Multivariate association of regional factors with heavy metal concentrations in moss and natural surface soil sampled across Norway between 1990 and 2010

Abstract

Assessing effects of air pollution needs the monitoring of atmospheric deposition. At least for enhancing the spatial resolution of measuring deposition by use of technical devices and of deposition modeling, mosses are used complementarily as biomonitors. In Norway, since 1985, nationwide surveys have been carried out every 5 years. This study aimed at investigating statistical relationships between heavy metal concentrations in samples of moss and natural surface soil, collected in spatial dense networks covering Norway, and regional factors. Heavy metal (HM) concentrations in moss samples collected in 1990, 1995, 2000, 2005, and 2010 and in natural surface soil specimens sampled in 1995 and 2005 across Norway were assessed statistically. Classification and regression trees were computed in order to uncover multivariate relationships between HM concentrations in moss and natural surface soil and potential influencing environmental factors that were integrated into the multivariate analyses. Atmospheric deposition of HM could be proved as the strongest predictor for HM concentrations in moss and natural surface soil samples. Land use within a 5-km radius and population density around the sampling sites were identified as further predictors of HM concentrations in moss and natural surface soil. HM monitoring with moss and natural surface soil samples indicates complementarily atmospheric deposition and thus should be carried out as long-term observation.