scholarly journals Nitrogen and the Baltic Sea: Managing Nitrogen in Relation to Phosphorus

2001 ◽  
Vol 1 ◽  
pp. 371-377 ◽  
Author(s):  
R. Elmgren ◽  
U. Larsson
Keyword(s):  
Stakeholder Participation ◽  
Minimum Cost ◽  
Cyanobacterial Blooms ◽  
Nutrient Loads ◽  
Surface Salinity ◽  
Amenity Values ◽  
Large N ◽  
Filamentous Macroalgae ◽  
Baltic Proper ◽  
The Baltic

The Baltic is a large, brackish sea (4 x 105 km2) extending from 54ÅN to ~66ÅN, with a fourfold larger drainage area (population 8 x 107). Surface salinity (2 to 8 PSU) and hence biodiversity is low. In the last century, annual nutrient loads increased to 106metric tons N and 5 x104ton P. Eutrophication is evident in the N-limited south, where cyanobacteria fix 2 to 4 x 105ton N each summer, Secchi depths have been halved, and O2-deficient bottom areas have spread. Production remains low in the P-limited north. In nutrient-enriched coastal areas, phytoplankton blooms, toxic at times, and filamentous macroalgae reduce amenity values. Loads need to be reduced of both N, to reduce production, and P, to limit N-fixing cyanobacterial blooms. When large N-load reductions have been achieved locally, algal biomass has declined. So far, P loads have been reduced more than N loads. If this continues, a P-limited Baltic proper may result, very different from previous N-limited conditions. Reaching the management goal of halved anthropogenic N and P loads at minimum cost will require better understanding of biogeochemical nutrient cycles, economic evaluation of proposed measures, and improved stakeholder participation.

21st century nutrient and oxygen dynamics in the Gulf of Bothnia

2021 ◽  
Author(s):  
Itzel Ruvalcaba Baroni ◽  
Jenny Hieronymus ◽  
Sam Fredriksson ◽  
Lars Arneborg
Keyword(s):  
21St Century ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Future Projections ◽  
Gulf Of Bothnia ◽  
Bottom Waters ◽  
Baltic Proper ◽  
The Baltic ◽  
Business As Usual ◽  
Historical Scenario

<p>The Gulf of Bothnia is the only sub-basin of the Baltic Sea with no serious eutrophication. However, long-term observations have shown degradation of the water quality over the past years, indicating warning signals for the future. Here, we use a high resolution ocean circulation model including biogeochemistry to study 21st century nutrient and oxygen changes in the Gulf of Bothnia. We analyze ensembles for 5 different scenarios; a historical (1975-2005) and 4 future projections (2006-2100). For the projections, two atmospheric <em>p</em>CO<sub>2 </sub>trajectories are used, RCP4.5 and RCP8.5, and two settings for nutrient loads are applied to each RCP scenario: one following the Baltic Sea Action Plan (BSAP) and the other assuming business as usual. We also test a historical scenario but with no local nutrient loads to better understand the biogeochemical influence of the lateral open boundary. The comparison of observations with the historical scenario shows that oxygen trends are well captured by the model despite a small bias in nutrient concentrations. Our results suggest that the Bothnian Bay is more sensitive to river loads than the Bothnian Sea, which is primarily affected by the inflows from the Baltic proper. All future projections show a decrease in phosphate concentrations and an increase in nitrate concentrations due to lower/higher input of phosphate/nitrate from the Baltic proper. Oxygen concentrations in bottom waters of the Gulf of Bothnia are not susceptible to become hypoxic in the future. However, when business as usual is applied for nutrient loads, oxygen concentrations decrease significantly over the entire future period and short episodes of low oxygen conditions in bottom waters (with less than 5 ml O<sub>2</sub>/l) become more frequent and more pronounced in the Bothnian Sea, especially towards the end of the century.</p><p> </p>

scholarly journals Fucus vesiculosus adapted to a life in the Baltic Sea: impacts on recruitment, growth, re-establishment and restoration

