title: Rainwater, soil water, and soil nitrate effects on oxygen isotope ratios of nitrous oxide produced in a green tea (Camellia sinensis) field in Japan.
abstract: BACKGROUND
  The oxygen exchange fraction between soil H(2)O and N(2)O precursors differs in soils depending on the responsible N(2)O-producing process: nitrification or denitrification. This study investigated the O-exchange between soil H(2)O and N(2)O precursors in a green tea field with high N(2)O emissions.
  
  
  METHODS
  The rainwater δ(18)O value was measured using cavity ring-down spectrometry (CRDS) and compared with that of soil water collected under the tea plant canopy and between tea plant rows. The intramolecular (15)N site preference in (β) N(α) NO (SP = δ(15)N(α) - δ(15)N(β)) was determined after measuring the δ(15)N(α) and δ(15)N(bulk) values using gas chromatography/isotope ratio mass spectrometry (GC/IRMS), and the δ(18) O values of N(2)O and NO(3)(-) were also measured using GC/IRMS.
  
  
  RESULTS
  The range of δ(18)O values of rainwater (-11.15‰ to -4.91‰) was wider than that of soil water (-7.94‰ to -5.64‰). The δ(18)O value of soil water at 50 cm depth was not immediately affected by rainwater. At 10 cm and 20 cm depths of soil between tea plant rows, linear regression analyses of δ(18)O-N(2)O (relative to δ(18)O-NO(3)(-)) versus δ(18) O-H(2)O (relative to δ(18)O-NO(3)(-)) yielded slopes of 0.76-0.80 and intercepts of 31-35‰.
  
  
  CONCLUSIONS
  In soil between tea plant rows, the fraction of O-exchange between H(2)O and N(2)O precursors was approximately 80%. Assuming that denitrification dominated N(2)O production, the net (18)O-isotope effect for denitrification (NO(3)(-) reduction to N(2)O) was approximately 31-35‰, reflecting the upland condition of the tea field.
authors.affiliation: Dept. of Environmental Science and Technology, Tokyo Institute of Technology G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zou
authors.affiliation: NARO Institute of Vegetable and Tea Science, 2769, Kanaya-Shishidoi, Shimada, Shizuoka, 428-8501, Japan.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Hirono
authors.affiliation: NARO Institute of Vegetable and Tea Science, 3-1-1 Kannondai, Tsukuba, Ibaraki, 305-8666, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Yanai
authors.affiliation: Dept. of Environmental Chemistry and Engineering, Tokyo Institute of Technology G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Hattori
authors.affiliation: Dept. of Environmental Science and Technology, Tokyo Institute of Technology G1-26, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Toyoda
authors.affiliation: Dept. of Environmental Chemistry and Engineering, Tokyo Institute of Technology G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan.|Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D000383:Agriculture; D028241:Camellia sinensis / Q000737:chemistry* / Q000378:metabolism; D058440:Denitrification; D007564:Japan; D013058:Mass Spectrometry; D009566:Nitrates / Q000737:chemistry*; D058465:Nitrification; D010103:Oxygen Isotopes / Q000032:analysis*; D011891:Rain / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D009566:Nitrates; D010103:Oxygen Isotopes; D012987:Soil; D014867:Water