Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol

Jiang, Xiaoqian; Vereecken, Harry; Willbold, Sabine; Bauke, Sara L.; Cade-Menun, Barbara J.; Bol, Roland; Nischwitz, Volker; Amelung, Wulf; Klumpp, Erwin

Dataset

FZJ-2017-01950

Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol

Jiang, X.FZJ* ; Klumpp, E. (Corresponding author)FZJ* ; Cade-Menun, B. J. ; Bol, R.FZJ* ; Nischwitz, V.FZJ* ; Willbold, S.FZJ* ; Vereecken, H.FZJ* ; Bauke, S. L. ; Amelung, W.FZJ*

2017

Please use a persistent id in citations: http://hdl.handle.net/2128/13895

Abstract: Phosphorus (P) species in colloidal and “dissolved” soil fractions may have different distributions. To understand which P species are potentially involved, we obtained water extracts from the surface soils of a gradient 5 from Cambisol, Stagnic Cambisol to Stagnosol from temperate grassland in Germany. These were filtered to <450 nm, and divided into three procedurally defined fractions: small-sized colloids (20–450 nm), nano-sized colloids (1–20 nm), and “dissolved P” (<1 nm), using asymmetric flow 10 field-flow fractionation (AF4), as well as filtration for solution 31P-nuclear magnetic resonance (NMR) spectroscopy. The total P of soil water extracts increased in the order Cambisol<Stagnic Cambisol<Stagnosol due to increasing contributions from the dissolved P fraction. Associations of C–Fe/Al–PO3􀀀 15 4 /pyrophosphate were absent in nanosized (1–20 nm) colloids from the Cambisol but not in the Stagnosol. The 31P-NMR results indicated that this was accompanied by elevated portions of organic P in the order Cambisol>Stagnic Cambisol>Stagnosol. Across all 20 soil types, elevated proportions of inositol hexakisphosphate (IHP) species (e.g., myo-, scyllo- and D-chiro-IHP) were associated with soil mineral particles (i.e., bulk soil and small-sized soil colloids), whereas other orthophosphate monoesters and phosphonates were found in the “dissolved” 25 P fraction. We conclude that P species composition varies among colloidal and “dissolved” soil fractions after characterization using advanced techniques, i.e., AF4 and NMR. Furthermore, stagnic properties affect P speciation and availability by potentially releasing dissolved inorganic and esterbound P forms as well as nano-sized organic matter–Fe/Al–P 30 colloids.

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