Influence of Mussel Culture on the Vertical Export of Phytoplankton Carbon in a Coastal Upwelling Embayment (Ría de Vigo,NW Iberia)

The goal of this paper is to find out whether suspended mussel culture affects the vertical fluxes of biogenic particles in the Ría de Vigo on a seasonal scale. With this aim, vertical fluxes of particulate organic carbon (POC) and the magnitude and composition of vertical export of phytoplankton carbon (Cphyto) collected in sediment traps were examined by comparing data obtained inside a mussel farming area (RaS) with those found at a reference station (ReS) not affected by mussels. Our results indicate that mussel farming has a strong impact on sedimentation fluxes under the rafts, not only increasing POC flux but also altering the magnitude and composition of Cphyto fluxes. Average POC flux at RaS (2564?±?1936 mg m^?2 day^?1) was four times higher than at ReS (731?±?276 mg m^?2 day^?1), and much of this increase was due to biodeposit fluxes (Cbiodep) which accounted for large proportion of POC flux (35–60 %). Indeed, because of this high Cbiodep flux, only a small proportion of the POC flux was due to Cphyto flux (3–12 %). At the same time, we observed an increased sedimentation of phytoplankton cells at RaS that could be explained by a combination of mechanisms: less energetic hydrodynamic conditions under mussel rafts, ballast effect by sinking mussel feces, and diatom aggregates. Moreover, mussel farming also altered the quality of the Cphyto flux by removing part of the predatory pressure of zooplankton and thus matching diatom composition in water column and sediment traps.     

Was the Black Sea catastrophically flooded in the early Holocene?

A catastrophic flooding of the Black Sea basin was proposed to have occurred during its reconnection to the ocean in the early Holocene. Possible cultural consequences of the flood include the migration of Neolithic farmers from around the Black Sea towards central Europe as well as the creation of flood myths. Stratigraphic and paleo-geomorphologic information from Danube delta aided by radiocarbon ages on articulated mollusks constrain the level in the Black Sea before the marine reconnection to ca 30 m below the present sea level rather than 80 m or lower. If the flood occurred at all, the sea level increase and the flooded area during the reconnection were significantly smaller than previously proposed.     

Determination of 137Cs activities in surface sediments and derived sediment accumulation rates in Thessaloniki Gulf, Greece

Surficial and core samples collected from the eastern Thessaloniki Gulf, located in the NW Aegean Sea, were analyzed for their sedimentation rate and inventories of ¹³⁷Cs and ²¹⁰Pb. The study of the spatial radionuclide dispersion in the specific region is essential for the assessment of marine pollution levels. The sedimentation rates were calculated from the vertical distribution of ¹³⁷Cs and excess ²¹⁰Pb in the sediment cores. The spatial distribution of ¹³⁷Cs was studied with respect to sediment characteristics such as the grain size of the sample and the organic carbon content. The activity concentrations were measured by means of gamma ray spectrometry using HPGe detector for ¹³⁷Cs and gross alpha counting using alpha counter for ²¹⁰Pb. The average sedimentation rate along the sediment cores is characterized by a consistent pattern and varies from 0.18?±?0.02 to 0.22?±?0.03?cm?year^?1. The ¹³⁷Cs inventories varied from 205?±?15 to 602?±?39?Bq?m^?2, while the ²¹⁰Pb inventories of the studied cores exhibited average value of 140?±?9?Bq?m^?2. Elevated ¹³⁷Cs activities were observed compared to certain Mediterranean marine areas; however, they were lower than the reported values in the Black Sea.     

Vertical sediment fluxes and wave-induced sediment resuspension in a shallow-water coastal lagoon

