TM 5-6630-215-12NOTE (Continued)Iron and sulfide will interfere by causing aturbidity with the Nessler reagent.Less commoninterferences such as hydrazine, glycine, variousaliphatic and aromatic amines, organic chlora-mines, acetone,aldehydes, and alcohols may causegreenish or other off colors or turbidity in theprepared sample.(a) Measure 25 ml demineralized water by filling a clean grad-uated cylinder to the 25 ml mark.Pour into a clean sample cell(b) Take a water sample by filling a second graduated cylinderto the 25 ml mark.Pour into another sample cell(c) Add 1.0 ml of Nessler reagent to both sample cells byusing the 1.0 ml calibrated dropper (or 1 ml transfer pipet).Swirlto mix.A yellow color will develop in the water sample if ammonianitrogen is present.Allow at least 10 minutes for the color todevelop but do not wait more than 25 minutes before completing steps(d) and (e).(d) Place the sample cell containing the prepared demineral-ized water solution into the cell holder (as a blank).Insert theNitrogen.Ammonia (Nessler method) meter scale into the meter andadjust the wavelength dial to 425 nm.Adjust the light control for ameter reading of zero mg/l.(e) Replace the cell containing the prepared demineralizedwater with the prepared water sample in the cell holder and read themg/l ammonia nitrogen (N).e. Nitrogen, Nitrate, High range 0-30 mg/l/(figs. 2-11 and 2-12,and para 2-18).(1) Nitrate represents the most completely oxidized state ofnitrogen commonly found in water.Nitrate-forming bacteria convertnitrites into nitrates under aerobic conditions and lightning convertslarge amounts of atmospheric nitrogen (N2) directly to nitrates.Many granular commercial fertilizers contain nitrogen in the form ofnitrates.(a) High levels of nitrate in water indicate biological wastesin the final stages of stabilization or run-off from heavily fertil-ized fields.Nitrate-rich effluents discharged into receiving waterscan degrade water quality by encouraging excessive growth of algae.Drinking waters containing excessive amounts of nitrates can causeinfant methemoglobinemia (blue babies).For this reason, a level of45 mg/l nitrate nitrogen has been established as the maximum allowableconcentration of nitrates in public drinking water supplies.2-46
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