NanoSIMS investigation of glycine-derived C and N retention with soil organo-mineral associations

• Published in: Biogeochemistry Vol. 125; no. 3; pp. 303 - 313
• Main Authors: Hatton, Pierre-Joseph, Remusat, Laurent, Zeller, Bernd, Brewer, Elizabeth A., Derrien, Delphine
• Format: Journal Article
• Language: English
• Published: Cham Springer 01.09.2015; Springer International Publishing; Springer Nature B.V; Springer Verlag
• Subjects: Amino acids; BIOGEOCHEMISTRY LETTERS; Biogeosciences; Chemical properties; Earth and Environmental Science; Earth Sciences; Ecosystems; Environmental Chemistry; Forest soils; Life Sciences; Mass spectrometry; Microorganisms; Organic matter; Retention; Sciences of the Universe; Soil density; Soil microorganisms; Soil organic matter; Soil surfaces; Soils; Spatial analysis; Spatial distribution; Topsoil; NanoSIMS; Soil; Glycine; Retention; Density; Biotic; biotic; soil; density; nanosims; glycine; retention
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-015-0138-8

While microbial-mineral-organic matter interactions are key features controlling the fates of low molecular-weight compounds in soils, direct investigations of how they control their fine-scale spatial distribution are scant. Here, we addressed how microbial transformations affect the retention of ¹³C/¹⁵N-labeled glycine in a forest topsoil 8 h after application. We assessed the contribution of soil microorganisms to glycine-derived ¹³C and ¹⁵N retention using γ-irradiated and non-irradiated soils. We tracked down the glycine-derived ¹³C and ¹⁵N at the surface of particles randomly isolated from soil density fractions using nano-scale secondary ions mass spectrometry (NanoSIMS) imaging. Eight hours after addition, 7 % of the glycine-derived ¹³C and ¹⁵N initially applied was recovered among soil density fractions, mainly via the activity of soil microorganisms (>85 % of total retention). Glycine-derived ¹³C and ¹⁵N distribution among density fractions was correlated with that of soil organic matter (SOM) determined by NanoSIMS (R ≥ 0.85), suggesting that the spatial patterns of the mineral-attached SOM controls the spatial distribution of the glycine-derived ¹³C and ¹⁵N. NanoSIMS images showed largely decoupled glycine-derived ¹³C and ¹⁵N spots preferentially attached to aggregated particles. We speculate that the glycine-derived ¹³C was principally found within or in the vicinity of microbial cells, whereas the glycine-derived ¹⁵N was mostly found as NH₄⁺ and/or exoenzymes spread across soil surfaces. The C:N ratios determined by NanoSIMS suggest that local chemical properties of mineral-attached SOM drive glycine-derived ¹⁵N attachment, with the preferential attachment to mineral-attached SOM rich in N (C:N ratios mostly <16). Few exceptions were found in presence of Al and Fe (hydr)oxides (>2.65 g cm⁻³).