| 1. |
- Boström, Kurt, et al.
(författare)
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Origin of iron-manganese-rich suspended matter in the Landsort Deep, NW Baltic Sea
- 1988
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203 .- 1872-7581. ; 24:1, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- Water sampling was undertaken in 1982 in the Landsort Deep, NW Baltic Sea, at eight depth levels. In the 0-150 m interval oxidizing conditions prevailed, with suspended phases being particularly rich in Fe (with a maximum at 150 m), Mn and Ba (with maxima at 100 m). The anoxic zone below 150 m showed high concentrations of dissolved Fe and particularly dissolved Mn which were much higher than in the Black Sea, for instance. This is probably due to the migratory behavior of the redoxcline in the Landsort Deep. The metal-rich suspended matter probably arises when dissolved Fe and Mn from the anoxic zone precipitate as hydroxyoxides at the redoxcline; lateral transport of such suspended matter may explain the large-scale selective loss of Mn and Ba from the Baltic basin.
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| 2. |
- Boström, Kurt, et al.
(författare)
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Selective removal of trace elements from the Baltic by suspended matter
- 1981
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Ingår i: Marine Chemistry. - 0304-4203 .- 1872-7581. ; 10:4, s. 335-354
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Tidskriftsartikel (refereegranskat)abstract
- Suspended matter was collected at 30 stations in the Baltic and Kattegatt, at the thermocline and at the bottom, and analysed for Na, Ca, Mg, Si, Ti, Al, Fe, Mn, Ba, Sr, Ni and V. The composition of the suspended matter varies considerably, but can be described as a mixture of: (1) 12-25% terrigenous detritus with much Si, Al, Ti and Fe; (2) 75-88% biological matter with much Ni, V and Ba; and (3) some Mn-oxyhydroxide.The annual efflux of water from the Baltic is about 460 km3, with a suspended load in the Baltic straits of 1.2-3.6 mg ash material l-1 These values imply that much Si, Ti, Al, Fe, Sr, Ni and V and particularly much Ba and Mn are lost from the Baltic in the suspended load.The average suspended matter is richer in Mn(5×), Ba(2.5×), Sr(4×) and V(1.8×) than permanently depositing Baltic sediments. These constituents are relatively enriched in pelagic deposits, i.e. it is likely that much Mn, Ba and V in deep-sea sediments derive from the continents via suspended transport. This conclusion is supported by the similarity between suspended matter and average Atlantic pelagic sediment.
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| 3. |
- Gustafsson, Örjan, et al.
(författare)
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Colloid dynamics and transport of major elements through a boreal river - brackish bay mixing zone
- 2000
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Ingår i: Marine Chemistry. - 0304-4203 .- 1872-7581. ; 71:1-2, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- A range of biogeochemical methodologies were applied to investigate how aggregation processes affected the phase distribution and mixing of Fe, Si, and organic carbon between the Kalix River and the Bothnic Bay, northernmost Baltic Sea (salinity≤3; the low-salinity zone (LSZ) was stretching over 60 km in the spring). During the dynamic springflood conditions studied, small 238U-234Th disequilibria, low sediment trap fluxes, laboratory mixing experiments, as well as results from an independent two-box, two-dimensional mixing model combine to suggest that no significant removal of Fe, Si, or organic C was occurring in the highly-resolved LSZ. While no conclusions may be drawn based solely on property-salinity plots over narrow salinity ranges, apparently linear graphs for Fe and Si over 3 separate years also suggest minimal removal in this regime. At the same time, size distributions both of elements -from cross-flow ultrafiltration - and of bulk suspended solids - from light scattering (photon correlation spectroscopy [PCS]) - indicated that significant aggregation was taking place.The aggregation-without-significant-settling scenario in this low-salinity mixing regime, with a geochemistry similar to that of neighboring Russian Arctic rivers, is hypothesized to result from a comparatively high organic-to-detrital matter characteristic of the aggregates. While first principles would indeed suggest that decreasing electrostatic repulsion during mixing lead to aggregation, a low specific density of mineral-poor amorphous organic aggregates may lead to transport of these authigenic particles further away from the river mouth. The role of detrital "sinkers" on vertical removal of suspended organic matter is discussed in the wider context of scavenging mechanisms in the ocean.
