| 1. |
- Reckermann, M., et al.
(author)
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Human impacts and their interactions in the Baltic Sea region
- 2022
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In: Earth Syst. Dynam.. - : Copernicus GmbH. - 2190-4987 .- 2190-4979. ; 13:1, s. 1-80
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Research review (peer-reviewed)abstract
- Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are strongly affected by human activities. A multitude of human impacts, including climate change, affect the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, and coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.
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| 2. |
- Ahlgren, Joakim, et al.
(author)
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Orsaker till minskande syrehalter i Bottenhavet
- 2017
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Reports (peer-reviewed)abstract
- Resultat från den nationella miljöövervakningen visar att syrehalterna i Bottenhavet har minskat sedan 1970-talet, en minskning som accelererat från 1990. För att ha möjlighet att på något sätt kunna åtgärda denna försämring av den marina miljön är det nödvändigt att identifiera orsakerna till denna syreminskning, eftersom olika orsaker kan kräva olika former av åtgärder. Om orsaken till exempel är ökad syreförbrukning beroende på regional övergödning, skulle detta innebära ökat behov av regionala reningsåtgärder. Målsättningen med projektet var därmed att ge en tillförlitlig förklaring till de sjunkande syrehalterna i Bottenhavet under de senaste 20 åren genom att använda data från de nationella miljöövervakningsprogrammen. De huvudhypoteser som undersöktes som orsaker till de sjunkande syrehalterna var: • Ökad regional gödning av Bottenhavet och därmed ökad produktion. • Tillförsel av syrefattigt och fosfatrikt från Egentliga Östersjön. • Starkare haloklin och försämrad ventilation av Bottenhavets djupvatten. • Ökad temperatur och ökad tillförsel av löst organiskt kol. Analys av tidsserier och modellanalyser utifrån miljöövervaknings- och forskningsdata visade att den observerade syrehaltsminskningen i Bottenhavets djupvatten främst beror på en ökning av vattentemperaturen och delvis på en ökning av löst organiskt kol i vattnet, samt tillflöde från Egentliga Östersjön. Dataanalysen visade däremot inget tydligt stöd för att ökad produktion av biomassa i Bottenhavet orsakat de minskande syrehalterna. Detta gäller indikatorer för växtplankton, sedimentation och bakterieplankton som alla förväntas öka vid ökad produktion och det finns således inga direkta indicier för att stödja hypotesen om ökad gödning av Bottenhavet. Sammantaget visar de analyser som gjorts inom projektet att Bottenhavets framtida hälsa främst gynnas av en kombination av åtgärder för att motverka globala klimatförändringar, samt åtgärder för att förbättra vattenkvaliteten i Egentliga Östersjön. Näringstillförsel från Bottenhavets avrinningsområden bedöms främst ha haft betydelse för syresituationen i kustnära vattenförekomster. Den bedöms därför inte i betydande omfattning ha orsakat de minskande syrehalterna i Bottenhavets utsjöområden.
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| 3. |
- Ahlgren, Joakim, et al.
(author)
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Temperature, DOC level and basin interactions explain the declining oxygen concentrations in the Bothnian Sea
- 2017
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In: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 170, s. 22-30
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Journal article (peer-reviewed)abstract
- Hypoxia and oxygen deficient zones are expanding worldwide. To properly manage this deterioration of the marine environment, it is important to identify the causes of oxygen declines and the influence of anthropogenic activities. Here, we provide a study aiming to explain the declining oxygen levels in the deep waters of the Bothnian Sea over the past 20 years by investigating data from environmental monitoring programmes. The observed decline in oxygen concentrations in deep waters was found to be primarily a consequence of water temperature increase and partly caused by an increase in dissolved organic carbon (DOC) in the seawater (R-Adj(2). = 0.83) as well as inflow from the adjacent sea basin. As none of the tested eutrophication-related predictors were significant according to a stepwise multiple regression, a regional increase in nutrient inputs to the area is unlikely to explain a significant portion of the oxygen decline. Based on the findings of this study, preventing the development of anoxia in the deep water of the Bothnian Sea is dependent on the large-scale measures taken to reduce climate change. In addition, the reduction of the nutrient load to the Baltic Proper is required to counteract the development of hypoxic and phosphate-rich water in the Baltic Proper, which can form deep water in the Bothnian Sea. The relative importance of these sources to oxygen consumption is difficult to determine from the available data, but the results clearly demonstrate the importance of climate related factors such as temperature, DOC and inflow from adjacent basins for the oxygen status of the sea.
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| 5. |
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| 6. |
- Wesslander, Karin, 1976, et al.