2019 ◽  
Vol 62 (1) ◽  
pp. 17-30
Author(s):  
Lena Kautsky ◽  
Susanne Qvarfordt ◽  
Ellen Schagerström
Keyword(s):  
Baltic Sea ◽  
Fucus Vesiculosus ◽  
Reproductive Age ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Nutrient Runoff ◽  
Low Salinity ◽  
The North ◽  
Baltic Proper ◽  
The Baltic

Abstract Fucus vesiculosus is common both on the tidal coasts of the North Atlantic and in the Baltic Sea, where it has adapted to low salinity and nontidal conditions over the last 7000 years. During the late 1970s and early 1980s, extensive declines of F. vesiculosus populations were reported in the Baltic Proper, mainly attributed to high nutrient loads. During the past 30–40 years, considerable efforts have been made to reduce nutrient runoff to coastal areas but few successful initiatives to restore F. vesiculosus populations have been performed. In this paper, we present how substratum manipulation, i.e. clean rocky surfaces, brushing rocks, Hildenbrandia rubra cover and different filamentous algae, as well as different algal exudates, affect the recruitment and survival of juvenile F. vesiculosus. Further, we show through a 5-year field experiment that it will take at least 4–5 years to reach reproductive age for F. vesiculosus in the Baltic Sea. We also present transplantation studies from two different areas, showing that epiphytic load, light, grazing and type of substratum are some of the factors that need to be taken into consideration in order to achieve successful restoration of F. vesiculosus.

scholarly journals Deposition of nitrogen and phosphorus on the Baltic Sea: seasonal patterns and nitrogen isotope composition

2008 ◽  
Vol 5 (4) ◽  
pp. 3013-3044 ◽  
Author(s):  
C. Rolff ◽  
R. Elmgren ◽  
M. Voss
Keyword(s):  
Isotope Composition ◽  
Seasonal Pattern ◽  
Nitrogen Isotope ◽  
Cyanobacterial Blooms ◽  
Organic N ◽  
Nitrogen And Phosphorus ◽  
Clear Seasonal Pattern ◽  
Baltic Proper ◽  
Upper Mixed Layer ◽  
The Baltic

Abstract. Atmospheric deposition of nitrogen and phosphorus on the Baltic Proper was estimated monthly at two coastal stations and two isolated islands in 2001 and 2002. Yearly nitrogen deposition ranged between 387 and 727 mg N m−2 yr−1 (average ~617) and was composed of ~10% organic N and approximately equal amounts of ammonium and nitrate. Winter nitrate peaks at the isolated islands possibly indicated ship emissions. Load weighted δ15N of deposited N was 3.7‰ and 0.35‰ at the coastal stations and the isolated islands respectively. Winter δ15N was ~3‰ lighter than in summer, reflecting winter dominance of nitrate. The light isotopic composition of deposited nitrogen may cause overestimates of nitrogen fixation in basin-wide isotopic budgeting, whereas relatively heavy deposition of ammonium during summer instead may cause underestimates of fixation in budgets of the upper mixed layer. δ15N in atmospherically deposited nitrate and ammonium was estimated by regression to –7.9 and 13.5‰ respectively. Phosphorus deposition showed no clear seasonal pattern and was considerably lower at the isolated islands. Organic P constituted 20–40% of annual P deposition. P deposition is unlikely to be a major source for cyanobacterial blooms but may potentially prolong an ongoing bloom.

scholarly journals Modeling point and non-point nutrient fluxes in river systems of lake Peipsi drainage basi

2019 ◽  
pp. 389-398
Author(s):  
Kristjan Piirimäe
Keyword(s):  
Large Scale ◽  
Sharp Decrease ◽  
Paper Analysis ◽  
Cyanobacterial Blooms ◽  
Nutrient Loads ◽  
Lake Peipsi ◽  
Baltic Sea Region ◽  
Long Term Trends ◽  
The Baltic

