An assessment of the total wet ammonium deposition in the East Siberia of Russia based on monitoring data

<p>Goal of Study: The study focuses on the application of developed spatial interpolation method [1] to assessment of atmospheric pollutant deposition fluxes. This case study was done for estimating the total ammonium wet deposition in the Eastern Siberia region of Russia. <br>Data: Measurement data for 2017 on the ammonium concentration in atmospheric precipitation were obtained from the stations within the Baikal natural preserved territory thanks to the international EANET network [2] and the Russian national network of precipitation chemistry (PCnet) operated by Roshydromet. <br>Method: On the first step of the algorithm, we prepare the point data on the concentration of from the measurements of PCnet stations in the region. On the second step, we interpolate the precipitation chemistry data to the meteorological stations located in the study region followed by calculation of deposition fluxes at all these sites. The values obtained are interpolated for the regular grid of 100-km by 100-km cells within region. Finally, the total pollutant wet deposition for whole region is a sum of deposition fluxes calculated for each cell.<br>Results: We calculated the weighted-average annual concentration (WAC) of ammonium in atmospheric precipitation at 7 stations of EANET and PCnet in the region. We interpolated the WAC data on the grid cells in the Lake Baikal preserved territory (BPT). The variation of ammonium WAC throughout the BPT is 0.9 mg/l (south of the region) to 0.1 mg/l (northwestern part) with average value of 0.34 mg/l for the whole region. <br>Based on the WAC data and the obtained precipitation amounts at 23 meteorological stations within BPT, we calculated the deposition fluxes for network of more spatial density combined of PC and meteorological stations. <br>Using the “point” calculation results, we have constructed a two-dimensional spatial interpolation of wet ammonium fluxes per each cell. According to the study results, the total amount of ammonium felt with precipitation out from the atmosphere in the territory around Lake Baikal is 42 thou. ton per year. The value of average deposition per cell of 100x100 km for BPT region is 666 ton while in the surround of the EANET station Listvyanka (west Baikal shore) is 828 ton. The spatial distribution of wet annual ammonium deposition is presented at the map of the region.</p><p>This study was carried out in the framework of the Research Projects АААА-А20-120013190049-4 «Development of methods and technologies for monitoring of environmental pollution under the influence of transboundary pollutants transport (UNECE: EMEP, ICP IM) and acid deposition in East Asia (EANET)» and АААА-А20-120020490070-3 «Development and improvement of methods and technologies for integrated background monitoring and comprehensive assessment of the environmental state and pollution in the Russian Federation including their dynamics»</p><p>Reference list:<br>1. Gromov S. A., Galushin D. A., Zhadanovskaya E. A. 2020. Estimation of the total wet sulfur and nitrogen deposition as a part of pollution balance in the south of the Russian Far East based on the monitoring data. - Geophysical Research Abstracts, EGU2020-13871, EGU General Assembly.<br>2. The Acid Deposition Monitoring Network in East Asia (EANET)- URL: https://www.eanet.asia/</p>

Changing nitrogen deposition with low δ15N−NH4 + and δ15N−NO3 − values at the Experimental Lakes Area, northwestern Ontario, Canada

Ammonium deposition at the International Institute for Sustainable Development Experimental Lakes Area (IISD–ELA), in northwestern Ontario, Canada, has doubled in the last 45 years and thus is no longer among the low nitrogen (N) deposition sites in North America. This may be related to the concurrent intensification of Manitoba agriculture to the west and upwind of the ELA. Large increases in ammonium deposition at the ELA were important in driving the observed trend and increased the NH4 + to NO3 − ratio of input to aquatic and terrestrial systems. Stable isotope analyses of two years of bulk (wet and dry) atmospheric deposition revealed very large ranges in δ15N−NH4 + (22‰ range), δ15N−NO3 − (18‰), and δ18O–NO3 − (19‰). Few other δ15N−NH4 +, δ15N−NO3 −, and δ18O–NO3 − values have been published for Canadian precipitation. Increases in δ15N of NH4 + and NO3 − in July occurred with increases in total N deposition. The wide range and seasonal trends of δ15N and δ18O values in ELA precipitation mean that studies characterizing N inputs to watersheds and lakes require an ongoing and comprehensive annual sampling regime. Global trends of declining δ15N of N deposition evident in lake sediment records may be a result of increases in NH4 + deposition with lower δ15N−NH4 + values. Similarly, the relationship in Lake Superior between increasing NO3 − and lower δ15N−NO3 − values may be explained by increased atmospheric deposition of N with low δ15N values.