The present study describes variations in the vertical fluxes measured concurrently with sediment traps at both a shallow water (4 m) and a deeper water (7.5 m) position in a coastal lagoon in April 1995. A tripod equipped with five sediment traps (trap openings at 0.35 m, 0.75 m, 1.05 m, 1.40 m, and 1.80 m above the seabed) was placed at the shallow water position. This tripod was deployed three times during the study period and deployment periods varied between 2 d and 5 d. The second sediment trap, placed at the deep water position in the central part of the lagoon, measured vertical flux for intervals of 12 h at 1.4 m above the seabed. The horizontal distance between the sediment traps was 8 km. The average maximum vertical flux at the shallow water position reached 27.9 g m⁻² d⁻¹ during a period of high, westerly wind speeds, and a maximum vertical flux of 16.9 g m⁻² d⁻¹ was reached at the deep water position during a period of high, easterly wind speeds. Both strong resuspension events were closely related to increased wave shear stress derived from surface waves. Maximum wave-induced resuspension rate was 10 times higher at the shallow water position and 3.8 times higher at the deep water position compared with the net sedimentation rate in the lagoon. Small resuspension events occurred at the shallow water position during periods of increased current shear stress, Estimations of conditions for transport of sediment between shallow water and deep water showed that particles must be resuspended to a height between 3 m and 4 m and that current speeds must be higher than about 0.1 m s⁻¹. An average sedimentation rate of 3.8 g m⁻² d⁻¹ was obtained at the shallow water position during a period without wave shear stress and low current shear stress. This rate measured by sediment traps is similar to a net sedimentation rate in the lagoon of 4.4 g m⁻² d⁻¹, which was determined by radiocarbon dating of a sediment core (Kristensen et al. 1995).     

Late Quaternary sediment dating and quantification of lateral sediment redistribution applying230Thex: a study from the eastern Atlantic sector of the Southern Ocean

High-resolution records of the natural radionuclide²³⁰Th were measured in sediments from the eastern Atlantic sector of the Antarctic circumpolar current to obtain a detailed reconstruction of the sedimentation history of this key area for global climate change during the late Quaternary. High-resolution dating rests on the assumption that the²³⁰Th_ex flux to the sediments is constant. Short periods of drastically increased sediment accumulation rates (up to a factor of 8) were determined in the sediments of the Antarctic zone during the climate optima at the beginning of the Holocene and the isotope stage 5e. By comparing expected and measured accumulation rate of²³⁰Th_ex, lateral sediment redistribution was quantified and vertical particle rain rates originating from the surface water above were calculated. We show that lateral contributions locally were up to 6.5 times higher than the vertical particle rain rates. At other locations only 15% of the expected vertical particle rain rate were deposited.     

Stratigraphic and structural characteristics of the Romanian Black Sea shelf

The Western Black Sea basin opened during Cretaceous times by back-arc rifting in association with a north dipping subduction at the rear of the Cretaceous–Early Tertiary Pontide volcanic arc. The sedimentary wedge developed on the shelf of the Romanian Black Sea sector reflects a complex interplay between large scale rifting, uplift of the orogenic flanks, large-scale post-rift subsidence and sea level changes. We examine the detailed structural configuration of this sector for a regional correlation with the adjacent offshore in Ukraine and Bulgaria. The evolution of the western Black Sea basin started in the Albian–Cenomanian times, when two extensional phases with significantly different directions (N–S and subsequently E–W) lead to the formation of a complex interplay between isolated blocks organised in horsts and grabens generally deepening eastwards. Superposition of normal faults footwall blocks from the two extensional episodes generated a deeply subsided area with enhanced accommodation space, i.e., the Histria Depression, and, consequently, recorded a larger thickness of Paleogene sediments in the post-rift stage. (Re)activation of faults and associated folding reflects repeated inversion during the Late Cretaceous–Oligocene times, associated with subsequent periods of non-deposition and/or erosion during moments of basin fill exposure. These periods of inversion recorded in the Black Sea are controlled by coeval orogenic deformations taking place in the Balkans, Pontides and the Crimean thrust belt. Sea level fluctuations during the Neogene and late Alpine tectonics in the neighbouring orogens caused massive sedimentation followed by sediment starvation and/or significant erosion. Large thicknesses of sediments accumulated during the Pontian, presumably associated with an extensional episode deepening the distal parts of the basin and with differential compaction structures. The interpretation of a high-quality seismic dataset combined with published data allowed the correlation of major structural units and lineaments defined onshore towards the Carpathians with the ones deeply buried below the western Black Sea basin sediments. Unit correlations are furthermore used to derive an integrated tectonic image of the western Black Sea area.     

