[B-BG02] [JJ] 地球惑星科学と微生物生態学の接点

[BBG02-P01] Nitrogen and oxygen isotope fractionation during anammox in the activated sludge

古田島 翔徳²、*木庭 啓介¹、池田 大輔²、寺田 昭彦²、井坂 和一 ^4,3、矢野 翠¹、眞壁 明子⁶、木村 裕哉⁴、仁科 一哉⁵、楊 宗興² (1.京都大学生態学研究センター、2.東京農工大学、3.東洋大学、4.日立製作所、5.国立環境研究所、6.海洋研究開発機構)

キーワード：アナモックス、窒素同位体比、酸素同位体比

Anammox is an important nitrogen removal pathway in many ecosystems. However, it is still unclear how important the anammox is quantitatively compared with the denitrification. Natural abundance of 15N and 18O of nitrogenous compounds such as ammonium, nitrate and nitrite can provide unique infromation to investigate the relative contribution of anammox to the total nitrogen removal, although the lack of reports on isotopic fractionation factors in the anammox cannot allow us to explore the use of stable isotope signature in the anammox studies.
We incubated the sludge anaerobically to trace the changes in concentrations and isotopic signatures of ammonium, nitrite and nitrate during the anammox process to calculate the isotopic fractionation factors. We found the large isotopic fractionations for ammonium oxidation and nitrite reduction by anammox. In addition, the inverse isotopic fractionation during nitrite oxidation to nitrate was observed. Moreover, the exchange rate of O atom between water and nitrite was higher than previously thought, indicating the importance of this process in regulating the isotope systematics. In the presentation, wapply the isotopic fractionation factors obtained from our incubation experiments to make a simple process model to see if isotopic signatures can detect the anammox in the denitrification-dominated environment.