Flyer Exzess N2 Brochure

Denitrification in Groundwater Determination of Excess-N2 Using the N2/Ar Method Contact GBA Laboratory Group GBA Gesellschaft fuer Bioanalytik mbH Daimlerring 37 31135 Hildesheim Germany Tel.: +49 (0)5121 / 750 96-50 eMail: hildesheim@gba-laborgruppe.de www.gba-laborgruppe.de Denitrification in Groundwater High levels of nitrate are a common problem in groundwater. In heavily fertilized agricultural areas, denitrification processes could hinder the detection of initial nitrate loads. Through denitrification, the ni-trate (NO3) is reduced to molecular nitrogen (N2) un-der anaerobic conditions via the intermediate steps, nitrite (NO2), nitric oxide (NO), and nitrous oxide (N2O). Thus, the molecular nitrogen accumulates in groundwater. Furthermore, all of the gaseous inter-mediate steps are considered to have an effect on the climate. Quantification of Nitrate Loads It is only possible to quantify initial nitrate loads in groundwater to a certain extent by determining the nitrate concentration. Therefore, low concentrations of nitrate do not necessarily indicate that there is no nitrate contamination, but instead could also be caused by a high degree of decomposition through denitrification processes. Using the N2/Ar method to determine excess nitrogen, conclusions can be drawn about the original amount of nitrate. Thus, even groundwater wells that contain little or no oxygen and nitrate can still be utilized to assess initial nitrate loads. N2/Ar Method Aside from nitrogen (N2), other gasses such as argon (Ar), oxygen (O2), and carbon dioxide (CO2) are soluble in groundwater in specific concentrations depending on the temperature among others. Whereas the con-centration of O2, CO2, and N2 can be altered by bio-chemical reactions such as microbial decomposition processes, the concentration of the noble gas argon remains constant. Thus, if the nitrate dissolved in groundwater is transformed into N2 through de-nitrification processes, the ratio of nitrogen to argon is also changed. The difference between the nitrogen concentration that is actually measured and the calculative solubility of nitrogen in water at a defined temperature and a defined air pressure determines the excess nitrogen content, which in that case must be a result of denitrification processes. Using the N2/Ar method enables you to identify areas with high nitrate loads by monitoring the groundwater in reductive aquifers. Furthermore, this method al-lows you to deduce the amount of sulfates that origi-nate from denitrification (oxidation of FeS2). Measurement Process The concentrations of the gasses nitrogen and argon in the water sample are determined using membrane-introduction mass spectrometry (MIMS). With special calculations, we ascertain the excess N2 content from the concentration of argon and nitrogen. Sampling Sampling can be carried out by one of GBA’s experi-enced and qualified experts. In addition to tempera-ture, conductivity, and pH value, we record oxygen content and redox potential during the pumping pro-cess with an electric submersible pump. The ground-water is pumped until these parameters stay constant. In the process, there should be an exchange of at least three times of the volume of the well. A portion of the groundwater is filled into special 100 mL containers through a bypass of the main current at a limited flow rate. However, one must ensure that the sample is filled slowly and without any swirling, so that the ex-change of gasses between the atmosphere and the water sample remains as low as possible. The volume of the bottles should be exchanged approximately two or three times. The bottles (two per measurement point) are sealed airtight without bubbling and subse-quently with an aluminum crimp cap. The samples are refrigerated at 4°C until analysis. Results In your report, you receive the measured concentra-tions of nitrogen and argon and the calculated excess N2 content. Upon request, as part of our comprehensive analytical services we will gladly provide you with the relevant contacts in order to obtain an expert appraisal of the results based on the specific hydrogeological condi-tions at the point of sampling. Reporting of Results The results are generally reported in electronic form as a PDF file. Other standard file formats are also possi-ble. If you have any special requirements for reporting your results, please, feel free to let us know. Quality The GBA Laboratory Group is a nationwide operating service laboratory. In addition to comprehensive ac-creditations according to DIN EN ISO/IEC 17025:2005, GBA is also authorized according to §3 Sec. 1 Line 3 ZWVO, §85b Sec. 2 Line 2 LWG, §125 NWG, and §44 NAbfG. If you have further questions about the GBA Labora-tory Group’s extensive analysis portfolio or authoriza-tions, please, feel free to contact us The GBA Analysis Spectrum In addition to these very special analysis methods, we offer a wide range of both routine analyses and special tests. This includes priority substances according to the European Water Framework Directive (EU-WFD), as well as pesticides and their metabolites, pharma-ceuticals and their metabolites, perfluorinated tensides (PFTs), brominated flame retardants, poly-chlorinated dibenzodioxins/dibenzofurans (PCDD/DF), and many more. In addition to groundwater, drinking water, surface water, and waste water, we also ana-lyze soil, waste, air, sludge, and many other matrices as well. Questions Do you have any further questions? Please, feel free to contact us at the location most convenient to you. Using their long-term experience, our competent con-sultants will gladly assist you POSITIVELY TRANSPARENT GBA Gesellschaft fuer Bioanalytik mbH Headquarters: GBA Gesellschaft für Bioanalytik mbH Goldtschmidtstraße 5 21073 Hamburg, Germany Tel.: +49 (0)40 / 79 71 72-0 service@gba-laborgruppe.de Pinneberg: GBA Gesellschaft für Bioanalytik mbH Mr. Peter Ludwig (PhD) Flensburger Straße 15 25421 Pinneberg, Germany Tel.: +49 (0)4101 / 79 46-0 pinneberg@gba-laborgruppe.de Gelsenkirchen: GBA Gesellschaft für Bioanalytik mbH Mr. Philipp Bueschler (PhD) Wiedehopfstraße 30 45892 Gelsenkirchen, Germany Tel.: +49 (0)209 / 97 61 9-0 gelsenkirchen@gba-laborgruppe.de Hildesheim: GBA Gesellschaft für Bioanalytik mbH Mr. Oliver Christel Daimlerring 37 31135 Hildesheim, Germany Tel.: +49 (0)5121 / 750 96-50 hildesheim@gba-laborgruppe.de Freiberg: GBA Gesellschaft für Bioanalytik mbH Mrs. Peggy Jedlicka Meißner Ring 3 09599 Freiberg, Germany Tel.: +49 (0)3731 / 16 30 83-0 freiberg@gba-laborgruppe.de