Dissolved silica in the subterranean estuary and the impact …
In past derivations of the marine silica budget, dissolved silica (DSi) inputs via submarine groundwater discharge (SGD) were generally given a cursory treatment based on limited, mostly inland aquifer data (e.g., (Laruelle et al., 2009; Tréguer and De La Rocha, 2013; Frings et al., 2016), despite the fact that several local and regional-scale …
Siliceous sediments | SpringerLink
For at least the past 540 million years, siliceous sediments have formed primarily by the deposition of biologically secreted opal particles that dissolve and …
SILICIFICATION
Silica—dissolved, and as amorphous or microquartz (opal, chalcendony, and microcrystalline quartz phases), and crystalline megaquartz—is a common component in sediments, and is found in solution and as nodules, cements, and clastic material. Fossilization involving silica occurs by three
Silicate weathering in anoxic marine sediments
1.. IntroductionThe weathering of silicate minerals exposed on the continents is the largest sink of atmospheric CO 2 on geological time scales (Wallmann, 2001).Clay minerals and dissolved metal ions are also produced during this reaction which may be summarized as: (1) Reactive silicates + CO 2 → clay minerals + dissolved cations + …
Asymptotic forms and solutions of the model for silica…
Early diagenesis of the coupled dissolved silica-opal system in bioturbated sediments may be explained by one of three possible models of increasing mathematical complexity, i.e. the simple, but unused constant-opal model (abbreviated C.O.), the Schink et al. (1975) model (abbreviated SG&F) for which Wong and Grosch (1978) have …
5 Weathering, Erosion, and Sedimentary Rocks
5.2 Weathering and Erosion. Bedrock refers to the solid rock that makes up the Earth's outer crust. Weathering is a process that turns bedrock into smaller particles, called sediment. Mechanical weathering includes pressure expansion, frost wedging, root wedging, and salt expansion.Chemical weathering includes carbonic acid and hydrolysis, …
Global importance, patterns, and controls of …
[1] Lentic water bodies (lakes and reservoirs) offer favorable conditions for silica (SiO 2) burial in sediments.Recent global estimates suggest that (1) lentic SiO 2 trapping is a globally important SiO 2 flux, …
SILICIFICATION
Silica—dissolved, and as amorphous or microquartz (opal, chalcendony, and microcrystalline quartz phases), and crystalline megaquartz—is a common component in …
Influence of seasonal phytodetritus deposition on biogenic silica
On time scales of months, surface sediments are transported to depths of 3-6 cm (McClintic et al., 2008), where the concentrations of dissolved silica in the pore water are close to the ...
Environmental geochemistry of dissolved and …
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Dissolved Silica and Deep-Sea Sediments
WEBAbstract. Most of the silica dissolved in sea water comes from silica-rich interstitial waters of marine sediments and from rivers carrying the products of subaerial …
CP
Abstract. Oxygen isotopes in biogenic silica (δ18OBSi) from lake sediments allow for quantitative reconstruction of past hydroclimate and proxy-model comparison in terrestrial environments. The signals of individual records have been attributed to different factors, such as air temperature (Tair), atmospheric circulation patterns, hydrological …
Dissolved aluminium in interstitial waters of recent
Dissolved Rare Earth Elements (REE) and radiogenic neodymium (Nd) isotope composition (ε Nd) of seawater are widely used geochemical tools in studying marine processes, but their modern ocean budgets are poorly understood.Recent discoveries of large benthic fluxes of REE with unique ε Nd signatures from marine …
Silica fluxes and opal dissolution rates in the northern …
Opal solubility is an important parameter in the rate expression of early diagenetic models of silica in deep-sea sediments. Whether the asymptotic dissolved silica concentration can be considered as the in situ opal solubility has long been a matter of debate (e.g. Boudreau, 1990; Van Cappellen and Qiu, 1997a; Rickert, 2000). As …
The diffusion coefficient of dissolved silica revisited
Introduction. The diffusion coefficient of dissolved silica (H 4 SiO 4) has been relatively little studied, although it is an essential parameter for the assessment of diffusive fluxes of this constituent, in particular across the water–sediment interface.It is not only a key parameter for diagenetic modelling, but also is needed for studying the …
Dissolution of silica and the development of
The dissolution of silica and diffusion of reactive dissolved Si in the porewaters of river sediments are investigated using sediments of different physical and chemical properties. Three sediments are considered: (a) from sectioned cores taken from a river-bed, (b) fine organic-rich surface sediment (<5 cm depth) installed in a fluvarium …
Release and uptake of dissolved silica in seawater by marine sediments
Abstract. Natural marine sediments can release dissolved silica to silica-poor seawater and can remove silica from seawater enriched with dissolved silica. These are fast reactions, with sufficient reaction occurring within the first 48 hours to indicate clearly the direction of the reaction. The relative importance of these two processes ...
