The occurrence and significance of biogenic opal in the regolith

Clarke, Jonathan

doi:10.1016/s0012-8252(02)00092-2

Cited by 151 publications

(99 citation statements)

References 43 publications

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“…Wetlands can modify nutrient fluxes along the aquatic continuum through transformation and storage. Silica rich biomass, together with the frequent occurrence of diatoms and sponges in wetlands, provides the potential for the accumulation of ASi rich soils (Clarke, 2003;Struyf et al, 2005). Struyf and Conley (2009) hypothesized that a trade-off between the storage of ASi in wetland soils and the export of DSi from wetlands depends on hydrological and vegetation characteristics.…”

Section: Introductionmentioning

confidence: 99%

Vegetation and proximity to the river control amorphous silica storage in a riparian wetland (Biebrza National Park, Poland)

et al. 2009

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Abstract. Wetlands can modify and control nutrient fluxes between terrestrial and aquatic ecosystems, yet little is known of their potential as biological buffers and sinks in the biogeochemical silica cycle. We investigated the storage of amorphous silica (ASi) in a central-European riparian wetland. The variation in storage of ASi in the soil of an undisturbed wetland was significantly controlled by two factors: dominance of sedges and grasses and distance to the river (combined R 2 =78%). Highest ASi storage was found near the river and in sites with a dominance of grasses and sedges, plants which are well known to accumulate ASi. The management practice of mowing reduced the amount of variation attributed to both factors (R 2 =51%). Although ASi concentrations in soils were low (between 0.1 and 1% of soil dry weight), ASi controlled the availability of dissolved silica (DSi) in the porewater, and thus potentially the exchange of DSi with the nearby river system through both diffusive and advective fluxes. A depth gradient in ASi concentrations, with lower ASi in the deeper layers, indicates dissolution. Our results show that storage and recycling of ASi in wetland ecosystems can differ significantly on small spatial scales. Human management interferes with the natural control mechanisms. Our study demonstrates that wetlands have the potential to modify the fluxes of both DSi and ASi along the land-ocean continuum and supports the hypothesis that wetlands are important ecosystems in the biogeochemical cycling of silica.Correspondence to: E. Struyf

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Section: Introductionmentioning

confidence: 99%

Vegetation and proximity to the river control amorphous silica storage in a riparian wetland (Biebrza National Park, Poland)

et al. 2009

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“…Si may inhibit Al-induced reduction of bioavailable phosphorus by binding Al preferentially. Short-term variability of Si concentrations in streams relates to hydrology (Johnson et al, 1969), season (Norton et al, 1999;Gèrard et al, 2002;Soulsby et al, 2001) and diatom utilisation (Clarke, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Dissolution rates of phytoliths may vary by 12 orders of magnitude, depending on coatings and Al concentration (Iler, 1973;Van Bennekom et al, 1989). Lake sediment contains up to tens of percent of diatoms and sponge spicules (Clarke, 2003). Interstitial water of lake sediment is enriched with dissolved Si that diffuses back into water (House et al, 2000;Rickert et al, 2002), increasing Si in the water column in the lake.…”

Section: Introductionmentioning

confidence: 99%

Increasing silicon concentrations in Bohemian Forest lakes

Veselý

Majer

Kopáček³

et al. 2005

Hydrol. Earth Syst. Sci.

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Long-term trends of dissolved silicon (Si) concentrations in five glacial lakes in the Bohemian Forest, Czech Republic, recovering from acidification show higher mobility of Si from the soil to surface waters despite lower atmospheric deposition of acids. Si increased by 0.95 to 1.95 µmol yr 1 (36 to 51%) from 19862004 and with increasing pH. A change in soil solution conditions because of a sharp decrease in acidic deposition has led to marked decline in Al mobility and to considerable decreases in dissolved Al, especially Al 3+ . The increase in Si may be related to: (1) unblocking of the inhibitory effect of dissolved Al on weathering of aluminosilicates, (2) biogenic opal (phytoliths) dissolving faster, and/or (3) lower Si precipitation as secondary aluminosilicates in soil. The change in Al speciation on the dissolution rate of biogenic silica is critical. A lack of change in Si at sites outside central Europe may be explained by small or no decline in mobility of dissolved Al. The effect of a long-term increase in temperature was probably minor.

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“…This increases the amount of silica in soils. Clarke (2003) explained that biogenic silica produced by vascular plant constitutes about 2 -3% of most soils. Some early works on silcrete (e.g.…”

Section: Cretaceous Origin Of the Poaceae Family Of Grass And The Higmentioning

confidence: 99%

Widespread Development of Silcrete in the Cretaceous and Evolution of the Poaceae Family of Grass Plants

Bata¹

2016

ESR

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The Cretaceous period, which is considered one of the most remarkable periods in Earth's history, saw episodes of abrupt greenhouse warming and cooling. The Cretaceous was also exceptional in that it was associated with the widespread occurrence of silcrete. To demonstrate this, the present study collated records of silcrete occurrences from the Jurassic to the present and compared them with records of variation in palaeotemperature and atmospheric CO 2 levels. Quartz solubility, which is one of the key factors that controls the rate of silcrete development, was also calculated over the same period. The results demonstrate that a marked increase (approximately 100%) in quartz solubility occurred during the Cretaceous. This was found to be a direct consequence of the extreme global warmth witnessed at that time. Furthermore, this study shows that silcrete occurrences are consistent with records of palaeotemperature and that silcretes have formed mostly in regions that have experienced warm climatic conditions, with no instances found in polar regions. The Poaceae family of grass plants are known to have evolved and diversified during the Cretaceous, which coincide with the period when silica was readily available. X-ray spectra and backscattered images from SEM examination of the internal structure of a modern wild grass (which belongs to the Poaceae family of grass plants) reveals that silica is an important constituent of the grass. This suggest a possible link between evolution of the Poaceae family in the Cretaceous and the high availability of silica during the Cretaceous.

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The occurrence and significance of biogenic opal in the regolith

Cited by 151 publications

References 43 publications

Vegetation and proximity to the river control amorphous silica storage in a riparian wetland (Biebrza National Park, Poland)

Vegetation and proximity to the river control amorphous silica storage in a riparian wetland (Biebrza National Park, Poland)

Increasing silicon concentrations in Bohemian Forest lakes

Widespread Development of Silcrete in the Cretaceous and Evolution of the Poaceae Family of Grass Plants

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