Simultaneous preparation of N2 and CO2 from water nitrates for δ15N and δ18O analysis on the example of the Zemborzycki Reservoir studies.

Nitrates are bioavailable compounds, which are necessary for every living organisms. However, their excess could be harmful, because it could lead to, i.e., methemoglobinemia, formation of carcinogenic nitrosamines and reservoir eutrophication. Isotopic analysis of δ15N and δ18O in nitrates allows to distinguish their different sources. To simplify the way of nitrate source monitoring, we developed a less complex and cheap "off-line" method for nitrate isotopic analysis, in which we obtain both gases required for isotopic analysis of NO3-, N2 for δ15N and CO2 for δ18O measurements, in one procedure. The developed method is based on simultaneous conversion of AgNO3 (mixed with C and placed into PtIr boat) to N2 and CO2 in a glass vacuum apparatus. A small amount of sample (8 mg of AgNO3) required for this procedure and a good reproducibility of the isotopic analysis (better than 0.3‰ for δ18O and 1‰ for δ15N) make this method a useful tool for environmental research. Using the developed method, we analyzed the isotopic composition of N and O in nitrates in the Zemborzycki Reservoir near Lublin (Poland), in 2015. The results indicate a large variation of δ15N (from -1.4 to +37.7‰) and δ18O (from +5.5 to +25.9‰) values in NO3- ions, while the concentration of NO3- varied from 0.2 to 15.3 mg/dm3. These preliminary results suggest that nitrate fertilizers probably are the main source of NO3- pollution. Our study points out the input of manure and/or sewage to the analyzed reservoir in the subsequent periods of sample collection.

Sulphur and oxygen isotopic composition of sulphates in springs feeding the Wieprz river and other springs of Lublin Upland and Roztocze.

Springs on Roztocze and Lublin Upland have been studied. Isotopic data are compared with data of chemical analyses. The results of studies allow us to distinguish five types of groundwaters. The differentiation is based upon different lithology; opokas, gaizes, sandy-silty-clay deposits, sands with shell sandstones, marly opokas, marly limestones and 'soft limestones of chalk type. A correlation can be observed between delta34S and the concentration of Ca or Mg ions also a correlation between HCO3- ion concentration and delta18O in sulphates. Probably these correlations are the result of some simultaneous processes, which occur in groundwater. The seasonal variations of the isotopic composition and sulphate concentration were observed in four springs feeding the upper Wieprz. The variations were simultaneous and often similar in these springs. Probably, these variations are caused by the admixture of sulphates coming from shallow water layers (or leached from soil); however the variations of the groundwater level may also change chemical and isotopic composition in groundwater.

Isotopic composition of sulfates: similarities - differences - misleadings.

Abstract In the hydrosphere sulfates of the following origin may exist: (1) evaporitic; they come from the leaching of sulfate rocks, (2) biological, formed by sulfur-oxidizing bacteria and (3) anthropogenic, which get into water with wastes, fertilizers or acid rains. Chemical analyses may reveal sulfates in water, but their origin cannot be assessed by means of chemical analysis. The sulfates of various origin may differ in their isotopic compositions. However, sometimes we can observe the similarity of δ(34)S of sulfates whose origin was entirely different. This similarity may be so suggestive that it could be misleading. This paper presents patterns of completely different sulfates whose δ(34)S are similar, though they have nothing in common. Other tables present patterns of sulfates whose origin is similar or even the same but their δ(34)S are characterized by great variety. All of the isotopic data presented in the tables were specially chosen from some of the results of the studies of the sulfates in waters in Poland. Isotopes techniques are becoming more popular and are useful for studies in many fields. These patterns may be a warning against drawing hasty conclusions from the results of δ-measuring.