Environmental geochemistry of dissolved and biogenic …
Generally, biological precipitation of amorphous silica (opal) by diatoms is the dominant process that removes dissolved Si (silicic acid, or Si(OH) 4) from overlying water and is an efficient conveyor of organic carbon to the sediments (Falkowski et …
Biogenic silica in wetlands and their relationship with soil …
In the basin of the Los Padres wetland, dissolved silica (DSi) concentration is near 840 ± 232 μmol/L and 211.83 ± 275.92 μmol/L in groundwaters and surface waters, respectively. BSi represents an 5.6–22.1% of the total suspension material, and 8–34% of the total mineralogical components of the wetland bottom sediments.
Dissolution kinetics of biogenic silica from the water …
Silica minerals in estuary sediments can control dissolved silica concentration (Rickert, 2000; Rickert et al., 2001). In laboratory experiments, release of silica from sediments containing silica ...
Dissolution kinetics of biogenic silica from the water …
It is therefore likely that inorganic coatings significantly reduce the release rate of dissolved silica from BSi remains in sediments. Organic coatings although inducing just a small solubility decrease (section 5.1), are obviously responsible for the large reactivity decrease of water column samples with depth.
Distribution and dissolution kinetics of biogenic silica in sediments …
The dissolution efficiency of sedssimentary biogenic silica (bSiO2) dramatically affects the regeneration of dissolved silicic acid (dSi) at the sediment-water interface, which is a crucial pathway to maintain Si balance and silicic productivity growth in marine environments. We conducted wet alkaline leach and flow-through experiments to …
Seasonal dynamics of the biogenic silica cycle in surface sediments …
In coastal waters and the ocean silicic acid (Si(OH) 4) is a key nutrient for primary producers (e.g. diatoms) and other siliceous organisms, because it is required for the formation of frustules and other hard parts made of biogenic silica (bSi). Especially in shallow waters like the southern North Sea, dissolution of bSi in surface sediments and …
Natural and human influences on dissolved silica …
As a macronutrient, dissolved silica ... DSi concentration may also have been influenced by sedimentation and releases from sediment [Koszelnik and Tomaszek, 2008; Wang et al., 2010]. In …
19 The Rock Cycle II: Sediment and Sedimentary Rock
Calcium ions, for example, are constantly delivered to carbonate sediments by living organisms, while dissolved silica (SiO 2) is removed by diatoms and Radiolaria. The result is that the most abundant ions left over in sea-water are sodium (Na + ) and chloride (Cl – ) ions, which make sea-water taste of salt.
Emerging understanding of the ecosystem silica filter
The annual fixation of dissolved Si (DSi) into terrestrial vegetation has been estimated to range from 60 to 200 Tmole, or 10–40 times more than the yearly export of DSi and biogenic Si (BSi) from the terrestrial geobiosphere to the coastal zone. Ecosystems form a large filter between primary mobilization of DSi from silicate weathering and its …
Dissolved silica‐driven dolomite precipitation in the Great …
Our results suggest that dissolved silica concentration is the primary control for dolomite and Mg-clay formation in the Great Salt Lake. Even though the North Arm has a much more concentrated Mg and Ca water from lack of freshwater input, dissolved silica levels in the South Arm (>0.5 m m ) and the Ridge-site ( ca 0.5 m m ) are much higher ...
7.2: Siliceous Sedimentary Rocks
Sources of dissolved silica. Ultimately, all dissolved silica can trace its origin back to the weathering and/or dissolution of existing silicate rocks or input from …
The Missing Silica Sink: Revisiting the Marine Sedimentary Si …
Burial of biogenic silica (bSi total) in high sedimentation rate continental margins remains highly uncertain.Cosmogenic 32 Si (t 1/2 ~140 years) can be used to trace the fates of bSi total postdeposition, including as opal (bSi opal) and diagenetically altered opal (bSi altered), the latter dominantly authigenic clay (bSi clay).To determine the …
(PDF) Asymptotic Forms and Solutions of the …
Early diagenesis of the coupled dissolved silica-opal system in bioturbated sediments may be explained by one of three possible models of increasing mathematical complexity, i.e. the simple, …
The diffusion of dissolved silica out of deep-sea sediments
Cores of marine sediment from the Atlantic Ocean were maintained in seawater in the laboratory for 2 years and showed large sustained releases of dissolved silica to the overlying water. The releas...