Mud volcanic natural phenomena in the South Caspian Basin: geology,fluid dynamics and environmental impact

The South Caspian sedimentary basin is a unique area with thick Mesozoic-Cenozoic sediments (up to 30–32 km) characterized by an extremely high fluid generation potential. The large amount of active mud volcanoes and the volumes of their gas emissions prove the vast scale of fluid generation. Onshore and offshore mud volcanoes annually erupt more than 10⁹ cubic meters of gases consisting of CH₄ (79–98%), and a small admixture of C₂H₆, C₃H₈, C₄H₁₀, C₅H₁₂, CO₂, N, H₂S, Ar, He. Mud volcanism is closely connected to the processes occurring in the South Caspian depression, its seismicity, fluctuations of the Caspian Sea level, solar activity and hydrocarbon generation.The large accumulations of gas hydrates are confined to the bottom sediments of the Caspian Sea, mud volcanoes crater fields (interval 0–0.4 m, sea depth 480 m) and to the volcanoes body at the depth of 480–800 from the sea bottom. Resources of HC gases in hydrates saturated sediments up to a depth of 100 m and are estimated at 0.2×10¹⁵–8×10¹⁵ m³. The amount of HC gases concentrated in them is 10¹¹–10¹² m³.The Caspian Sea, being an inland closed basin is very sensitive to climatic and tectonic events expressed in sea level fluctuations. During regressive stages as a result of sea level fall and the reducing of hydrostatic pressure the decomposition of gas hydrates and the releasing of a great volume of HC gases consisting mainly of methane are observed.From the data of deep drilling, seismoacoustics, and deep seismic mud volcanic activity in the South Caspian Basin started in the Lower Miocene. Activity reached its highest intensity at the boundary between the Miocene and Pliocene and was associated with dramatic Caspian Sea level fall in the Lower Pliocene of up to 600 m, which led to the isolation of the PaleoCaspian from the Eastern ParaTethys. Catastrophic reduction of PaleoCaspian size combined with the increasing scale of mud volcanic activity caused the oversaturation and intoxication of water by methane and led to the mass extinction of mollusks, fishes and other groups of sea inhabitants. In the Upper Pliocene and Quaternary mud volcanism occurred under the conditions of a semi-closed sea periodically connected with the Pontian and Mediterranean Basins. Those stages of Caspian Sea history are characterized by the revival of the Caspian organic world.Monitoring of mud volcanoes onshore of the South Caspian demonstrated that any eruption is predicted by seismic activation in the region (South-Eastern Caucasus) and intensive fluid dynamics on the volcanoes.     

Reconstruction of the conditions of Late Holocene sedimentation by integrated analysis of a core of the bottom sediments from the Chukchi Sea

Integrated studies were performed on bottom sediments collected in the Chukchi Sea in the northern part of the Gerald Canyon 150 km northeast from Wrangel Island. The recent sedimentation rate amounted to 0.9 mm/year by ²¹⁰Pb at the sampling site. The concentrations of biogenic components (SiO_2bio, С_org, N_tot, and Br) were minimum at the lower part of the core, where an increase of Thalassiosira antarctica antarctica, probably results from low biological productivity during the Maunder Minimum. The increased concentrations of biogenic components, as well as the decreased values of magnetic susceptibility and X-ray density, in the upper part of the core (1–2 cm) correspond to the last decade of recent of global warming.     

Evidence of the transgression lake of the Subei basin during Late Cretaceous and Paleocene and its geological significance

Based on analysis of the well drilling core from Subei basin, the authors conclude that during the Late Cretaceous and Paleocene, Subei basin was linked with the sea and the deposit was affected by transgression. The cause of marine transgression may be that since Late Cretaceous and Paleocene tension power had predominated ground-stress conditions of the East China Sea and developed a series of half-graben-like basins filled by a huge thick sediment of the Early Tertiary in the shelf of Huabei-Bohai gulf, Subei-South Yellow Sea and East China Sea. Consequently, seawater transgressed from the East China Sea to the Yellow Sea and linked halfgraben-like basins on the shelf to the sea within a short period. During the sedimentation of the Late Cretaceous Taizhou Formation and Paleocene Funing Formation, the Subei basin had formed the ostracoda-enriched dark shale, including predominantly the whole basin E₁ f ₂ Formation and E₁ f ₄ Formation and local K₂ t ₂ Formation, which became the main source rocks of the basin. The evidence of paleontology, minerals in rocks and geochemistry can help confirm the environment of the lake basin that developed during the Late Cretaceous and Paleocene. We generally designate this environment as “near sea lake basin” and the sea-transgressed layer and member as “transgression lake basin”.Whereas, it is generally called “inland lake and river alluvium plain” during the sedimentation of the Eocene Dainan Formation and Sanduo Formation. This research is not only significant to the paleogeographic reconstruction of the Subei basin during the Late Cretaceous and Paleocene, but also important in understanding the development and distribution of the source rocks and evaluating the potential of oil and gas generation. __________ Translated from Acta Sedimentologica Sinica, 2007, 25(3): 380–385 [译自: 沉积学报]     

