Precipitation chemistry over the Indian region

The present study is based on the precipitation chemistry data from the Background Air Pollution Monitoring Network (BAPMoN) in the Indian region, for the period 1976-87. Sampling is made on an event basis and the pH and electrical conductivity of the samples are determined from filtered samples immediately after cessation of rain. The chemical analysis is performed on monthly mixed samples. No trend is found in the pH of rainwater from background areas except at Allahabad, Pune and Visakhapatnam which suffer from sizable anthropogenic influences. The pH seems to be related more to NO3 ions compared to SO4-2 ions. A natural buffer appearing in the form of alkaline soil-derived species seems adequateat most places (except Mohanbari), in keeping a check on progressive acidification despite steady increase in concentration of nitrates. The ion balance cannot be achieved without including the presence of HCO3, which when done explains the observed electrical conductivity of rainwater. The interaction of marine aerosols with acid aerosols has also been studied for the marine regions in the Indian areas and reveals a substantial removal of chloride from sea-salt. Inland sources of NaCl have also been identified from the BAPMoN data.

Role of aerosols in deciding pH of rainwater

Nature of precipitation – alkaline or acidic – depends upon the concentration of major water soluble inorganic gaseous and soil derived particulates dissolved in it. If concentration of cations is higher than that of anions, the precipitation becomes alkaline and vise-a-versa. pH is the main parameter indicating the nature of precipitation. If pH of the solution is < 5.65, it is acidic and > 5.65, alkaline, in the pH scale ranging between 0 & 14. Difference in the chemical composition of rainwater having pH in the alkaline range and acidic range has been studied in this paper. For this purpose, precipitation chemistry data of Allahabad, Jodhpur, Mohanbari and Nagpur for the period 1988-97 have been considered. APWM & S.D. have been worked out. Precipitation chemistry data considering APWM values in acidic range and in alkaline range have been separated and compared. Coefficients of correlation have been calculated in possible cation-anion combinations. It is seen that the lowest pH values (monthly mean) have been recorded during 1997 – MHB (3.77), NGP (4.12), both in acidic range. % Frequency of occurrences of pH values in acidic range was the highest at Mohanbari (66%) in the study period. Jodhpur recorded all pH values in alkaline range indicating influence of soil derived alkaline particulates. Among cations Ca+² has shown its dominance over all cations. Jodhpur has recorded the highest APWM value of Ca+² (9.27mg/lit) in 1997. Data have also been compared with WMO Laboratory simulated acid rain sample analysis data and other non-departmental data. Results are discussed in the paper.

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

&lt;p&gt;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.&amp;#160;&lt;br&gt;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.&amp;#160;&lt;br&gt;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.&lt;br&gt;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.&amp;#160;&lt;br&gt;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.&amp;#160;&lt;br&gt;Using the &amp;#8220;point&amp;#8221; 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.&lt;/p&gt;&lt;p&gt;This study was carried out in the framework of the Research Projects &amp;#1040;&amp;#1040;&amp;#1040;&amp;#1040;-&amp;#1040;20-120013190049-4 &amp;#171;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)&amp;#187; and &amp;#1040;&amp;#1040;&amp;#1040;&amp;#1040;-&amp;#1040;20-120020490070-3 &amp;#171;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&amp;#187;&lt;/p&gt;&lt;p&gt;Reference list:&lt;br&gt;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.&lt;br&gt;2. The Acid Deposition Monitoring Network in East Asia (EANET)- URL: https://www.eanet.asia/&lt;/p&gt;

Hydrochemical and Isotopic Applications in the Western Aosta Valley (Italy) for Sustainable Groundwater Management

This research gives an overview of the status of water resources in the western Aosta Valley (Italy). Surface water, groundwater and precipitation were sampled during five sampling campaigns, and chemical analyses were performed and interpreted. Stable isotopes (δ18O and δ2H) were evaluated. This study highlights the relationships between water quality and quantity and local conditions (i.e., aquifer lithology, mixing into the aquifer, proximity to towns, contribution of snowmelt and ice melt to groundwater recharge, amount of rain, and season and altitude of the sampling location). A relationship between dust dispersed in the atmosphere as aerosols from the nearby Piedmont Region and the precipitation chemistry was identified, highlighting the presence of interregional conditions. Furthermore, isotopic analyses allowed the identification of aquifer feeding by both rainwater and glacial meltwater. Additionally, two origins for rainfall were identified: the Mediterranean Sea in winter and the Atlantic Ocean in summer. Finally, a local meteoric water line was calibrated for the study area. This research highlights the importance of implementing both traditional and isotopic techniques for water analysis to achieve optimal and sustainable management of water resources.