A proposed abiotic reaction scheme for hydroxylamine and monochloramine under chloramination relevant drinking water conditions.

Drinking water monochloramine (NH2Cl) use may promote ammonia-oxidizing bacteria (AOB). AOB use (i) ammonia monooxygenase for biological ammonia (NH3) oxidation to hydroxylamine (NH2OH) and (ii) hydroxylamine oxidoreductase for NH2OH oxidation to nitrite. NH2Cl and NH2OH may react, providing AOB potential benefits and detriments.

Direct gas injection method: a simple modification to an elemental analyzer/isotope ratio mass spectrometer for stable isotope analysis of N and C from N2O and CO2 gases in nanomolar concentrations.

Rationale: Stable isotope analyses of trace amounts of nitrous oxide gas require special instrumentation and laborious sample preparation methods that have hindered many laboratories from measuring this potent greenhouse gas. A simple modification to an Elemental Analyzer (EA) coupled to an Isotope Ratio Mass Spectrometry (IRMS) setup that allows users to measure the N and C isotopic ratios of nitrous oxide (N(2)O) and carbon dioxide (CO(2)) by injecting the gases directly into the EA is described.

Methods: The standard EA was fitted with a gas injection port and a home-made packed column filled with Hayesep Q polymer.