Pyritization processes and greigite formation in the advancing sulfidization front in the upper Pleistocene sediments of the Black Sea

Pyritization in late Pleistocene sediments of the Black Sea is driven by sulfide formed during anaerobic methane oxidation. A sulfidization front is formed by the opposing gradients of sulfide and dissolved iron. The sulfidization processes are controlled by the diffusion flux of sulfide from above and by the solid reactive iron content. Two processes of diffusion-limited pyrite formation were identified. The first process includes pyrite precipitation with the accumulation of iron sulfide precursors with the average chemical composition of FeS_n (n = 1.10-1.29), including greigite. Elemental sulfur and polysulfides, formed from H₂S by a reductive dissolution of Fe(III)-containing minerals, serve as intermediates to convert iron sulfides into pyrite. In the second process, a “direct” pyrite precipitation occurs through prolonged exposure of iron-containing minerals to dissolved sulfide. Methane-driven sulfate reduction at depth causes a progressive formation of pyrite with a δ³⁴S of up to +15.0‰. The S-isotopic composition of FeS₂ evolves due to contributions of different sulfur pools formed at different times. Steady-state model calculations for the advancement of the sulfidization front showed that the process started at the Pleistocene/Holocene transition between 6360 and 11 600 yr BP. Our study highlights the importance of anaerobic methane oxidation in generating and maintaining S-enriched layers in marine sediments and has paleoenvironmental implications.     

山东半岛东部海域悬浮体分布季节变化及其冬季输送通量研究

山东半岛东部近岸海域流系和水团要素季节变化显著,沉积动力环境特殊,发育有剖面形状独特的泥质沉积体。基于两个年度的夏、冬季山东半岛东部近岸海域水体温度、浊度、悬浮体浓度和海流等调查资料,分析了水团要素分布季节变化特征,并结合研究区域冬季海流和余流分布特征,计算了冬季经山东半岛东部近岸海域向南输送的悬浮体净通量。结果表明:山东半岛东部近岸海域悬浮体分布受沿岸流、黄海冷水团和黄海暖流等流系季节变化的影响存在显著季节变化。夏季,水体垂向层结和黄海冷水团均可抑制悬浮体垂向和东西向扩散。与以往的研究有所不同的是,冬季大量悬浮体可穿越沿岸流与黄海暖流形成的海流切变锋面,进入黄海暖流向北输送,海流切变锋的屏障作用会随着黄海暖流的减弱或东移而削弱。每年冬季经山东半岛东部近岸海域输送的悬浮体占渤海海峡向外海输送的悬浮体年净通量的3.22%~9.10%,冬季的悬浮体输送量较大,占冬季渤海海峡向外海输送的悬浮体年净通量的6.84%~19.38%。     

Enhanced Benthic Nutrient Flux During Monsoon Periods in a Coastal Lake Formed by Tideland Reclamation

Sediment and water quality were investigated in an artificial coastal lake (Saemangeum Lake, Korea) that was formed by constructing a 33-km long sea-dyke offshore from the mouths of two adjacent rivers, which discharge into the Yellow Sea. Sediment showed drastic increases in fine fraction (silt and clay) after the dyke construction. TN, TP, and OC contents in the sediment showed the similar spatial variation to that of fine fraction. A mixing model indicated benthic fluxes of nutrients such as PO₄, NH₄, and SiO₂, which were considerably elevated during the summer monsoon season. It is revealed that this phenomenon was associated with the development of strong salinity stratification, elevated water temperature, and increased groundwater discharge. However, a change in the sedimentation environment due to dyke construction is suggested as the primary reason for the enhanced benthic fluxes.     

Mollusks from the lower quaternary Chauda sediments of the Black Sea

The analysis of paleontological remains in many samples from the Lower Quaternary Chauda sediments drilled and cored on the Bulgarian shelf of the Black Sea revealed widespread mollusks of the genera Didacna and Dreissena (Didacna tschaudae guriana, D. tschaudae, D. pleistopleura, D. crassa guriensis, Dreissena rostriformis tschaudae, D. rostriformis abchasica) accompanied by reworked Neogene representatives of the genus Digressodacna. In numerous places of a continental slope and an adjacent deep-sea depressions near Crimea and Caucasus the similar mollusc assemblage is described in the redeposited state for the first time. The composition of palynological spectra and diatom assemblages in shelf sediments indicates climate changes during the Chaudan period. The Chaudan mollusk fauna from the Black Sea sediments, which is lacking Caspian Bakuan species characteristic of the Chauda stratotype, is compositionally close to the mollusk assemblage from basal layers of the Chauda Horizon in the Guriya area of Georgia (“Gurian” Chauda). These data imply repeated changes in the level of the Chaudan basin between present-day isobaths of −30...−50 to −140 m.     

