Rates of atmospheric nitrogen deposition to agricultural and natural lands within the Lower Dniester catchment

Purpose of the work was to quantify and compare the rates of atmospheric bulk nitrogen (N) deposition to the natural wetland and two managed areas within the Lower Dniester catchment in 2011-2019. Methodology. To collect atmospheric bulk (dry and wet) deposition we used custom-made accumulative samplers. We determined dissolved inorganic N (DIN) compounds in samples with ion chromatography and water soluble and total N (TN) with routine wet chemistry. Results and Conclusions. Croplands in the Lower Dniester basin have been recognized as a highly N polluted areas being both local sink and potential source of TN acting as a local threat for nearby natural and semi-natural ecosystems. Mean annual TN depositions have been quantified to be 20.1±0.3, 14.1±0.1 and 10.0±0.3 kgN/ha for cropland, garden and natural wetland sites respectively. We have found significant increase of NH4 + and decreased of NO3 - in DIN deposition with overall decrease and stabilization of DIN in 2018-2019. Substantial contribution of ‘previously unaccounted’ TON (66-72%) to TN was assumed to be region-specific. Besides, ca. 52-68% of water soluble TN had an organic origin and could be considered as additional easy available N source for both terrestrial and aquatic ecosystems within the study region.