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Isotopomeric analysis of N 2 O dissolved in a river in the Tokyo metropolitan area
Author(s) -
Toyoda Sakae,
Iwai Hiroyuki,
Koba Keisuke,
Yoshida Naohiro
Publication year - 2009
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3945
Subject(s) - isotopomers , troposphere , atmosphere (unit) , estuary , atmospheric sciences , nitrous oxide , chemistry , environmental chemistry , environmental science , ozone , greenhouse gas , hydrology (agriculture) , oceanography , meteorology , geology , geotechnical engineering , organic chemistry , molecule , physics
River water has been suggested as a potential source of nitrous oxide (N 2 O), which is a greenhouse gas that is accumulating rapidly in the troposphere and which is a precursor to stratospheric NO x that depletes ozone. Previous studies on freshwater N 2 O sources have specifically examined estuaries where sedimentary N 2 O production might be important and a few points near anthropogenic nitrogen sources such as agricultural or municipal wastewater areas. Here we present the first observation of a temporal and horizontal distribution of N 2 O and its isotopomers between the midstream and estuary of an urban river. Surface water was supersaturated (100–6800%) with N 2 O at all stations during the study period. The average or maximum saturation value was greater than described in most previous reports. High N 2 O concentrations were observed near sewage plants and the unique signature of isotopomer ratios implied direct N 2 O addition from the plants. The isotopomer ratios also suggested N 2 O production/consumption at the sediment‐water interface. Fluxes and isotopomer ratios of N 2 O, from the river to the atmosphere, estimated from our observations, indicated that the urban river is indeed a source of atmospheric N 2 O and that its production could be distinguished from other natural or anthropogenic sources using isotopomer ratios. Copyright © 2009 John Wiley & Sons, Ltd.