Nitrogen Isotope Studies Research Articles

A nitrogen-isotope study of the sources of nitrate contamination in groundwater of the pleistocene coastal plain aquifer, Israel

An elevated level of NO 3 (mean value for 1981 was 53 mg l −1 NO 3 as NO 3 − occurs in phreatic groundwater in the Coastal Plain sandy aquifer, Israel. NO 3 − in water with a wide range of concentrations has δ 15N in the range of +4.7 to + 11.4‰ , suggesting derivation from oxidation of soil organic matter and (in specific cases) from animal wastes. Only one sample has δ 15N = −0.3‰ that would indicate derivation through fertilizer application. Water from sewage treatment plant used for irrigation, or for filtration into the aquifer, is highly enriched in 15N ( + 19.2 to +28.8‰), reflecting ammonia volatilization. The isotopic data are consistent with the model presented by Ronen et al. that suggested that the main sources of NO 3 contamination in groundwater in the region are: oxidation of organic matter during cultivation of virgin land and swamp reclamation.

Isotopic measurement of atmospheric nitrogen compounds

A short review of nitrogen isotope studies as related to atmospheric compounds is presented. Methods utilized for the collection and conversion of various nitrogen containing compounds found in the atmosphere to N2 suitable for mass spectrometric measurement are described. Preliminary results obtained on the concentration of and 15 N/ 14 N ratio in N 2 from NH 4 + , NO 3 ? , N 2 O and NO 2 in air and other samples are given and the results with respect to NH 4 + and NO 3 ? in precipitation are discussed briefly. DOI: 10.1111/j.2153-3490.1974.tb01963.x

Isotopic measurement of atmospheric nitrogen compounds

A short review of nitrogen isotope studies as related to atmospheric compounds is presented. Methods utilized for the collection and conversion of various nitrogen containing compounds found in the atmosphere to N2 suitable for mass spectrometric measurement are described. Preliminary results obtained on the concentration of and 15N/14N ratio in N2 from NH4+, NO3-, N2O and NO2 in air and other samples are given and the results with respect to NH4+ and NO3- in precipitation are discussed briefly.DOI: 10.1111/j.2153-3490.1974.tb01963.x

Storage of human platelets in liquid nitrogen isotopic studies.

Concentrated platelet suspensions in 5% DMSO —5% PVP (MW 17,500) in plasma were frozen in sterile, slliconized glass vials at a rate of 1‐3C per minute to — 40C They were then immersed in liquid nitrogen and stored for a period of six to 12 months. After rapid thawing, platelets were labeled with 51Cr and injected into hematologically normal and ABO‐ and RH‐ compatible subjects.The radioactive recovery of frozen platelets, two hours after injection, was 11 per cent (3.9‐22). The recovery of fresh platelets labelled under the same conditions was 36 per cent (30‐50%). The platelet survival time was found to be four to six days for frozen platelets and six to nine days for fresh platelets.These results suggest that platelets frozen and stored in liquid nitrogen have a definite but reduced therapeutic efficiency. The method looks valuable for some blood banks.

An improved procedure for the measurement of 15N content by mass spectrometry

The stable isotope 15N represents the only one available for nitrogen isotopic studies. Therefore, analysis by mass spectrometry is an obligatory step in measuring 15N content. Rittenberg et al. (1–3) have described the necessary apparatuses and have given details for suitable preparation of samples. According to Rittenberg, gaseous nitrogen to be analysed at the mass spectrometry is obtained by oxidation of NH 4 + with alkaline hypobromite. Several authors (4–6) have suggested modifications or improvements at different steps of the entire procedure. Having had ecperience in mass spectrometer analysis for some years we have found of advantage to introduce a few more modifications. These are mainly concerned with (i) the use of modified Rittenberg tubes, (ii) the procedure for getting rid of interfering gases from the samples, (iii) method of evaluation of air correction. These modifications are to be described in the present paper.