| 1. |
- Apler, Anna, 1980-
(författare)
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Contaminated organic sediments of anthropogenic origin: impact on coastal environments
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Baltic Sea is negatively affected by legacy pollutants such as metals and persistent organic pollutants (POPs) that are known to have adverse effects on living organisms, including, humans and were banned decades ago. This thesis addresses the dispersal of these pollutants from heavily contaminated, cellulose-rich sediments of industrial origin in the Ångermanälven river estuary in northern Sweden. Relatively thick deposits, known as fiberbanks, in the studied area derive from historical wastewater emissions from the pulp and paper industry (P&PI) that began in the 19th century. These fiberbanks formed on shallow seabeds, where they currently remain. In addition, extensive areas of the deeper seabed are covered by fiber-rich sediments. The fiberbanks contain higher levels of pollutants than the fiber-rich sediments and the sediments less affected by P&PI emissions, and the fiberbank concentrations may be of ecotoxicological concern. Metals and POPs were found to be strongly partitioned to organic material and partitioning coefficients were higher in fiberbanks that contain elevated levels of organic matter. Metals and POPs were detectable in sampled pore water, even if low sediment-water fluxes of metals were expected. Metal contaminant concentrations in sampled bottom water were measured before and after resuspension of underlying sediments, which showed that concentrations of particle bound metals dominated over dissolved forms. One out of three studied fiberbank sites was covered with a natural capping layer that probably shields the water column from metals in the deposit underneath. Studies of geological archives in the form of sediment cores show the rise and fall of an anthropogenic industrial era and the recovery of an aquatic system, but the established chemostratigraphy fails to reveal the current hotspots (fiberbanks) that will stay for decades to come. The potential impacts of climate change and isostatic land uplift are factors that complicate the long-term risk assessment of fiberbanks. These knowledge gaps combined with the lack of a common risk assessment strategy for contaminated sediments hinder the achievement of national quality objectives (NQOs) and fulfillment of Agenda 2030 goals. Fiberbanks resulted from an accelerating global demand for paper products and hence, the issue of these artificial seabed forms is an example of how the geological epoch of humankind, the Anthropocene, can be viewed in a cross-scalar perspective and be important in the management of a sustainable future in the Baltic Sea region.
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| 2. |
- Apler, Anna, 1980-
(författare)
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Dispersal and environmental impact of contaminants in organic rich, fibrous sediments of industrial origin in the Baltic Sea
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The health of the Baltic Sea is negatively affected by hazardous substances such as metals and persistent organic pollutants (POPs), which include legacy pollutants that were banned decades ago, but still circulate in the ecosystem. Elevated levels of legacy pollutants, identified by HELCOM as key hazardous substances, have been found in accumulations of fibrous sediments, so-called fiberbanks and fiber-rich sediments, which derive from old pulp mills along the Swedish north coast. The fiberbanks are deposited in shallow water and bathymetrical models show evidence of their erosion, potentially caused by propeller wash, submarine landslides and gas ebullition. This thesis addresses the potential dispersal of key substances from three fiberbank sites located in a non-tidal Swedish estuary, in which metals and POPs are present in concentrations that may pose a risk for benthic organisms. Metals and POPs are partitioned to organic material and, as expected, show the highest partitioning coefficients (KD) in fiberbanks that have higher TOC levels compared to adjacent areas with fiber-rich sediments (natural clay sediments mixed up with fibers) or relatively unaffected postglacial clays. However, many analytes were found to be present in quantifiable concentrations in pore water, which indicates diffusion of substances from the solid phase to the aqueous phase. To assess the dispersive influence of an abrupt erosional event on dispersion, metals were measured in undisturbed bottom water and in bottom water disturbed by artificial re-suspension of fibrous sediments. The bioavailable, dissolved fraction of metals decreased in bottom water after re-suspension, probably due to the particle concentration effect. In contrast, the total concentrations of metals and number of quantifiable metals increased with particle concentration caused by re-suspension. At one station, the total concentration of chromium (Cr) was elevated to a level where it may lower the ecological status of the water body during periods of substantial erosion (e.g. spring floods or submarine landslides). Analyses of disturbed bottom water revealed, however, that minerogenic particles were preferentially re-suspended compared to organic. This suggests that physical erosion and re-suspension of fiberbank sediments might have a larger effect on dispersal of metals than on POPs.
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| 3. |
- Apler, Anna, 1980-, et al.
