Harold J. Hughes

Controlling the mass bias introduced by anionic and organic matrices in silicon isotopic measurements by MC-ICP-MS

One of the most widely used sample preparation methods for Si isotopic analyses (δ30Si and δ29Si) is based on cationic chromatography, which does not remove anions from samples. Although it was first thought that the presence of anions in natural concentrations does not distort the isotopic analyses, it has recently been shown that the presence of sulfate can induce a significant shift in isotopic ratio measurements above SO42−/Si ratios (wt) of 0.02. Here, we show that dissolved organic matter can also induce a major Si isotopic bias when analysing river waters. To overcome these non-spectral matrix effects we propose fast and reliable ways, tested on natural freshwater and rock digestion solutions. The sulfate matrix effect is solved by adding to both sample and bracketing standard sulfuric acid in large excess compared to the naturally occurring SO42−. The organic matrix is mineralized by the combined action of UV-C and ozone. We also provide the first δ30Si signature measurements of two common geostandards: SGR-1 (δ30Si = +0.03‰) and FeR-1 (δ30Si = −0.20‰).

Landscape cultivation alters d30Si signature in terrestrial ecosystems

Despite increasing recognition of the relevance of biological cycling for Si cycling in ecosystems and for Si export from soils to fluvial systems, effects of human cultivation on the Si cycle are still relatively understudied. Here we examined stable Si isotope (δ30Si) signatures in soil water samples across a temperate land use gradient. We show that – independent of geological and climatological variation – there is a depletion in light isotopes in soil water of intensive croplands and managed grasslands relative to native forests. Furthermore, our data suggest a divergence in δ30Si signatures along the land use change gradient, highlighting the imprint of vegetation cover, human cultivation and intensity of disturbance on δ30Si patterns, on top of more conventionally acknowledged drivers (i.e. mineralogy and climate).

Landscape cultivation alters delta Si-30 signature in terrestrial ecosystems

Despite increasing recognition of the relevance of biological cycling for Si cycling in ecosystems and for Si export from soils to fluvial systems, effects of human cultivation on the Si cycle are still relatively understudied. Here we examined stable Si isotope (δ30Si) signatures in soil water samples across a temperate land use gradient. We show that – independent of geological and climatological variation – there is a depletion in light isotopes in soil water of intensive croplands and managed grasslands relative to native forests. Furthermore, our data suggest a divergence in δ30Si signatures along the land use change gradient, highlighting the imprint of vegetation cover, human cultivation and intensity of disturbance on δ30Si patterns, on top of more conventionally acknowledged drivers (i.e. mineralogy and climate).

Erratum: CORRIGENDUM: Landscape cultivation alters δ30Si signature in terrestrial ecosystems

Scientific Reports 5, Article number: 7732 10.1038/srep07732 (2015); Published: January132015; Updated: March152015 Jean-Thomas Cornelis was included in the Acknowledgements but omitted from the author list in the original version of this Article. This has been corrected in the PDF and HTML versions of the Article and in the Supplementary Information. Acknowledgements “F.I.V. thanks Special Research Funding of the University of Antwerp (BOF-UA) for PhD fellowship funding and Patrick Frings, Ryan Taylor and Jean-Thomas Cornelis for proof-reading and editing the manuscript. We also acknowledge Flemish Science Foundation (FWO) for funding the project “Tracking the biological control on Si mobilisation in upland ecosystems” (project number G014609N).” Now reads “F.I.V. thanks Special Research Funding of the University of Antwerp (BOF-UA) for PhD fellowship funding and Patrick Frings and Ryan Taylor for editing the manuscript as native speakers. We also acknowledge Flemish Science Foundation (FWO) for funding the project “Tracking the biological control on Si mobilisation in upland ecosystems” (project number G014609N) and BELSPO for funding the project SOGLO.” Author contributions “F.I.V. collected the samples and wrote the first drafts. C.D. and H.H. optimised and developed the isotopic analytical method, analysed the samples, made the data processing, and co-developed the discussion. F.I.V., W.C., E.S., G.G. and B.R. were involved in site selection and/or installation of the land use gradient. B.R. and A.L.B. provided background data on clay analysis and Si fractions in the soil. P.M., E.S., L.A. and G.G. initialised and conceptualised the work on Si biogeochemistry in joint collaborations. All authors contributed to the writing and methodological development of the paper.” Now reads “F.I.V. collected the samples and wrote the first drafts. C.D. and H.H. optimised and developed the isotopic analytical method, analysed the samples, made the data processing, and C.D., H.H. and J-T C. co-developed the discussion. F.I.V., W.C., E.S., G.G. and B.R. were involved in site selection and/or installation of the land use gradient. B.R. and A.L.B. provided background data on clay analysis and Si fractions in the soil. P.M., E.S., L.A. and G.G. initialised and conceptualised the work on Si biogeochemistry in joint collaborations. All authors contributed to the writing and methodological development of the paper.” The original Article contained an error in the calculation of the weathering index Total Reserve in Bases (TRB) in figure 2b. The correct figure 2 appears below as Figure 1. Figure 1 (a) Scatterplot of biogenic silica (BSi) in mg g−1 dry soil in the soil profile, (b) Total Reserve in Bases (TRB = [Na] + [Mg] + [Ca] + [K]) weathering index calculated on dry soil, in cmol charge kg−1. Sites are represented by symbols: ...