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| 4. |
- Ingri, Johan, et al.
(författare)
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Chemistry of suspended particles in the southern Baltic Sea
- 1991
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Ingår i: Marine Chemistry. - 0304-4203 .- 1872-7581. ; 32:1, s. 73-87
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved and suspended concentrations of Al, Ba, Fe, Mn, and Si and suspended P and Ti have been studied in the Baltic proper, the Belt Sea-Kattegat and the Åland Sea. Approximately 20% of total Al, Fe and Mn, 75% of total Si and 99% of total Ba passed a 0.45-μm filter in subsurface water from the Baltic proper. The suspended phase can be divided into three major components, a detrital, a Mn rich and an organic phase. Suspended Al, Ti and most Fe were present in detrital particles. Approximately 50% of suspended Si was detrital while the amount of P in the detrital component was negligible. Suspended P showed a positive correlation to the non-detrital Fe concentration. Non-detrital Mn was strongly enriched in the suspended phase. In some samples 50% of the ashed suspended load was Mn. The Mn-rich particles originate from seasonally anoxic waters within the Baltic proper. During an anoxic episode in the Landsort Deep high dissolved concentrations of Mn were built up in the oxygen-free zone. A concentration of 700 μg l-1 was measured in the bottom water. Dissolved Mn concentrations dropped to values below 1 μg l-1, when the whole water column was oxygenated. Mn-rich particles, 40-80 μg l-1 suspended Mn, were found in the former reduced zone. Large temporal variations in the dissolved and suspended Mn concentrations were observed in the oxidized water column during the studied period. Both Ba and P were scavenged by the Mn-rich phase.
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| 5. |
- Widerlund, Anders
(författare)
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Early diagenetic remobilization of copper in near-shore marine sediments : a quantitative pore-water model
- 1996
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203 .- 1872-7581. ; 54:1-2, s. 41-53
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Tidskriftsartikel (refereegranskat)abstract
- Solid-phase and pore-water Cu have been determined for two cores in the low-salinity (2-3‰) Kalix River estuary, Sweden. The pore-water Cu concentration in the oxidized surface layer of the sediment (32-42 nmol l-1) exceeded the Cu concentration in the overlying bottom water (10-11 nmol l-1) by a factor of 3-4. Assuming that organic matter degradation follows first-order kinetics, a multi-G model with two organic matter fractions of different reactivity was used to describe the early diagenetic decomposition of organic matter. An estimated Cu/C mole ratio of 5.10-5 was obtained from sediment trap data. By combining this ratio with a steady-state pore-water Cu model, the early diagenetic remobilization of Cu was linked to the decomposition of organic matter. The rate constant for the reaction that releases Cu could be set equal to the decay constant of the highly reactive organic matter fraction (2.0 yr-1). This highly reactive fraction was decomposing under aerobic conditions close to the sediment-water interface. Early diagenetic remobilization of Cu in these sediments thus appears to be entirely controlled by aerobic decomposition of organic matter. An estimate of the diffusive benthic efflux of Cu (2.9 nmol cm-2 yr-1) suggests that ˜ 3% of the amount of Cu being deposited is released back into the water column.The pore-water model supports the idea that the Redfield model for the biological control of nitrogen and phosphorus can be extended to certain bioreactive trace elements.
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| 6. |
- Abbas, Zareen, 1962, et al.
