DOI: 10.1007/s10533-018-0429-y
Scopus记录号: 2-s2.0-85042116906
论文题名: Amino acid δ15N indicates lack of N isotope fractionation during soil organic nitrogen decomposition
作者: Philben M. ; Billings S.A. ; Edwards K.A. ; Podrebarac F.A. ; van Biesen G. ; Ziegler S.E.
刊名: Biogeochemistry
ISSN: 0168-2563
EISSN: 1573-515X
出版年: 2018
卷: 138, 期: 1 起始页码: 69
结束页码: 83
语种: 英语
英文关键词: Amino acid stable isotopes
; Ammonification
; Nitrogen isotope fractionation
; Soil organic nitrogen
; δ15N
Scopus关键词: amino acid
; ammonification
; decomposition
; isotopic fractionation
; metabolite
; microbial activity
; nitrogen isotope
; organic nitrogen
; Podzol
; soil nitrogen
; stable isotope
英文摘要: The interpretation of natural abundance δ15N in soil profiles and across ecosystems is confounded by a lack of understanding of possible N isotope fractionation associated with soil organic nitrogen (SON) decomposition. We analyzed the δ15N of hydrolysable amino acids to test the extent of fractionation associated with the depolymerization of peptides to amino acids and the mineralization of amino acids to NH4 + (ammonification). Most amino acids are both synthesized and degraded by microbes, complicating interpretation of their δ15N. However, the “source” amino acids phenylalanine and hydroxyproline are degraded and recycled but not resynthesized. We therefore used their δ15N to isolate the effects of N isotope fractionation during SON depolymerization and ammonification. We used complementary field and laboratory approaches to evaluate the change in amino acid δ15N during decomposition. First, we measured amino acid δ15N changes with depth in the organic horizons of podzolic soils collected from the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect (NL-BELT), Canada. The δ15N of most amino acids increased with depth by 3 similar to the increase in bulk δ15N. However, the δ15N of the “source” amino acids did not change with depth, indicating lack of N isotope fractionation during their depolymerization and ammonification. Second, we assessed the change in amino acid δ15N following 400 days of laboratory incubation. This approach isolated the effect of decomposition on δ15N by eliminating plant N uptake and reducing leaching of N from the soil. Amino acid δ15N did not change during incubation despite extensive turnover of the amino acid pool, supporting our conclusion of a lack of N isotope fractionation during SON decomposition. Our results indicate the often-observed trend of increasing δ15N with soil depth likely results from the mycorrhizally-mediated transfer of 14N from depth to the surface and accumulation of 15N-enriched necromass of diverse soil microbes at depth, rather than as a direct result of SON decomposition. © 2018, Springer International Publishing AG, part of Springer Nature. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/83175
Appears in Collections: 气候减缓与适应 气候变化事实与影响
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作者单位: Department of Earth Sciences, Memorial University, St. John’s, NL, Canada; Department of Ecology and Evolutionary Biology, Kansas Biological Survey, University of Kansas, Lawrence, KS, United States; Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre, Corner Brook, NL, Canada; CREAIT - Stable Isotope Laboratory, Memorial University, St. John’s, NL, Canada; Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States; United State Department of Agriculture, Natural Resources Conservation Service, Columbus, IN, United States
Recommended Citation:
Philben M.,Billings S.A.,Edwards K.A.,et al. Amino acid δ15N indicates lack of N isotope fractionation during soil organic nitrogen decomposition[J]. Biogeochemistry,2018-01-01,138(1)