N and P compounds work as key elements causing bioproduction and eutrophication inwater bodies of the Baltic Sea region, A large-scale dynamic GIS-embedded PolFlowmodel considers all point and diffuse emission sources in a river basin simulating alsotransport and retention of nutrients in time steps of five years, This modeling approachwas originally developed for simulating past and present nutrient loads for the Rhine andElbe rivers. In addition, a statistical model MESAW was employed for nutrient sourceapportionment and emission estimations. This paper analysis the modeling results in LakePeipsi basin, shared by Estonia, Russia and Latvia, for long-term trends since 1985 till1999. Results of modeling, as well as monitoring data indicate quite stable long-term Pload while agricultural N load has decreased significantly in connection with dramaticchanges in agricultural structures. That, in turn, has lead to sharp decrease ofN/P ratio inriverine runoff while in lakes (L Peipsi, L Vortsjii.rv) and coastal seas, NIP ratio hasdropped below 10. These changes, enhancing cyanobacterial blooms, have significantlyworsened the ecological state of these water bodies, in the conditions of decreasedemissions. The paper concludes that wastewater treatment should focus on better removalofphosphorus.

Optimization of Nutrient Removal in Stockholm

1991 ◽  
Vol 24 (7) ◽  
pp. 103-111 ◽  
Author(s):  
G. Brattberg ◽  
L.-G. Reinius ◽  
M. Tendaj
Keyword(s):  
Nutrient Removal ◽  
Sewage Treatment ◽  
Water Source ◽  
Chemical Precipitation ◽  
Phosphorus Load ◽  
Sewage Treatment Plants ◽  
Limiting Nutrient ◽  
Baltic Proper ◽  
Mechanical Stage ◽  
The Baltic

Stockholm was founded at the point where the waters of Lake Mälaren emerge into the Baltic Sea. Lake Mälaren is the water source of the water works of Stockholm. The Lake also receives water from one of the sewage treatment plants. The outlet from the two other sewage treatment plants are in the inner part of the archipelago. During 1968-73 the treatment was improved, after which the phosphorus load to the receiving water significantly decreased. The total P concentration in the surface water has decreased since 1970 and phosphorus has replaced nitrogen as the most limiting nutrient throughout the entire archipelago within 50 km from Stockholm. To further reduce the eutrophication a continued reduction of the phosphorus load is most effective. For the Baltic proper as a whole, where primary nitrogen limitation is present, it is important to reduce the supply of nitrogen to the greatest possible extent. The treatment plants in Stockholm are located in subsurface rock-chambers. The treatment includes mechanical, biological and chemical treatment. In the mechanical stage the sewage is treated in screens, grit chambers and primary sedimentation. The biological stage is a conventional activated sludgeprocess. For the chemical precipitation ferroussulphateis added before the screens. The sludge is stabilized in anaerobic digesters and dewatered in centrifuges before disposal on farmland. To meet more stringent requirements on nitrification and nitrogen removal several projects are going on to optimize the nutrient removal. The aim of these investigations is to improve the plants' performance within the existing plant.

scholarly journals Remediating Agricultural Legacy Nutrient Loads in the Baltic Sea Region

2021 ◽  
Vol 13 (7) ◽  
pp. 3872
Author(s):  
Julia Tanzer ◽  
Ralf Hermann ◽  
Ludwig Hermann
Keyword(s):  
Baltic Sea ◽  
Agricultural Soils ◽  
Economic Benefits ◽  
Current Data ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Nutrient Emissions ◽  
Long Run ◽  
The Baltic ◽  
Agricultural Legacy

The Baltic Sea is considered the marine water body most severely affected by eutrophication within Europe. Due to its limited water exchange nutrients have a particularly long residence time in the sea. While several studies have analysed the costs of reducing current nutrient emissions, the costs for remediating legacy nutrient loads of past emissions remain unknown. Although the Baltic Sea is a comparatively well-monitored region, current data and knowledge is insufficient to provide a sound quantification of legacy nutrient loads and much less their abatement costs. A first rough estimation of agricultural legacy nutrient loads yields an accumulation of 0.5–4.0 Mt N and 0.3–1.2 Mt P in the Baltic Sea and 0.4–0.5 Mt P in agricultural soils within the catchment. The costs for removing or immobilising this amount of nutrients via deep water oxygenation, mussel farming and soil gypsum amendment are in the range of few tens to over 100 billion €. These preliminary results are meant as a basis for future studies and show that while requiring serious commitment to funding and implementation, remediating agricultural legacy loads is not infeasible and may even provide economic benefits to local communities in the long run.