(författare)
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Monte Carlo simulation of the dissociation constants of CO2 in 0 to 1 molal sodium chloride between 0 and 25 °C
- 2013
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 150:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Stoichiometric dissociation constants of the carbon dioxide system in NaCl solution between 0 and 1 mol and 0 to 25 °C were estimated by Monte Carlo (MC) simulations, and compared with Pitzer calculations and experimental measurements. The MC simulations used experimentally determined dielectric constants of water at different temperatures, and optimal agreement with the experimental data and Pitzer calculations was achieved by adjusting the ionic radii. This simple procedure resulted in effective ionic radii which were further used to simulate the activity coefficients of salt mixtures. The first and second stoichiometric dissociation constants of carbonic acid in NaCl solution (pK1⁎ and pK2⁎) were estimated from the MC-derived activity coefficients of mixed salts in NaCl. The MC results are in good agreement with the experimental data as well as with the Pitzer calculations. This study shows that Monte Carlo simulations in the temperature and ionic strength range relevant to seawater can provide pK values of the same quality as Pitzer calculations, and constitutes the first step in developing a temperature-dependent MC model for seawater. While MC calculations require greater computing resources, the number of parameters derived by fitting to thermodynamic data is substantially smaller than for Pitzer calculations.
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| 7. |
- Andersson, Maria, et al.
(författare)
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Air-sea exchange of volatile mercury in the North Atlantic Ocean
- 2011
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 125:1-4, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Part of the Beringia 2005 expedition covered the North Atlantic Ocean. During this passage, dissolved gaseous mercury (DGHg) in seawater and atmospheric concentrations of total gaseous mercury (TGHg), carbon monoxide (CO), and ozone (O-3) were measured continuously at high resolution. In addition, meteorological parameters such as wind speed and water temperature were measured continuously by the ship's meteorological instrumentation. The DGHg concentration was measured using a continuous equilibrium system where the elemental mercury in the sea water was equilibrated with a stream of gas. The DGHg concentration was calculated using DGHg=Hg-eq/k(H), where Hg-eq is the concentration of elemental mercury in the equilibrated air and k(H), is the dimensionless Henry's law constant. The degree of saturation was determined directly from the measurements S = Hg-eq/TGHg. The water sampled had an average DGHg concentration of 58 +/- 10 fM and the average TGHg concentration was determined to 1.7 +/- 0.1 ng m(-3). The water sampled was under- and super-saturated with respect to elemental mercury covering a large range of saturation of 70 to 230% resulting in an average degree of saturation of 150 +/- 30%. Therefore, both evasion and deposition of elemental mercury were observed in the sampled water. In the light of the average flux, 2.1 +/- 1.8 pmol m(-2) h(-1), it is concluded that mostly evasion occured during the sampling period. (C) 2011 Elsevier B.V. All rights reserved.
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| 8. |
- Andersson, Maria, 1980, et al.
(författare)
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Enhanced concentrations of dissolved gaseous mercury in the surface waters of the Arctic Ocean
- 2008
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 110:3-4, s. 190-194
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Tidskriftsartikel (refereegranskat)abstract
- During an almost three months long expedition in the Arctic Ocean, the Beringia 2005, dissolved gaseous mercury (DGM) was measured continuously in the surface water. The DGM concentration was measured using an equilibrium system, i.e. the DGM in the water phase equilibrated with a stream of gas and the gas was thereafter analysed with respect to its mercury content. The DGM concentrations were calculated using the following equation, DGM = Hg eq / k H' where Hg eq is the equilibrated concentration of elemental mercury in the gas phase and k H' is the dimensionless Henry's law constant at desired temperature and salinity. During the expedition several features were observed. For example, enhanced DGM concentration was measured underneath the ice which may indicate that the sea ice acted as a barrier for evasion of mercury from the Arctic Ocean to the atmosphere. Furthermore, elevated DGM concentrations were observed in water that might have originated from river discharge. The gas-exchange of mercury between the ocean and the atmosphere was calculated in the open water and both deposition and evasion were observed. The measurements showed significantly enhanced DGM concentrations, compared to more southern latitudes. © 2008 Elsevier B.V. All rights reserved.
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| 9. |
- Andersson, Maria, 1980, et al.
