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| Titel |
Exploring new Routes for Identifying Phosphorus Species in Terrestrial and Aquatic Ecosystems with 31P NMR |
| VerfasserIn |
Johan Vestergren, Per Persson, Annelie Sundman, Ulrik Ilstedt, Reiner Giesler, Jurgen Schleucher, Gerhard Gröbner |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097513
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| Publikation (Nr.) |
 EGU/EGU2014-13105.pdf |
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| Zusammenfassung |
| Phosphorus (P) is the primary growth-limiting nutrient in some of the world’s biomes. Rock
phosphate is a non-renewable resource and the major source of agricultural fertilizers.
Predictions of P consumption indicate that rock phosphate mining may peak within 35 years,
with severe impacts on worldwide food production1. Organic P compounds constitute a major
fraction of soil P, but little is known about the dynamics and bioavailability of organic P
species. Our aim is to develop new liquid and solid state 31P-NMR (nuclear magnetic
resonance) techniques to identify P-species in water and soils; information required for
correlating P speciation with plant and soil processes2, and eventually to improve P use. Soil
organic P is frequently extracted using NaOH/EDTA, followed by characterization of the
extract by solution 31P-NMR. However, the obtained NMR spectra usually have poor
resolution due to line broadening caused by the presence of paramagnetic ions. Therefore,
we successfully developed an approach to avoid paramagnetic line broadening by
precipitation of metal sulfides. Sulfide precipitation dramatically reduces NMR
line widths for soil extracts, without affecting P-composition. The resulting highly
improved resolution allowed us to apply for the first time 2D 1H,31P-NMR methods to
identify different P monoesters in spectral regions which are extremely crowded in 1D
NMR spectra.3 By exploiting 2D 1H-31P NMR spectra of soil extracts we were
able to unambiguously identify individual organic P species by combining 31P and
1H chemical shifts and coupling constants. This approach is even suitable for a
structural characterization of unknown P-components and for tracing degradation
pathways between diesters and monoesters3,4.Currently we apply our approach on
boreal4 and tropical soils with focus on Burkina Faso. In addition we also monitor
P-species in aqueos ecosystems. For this purpose stream water from the Krycklan
catchment in northern Sweden5 has been used to develop a new method to retrieve and
characterize P components in water. By utilizing passive sampling with ion-exchange resin
and subsequent analysis with solid state 31P MAS NMR we could identify various
P-species extracted from the aquatic systems. By using this approach we can also
study the dynamics of the absorption process at the resin as a function of P-species
and temperature. This even enabled us to extract the fraction of bound versus free
P as a function of temperature for different model P-components (manuscript in
preparation).
REFERENCES:
Gilbert N. Nature 461 716-718 (2009)
Vincent AG. et al., Biogeochemistry, 10.1007/s10533-011-9612-0 (2011).
Vestergren J et al., Environ. Sci. Technol, 46, 3950-3956, (2012).
Vincent AG et al., Plant Soil, 367, 149-162, (2013).
Laudon H., et al., Water Resour. Res., 49, 7154–7158, (2013). |
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