scholarly journals A Baltic Sea estuary as phosphorus source and sink

2017 ◽  
Author(s):  
Jakob Walve ◽  
Maria Sandberg ◽  
Ulf Larsson ◽  
Christer Lännergren
Keyword(s):  
Baltic Sea ◽  
Deep Water ◽  
Sewage Treatment ◽  
Vertical Mixing ◽  
Turnover Time ◽  
Nutrient Inputs ◽  
P Release ◽  
Oxygen Conditions ◽  
Tightly Coupled ◽  
P Balance

Abstract. Internal phosphorus (P) loading from sediments, controlled by hypoxia, is often assumed to hamper the recovery of lakes and coastal areas from eutrophic conditions. We use a box-model to calculate seasonal and annual inputs, export, retention and internal cycling of P in the inner archipelago of Stockholm, Sweden (Baltic Sea) in 1968–2015. The area receives freshwater from Lake Mälaren and treated sewage from the greater Stockholm area. The sewage treatment plants (STPs) have improved their nutrient removal in steps, starting with P in 1972 and nitrogen in 1996. In the first 10–20 years after the main P load reduction in 1972–76, the model shows, in comparison to the load, a small negative annual P balance, probably due to release from legacy sediment P stores. The now stabilized, near neutral P balance indicates no continued internal loading from legacy P, but P retention is low, despite improved oxygen conditions. Seasonally, sediments are a P sink in spring and a P source in summer and autumn. Most of the deep-water P release from sediments in summer-autumn appears to be derived from the settled spring bloom and is exported during winter. Oxygen consumption and P release in the deep water are generally tightly coupled, indicating limited control by P binding to iron-oxyhydroxides under oxic conditions. However, in years of deep-water hypoxia enhanced P release suggest contribution from redox-sensitive P stores. The oxygen conditions in the area have generally improved, probably due both to lower sedimentation of organic matter from the 1970s and lower STP ammonium loads from the late 1990s. Increased oxygen inputs to the intermediate and deep waters due to weakened stratification and enhanced vertical mixing have probably also contributed, while increased respiration rates due to elevated bottom water temperatures probably explain worsened oxygen conditions during the 1990s. Since the P turnover time is short and legacy P minute, measures to bind P in Stockholm inner archipelago sediments would primarily accumulate P imported from the Baltic Sea and from Lake Mälaren inflow, and management here should focus on reducing external nutrient inputs.

scholarly journals A Baltic Sea estuary as a phosphorus source and sink after drastic load reduction: seasonal and long-term mass balances for the Stockholm inner archipelago for 1968–2015

2018 ◽  
Vol 15 (9) ◽  
pp. 3003-3025 ◽  
Author(s):  
Jakob Walve ◽  
Maria Sandberg ◽  
Ulf Larsson ◽  
Christer Lännergren
Keyword(s):  
Oxygen Consumption ◽  
Baltic Sea ◽  
Deep Water ◽  
Sewage Treatment ◽  
Turnover Time ◽  
Early Summer ◽  
Load Reduction ◽  
P Release ◽  
Tightly Coupled ◽  
P Balance

Abstract. Internal phosphorus (P) loading from sediments, controlled by hypoxia, is often assumed to hamper the recovery of lakes and coastal areas from eutrophication. In the early 1970s, the external P load to the inner archipelago of Stockholm, Sweden (Baltic Sea), was drastically reduced by improved sewage treatment, but the internal P loading and its controlling factors have been poorly quantified. We use two slightly different four-layer box models to calculate the area's seasonal and annual P balance (input–export) and the internal P exchange with sediments in 1968–2015. For 10–20 years after the main P load reduction, there was a negative P balance, small in comparison to the external load, and probably due to release from legacy sediment P storage. Later, the stabilized, near-neutral P balance indicates no remaining internal loading from legacy P, but P retention is low, despite improved oxygen conditions. Seasonally, sediments are a P sink in spring and a P source in summer and autumn. Most of the deep-water P release from sediments in summer–autumn appears to be derived from the settled spring bloom and is exported to outer areas during winter. Oxygen consumption and P release in the deep water are generally tightly coupled, indicating limited iron control of P release. However, enhanced P release in years of deep-water hypoxia suggests some contribution from redox-sensitive P pools. Increasing deep-water temperatures that stimulate oxygen consumption rates in early summer have counteracted the effect of lowered organic matter sedimentation on oxygen concentrations. Since the P turnover time is short and legacy P small, measures to bind P in Stockholm inner archipelago sediments would primarily accumulate recent P inputs, imported from the Baltic Sea and from Lake Mälaren.