CORRIGENDUM: Landscape cultivation alters δ30Si signature in terrestrial ecosystems

Scientific Reports 5, Article number: 7732 10.1038/srep07732 (2015); Published: January132015; Updated: March152015 Jean-Thomas Cornelis was included in the Acknowledgements but omitted from the author list in the original version of this Article. This has been corrected in the PDF and HTML versions of the Article and in the Supplementary Information. Acknowledgements “F.I.V. thanks Special Research Funding of the University of Antwerp (BOF-UA) for PhD fellowship funding and Patrick Frings, Ryan Taylor and Jean-Thomas Cornelis for proof-reading and editing the manuscript. We also acknowledge Flemish Science Foundation (FWO) for funding the project “Tracking the biological control on Si mobilisation in upland ecosystems” (project number G014609N).” Now reads “F.I.V. thanks Special Research Funding of the University of Antwerp (BOF-UA) for PhD fellowship funding and Patrick Frings and Ryan Taylor for editing the manuscript as native speakers. We also acknowledge Flemish Science Foundation (FWO) for funding the project “Tracking the biological control on Si mobilisation in upland ecosystems” (project number G014609N) and BELSPO for funding the project SOGLO.” Author contributions “F.I.V. collected the samples and wrote the first drafts. C.D. and H.H. optimised and developed the isotopic analytical method, analysed the samples, made the data processing, and co-developed the discussion. F.I.V., W.C., E.S., G.G. and B.R. were involved in site selection and/or installation of the land use gradient. B.R. and A.L.B. provided background data on clay analysis and Si fractions in the soil. P.M., E.S., L.A. and G.G. initialised and conceptualised the work on Si biogeochemistry in joint collaborations. All authors contributed to the writing and methodological development of the paper.” Now reads “F.I.V. collected the samples and wrote the first drafts. C.D. and H.H. optimised and developed the isotopic analytical method, analysed the samples, made the data processing, and C.D., H.H. and J-T C. co-developed the discussion. F.I.V., W.C., E.S., G.G. and B.R. were involved in site selection and/or installation of the land use gradient. B.R. and A.L.B. provided background data on clay analysis and Si fractions in the soil. P.M., E.S., L.A. and G.G. initialised and conceptualised the work on Si biogeochemistry in joint collaborations. All authors contributed to the writing and methodological development of the paper.” The original Article contained an error in the calculation of the weathering index Total Reserve in Bases (TRB) in figure 2b. The correct figure 2 appears below as Figure 1. Figure 1 (a) Scatterplot of biogenic silica (BSi) in mg g−1 dry soil in the soil profile, (b) Total Reserve in Bases (TRB = [Na] + [Mg] + [Ca] + [K]) weathering index calculated on dry soil, in cmol charge kg−1. Sites are represented by symbols: ...