Tracing the origin of dissolved silicon transferred from various soil-plant systems towards rivers: a review

Cornélis, Jean-Thomas; Delvaux, Bruno; Georg, R. Bastian; Lucas, Yves; Ranger, Jacques; Opfergelt, Sophie

doi:10.5194/bg-8-89-2011

Cited by 249 publications

(161 citation statements)

References 205 publications

(322 reference statements)

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“…Nevertheless, variations in CSi a with depth in continuously forested ecosystems did not reflect variations of soil OC with depth. Several factors such as a varying phytolith input of roots with depth (Gill and Jackson, 2000), vertical translocation of phytoliths (Alexandre et al, 1997;Meunier et al, 1999), variations in silica solubility or (re-) precipitation of pedogenic silica (Cornelis et al, 2011b) with depth could all contribute to the observed ASi distribution. Our data do not allow to identify the relative contribution of each of these processes.…”

Section: Amorphous Silica and Organic Carbonmentioning

confidence: 99%

Anthropogenic impact on amorphous silica pools in temperate soils

et al. 2011

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Abstract. Human land use changes perturb biogeochemical silica (Si) cycling in terrestrial ecosystems. This directly affects Si mobilisation and Si storage and influences Si export from the continents, although the magnitude of the impact is unknown. A major reason for our lack of understanding is that very little information exists on how land use affects amorphous silica (ASi) storage in soils. We have quantified and compared total alkali-extracted (PSi a ) and easily soluble (PSi e ) Si pools at four sites along a gradient of anthropogenic disturbance in southern Sweden. Land use clearly affects ASi pools and their distribution. Total PSi a and PSi e for a continuous forested site at Siggaboda Nature Reserve (66 900 ± 22 800 kg SiO 2 ha −1 and 952 ± 16 kg SiO 2 ha −1 ) are significantly higher than disturbed land use types from the Råshult Culture Reserve including arable land (28 800 ± 7200 kg SiO 2 ha −1 and 239 ± 91 kg SiO 2 ha −1 ), pasture sites (27 300 ± 5980 kg SiO 2 ha −1 and 370 ± 129 kg SiO 2 ha −1 ) and grazed forest (23 600 ± 6370 kg SiO 2 ha −1 and 346 ± 123 kg SiO 2 ha −1 ). Vertical PSi a and PSi e profiles show significant (p < 0.05) variation among the sites. These differences in size and distribution are interpreted as the long-term effect of reduced ASi replenishment, as well as changes in ecosystem specific pedogenic processes and increased mobilisation of the PSi a in disturbed soils. We have also made a first, though rough, estimate of the magnitude of change in temperate continental ASi pools due to human disturbance. Assuming that our data are representative, we estimate that total ASi storage in soils has declined by ca. 10 % since the onset of agricultural development (3000 BCE). Recent agricultural expansion (after 1700 CE) may have resulted in an average additional export of 1.1 ± 0.8 Tmol Si yr −1 from the soil reservoir to aquatic ecosystems. This is ca. 20 % to the global land-ocean SiCorrespondence to: W. Clymans (wim.clymans@ees.kuleuven.be) flux carried by rivers. It is necessary to update this estimate in future studies, incorporating differences in pedology, geology and climatology over temperate regions, but data are currently not sufficient. Yet, our results emphasize the importance of human activities for Si cycling in soils and for the land-ocean Si flux.

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Section: Amorphous Silica and Organic Carbonmentioning

confidence: 99%

Anthropogenic impact on amorphous silica pools in temperate soils

et al. 2011

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“…The Si fluxes recycled by plants are substantial; for example, Si take up by tropical forests or grasslands can reach 2 to 10 times Si fluxes generated from the dissolution of soil silicates that are exported to stream water (e.g., Blecker et al, 2006;Struyf and Conley, 2009;Cornelis et al, 2011;Alexandre et al, 2011). Inside the plant, Si is transported in the sap and deposited inside the cells, in the cell walls and in extracellular spaces of stems and leaves as micrometric hydrous amorphous silica particles called phytoliths.…”