Development of a pulverized fly ash suspension grout

A Greek lignite fly ash was selected because of its hydraulic properties and was pulverized to produce a specific surface of 8300 cm²/g, and a gradation with D₁₅, D₅₀, and D₈₅ equal to 1.3 m, 6 m and 20 m, respectively. The pulverized fly ash suspension properties were optimized by adding a suitable superplasticizer and a suitable accelerator at optimum dosages. The experimental evaluation of suspension properties included sedimentation tests, viscosity'measurements, rheological properties, setting times and development of strength with time. Groutability and effectiveness were evaluated by injecting selected suspensions into clean sands. Pulverization improves remarkably the behavior of fly ash suspensions. Suspensions with water to solids ratios of 1.5:1 and 2:1 by weight and containing additives, behave as Bingham fluids, have apparent viscosity lower than 70 cP, bleed capacity lower than 5%, initial setting time lower than 24 h, and can be injected into relatively coarse sands. These characteristics are comparable to those obtained for ordinary and microfine cement suspensions, showing that pulverized fly ash suspensions can be used for permeation grouting.     

Geochemical investigation and characterisation of Neogene sediments from Valjevo-Mionica Basin (Serbia)

Sediments from the Valjevo-Mionica Basin of Neogene age were investigated in this study using different geochemical methods. The results of the inorganic part analyses suggest that during genesis of the sediments, the contents of Na₂O, B and As changed the most, which indicates that genesis of the investigated sediments was followed by climate changes and volcanic activity. The quantity of other macro- and microelements did not vary significantly. Investigations of the organic substance showed that it is native organic matter, which has been preserved to a significant extent, formed predominantly of algal precursor organisms, which provided good quality, deposited under reducing conditions and that it is at a low maturity level. As it has been established that genesis of the investigated sediments was mostly affected by an arid climate with more intensive salinity, the aim of this study, was also to identify the processes which were the most affected by the change in salinity, as well as biomarkers which are the most sensitive to this change. The results led to the conclusion that the salinity increase in the depositional environment had a primary effect on the preservation of the organic substance and the formation of the mineral searlesite. In addition, it was noticed that besides the Sq/nC₂₆ ratio, the parameters nC₁₇/nC₂₇, CPI and Ph/nC₁₈, are also significantly sensitive to salinity change in a depositional environment in case of immature organic substance deposited under reducing conditions.     

Rapid, oxygen-dependent microbial Mn(II) oxidation kinetics at sub-micromolar oxygen concentrations in the Black Sea suboxic zone

Microbial Mn(II) oxidation kinetics in response to oxygen concentration were assessed in suboxic zone water at six sites throughout the Black Sea. Mn(II) oxidation rates increased asymptotically with increasing oxygen concentration, consistent with Michaelis-Menten enzyme kinetics. The environmental half-saturation constant, K_E, of Mn(II) removal (oxidation) varied from 0.30 to 10.5 μM dissolved oxygen while the maximal environmental rate, V_E−max, ranged from 4 to 50 nM h⁻¹. These parameters varied spatially and temporally, consistent with a diverse population of enzymes catalyzing Mn oxide production in the Black Sea. Coastally-influenced sites produced lower K_E and higher V_E−max constants relative to the Western and Eastern Gyre sites. In the Bosporus Region, the Mn(II) residence time calculated using our K_E and V_E−max values with 0.1 μM oxygen was 4 days, 25-fold less than previous estimates. Our results (i) indicate that rapid Mn(II) oxidation to solid phase Mn oxides in the Black Sea’s suboxic zone is stimulated by oxygen concentrations well below the 3-5 μM concentration reliably detected by current oceanographic methods, (ii) suggest the existence of multiple, diverse Mn(II)-oxidizing enzymes, (iii) are consistent with shorter residence times than previously calculated for Mn(II) in the suboxic zone and (iv) cast further doubt on the existence of proposed reactions coupling solid phase Mn oxide production to electron acceptors other than oxygen.     

