| 1. |
- Rosentau, A., et al.
(författare)
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A Holocene relative sea-level database for the Baltic Sea
- 2021
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 266
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Tidskriftsartikel (refereegranskat)abstract
- We present a compilation and analysis of 1099 Holocene relative shore-level (RSL) indicators located around the Baltic Sea including 867 relative sea-level data points and 232 data points from the Ancylus Lake and the following transitional phase. The spatial distribution covers the Baltic Sea and near-coastal areas fairly well, but some gaps remain mainly in Sweden. RSL data follow the standardized HOLSEA format and, thus, are ready for spatially comprehensive applications in, e.g., glacial isostatic adjustment (GIA) modelling. We apply a SQL database system to store the nationally provided data sets in their individual form and to map the different input into the HOLSEA format as the information content of the individual data sets from the Baltic Sea area differs. About 80% of the RSL data is related to the last marine stage in Baltic Sea history after 8.5 ka BP (thousand years before present). These samples are grouped according to their dominant RSL tendencies into three clusters: regions with negative, positive and complex (transitional) RSL tendencies. Overall, regions with isostatic uplift driven negative tendencies dominate and show regression in the Baltic Sea basin during the last marine stage. Shifts from positive to negative tendencies in RSL data from transitional regions show a mid-Holocene highstand around 7.5-6.5 ka BP which is consistent with the end of the final melting of the Laurentide Ice Sheet. Comparisons of RSL data with GIA predictions including global ICE-5G and ICE-6G_C ice histories show good fit with RSL data from the regions with negative tendencies, whereas in the transitional areas in the eastern Baltic, predictions for the mid-Holocene clearly overestimate the RSL and fail to recover the midHolocene RSL highstand derived from the proxy reconstructions. These results motivate improvements of ice-sheet and Earth-structure models and show the potential and benefits of the new compilation for future studies. (C) 2021 The Authors. Published by Elsevier Ltd.
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| 2. |
- Stalnacke, P., et al.
(författare)
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Nitrogen surface water retention in the Baltic Sea drainage basin
- 2015
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 19:2, s. 981-996
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we estimate the surface water retention of nitrogen (N) in all the 117 drainage basins to the Baltic Sea with the use of a statistical model (MESAW) for source apportionment of riverine loads of pollutants. Our results show that the MESAW model was able to estimate the N load at the river mouth of 88 Baltic Sea rivers, for which we had observed data, with a sufficient degree of precision and accuracy. The estimated retention parameters were also statistically significant. Our results show that around 380 000 t of N are annually retained in surface waters draining to the Baltic Sea. The total annual riverine load from the 117 basins to the Baltic Sea was estimated at 570 000 t of N, giving a total surface water N retention of around 40 %. In terms of absolute retention values, three major river basins account for 50% of the total retention in the 117 basins; i.e. around 104 000 t of N are retained in Neva, 55 000 t in Vistula and 32 000 t in Oder. The largest retention was found in river basins with a high percentage of lakes as indicated by a strong relationship between N retention (%) and share of lake area in the river drainage areas. For example in Gota alv, we estimated a total N retention of 72 %, whereof 67% of the retention occurred in the lakes of that drainage area (Lake Vanern primarily). The obtained results will hopefully enable the Helsinki Commission (HELCOM) to refine the nutrient load targets in the Baltic Sea Action Plan (BSAP), as well as to better identify cost-efficient measures to reduce nutrient loadings to the Baltic Sea.
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| 3. |
- Stålnacke, P, et al.
(författare)
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Changes in nutrient levels in some Eastern European rivers in response to large-scale changes in agriculture
- 2004
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Ingår i: Water Science and Technology. - 0273-1223 .- 1996-9732. ; 49:3, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- Since the late 1980s, the use of commercial fertilisers in most Eastern European countries has decreased at an unprecedented rate. We examined the impact of this dramatic reduction in agricultural inputs on concentrations of nutrients in four rivers in Eastern Europé: the Emajogi and Õhnejogi (Estonia), the Daugava (Latvia), and the Tisza (Hungary). Time series of nitrate (NO3-N) and phosphate (PO4-P) concentrations and data on runoff were selected to represent catchments with substantial areas of agricultural land and available time series of sufficient length and frequency. The study period was 1987-1998. We detected downward trends in nitrate-N and phosphate-P in only two of the four rivers. Our results imply that the response to the extensive decrease in agricultural intensity since the late 1980s has been slow and limited in many rivers. Corresponding results in the literature are inconclusive and comprise several examples of both decreasing and non-decreasing nutrient concentrations. Our findings, along with similar data from other studies, indicate that large cuts in nutrient inputs do not necessarily induce an immediate response, particularly in medium-sized and large catchment areas. Moreover, the difference we noted between nitrogen and phosphorus suggests that factors other than reduced fertiliser application influenced the inertia of the water quality response.
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| 4. |
- Vassiljev, A, et al.
(författare)
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A dual-porosity model for nitrogen leaching from a watershed
- 2004
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 49:2, s. 313-322
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Tidskriftsartikel (refereegranskat)abstract
- The MASONW (MACRO + SOILN + Watershed) model describing nitrogen leaching in watersheds was developed and tested. The model is based on the MACRO and SOILN models. The dual-porosity model MACRO simulates water flow on the field scale. The SOILN model describes turnover and leaching of nitrogen. Two main features of a watershed have been added into these two models: (a) the existence of a river system, and (b) variable thickness of the aeration zone within a watershed. Good agreement between the output of the MASONW model and observed data for water discharge and nitrate concentrations were achieved in the Odense watershed (496 km2) in Denmark.
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