scholarly journals Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives

2007 ◽  
Vol 11 (5) ◽  
pp. 1593-1607 ◽  
Author(s):  
C. Humborg ◽  
C.-M. Mörth ◽  
M. Sundbom ◽  
F. Wulff
Keyword(s):  
Global Warming ◽  
Baltic Sea ◽  
Sewage Treatment ◽  
Agricultural Practices ◽  
Optimal Growth ◽  
Biogenic Elements ◽  
Nutrient Inputs ◽  
The Baltic Sea ◽  
Soil Infiltration ◽  
The Baltic

Abstract. The paper reviews critical processes for the land-sea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage treatment, agricultural practices and increased hydropower demand (for N, P and Si) and of global warming, i.e., changes in hydrological patterns (for C). These most significant drivers will not only change the total amount of nutrient inputs and fluxes of organic and inorganic forms of carbon to the Baltic Sea, their ratio (C:N:P:Si) will alter as well with consequences for phytoplankton species composition in the Baltic Sea. In summary, we propose that N fluxes may increase due to higher livestock densities in those countries recently acceded to the EU, whereas P and Si fluxes may decrease due to an improved sewage treatment in these new EU member states and with further damming and still eutrophic states of many lakes in the entire Baltic Sea catchment. This might eventually decrease cyanobacteria blooms in the Baltic but increase the potential for other nuisance blooms. Dinoflagellates could eventually substitute diatoms that even today grow below their optimal growth conditions due to low Si concentrations in some regions of the Baltic Sea. C fluxes will probably increase from the boreal part of the Baltic Sea catchment due to the expected higher temperatures and heavier rainfall. However, it is not clear whether dissolved organic carbon and alkalinity, which have opposite feedbacks to global warming, will increase in similar amounts, because the spring flow peak will be smoothed out in time due to higher temperatures that cause less snow cover and deeper soil infiltration.

scholarly journals Riverine transport of biogenic elements to the Baltic Sea – past and possible future perspectives

2007 ◽  
Vol 4 (3) ◽  
pp. 1095-1131 ◽  
Author(s):  
C. Humborg ◽  
C.-M. Mörth ◽  
M. Sundbom ◽  
F. Wulff
Keyword(s):  
Global Warming ◽  
Baltic Sea ◽  
Sewage Treatment ◽  
Agricultural Practices ◽  
Optimal Growth ◽  
Biogenic Elements ◽  
Nutrient Inputs ◽  
The Baltic Sea ◽  
Soil Infiltration ◽  
The Baltic

Abstract. The paper reviews critical processes for the land-sea fluxes of biogenic elements (C, N, P, Si) in the Baltic Sea catchment and discusses possible future scenarios as a consequence of improved sewage treatment, agricultural practices, increased hydropower demand and global warming, i.e., changes in hydrological patterns. These most significant drivers will not only change the total amount of nutrient inputs and fluxes of organic and inorganic forms of carbon to the Baltic Sea, their ratio (C:N:P:Si) will alter as well with consequences for phytoplankton species composition in the Baltic Sea. In summary, we propose that N fluxes will increase due to higher live stock densities in those countries recently acceded to the EU, whereas P and Si fluxes will decrease due to an increase in sewage treatment in these new EU member states and with further damming and still eutrophic states of many lakes in the entire Baltic Sea catchment. This might eventually decrease cyanobacteria blooms in the Baltic but increase the potential for other nuisance blooms. Dinoflagellates will be substituting diatoms that even today grow below their optimal growth conditions due to low Si concentrations in some regions of the Baltic Sea. C fluxes will probably increase from the boreal part of the Baltic Sea catchment due to the expected higher temperatures and heavier rainfall. However, it is not clear whether both dissolved organic carbon and alkalinity, that have opposite feedbacks to global warming will increase in similar amounts, since the spring flow peak will be smoothed out in time due to higher temperatures that cause less snow cover and deeper soil infiltration.