A large methane plume east of Bear Island (Barents Sea): implications for the marine methane cycle

A pockmark field extending over 35 km² at 74°54N, 27°3E, described by Solheim and Elverhøi (1993), was re-surveyed and found to be covered with more than 30 steep-sided craters between 300 and 700 m in diameter and up to 28 m deep. The craters are thought to have been formed by an explosive gas eruption. Anomalously high concentrations of methane in the shelf waters around the craters suggest that a strong methane source near this area is still active today. Methane enrichment more than 10 km away from the crater field indicates the large dimensions of a plume and the amount of gas released from sources below the seafloor of the Barents Sea shelf. From the characteristic vertical decrease of methane towards the sea surface, it is concluded that biota are extensively using this energy pool and reducing the methane concentration within the water column by about 98% between 300 m depth and the sea surface. Degassing to the atmosphere is minimal based on the shape of the methane concentration gradient. Nevertheless, the net flux of methane from this area of the Barents Sea is about 2.9 × 10⁴ g CH₄ km^–2 yr^–1 and thus in the upper range of the presently estimated global marine methane release. This flux is a minimum estimate and is likely to increase seasonally when rough weather leads to more effective vertical mixing during autumn and winter. The amount of methane consumed in the water column, however, is about 50 times greater and hence should significantly contribute to the marine carbon inventory.     

Terrestrial sediment yield and the lifetimes of reservoirs, lakes, and larger basins

Water reservoirs, lakes, and larger basins, including their drainage areas, represent sedimentologically closed to semi-closed denudation-accumulation systems. The mean rates of mechanical denudation, DR_me, and clastic sedimentation, SR_me, are related by the ratio of the drainage/lake area, A_d/A_l. If the latter is known, DR_me (or the specific sediment yield SY in t per km²/a) can be calculated from SR_me, or vice versa. The best data for modern SY mainly come from the sediment fills of artificial reservoirs. Small drainage areas of mountainous regions show SY values up to two orders of magnitude higher than lowlands and approximately one order higher than larger regions of mixed relief. This is also true of arid to semi-arid zones which often provide approximately as much sediment (SY) as humid temperate and even tropical zones of comparable relief. Lithology and climate (river runoff) also may play some role for SY from catchments of limited size. The importance of these factors is exemplified by perialpine lakes and two East African lakes. Sediment yields gained from some large reservoirs compare well with long-term denudation rates derived from geological studies (e.g., the Tarbela dam reservoir along the Indus River). In many other cases, human activities have raised SY by factors of 2–10, locally up to >100. Artificial reservoirs in mountainous regions with SY in the range of 300–2000?t?per?km²/a tend to become filled within several tens to hundreds of years; some have even shorter lifetimes. Perialpine lakes of the Alps and British Columbia are strongly affected by delta prograding and have lifetimes mostly between 15 and 40?ka. Closed lake systems in deep morphological depressions (Lake Bonneville, Aral Sea, northern Caspian Sea) have a high potential for sediment storage up to the level of spillover and therefore can persist over long time periods. Basins with markedly subsiding basin floors (lakes of the East African rift zone, the southern Caspian Sea, and the Black Sea, both on oceanic crust) can survive for many Ma in the future, despite relatively high terrigenous input.     

On the character of Black Sea level rise during the Holocene

The character of changes in the mollusk fauna in the Late Pleistocene and Holocene sediments within the Bulgarian, Northwestern, Crimean, and Kerch segments of the Black Sea shelf has been examined. A bed containing fossil remains of brackish-water and marine mollusks was recognized in these sediments; the bed accumulated, based on results of radiocarbon datings, 500–1000 years ago. The obtained data do not support the existing notion of a catastrophic fill-up of the Black Sea Basin by marine Mediterranean water [19].     

Dissolved aluminium in interstitial waters of recent marine sediments

Measurements of the concentration and vertical distribution of dissolved aluminium and silica, and of pH. in interstitial waters of recent marine sediments from the North Sea and the Mediterranean Sea were performed to evaluate the behaviour of aluminium during early diagenesis. The results suggest that thermodynamic equilibria alone do not control the concentrations of dissolved species in the system Al-Si-O₂-H₂O during early diagenesis. Rather, these concentrations are governed by dynamic factors involving mineral dissolution-precipitation reactions and diffusion.