Na, Cl and Br in needles of norway spruce (P.Abies) and in the aerosol adhering to the needles∗

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Abstract
One year old needles of Norway spruce have been washed free of adhering wax and aerosol. Na, Cl and Br concentrations were determined in both fractions by neutron activation analysis. The range of the needle concentrations among the 47 sites investigated was found to be extremely large for Na, large for Br and moderate for Cl. The highest values were found near motorways. Mean concentrations for relatively clean sites are 3.7 ppm Na, 420 ppm Cl and 407 ppb Br. The quantities of these elements in the needle and in the adhering aerosol correlate. The main souce of Na in the aerosol in winter and spring is de‐icing salt, whose influence on the needle concentrations can be seen at a distance of many hundreds of meters from the nearest road. It is probable that the Na and Br needle concentrations are predominantly determined by foliar uptake of the ions from the aerosol and this may partially be trae for Cl. The concentrations of all three elements in the needles correlate with each other in the complete set of samples, but not at relatively clean sites alone.