(författare)
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The Anthropocene in the northern Baltic Sea – the case of contaminated fiberbanks and implications for sustainable development
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The epoch of humankind, the Anthropocene, is usually characterized by the global gaze, which places its focus on global environmental phenomena i.e. global warming and ocean acidification. In this article we argue that the Anthropocene could be better understood with a cross-scalar perspective and present the case of anthropogenic contaminated “fiberbanks” as an example. We present a geological example of the Anthropocene in a Swedish river estuary in the northern Baltic Sea, which hosted nine P&P mills along its’ shores and received large amounts of metal containing wastewater during the 20th century. As a result of the great acceleration and an increased national and global demand for pulp and paper products these fiberbanks formed in shallow waters. As artificial seabed features these thick deposits of contaminated organic-rich material negatively affect the adjacent aquatic environment. By constructing a chemostratigraphy based on sediment cores from accumulation areas and a metal pollution index we show how the aquatic system has recovered from metal pollution. We note, however, that the established stratigraphy fails to identify the fiberbanks, which remain in the shallow zones and are contaminant hotspots. In Sweden, there is an insufficient knowledge of contaminated sediments for a sustainable water and marine management. This knowledge gap in combination with human induced climate changes that may chemically and physically affect sediments and thus, alter dispersion of imbedded pollutants, results in poor understanding and long-term perception of the risks of contaminant dispersion from fiberbanks. We claim that these gaps of knowledge must be filled in order to reach an effective conservation at the same time as a sustainable blue growth in the northern Baltic Sea.
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| 4. |
- Lougheed, Bryan C., et al.
(författare)
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Bulk sediment 14C dating in an estuarine environment: : How accurate can it be?
- 2017
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Ingår i: Paleoceanography. - : AMER GEOPHYSICAL UNION. - 0883-8305 .- 1944-9186. ; 32:2, s. 123-131
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Due to a lack of marine macrofossils in many sediment cores from the estuarine Baltic Sea, researchers are often forced to carry out 14C determinations on bulk sediment samples. However, ambiguity surrounding the carbon source pathways that contribute to bulk sediment formation introduces a large uncertainty into 14C geochronologies based on such samples, and such uncertainty may not have been fully considered in previous Baltic Sea studies. We quantify this uncertainty by analyzing bulk sediment 14C determinations carried out on densely spaced intervals in independently dated late-Holocene sediment sequences from two central Baltic Sea cores. Our results show a difference of ~600?14C?yr in median bulk sediment reservoir age, or R(t)bulk, between the two core locations (~1200?14C?yr for one core, ~620?14C?yr for the other), indicating large spatial variation. Furthermore, we also find large downcore (i.e., temporal) R(t)bulk variation of at least ~200?14C?yr for both cores. We also find a difference of 585?14C?yr between two samples taken from the same core depth. We propose that studies using bulk sediment 14C dating in large brackish water bodies should take such spatiotemporal variation in R(t)bulk into account when assessing uncertainties, thus leading to a larger, but more accurate, calibrated age range.
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| 5. |
- Moros, Matthias, et al.
(författare)
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Is 'deep-water formation' in the Baltic Sea a key to understanding seabed dynamics and ventilation changes over the past 7,000 years?
- 2020
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 550, s. 55-65
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Tidskriftsartikel (refereegranskat)abstract
- Numerous hydro-acoustic studies of the seabed of the Baltic Sea have revealed the unusual occurrence of sediment contourite drifts and re-suspension at greater water depths. In addition, radiocarbon dating of bulk sediments indicates significant age reversals. We present new geophysical, sediment proxy data (including extensive radiocarbon dating) and hydrographic measurements, which are combined with results of numerous marine geological studies performed during the last decades. These data indicate that a deep-water formation process significantly affected the seabed dynamics during regional climatically cold phases during the last c. 7,000 years. We propose that, during the colder periods (e.g. the Little Ice Age), newly formed bottom waters likely caused widespread re-suspension of organic carbon-rich laminated sediments that were deposited during the preceding warm periods in shallower areas, and this material was transported to and re-deposited in the deeper parts of the Baltic Sea sub-basins. In our scenario, a topographic feature, known as the Baltic Sea Klint, acted as a hydrographic barrier for deep-water formed in the northern Baltic. Thus, during the cold periods increased lateral matter influx from the northern Baltic led to the accumulation of much thicker macroscopically homogenous clayey sediments in sub-basins north of the Klint. Moreover, deep-water formation produced bottom currents that led to the formation of sediment contourite drifts at water depths of> 200 m in the Bothnian Sea, the Aland Deep and northern central Baltic Sea sub-basins. Bottom water ventilation in the Baltic Sea is generally assumed to be determined solely by the inflow of oxygen-rich, saline water from the North Sea, but we challenge this assumption and postulate that deep-water formation is a key process that ventilates the bottom waters of the Baltic Sea during climatically cold periods with substantial implications for its sedimentary archive.
