Atmospheric deposition of acidifying compounds onto forests in The Netherlands: throughfall measurements compared to deposition estimates from inference

Abstract

In this study throughfall measurements of acidifying components have been compared to deposition results from inference for forests in The Netherlands. Corrections have been applied for the contribution of neutral salts and sea salt to the throughfall samples. Furthermore, corrections have been applied for the dry deposition of gases and aerosols onto the funnels of the open samplers used for throughfall measurements. The corrected throughfall measurements agreed better with the inference results than the uncorrected fluxes for SO4, NH4 and total potential acid. Corrections did have almost no effect on NO3 fluxes. The correlation between corrected net throughfall fluxes (throughfall minus fluxes measured in the open field) and dry deposition estimates from inference was found to be significant for all fluxes. This reflects the correlation between the spatial distribution of net throughfall and dry deposition. Corrected throughfall fluxes were significantly higher for SO4 (45%) and NH4 (13%) and significantly lower for NO3 (33%), on the average. The fluxes of total potential acid were found to be somewhat higher for the corrected throughfall fluxes (14%), but not significantly.