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  • 1.
    Bauer, Susanne
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Blomqvist, Sven
    Department of Ecology, Environment and Plant Sciences, Stockholm University.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Distribution of dissolved and suspended particulate molybdenum, vanadium, and tungsten in the Baltic Sea2017In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 196, p. 135-147Article in journal (Refereed)
    Abstract [en]

    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.

  • 2.
    Boström, Kurt
    et al.
    Luleå tekniska universitet.
    Burman, J-O
    Luleå tekniska universitet.
    Pontér, Christer
    Luleå tekniska universitet.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Selective removal of trace elements from the Baltic by suspended matter1981In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 10, no 4, p. 335-354Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Boström, Kurt
    et al.
    Stockholms Universitet.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pontér, Christer
    Luleå tekniska universitet.
    Origin of iron-manganese-rich suspended matter in the Landsort Deep, NW Baltic Sea1988In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 24, no 1, p. 93-98Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Gustafsson, Örjan
    et al.
    Stockholms Universitet.
    Larsson, Jenny
    Stockholms Universitet.
    Andersson, Per
    Swedish Museum of Natural History.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The POC / 234Th ratio of settling particles isolated using split flow-thin cell fractionation (SPLITT)2006In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 100, no 3-4, p. 314-322Article in journal (Refereed)
    Abstract [en]

    The common assumption that the ratio between particulate organic carbon (POC) and particulate 234Th obtained from shallow sediment traps and filterable particles are representative of the ratio in the total particle settling flux should be treated with caution in view of well-known biases associated with tethered shallow sediment traps and the decoupling between size and settling velocity of many natural particle regimes. To make progress toward reliably constraining the POC / 234Th ratio on truly settling particles, we have tested here a settling collection technique designed to remove any hydrodynamic bias; split flow-thin cell fractionation (SPLITT). These first results from a North Sea fjord and an open Baltic Sea time-series station indicates that the POC / 234Th ratio on the more complete particle-settling spectrum, isolated with SPLITT, was higher than the POC / 234Th ratio obtained simultaneously from tethered shallow sediment traps in seven out of seven parallel deployments with an average factor of 210%. The POC / 234Th ratio from the SPLITT was either in the same range or higher than that obtained on filtered "bulk" particles. To explain this novel data we hypothesize that the slowest settling fraction is organic-matter rich and does not strongly complex 234Th (i.e., high POC / 234Th). We suggest that this ultra-slow sinking fraction is better collected by SPLITT than with tethered sediment traps because of minimized hydrodynamic bias. This was tested using the ratio of POC / Al as a tracer of detrital mineral-ballast influenced settling velocity. The higher POC / Al ratios in SPLITT samples relative to in traps is consistent with the hypothesis that SPLITT is better suited for collecting also the slow-settling component of sinking particles. This important slow-settling component appears to here consist primarily of non-APS/TEP components of plankton exudates or other less-strongly 234Th-complexing organic matter. Further applications of the SPLITT technique are likely to return increasingly new insights on the composition (including "truly settling" POC / 234Th) of the total spectrum of particles settling out of the upper ocean.

  • 5.
    Gustafsson, Örjan
    et al.
    Institute of Applied Environmental Research (ITM), Stockholm University.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Andersson, Per S
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Roos, Per
    Department of Radiation Physics, Lund University.
    Ledin, Anna
    Department of Environmental Science and Engineering, Technical University of Denmark.
    Colloid dynamics and transport of major elements through a boreal river - brackish bay mixing zone2000In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 71, no 1-2, p. 1-21Article in journal (Refereed)
    Abstract [en]

    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.

  • 6.
    Ingri, Johan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Löfvendahl, Runo
    Stockholms Universitet.
    Boström, Kurt
    Stockholms Universitet.
    Chemistry of suspended particles in the southern Baltic Sea1991In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 32, no 1, p. 73-87Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Ingri, Johan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nordling, Susanna
    Institute of Applied Environmental Research (ITM), Stockholm University.
    Larsson, Jenny
    Institute of Applied Environmental Research (ITM), Stockholm University.
    Rönnegård, Jenny
    Institute of Applied Environmental Research (ITM), Stockholm University.
    Nilsson, Nina
    Institute of Applied Environmental Research (ITM), Stockholm University.
    Rodushkin, Ilia
    Dahlqvist, Ralf
    Department of Geology and Geochemistry, Stockholm University.
    Andersson, Per
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm.
    Gustafsson, Örjan
    Institute of Applied Environmental Research (ITM), Stockholm University.
    Size distribution of colloidal trace metals and organic carbon during a coastal bloom in the Baltic Sea2004In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 91, no 1-4, p. 117-130Article in journal (Refereed)
    Abstract [en]

    The physico-chemical speciation of organic carbon and selected metals was measured during a coastal bloom in Ekhagen Bay, Baltic Sea, using ultrafiltration.One important objective with the study was to see if any depletion of trace metals could be measured in the directly bioavailable fraction (<1000 Da, the soluble low molecular weight fraction, LMW) during a plankton bloom. Filters with five different cut-offs were used (1 kD (1000 Da), 5 kD, 10 kD, 100 kD and 0.22 μm) in order to delineate the size distribution of colloidal organic carbon (COC) and trace metals. During the bloom in May, LMW Al, Co, Cu, Mn and Ni concentrations decreased although the colloidal and particulate concentrations were relatively high. Data show that desorption of colloidal and particulate bound trace metals to the LMW fraction was slower than the process depleting the LMW fraction. Estimates of the maximum active uptake of Cu, Ni and Mn by the phytoplankton, and the loss of non-bioactive Al from the LMW fraction, indicate that processes other than active uptake by phytoplankton must contribute to the observed depletion of trace metals in the LMW fraction. Hence, in order to estimate the bioavailable pool of trace metals for plankton during bloom conditions, these other processes must be understood and quantified. Transparent Exopolymeric Particles (TEP, reflecting sugar-rich phytoplankton exudates) increased around eight times during the plankton bloom. We hypothesize that the formation of TEP is a process that might be important for the transfer of trace metals from the LMW to the particulate fraction during the phytoplankton bloom, but the significance of TEP for this depletion in Baltic Sea surface water remains to be shown.