The History of Cyanobacterial Blooms in the Baltic Sea

AMBIO ◽  
2001 ◽  
Vol 30 (4) ◽  
pp. 172-178 ◽  
Author(s):  
Terttu Finni ◽  
Kaisa Kononen ◽  
Riitta Olsonen ◽  
Kerstin Wallström
Keyword(s):  
Baltic Sea ◽  
Cyanobacterial Blooms ◽  
The Baltic Sea ◽  
History Of ◽  
The Baltic

scholarly journals An integrated simulation model to evaluate national measures for the abatement of agricultural nutrients in the Baltic Sea

2009 ◽  
Vol 18 (3-4) ◽  
pp. 440-459 ◽  
Author(s):  
K. HYYTIÄINEN ◽  
H. AHTIAINEN ◽  
J. HEIKKILÄ
Keyword(s):  
Water Quality ◽  
Simulation Model ◽  
Baltic Sea ◽  
Arable Land ◽  
Gulf Of Finland ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
The Baltic ◽  
Bothnian Bay ◽  
The Gulf Of Finland

This study introduces a prototype model for evaluating measures to abate agricultural nutrients in the Baltic Sea from a Finnish national perspective. The stochastic simulation model integrates nutrient dynamics of nitrogen and phosphorus in the sea basins adjoining the Finnish coast, nutrient loads from land and other sources, benefits from nutrient abatement (in the form of recreation and other ecosystem services) and the costs of agricultural abatement activities. The aim of the study is to present the overall structure of the model and to demonstrate its potential using preliminary parameters. The model is made flexible for further improvements in all of its ecological and economic components. The results of a sensitivity analysis suggest that investments in reducing the nutrient load from arable land in Finland would become profitable only if the neighboring countries in the northern Baltic committed themselves to similar reductions. Environmental investments for improving water quality yield the highest returns for the Bothnian Bay and the Gulf of Finland, with smaller returns for the Bothnian Sea. Somewhat surprisingly, in the Bothnian Bay the abatement activities become profitable from the national viewpoint, because the riverine loads from Finland represent a high proportion of the total nutrient loads. In the Gulf of Finland, this proportion is low, but the size of the coastal population benefiting from improved water quality is high.;

scholarly journals Causes of the extensive hypoxia in the Gulf of Riga in 2018

2021 ◽  
Author(s):  
Stella-Theresa Stoicescu ◽  
Jaan Laanemets ◽  
Taavi Liblik ◽  
Māris Skudra ◽  
Oliver Samlas ◽  
...  
Keyword(s):  
Bottom Layer ◽  
Oxygen Depletion ◽  
Phosphorus Release ◽  
Meteorological Conditions ◽  
Mitigation Measures ◽  
Sediment Surface ◽  
Water Volume ◽  
Gulf Of Riga ◽  
Baltic Proper ◽  
The Baltic

Abstract. The Gulf of Riga is a relatively shallow bay connected to the deeper central Baltic Sea (Baltic Proper) via straits with sills. The decrease in the near-bottom oxygen levels from spring to autumn is a common feature in the gulf, but in 2018, hypoxia was exceptional. We analyzed temperature, salinity, oxygen, and nutrient data collected in 2018 and historical data available from environmental databases. Forcing data from the study year were compared with their long-term means and variability. The year 2018 was exceptional due to occasionally dominating north-easterly winds supporting the inflow of saltier waters from the Baltic Proper and meteorological conditions causing fast development of thermal stratification in spring. Existing stratification hindered vertical transport between the near-bottom layer (NBL) and the water layers above it. The estimated oxygen consumption rate at the sediment surface in spring-summer 2018 was about 1.7 mmol O2 m−2 h−1 that exceeded the oxygen input to the NBL due to advection and mixing. We suggest that the observed pronounced oxygen depletion was magnified by the prolonged stratified season and haline stratification in the deep layer that maintained a decreased water volume between the seabed and the pycnocline. The observed increase in phosphate concentrations in the NBL in summer 2018 suggests a significant sediment phosphorus release in hypoxic conditions counteracting the mitigation measures to combat eutrophication. We conclude, if similar meteorological conditions as in 2018 could occur more frequently in the future, such extensive hypoxia would be more common in the Gulf of Riga and other coastal basins with similar morphology and human-induced elevated input of nutrients.

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