scholarly journals Comparative studies of pelagic microbial methane oxidation within two anoxic basins of the central Baltic Sea (Gotland Deep and Landsort Deep)

2013 ◽  
Vol 10 (7) ◽  
pp. 12251-12284 ◽  
Author(s):  
G. Jakobs ◽  
G. Rehder ◽  
G. Jost ◽  
K. Kießlich ◽  
M. Labrenz ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Methane Oxidation ◽  
Deep Water ◽  
Methane Concentration ◽  
Vertical Mixing ◽  
Depth Interval ◽  
Type I ◽  
Gotland Deep ◽  
Redox Zone ◽  
Redox Zones

Abstract. Pelagic methane oxidation was investigated in dependence on differing environmental conditions within the redox zone of the Gotland Deep (GD) and Landsort Deep (LD), central Baltic Sea. The redox zone of both deeps, which indicates the transition between oxic and anoxic conditions, was characterized by a pronounced methane concentration gradient between the deep water (GD: 1233 nM, LD: 2935 nM) and the surface water (GD and LD < 10 nM), together with a 13C CH4 enrichment (δ13C CH4 deep water: GD −84‰, LD −71‰ ; redox zone: GD −60‰, LD −20‰ ; δ13C CH4 vs. Vienna Pee Dee Belemnite standard), clearly indicating microbial methane consumption in that specific depth interval. Expression analysis of the methane monooxygenase identified one active type I methanotrophic bacterium in both redox zones. In contrast, the turnover of methane within the redox zones showed strong differences between the two basins (GD: max. 0.12 nM d–1 and LD: max. 0.61 nM d–1), with a four times higher turnover rate constant (k) in the LD (GD: 0.0022 d–1, LD: 0.0079 d–1). Vertical mixing rates for both deeps were calculated on the base of the methane concentration profile and the consumption of methane in the redox zone (GD: 2.5 × 10–6 m2 s–1 LD: 1.6 × 10–5 m2 s–1). Our study identified vertical transport of methane from the deep water body towards the redox zone as well as differing hydrographic conditions within the oxic/anoxic transition zone of these deeps as major factors that determine the pelagic methane oxidation.

scholarly journals Comparative studies of pelagic microbial methane oxidation within the redox zones of the Gotland Deep and Landsort Deep (central Baltic Sea)

2013 ◽  
Vol 10 (12) ◽  
pp. 7863-7875 ◽  
Author(s):  
G. Jakobs ◽  
G. Rehder ◽  
G. Jost ◽  
K. Kießlich ◽  
M. Labrenz ◽  
...  
Keyword(s):  
Surface Water ◽  
Baltic Sea ◽  
Methane Oxidation ◽  
Deep Water ◽  
Methane Concentration ◽  
Vertical Mixing ◽  
Gotland Deep ◽  
Hydrographic Conditions ◽  
Redox Zone ◽  
Redox Zones

