The effect of the exclusion of dry and wet deposition on visible symptoms and accumulation of sulphur and fluoride by Picea abies needles near point‐sources

Abstract

The effect of air pollutants on conifers was studied throughout the year near industrial point‐sources using two types of half‐open chambers for excluding wet or dry deposition around selected trees. Results indicate that pollutant uptake from dry deposition and wash‐off effect by rain have overriding influence in the internal accumulation of pollutants by needles. The exclusion of wet deposition substantially enhanced pollutant accumulation in the needles and suggests that wet deposition itself has a minor direct effect on accumulation near point‐sources. Near the fertilizer plant the trees growing in filtered air exhibited fewer visible symptoms and had lower accumulations of fluoride. This suggests that decreasing the gaseous air pollutants would improve the condition of conifers at this site. Results suggest also that besides high needle pollutant content, winter conditions are needed to facilitate visible injury development.