(författare)
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Seasonal and daily variation of mercury evasion at coastal and off shore sites from the Mediterranean Sea
- 2007
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 104:3-4, s. 214-226
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved gaseous mercury (DGM) was measured continuously using two newly developed techniques and a manual technique. The continuous techniques were based on the equilibrium between the aqueous and gaseous phase (DGM = Hg-extr / H', Hg-extr is the measured mercury concentration in the gas phase, H' is the Henry's Law coefficient at the desired temperature). In order to calculate the annual mercury evasion from the Mediterranean Sea, diurnal and seasonal measurements of DGM, total gaseous mercury in air (TGM), water temperature and wind speed were performed. During August 2003, March-April 2004 and October-November 2004 measurements of these parameters were conducted on board the RV Urania. The continuous measurements of DGM showed a diurnal variation in concentration, at both coastal and off shore sites, with higher concentrations during daytime than nighttime. The concentration difference could be as large as 130 fM between day and night. The degree of saturation was calculated directly from the measurements, S = Hg-extr / TGM and was found to vary between the different seasons. The highest average degree of saturation (850%) and the largest variation in saturation (600-1150%) was observed during the summer. The spring showed the lowest variation (260-360%) and the lowest average degree of saturation (320%). The autumn also showed a large variation in saturation (500-1070%) but a lower average (740%) compared to the summer cruise. This might be explained by the temperature difference between the different seasons, since that parameter varied the most. The flux from the sea surface was calculated using the gas exchange model developed by Nightingale et al. [Nightingale, P.D., Malin, G., Law, C.S., Watson, A.J., Liss, P. S., Liddicoat, M.I., Boutin, J., Upstill-Goddard, R. C., 2000. In situ evaluation of air-sea gas exchange parameterization using novel conservative and volatile tracers. Global Biogeochemical Cycles, 14(l):373-387]. The evasion varied between the different seasons with the highest evasion during the autumn, 24.6 pmol m(-2) h(-1). The summer value was estimated to 22.3 pmol m(-2) h(-1) and the spring to 7.6 pmol m(-2) h(-1). Using this data the yearly evasion from the Mediterranean Sea surface was estimated to 77 tons. (C) 2006 Elsevier B.V. All rights reserved.
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| 10. |
- Bauer, Susanne, et al.
(författare)
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Distribution of dissolved and suspended particulate molybdenum, vanadium, and tungsten in the Baltic Sea
- 2017
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Ingår i: Marine Chemistry. - : Elsevier. - 0304-4203 .- 1872-7581. ; 196, s. 135-147
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Tidskriftsartikel (refereegranskat)abstract
- In natural waters, dissolved oxyanions often dominate over the particle-bound element fraction. Still, the scavenging of oxyanions by suspended particles might contribute significantly to their dynamic cycling and distribution. To investigate how oxyanions are affected by manganese (Mn) redox cycling, detailed depth profiles across the pelagic redox zone at the Landsort Deep, Baltic Sea, were collected for molybdenum (Mo), vanadium (V), and tungsten (W), for both dissolved (<0.22 µm) and suspended particulate (>0.22 µm) fractions.All three oxyanions show a non-conservative behavior in the stratified Landsort Deep. Strong linear correlations with Mn in the particulate fraction in the redox zone of the Landsort Deep suggest that Mn redox cycling influences their distribution. In the dissolved fraction, Mo, V, and W exhibited rather different behavior. Molybdenum was depleted below the redox zone, while V was depleted only within the redox zone. Tungsten concentrations increased within the redox zone, being three times higher in the sulfidic zone than in the surface water. Unlike Mo, W shows no tendency for adsorption or co-precipitation under the prevailing weak sulfidic conditions in the deep water of the Landsort Deep and is, therefore, not exported to the underlying sediment.The Landsort Deep data were compared with data from the northern Baltic Sea (Bothnian Bay, Kalix River and Råne River estuaries), where particulate iron (Fe) occurs in high abundance. The particulate fractions of Mo, V, and W decreased during mixing in these estuaries. Vanadium showed the most drastic reduction, with a decrease in dissolved and particulate fractions, indicating that different processes influence the distribution of these oxyanions.
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