(author)
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Observed carbon dioxide and oxygen dynamics in a Baltic Sea coastal region
- 2011
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In: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 86:1-2, s. 1-9
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Journal article (peer-reviewed)abstract
- In April 2006, diurnal variations of carbon dioxide (CO2) and oxygen (O2) in the surface water east of Gotland in the Baltic Sea were investigated with a unique multitechnology approach. Several parameters were measured simultaneously providing an overviewof the CO2 system.Moored instrumentswere continuously recording partial pressure of CO2 in the surface water (pCO2 w), currents,mixing,waves, salinity, temperature and O2. Measurements of total alkalinity (AT) and dissolved inorganic carbon (CT) were taken from R/V Skagerak. These measurements were converted to pCO2 w to support the continuous pCO2 w data and also calculate the air–sea exchange of CO2. Additionally, the time derivatives of O2 and CT concentrations in the water were determined using incubations and a Productivity Autosampler (PA). O2 and pCO2 w were significantly anti-correlated and periods dominated of either biological processes, mixing, air–sea exchange or a combination of these were detected. O2 and pCO2 w had a daily cycle and variations occurred on the 1 h time scale. In April 2006, the seawas a CO2 sink and the averaged parameterized air–sea exchange was −1.0±0.6 mmol m−2 h−1.
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| 7. |
- Andrén, Thomas, 1954-, et al.
(author)
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Östersjön förändras ständigt
- 2005
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In: Upsala nya tidning. - 1104-0173. ; :8/6:8 juni
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Journal article (pop. science, debate, etc.)
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| 8. |
- Bernd, Schneider, et al.
(author)
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Biogeochemical cycles : Biological Oceanography of the Baltic Sea
- 2017
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In: Springer. - Dordrecht : Springer. - 9789400706675 ; , s. 87-122
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Book chapter (peer-reviewed)abstract
- 1. The internal cycles of carbon, nitrogen and phosphorus in the Baltic Sea are, like in other seas, mainly controlled by biological production and degradation of organic matter (OM). 2. Biological activity also modulates the acid/base balance (pH), which is mainly a function of alkalinity and the total CO2 concentration. 3. Particulate organic matter (POM) produced in the photic zone sinks into deeper water layers and is deposited on the sediment surface, where it is mineralised. Mineralisation is a form of microbial oxidation and thus leads to oxygen depletion. Due to its semi-enclosed position and its bottom topography, large-scale oxygen depletion of deep bottoms is common in the Baltic Sea. 4. Under anoxic conditions, the burial of phosphorus bound to ferric oxide is inhibited and the availability of phosphate for incorporation in new OM production increases. 5. In stagnant waters, the oxic/anoxic interface may migrate from the sediment into the water column, forming a pelagic redoxcline. Such a redoxcline occurs in large areas of the Baltic Sea. 6. At oxygen concentrations close to zero, nitrate acts as an oxidant and is reduced to elemental nitrogen (denitrification). After the exhaustion of both oxygen and nitrate, OM is oxidised by sulphate, which is reduced to toxic hydrogen sulphide. 7. The final step in the mineralisation process is the microbial formation of methane in deeper sediment layers, which reflects the internal oxidation/reduction of OM. 8. A significant fraction of the organic carbon, nitrogen and phosphorus escapes mineralisation and is permanently buried in the sediment. On a long-term basis, this loss, together with export to the North Sea and internal sinks, is mainly balanced by riverine inputs and atmospheric deposition to the Baltic Sea.
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| 9. |
- Chen, Deliang, 1961, et al.
(author)
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Climate-induced variability of sea level in Stockholm: Influence of air temperature and atmospheric circulation
- 2005
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In: Advances in Atmospheric Sciences. - 0256-1530. ; 22:5, s. 655-664
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Journal article (peer-reviewed)abstract
- This study is focused on climate-induced variation of sea level in Stockholm during 1873-1995. After the effect of the land uplift is removed, the residual is characterized and related to large-scale temperature and atmospheric circulation. The residual shows an overall upward trend, although this result depends on the uplift rate used. However, the seasonal distribution of the trend is uneven. There are even two months (June and August) that show a negative trend. The significant trend in August may be linked to fresh water input that is controlled by precipitation. The influence of the atmospheric conditions on the sea level is mainly manifested through zonal winds, vorticity and temperature. While the wind is important in the period January-May, the vorticity plays a main role during June and December. A successful linear multiple-regression model linking the climatic variables (zonal winds, vorticity and mean air temperature during the previous two months) and the sea level is established for each month. An independent verification of the model shows that it has considerable skill in simulating the variability.
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| 10. |
- Claremar, Björn, et al.
(author)
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Deposition of acidifying and neutralising compounds over the Baltic Sea drainage basin between 1960 and 2006
- 2013
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In: Boreal Environment Research. - 1239-6095 .- 1797-2469. ; 18:6, s. 425-445
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Journal article (peer-reviewed)abstract
- This study produced a gridded database of acidifying and eutrophying deposition in the Baltic Sea and its drainage basin for the period 1960-2006. Data from various data sets were combined to generate monthly atmospheric (wet) deposition of cations (Ca2+, Mg2+, Na+, K+ and NH4+) and anions (SO42-, NO3- and Cl-). Output of a chemical transport model and interpolated measurements were used, and when these were not available, trends and seasonal cycles were constructed from historical emissions and deposition data. These methods lose some spatial patterns, but the mean trends reflect the influence of east-European emissions more than earlier studies with more westerly-centred observations. The calculated depositions of sulphur, nitrogen and calcium (correlated with sulphur emission) increased from 1960 to 1990 and then decreased until 2006. The trend is most evident for sulphur with a 100% increase followed by a 73% decrease.
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