Nitrogen loss by anaerobic ammonium oxidation in unconfined aquifer soils

• Published in: Scientific reports 2017-01, Vol.7 (1), p.40173-40173, Article 40173
• Main Authors: Wang, Shanyun, Radny, Dirk, Huang, Shuangbing, Zhuang, Linjie, Zhao, Siyan, Berg, Michael, Jetten, Mike S. M., Zhu, Guibing
• Format: Article
• Language: English
• Subjects: 38/22; 38/23; 38/61; 704/172/169/209; 704/47; Ammonia; Ammonia-oxidizing bacteria; Ammonium; Aquifers; Bacteria; Biosphere; Cores; Denitrification; Groundwater; Humanities and Social Sciences; multidisciplinary; Nitrates; Nitrites; Nitrogen; Nitrogen cycle; Nitrogen removal; Nutrient removal; Oxidation; Polymerase chain reaction; rRNA; Science; Science (multidisciplinary); Soil microorganisms; Soil profiles; Soils; Unconfined aquifers; Vadose water
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep40173

Anaerobic ammonium oxidation (anammox) is recognized as an important process for nitrogen cycling, yet little is known about its role in the subsurface biosphere. In this study, we investigated the presence, abundance, and role of anammox bacteria in upland soil cores from Tianjin, China (20 m depth) and Basel, Switzerland (10 m depth), using isotope-tracing techniques, (q)PCR assays, and 16 S rRNA & hzs B gene clone libraries, along with nutrient profiles of soil core samples. Anammox in the phreatic (water-saturated) zone contributed to 37.5–67.6% of the N-loss (up to 0.675 gN m −2 d −1 ), with anammox activities of 0.005–0.74 nmolN g −1 soil h −1 , which were even higher than the denitrification rates. By contrast, no significant anammox was measured in the vadose zone. Higher anammox bacterial cell densities were observed (0.75–1.4 × 10 7 copies g −1 soil) in the phreatic zone, where ammonia-oxidizing bacteria (AOB) maybe the major source of nitrite for anammox bacteria. The anammox bacterial cells in soils of the vadose zone were all