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| 6. |
- Moros, Matthias, et al.
(författare)
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Towards an event stratigraphy for Baltic Sea sediments deposited since AD 1900 : approaches and challenges
- 2017
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Ingår i: Boreas. - : Wiley. - 0300-9483 .- 1502-3885. ; 46:1, s. 129-142
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Tidskriftsartikel (refereegranskat)abstract
- Reconstructions of environmental changes at sub-decadal to decadal resolution based on central Baltic Sea sediments rely on accurate and precise high-resolution sediment depth/age relationships. A model chronology for Baltic Sea sediments is presented here based on established historical records of anthropogenic radionuclides (Cs-137/Am-241/bomb(14)C), polychlorinated biphenyls (PCBs), lead (Pb) and stable lead isotope (Pb-206/207 ratios), and radionuclide Pb-210 and C-14 decay dating methods. Marker horizons consisting of chemical precipitates formed by documented Major Baltic Inflow (MBIs) events and an extended diatom bloom period were also integrated into the model. The main time markers in Baltic Sea sediments that formed during the last 120years were the following: (i) the deepest observation of Pb-210(unsupp.) (marking the Pb-210 dating horizon) and departure of Hg from natural background levels at c.AD 1900; (ii) first detectable presence of PCBs at AD 1935; (iii) radionuclide production (i.e. Am-241) due to nuclear weapons testing between AD 1954 and AD 1975, with a peak in AD 1963; (iv) maximum heavy metal and PCB concentrations in the AD 1960s/1970s; (v) the Chernobyl nuclear accident in AD 1986 as a sharp Cs-137 increase; (vi) exceptionally strong diatom blooms with a massive diatom layer found in the Eastern Gotland Basin in AD 1988-1990; and (vii) characteristic manganese-carbonate layers in the deeper central basins formed by MBIs in AD 1993 and AD 2003. A precise and accurate sediment depth/age relationship can only be achieved in restricted areas of the Baltic Sea where continuous sedimentation has prevailed and there has been limited postdepositional disturbance. We demonstrate that parallel Hg and Cs-137 measurements can be used to assess the quality of sediment sequences for high-resolution environmental reconstructions. We show examples of sediment profiles that conform to the historical record, and examples from Western Baltic Sea areas where it appears to be impossible to establish accurate geochronologies.
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| 7. |
- Nyberg, Johan, et al.
(författare)
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Spatial characterization of seabed environmental conditions and geotechnical properties for the development of marine renewable energy in Sweden
- 2022
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Ingår i: Quarterly journal of engineering geology and hydrogeology. - : Geological Society of London. - 1470-9236 .- 2041-4803. ; 55:4, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- Although knowledge of seabed properties is of high importance in selecting sites and determining technical designs and solutions for renewable energy offshore installations, it is often overlooked in marine spatial planning, owing to the absence of appropriate spatial analysis of these conditions. Identification and quantification of seabed conditions and geotechnical properties in finding safe and environmentally sustainable areas for installations of offshore renewable energy are therefore presented, using information produced in marine geological mapping. Six seabed environmental and 13 geotechnical parameters, which can be extracted from existing marine geological information and are of importance in analysing environmental conditions and planning designs are identified and presented, in addition to the suitability of various installation techniques for different areas on the Swedish seabed. Geographical information systems (GIS) are used to geo spatially evaluate the different parameters in finding suitable locations and cable routes for a wave energy plant with gravity and/or suction caisson foundations. The presented categories and ranges of the environmental and geotechnical values for the various parameters have the possibility to be improved as new data are produced from future mapping. The parameters identified and presented here are valuable as they can be incorporated into multi-parameter evaluations for optimal site selection of different offshore installations.
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| 8. |
- Snowball, Ian, et al.