  • 8.
    Ingri, Johan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Suteerasak, Thongchai
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bauer, Susanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Changes in trace metal sedimentation during freshening of a coastal basin2014In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 167, p. 2-12Article in journal (Refereed)
    Abstract [en]

    Holocene freshening has turned the Bothnian Bay, northern Baltic Sea into an oligotrophic basin. Sequestering of trace elements has changed significantly during the oligotrophication process. In principle, trace metals have been transferred from permanently buried sulfides to Fe–Mn-oxyhydroxides in the top layers of the sediment. The oxyhydroxide layers restrict the flux of trace metals from the sediment to the oxic bottom water. Hence, Fe–Mn cycling in the suboxic sediment enriches a number of trace metals in the surface sediment. Arsenic, Sn, Ge and Bi show enrichment in the Fe-oxyhydroxide layer, whereas Mo, Cd, Ni, Co, Cu, and Sb are enriched in the uppermost Mn-oxyhydroxide layer. This natural redox cycling in the sediment obscures pollution effects.The oligotrophication process started approximately 3500 years ago, reflected in decreasing deposition of Zn, a proxy for phytoplankton production, and formation of Mn oxyhydroxide layers. Similarly, Ba/Al data indicate a decrease in the pelagic input of plankton. Barium data also suggest that dissolved sulfide in the sediment never reached high concentrations. Germanium is closely related to Ba, suggesting that Ge can be used as a proxy for phytoplankton production. Vanadium, U, Re, and Mo all indicate that the bottom water never has been significantly sulfidic during the last 5500 years. Rhenium data indicate that the organic carbon oxidation rate has decreased during the last 5500 years. Cadmium follows the organic matter distribution, but started to increase 1000 YBP (years before present). The reason for this enhanced input of Cd is unclear.

  • 9.
    Walve, Jakob
    et al.
    Department of Ecology, Environment and Plant Sciences, Stockholm University.
    Gelting, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Trace metals and nutrients in Baltic Sea cyanobacteria: Internal and external fractions and potential use in nitrogen fixation2014In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 158, p. 27-38Article in journal (Refereed)
    Abstract [en]

    Even though the availability of trace metals influences nitrogen fixation and growth of cyanobacteria, field data on their cellular metal composition are scarce. In this study, contents of Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and the major elements C, N, P and Si were studied in filamentous, nitrogen-fixing cyanobacteria sampled over the growth season March-October at two locations in the Baltic proper (years 2004 and 2007) and one location in the Bothnian Sea (2006). The Al and Ti contents indicated that lithogenic Fe was an important Fe fraction associated with Nodularia spumigena, but not with Aphanizomenon sp. Treatment with an oxalate-EDTA solution indicated that less than 5% of total Fe was adsorbed as oxides, but relatively high adsorbed fractions were found for Mn and Cu. Despite large variation in biomass and dissolved Fe concentrations, the Fe:C ratio of Aphanizomenon was highly consistent within years and across sampling stations (76 ± 13 μmol mol- 1 C, average ± 1SD), indicating growth controls other than Fe. Species-mixed samples corrected for lithogenic metals indicate similar Fe content in Nodularia as in Aphanizomenon. Calculations based on the use efficiency of Mo for N2 fixation indicates that most Mo in Nodularia and at least a third of the Mo in Aphanizomenon is used in nitrogenase, corresponding to 5-24% of the Fe content. The high Ni content suggests excess storage or extensive use in enzymes such as Ni superoxide dismutase or in Fe-dependent Ni-hydrogenases. The trace metal composition of the investigated Baltic cyanobacteria was similar to that reported for the oceanic genus Trichodesmium, suggesting common physiological requirements of these filamentous nitrogen-fixing cyanobacteria.

  • 10.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Early diagenetic remobilization of copper in near-shore marine sediments: a quantitative pore-water model1996In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 54, no 1-2, p. 41-53Article in journal (Refereed)
    Abstract [en]

    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.

  • 11.
    Österlund, Helene
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gelting, Johan
    Nordblad, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Baxter, Douglas
    ALS Scandinavia AB.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Copper and nickel in ultrafiltered brackish water: labile or non-labile?2012In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 132-133, no 1, p. 34-43Article in journal (Refereed)
    Abstract [en]

    Copper and nickel were sampled at three stations in the Baltic Sea using diffusive gradients in thin films (DGT) passive samplers and ultrafiltration (< 1 kDa). Two versions of DGT devices were used, the normal open pore (OP) and a restricted pore (RP). The OP DGT and RP DGT concentrations closely followed each other both in depth profiles and time series. The lack of significant difference between OP and RP DGT suggests that the labile complexes were smaller than the pore size of the RP gel (approximately 1 nm). These data, together with OP DGT measurements at the same location in two different years, clearly demonstrate that the DGT method is robust and indicates reproducible results during routine field conditions.Between 50 and 80% of the ultrafiltered fractions for Ni and Cu could not be detected by the DGT method, using standard procedures. This suggests the presence of complexing ligands for Cu and Ni. Assuming 100% complexation of Ni to fulvic acid ligand gave DGT concentrations similar to ultrafiltered Ni concentrations. The equivalent calculation for Cu indicates that up to 75% of the ultrafiltered Cu fraction is non-labile. The non-labile Cu complexes are proposed to be produced at sea since the fraction increases with decreasing terrestrial influence.

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