Section: Introductionmentioning

confidence: 99%

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

et al. 2015

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Abstract. Phytoliths contain occluded organic compounds called phytC. Recently, phytC content, nature, origin, paleoenvironmental meaning and impact in the global C cycle have been the subject of increasing debate. Inconsistencies were fed by the scarcity of in situ characterizations of phytC in phytoliths. Here we reconstructed at high spatial resolution the 3-D structure of harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While this technique has been widely used for 3-D reconstruction of biological systems it has never been applied in high-resolution mode to silica particles. Simultaneously, we investigated the location of phytC using nanoscale secondary ion mass spectrometry (NanoSIMS). Our data evidenced that the silica structure contains micrometric internal cavities. These internal cavities were sometimes observed isolated from the outside. Their opening may be an original feature or may result from a beginning of dissolution of silica during the chemical extraction procedure, mimicking the progressive dissolution process that can happen in natural environments. The phytC that may originally occupy the cavities is thus susceptible to rapid oxidation. It was not detected by the NanoSIMS technique. However, another pool of phytC, continuously distributed in and protected by the silica structure, was observed. Its N / C ratio (0.27) is in agreement with the presence of amino acids. These findings constitute a basis to further characterize the origin, occlusion process, nature and accessibility of phytC, as a prerequisite for assessing its significance in the global C cycle.

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“…Earlier studies have hypothesized that volcanic glass shards substantially contribute to measured Si Alk (Cornelis et al, 2011b;Lyle and Lyle, 2002;Sauer et al, 2006). In the following, we discuss the specific dissolution characteristics of glass shards, during alkaline extraction and implications for soil and palaeoecological studies.…”

Section: Discussionmentioning

confidence: 99%

“…Cornelis et al (2011b) reviewed sources that may completely dissolve and find that in addition to biogenic remains (e.g. phytoliths, diatoms), inorganic forms such as Al-Si precipitates, volcanic glass shards, adsorbed Si on amorphous iron oxides, and nanocrystalline fractions such as allophanes and imogolite can comprise a substantial portion of the nonlinearly dissolving Si.…”

Section: Introductionmentioning

confidence: 99%

The contribution of tephra constituents during biogenic silica determination: implications for soil and palaeoecological studies

et al. 2015

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Abstract. Biogenic silica (BSi) is used as a proxy by soil scientists to identify biological effects on the Si cycle and by palaeoecologists to study environmental changes. Alkaline extractions are typically used to measure BSi in both terrestrial and aquatic environments. The dissolution properties of volcanic glass in tephra deposits and their nanocrystalline weathering products are hypothesized to overlap those of BSi; however, data to support this behaviour are lacking. The potential that Si-bearing fractions dissolve in alkaline media (Si Alk ) that do not necessarily correspond to BSi brings the applicability of BSi as a proxy into question. Here, analysis of 15 samples reported as tephra-containing allows us to reject the hypothesis that tephra constituents produce an identical dissolution signal to that of BSi during alkaline extraction. We found that dissolution of volcanic glass shards is incomplete during alkaline dissolution. Simultaneous measurement of Al and Si used here during alkaline dissolution provides an important parameter to enable us to separate glass shard dissolution from dissolution of BSi and other Si-bearing fractions. The contribution from volcanic glass shards (between 0.2 and 4 wt % SiO 2 ), the main constituent of distal tephra, during alkaline dissolution can be substantial depending on the total Si Alk . Hence, soils and lake sediments with low BSi concentrations are highly sensitive to the additional dissolution from tephra constituents and its weathering products. We advise evaluation of the potential for volcanic or other non-biogenic contributions for all types of studies using BSi as an environmental proxy.

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Tracing the origin of dissolved silicon transferred from various soil-plant systems towards rivers: a review

Abstract: Abstract. Silicon (Si) released as H 4 SiO 4 by weathering of Si-containing solid phases is partly recycled through vegetation before its land-to-rivers transfer. By accumulating in terrestrial plants to a similar extent as some major macronutrients (0

Cited by 249 publications

References 205 publications

Anthropogenic impact on amorphous silica pools in temperate soils

Anthropogenic impact on amorphous silica pools in temperate soils

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

The contribution of tephra constituents during biogenic silica determination: implications for soil and palaeoecological studies

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