(författare)
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Bacterial magnetite in Swedish varved lake-sediments: a potential bio-marker of environmental change
- 2002
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Ingår i: Quaternary International. - 1873-4553. ; 88, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- Detailed mineral magnetic measurements were carried out on three varved lake-sediment sequences in Sweden, which extend to ca. 7000 BC. The comparison of the magnetic properties of the organic rich varved lake-sediments with their respective catchment materials indicates that the magnetic properties of the sediments are dominated by relatively high concentrations of single-domain magnetite magnetosomes produced by magnetotactic bacteria. The dimictic nature of the lakes, which help form and preserve the varves due to the weakly oxic or suboxic environment, also appear to be suitable for a high degree of magnetosome preservation. The concentration of the magnetosomes in two of the sequences, as determined by mass specific magnetic measurements, exhibits a positive linear relationship with the total organic carbon content and suggests that magnetic remanence measurements reflect lake productivity, via processes of organic matter accumulation and decomposition. Further research should focus on the potential to use the fossil magnetosomes as proxy-climate/environmental change indicators and as recorders of geomagnetic field variations and behaviour. (C) 2002 Elsevier Science Ltd and INQUA. All rights reserved.
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| 9. |
- Snowball, Ian, et al.
(författare)
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FENNOSTACK and FENNORPIS: Varve dated Holocene palaeomagnetic secular variation and relative palaeointensity stacks for Fennoscandia
- 2007
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 1385-013X .- 0012-821X. ; 255, s. 106-116
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Tidskriftsartikel (refereegranskat)abstract
- A Holocene palaeomagnetic secular variation master curve (FENNOSTACK) and a relative palaeointensity curve (FENNORPIS) for Fennoscandia are presented. These curves were produced by stacking palaeomagnetic data obtained from six annually laminated (varved) lake sediment sequences and one non-laminated sediment sequence. The six independent varve chronologies were combined to form a timescale, which extends between the present year and 10,200 Cal yr BP. Smoothed inclination and declination curves show trends that are similar to a palaeomagnetic secular variation curve for the United Kingdom, except that the ages of most of the statistically significant features are a few hundred years younger in the Fennoscandian data set. These differences are most likely due to excessively old ages of the United Kingdom features produced by the radiocarbon dating of bulk sediments. The standardized relative palaeointensity stack shows that the intensity of the geomagnetic field in Fennoscandia was highest at 2300 Cal yr BP and lowest at 7000 Cal yr BP. Three palaeointensity peaks (PIPs) and three palaeointensity lows (PILs) are identified in FENNORPIS and indicate that the intensity of geomagnetic field varied significantly on millennial scales in this region during the Holocene, but there is much scatter in the reconstruction prior to 8000 Cal yr BP. Higher frequency palaeointensity features present in individual records are not significant in the stacked data set, which implies that these are a result of local environmental bias. Significant discrepancies exist between the data and the output of the CALS7K.2 geomagnetic field model for the last 7000 yr. In particular, the largest declination swing observed in the data at 2670 Cal yr BP (feature “f”) is not produced by the model, which is most likely due to the influence of an inaccurately dated Icelandic secular variation curve on the model result. Short term trends in standardized relative palaeointensity do differ from the model output, but it is difficult to make a comparison because of the relative nature of the sediment record. Better absolute palaeointensity data are needed to reduce uncertainties in reconstructions of past geomagnetic field strength.
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| 10. |
- Snowball, Ian, et al.
(författare)
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Radiocarbon wiggle matching of Swedish lake varves reveals asynchronous climate changes around the 8.2 kyr cold event
- 2010
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Ingår i: Boreas. - : Wiley. - 1502-3885 .- 0300-9483. ; 39:4, s. 720-733
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Tidskriftsartikel (refereegranskat)abstract
- A series of nine radiocarbon measurements obtained at increments of 50 years was used to wiggle match varved sediments in Lake Kalksjon (west central Sweden) to the calendar year time scale provided by the tree-ring-derived radiocarbon calibration curve. The anchor point for a series of 400 varves known to span the '8.2 kyr cold event' was derived from a combination of correlation analysis, Monte Carlo statistics and Bayesian age modelling. The GRIP and NorthGRIP ice-cores were matched to the same absolute time scale by comparing Be-10 data and tree-ring Delta C-14. The radiocarbon-based wiggle match, organic carbon measurements, mineral magnetic parameters and XRF data reconstruct a distinct period of enhanced erosion in Kalksjon's catchment between 8066+/-25 and 7920+/-25 cal. yr BP. Prior to human impact, the increased erosion in the boreal environment is assigned to increased winter precipitation in the form of snow, which caused spring meltwater discharge to intensify. Our results suggest that the abrupt onset of increased winter precipitation in west central Sweden started at least 50 years after the onset of the '8.2 kyr cold event' as defined by oxygen isotope data from Greenland. The study highlights the value of synchronized time scales in the reconstruction of abrupt climate changes based on proxy data.
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