrial surfaces. Seasonal decreases in plant concentrations indicate evaporative processes, and volatilization from vegetation was confirmed by calculated fugacity gradients. However, volatilization contributes very little to air concentrations and the subsequent fractionation upslope, which appears to be dominated by long-range transport. Multivariate analysis revealed that, in addition to cooler temperatures, other environmental conditions common to mountain ecosystems, such as elevated precipitation and lower pressure, promote chemical deposition onto vegetation.