Testing Ion Exchange Resin for quantifying bulk and throughfall deposition of macro and micro-elements on forests

Abstract. Atmospheric deposition is a major nutrient influx in ecosystems and high anthropogenic deposition may disrupt ecosystem functioning. Quantification of the deposition flux is required to understand the impact of such anthropogenic pollution. However, current methods to measure nutrient deposition are costly, labor intensive and potentially inaccurate.

Ion Exchange Resin (IER) appears a promising cost-and labor-effective method. The IER-method is potentially suited for deposition measurements on coarse time scales and for areas with little rainfall and/or low elemental concentrations. The accuracy of the IER-method is, however, hardly classified beyond nitrogen. We tested the IER-method for bulk deposition and throughfall measurements of macro and micro-elements, assessing resin adsorption capacity, recovery efficiency, and field behavior.

We show that IER is able to adsorb 100 % of Ca, Cu, Fe, K, Mg, Mn, P, S, Zn and NO₃ and >96 % of P and Na. Loading the resin beyond the capacity resulted mainly in losses of Na, P, NH₄ while losses of Ca, Cu, Fe, Mg, Mn and Zn were hardly detected. Heat (40 °C), drought and frost (-15 °C) reduced the adsorption of P by 25 %. Recovery was close to 100 % for NH₄ and NO₃ using KCl (1 or 2M) while high (83–93 %) recoveries of Ca, Cu, Fe, K, Mg, Mn and S were found using HCl as an extractant (2–4M). We found good agreement between the conventional and the IER-method for field conditions.

Overall, IER is a powerful tool for the measurement of atmospheric deposition of a broad range of elements as the measurements showed high accuracy. The IER-method has therefore the potential to expand current monitoring networks and increase the number of sampling sites.