Abstract. Pelagic methane oxidation was investigated in dependence on differing hydrographic conditions within the redox zone of the Gotland Deep (GD) and Landsort Deep (LD), central Baltic Sea. The redox zone of both deeps, which indicates the transition between oxic and anoxic conditions, was characterized by a pronounced methane concentration gradient between the deep water (GD: 1233 nM, 223 m; LD: 2935 nM, 422 m) and the surface water (GD and LD < 10 nM). This gradient together with a 13C CH4 enrichment (δ13C CH4 deep water: GD −84‰, LD −71‰; redox zone: GD −60‰, LD −20‰; surface water: GD −47‰, LD −50‰; δ13C CH4 vs. Vienna Pee Dee Belemnite standard), clearly indicating microbial methane consumption within the redox zone. Expression analysis of the methane monooxygenase identified one active type I methanotrophic bacterium in both redox zones. In contrast, the turnover of methane within the redox zones showed strong differences between the two basins (GD: max. 0.12 nM d−1, LD: max. 0.61 nM d−1), with a nearly four-times-lower turnover time of methane in the LD (GD: 455 d, LD: 127 d). Vertical mixing rates for both deeps were calculated on the base of the methane concentration profile and the consumption of methane in the redox zone (GD: 2.5 × 10–6 m2 s−1, LD: 1.6 × 10–5 m2 s−1). Our study identified vertical transport of methane from the deep-water body towards the redox zone as well as differing hydrographic conditions (lateral intrusions and vertical mixing) within the redox zone of these deeps as major factors that determine the pelagic methane oxidation.

Sewage Treatment Challenges and Opportunities in the Nottawasaga River Watershed

1997 ◽  
Vol 32 (4) ◽  
pp. 733-750
Author(s):  
R. Mark Palmer
Keyword(s):  
Water Resources ◽  
Water Resources Management ◽  
Management Strategy ◽  
River Flow ◽  
Computer Modelling ◽  
Treatment Plan ◽  
Sewage Treatment ◽  
Nutrient Inputs ◽  
River Watershed ◽  
Resources Management

Abstract Sewage treatment studies at the watershed scale, compared to case-by-case community projects, ensures the most cost-efficient investment of funds commensurate with environmental requirements to sustain growth. A three-year environmental assessment study for the town of New Tecumseth, Ontario, examined all nutrient inputs to the Nottawasaga River watershed. Other challenging watershed constraints were investigated, such as stream and river flow takings for irrigation and sediment transport, prior to the selection of the master sewage treatment plan. The findings from the field research and computer modelling were used to (1) place a realistic perspective on nutrient impacts, present and future, attributable to treated sewage effluent; (2) design a master plan that could be used as an opportunity in terms of reusing the effluent locally for agricultural irrigation; (3) provide a real-time assurance of the plan’s performance/compliance, based on the actual carrying capacity of the aquatic ecosystem; (4) stage the construction of the plan in a cost-effective and environmentally sound manner; and (5) recommend a water resources management strategy to control other nutrient and sediment load sources within the watershed. The recommended master sewage treatment plan and water resources management strategy can restore the Ministry of Environment and Energy provincial water quality objective concentration for total phosphorus within the river during 7Q20 flow conditions.

Bioavailability of phosphorus as a tool for efficient P reduction schemes

1998 ◽  
Vol 37 (3) ◽  
pp. 241-247 ◽  
Author(s):  
Peter Gerdes ◽  
Sabine Kunst
Keyword(s):  
Sewage Treatment ◽  
Cost Effective ◽  
Effective Management ◽  
Lower Saxony ◽  
Effective Strategies ◽  
P Balance ◽  
Different Sources ◽  
Total P ◽  
P Sources ◽  
P Bioavailability

The bioavailability of phosphorus from different sources has been evaluated in the catchment area of the River Ilmenau (Lower-Saxony, Germany) by using algal assays. The P bioavailability describes the different potential of P from various sources of supporting eutrophication. Effluents from sewage treatment plants were highly bioavailable (72% of TP) whereas rainwater (26%) and erosion effluents (30%) showed a low bioavailability. In order to develop effective strategies to minimize P inputs into the river, source specific P bioavailability indices were determined and combined with a P balance to calculate inputs of vioavailable P (BAP) instead of total P (TP). It could be shown that the relative importance of the different P sources changes when applying BAP. Measures to reduce P inputs into the River Ilmenau will take P bioavailability into consideration and therefore lead to a more cost-effective management.

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