Russow Rolf, Tauchnitz Nadine, Spott Oliver, Mothes Sibylle, Bernsdorf Sabine, Meissner Ralph
a Department of Soil Physics , Helmholtz Centre for Environmental Research - UFZ , Halle (Saale) , Germany.
Isotopes Environ Health Stud. 2013;49(4):438-53. doi: 10.1080/10256016.2013.831089.
Under natural conditions, peatlands are generally nitrate-limited. However, recent concerns about an additional N input into peatlands by atmospheric N deposition have highlighted the risk of an increased denitrification activity and hence the likelihood of a rise of emissions of the greenhouse gas nitrous oxide. Therefore, the aim of the present study was to investigate the turnover of added nitrate in a drained and a rewetted peatland using a [(15)N]nitrate-bromide double-tracer method. The double-tracer method allows a separation between physical effects (dilution, dispersion and dislocation) and microbial and chemical nitrate transformation by comparing with the conservative Br(-) tracer. In the drained peat site, low NO3(-) consumption rates have been observed. In contrast, NO3(-) consumption at the rewetted peat site rises rapidly to about 100% within 4 days after tracer application. Concomitantly, the (15)N abundances of nitrite and ammonium in soil water increased and lead to the conclusion that, besides commonly known NO3(-) reduction to nitrite (i.e. denitrification), a dissimilatory nitrate reduction to ammonium has simultaneously taken place. The present study reveals that increasing NO3(-) inputs into rewetted peatlands via atmospheric deposition results in a rapid NO3(-) consumption, which could lead to an increase in N2O emissions into the atmosphere.
在自然条件下，泥炭地通常受硝酸盐限制。然而，近期对大气氮沉降向泥炭地额外输入氮的担忧，凸显了反硝化活性增加的风险，进而增加了温室气体氧化亚氮排放上升的可能性。因此，本研究的目的是使用[¹⁵N]硝酸盐-溴双示踪剂方法，研究排水泥炭地和重新湿润泥炭地中添加硝酸盐的周转情况。双示踪剂方法通过与保守的Br⁻示踪剂比较，能够区分物理效应（稀释、扩散和位移）以及微生物和化学硝酸盐转化。在排水泥炭地，观察到较低的NO₃⁻消耗率。相比之下，重新湿润泥炭地在施加示踪剂后4天内，NO₃⁻消耗迅速上升至约100%。与此同时，土壤水中亚硝酸盐和铵的¹⁵N丰度增加，得出的结论是，除了常见的NO₃⁻还原为亚硝酸盐（即反硝化作用）外，还同时发生了异化硝酸盐还原为铵的过程。本研究表明，通过大气沉降向重新湿润泥炭地增加NO₃⁻输入会导致NO₃⁻快速消耗，这可能导致大气中N₂O排放增加。
