Water Transport and Water Retention in Five Connected Subbasins in the Baltic Sea—Simulations using a General Mass-Balance Modeling Approach for Salt and Substances

Håkanson, Lars; Lindgren, Dan

doi:10.2112/08-1082.1

Cited by 6 publications

(5 citation statements)

References 24 publications

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“…The significant increase in Z Sd in the Bothnian Bay after 2016 (Fig. 7D) is either related to some unexplained interannual variability or truly represents an increase in water transparency happening in the Bothnian Bay due to the shorter residence time of the water mass and reduced nutrient loads there (Håkanson & Lindgren 2010). In either case, this location needs further study.…”

Section: Merged Satellite and In Situ Time Series Of Z Sdmentioning

confidence: 96%

Baltic Sea transparency from ships and satellites: centennial trends

Kahru

Elmgren

Fleming³

et al. 2022

Mar. Ecol. Prog. Ser.

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Water transparency can be measured with optical instruments and estimated with satellite sensors, but such measurements have been widely available for only a few decades. Estimates of water transparency using a white disk called a Secchi disk have been made for over a century and can be used to estimate long-term trends. However, historic in situ measurements of the Secchi depth (ZSd) were irregular in space and time and are difficult to interpret in regular time series due to biases introduced by changing locations and the timing of measurements. Satellite data time series, on the other hand, have consistent resolution in both space and time but cover too short a time to resolve climate-scale trends. We normalized historic ZSd measurements in the Baltic Sea with a satellite-derived mean climatology at 5 d temporal and 4 km spatial resolutions and created a merged time series of ZSd for the last century. The mean ZSd in the Baltic Sea from 1927-2020 decreased by 4.2 ± 0.6 m at a rate of 0.045 ± 0.06 m yr-1. Most of the change happened before 1987, and a further decrease was evident primarily in the satellite data during the 1998-2008 period. After 2008, no significant trend in ZSd and or the coefficient of diffuse light attenuation was detected in the Baltic Sea. However, in some sub-basins of the Baltic Sea, the decrease in ZSd continued even after that. The decrease in spectral water transparency in recent decades was highest in the 412 nm band, indicating an increase in the concentration of chromophoric dissolved organic matter.

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Section: Merged Satellite and In Situ Time Series Of Z Sdmentioning

confidence: 96%

Baltic Sea transparency from ships and satellites: centennial trends

Kahru

Elmgren

Fleming³

et al. 2022

Mar. Ecol. Prog. Ser.

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“…Published by ECSDEV, Via dei Fiori, 34, 00172, Rome, Italy http://ecsdev.org Sea, we first divide the water area into the following basins: Baltic Proper (BP), Gulf of Finland (GF), Gulf of Riga (GR), Bothnian Sea (BS), Bothnian Bay (BB), and Danish Straits and Kattegat (DS+KT), as shown in Figure 1. We then follow the studies by Savchuk (2005), Håkanson and Lindgren (2010) and subdivide the basins into three compartments: the surface-water layer (SW), middle-water layer (MW) and deep-water layer (DW). The compartments' physical characteristics including depths of the basins and the surface area are presented in Table 1.…”

Section: Study Areamentioning

confidence: 99%

“…The surface water layer is considered to be up to 44 meters deep, the middle water layer is between 44 and 75 meters (except for the Bothnian Sea), and the deep water layer takes up to 105 meters for the Gulf of Finland and 459 for the Baltic Proper. Regarding the Bothnian Sea, even though its depth is 301 meters, we prefer to model it as a basin with two compartments -the surface and deep water layers in line with the calculations of water exchange between the basins as in the study of Håkanson and Lindgren (2010). by Helsinki Commission (HELCOM).…”

Section: Study Areamentioning

confidence: 99%

“…Note that the decay rates are small in comparison to interactions with other compartments through water exchange. The interaction terms ji  were calibrated based on the estimates of annual water fluxes for the Baltic Sea presented in Håkanson and Bryhn (2008) and Håkanson and Lindgren (2010), assuming the total volume of water in each basin remains constant. Obviously, water is exchanged only with the adjacent basins; the zero values of parameters ji  mean that no water exchange occurs between the compartments.…”

Section: Study Areamentioning

confidence: 99%

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Modeling Multiple Interacting Nutrient Stocks:Application to the Baltic Sea

Kuosmanen

Kuosmanen²

2018

EJSD

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Eutrophication of water bodies is a worldwide ecological problem caused by excessive amounts of nutrients. This paper develops an accounting method for modeling multiple interacting stocks of nutrients, which applies the dynamic nutrient balance approach to calculate empirical nutrient budgets. The proposed model of multiple interacting stocks draws an explicit connection between nutrient stocks on land and nutrient stocks in the sea, which in turn links estimated marine nutrient stocks with the empirical data of nutrient concentrations. The model is applied to the Baltic Sea, where stocks of nitrogen and phosphorus are calculated for six basins, drawing distinction between surface, middle and deep water layers of the basins, and taking into account spatial interactions of nutrients within the water layers and between the basins. The model is calibrated using empirical data on nutrient loads and concentrations. Finally, we apply the model to forecast future development of nitrogen and phosphorus concentrations under different abatement scenarios.

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“…26 Accumulation areas occupy around one third of the bottom area of the Baltic Proper. 9,25,[27][28][29] In this paper, we analyze 12 sediment cores collected in the Baltic Proper between 61 m and 175 m water depth and calculate the amounts of mobile phosphorus. We assume that our sediment results can be representative of the order-of-magnitude estimate for the entire bottom area of the Baltic Proper.…”

Section: Introductionmentioning

confidence: 99%

Estimating the Pool of Mobile Phosphorus in Offshore Soft Sediments of the Baltic Proper

Malmaeus

Karlsson

2011

Air, Soil and Water Research

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Background: Eutrophication is a major threat to many coastal ecosystems worldwide. This paper deals with the sediment-water exchange of phosphorus, one of the elements that may stimulate primary production in the aquatic environment. The lack of phosphorus-binding capacity in sediments at low redox-potential is recognized as an important mechanism for eutrophication-related effects in some areas. Methods: Twelve sediment cores were collected in the Baltic Proper between 61 m and 175 m water depth and a number of phosphorus fractions were analyzed. Integrating the concentrations over the depth profiles, the amounts of mobile phosphorus were estimated in each core. Results: It was found that sediments below the redox cline in the Baltic Proper contained small amounts of mobile phosphorus. The total amount of mobile phosphorus in the entire Baltic Proper sediments below 65 m water depth was estimated to between 55,000 tonnes and 156,000 tonnes or between less than 10% to around 25% of the phosphate in the system (water plus sediments). This represents the maximum amount of phosphorus that could possibly be released to the water column from these areas. We argue that the most reasonable estimate of the pool of mobile phosphorus in the sediments is the lower number. Conclusion: The amounts of mobile phosphorus in sediment cores with oxidized surface layers were higher compared with sediment cores with reduced surfaces, indicating that there is a potential phosphorus-binding capacity in sediments below the redox cline if oxic conditions improved. Oxygenation of the Baltic Proper bottom water between 65 m and 100 m could probably remove around 100,000 tonnes of phosphorus from the water column and reduce phosphorus concentrations in the deep water by on average 30 mg/m 3 , which would possibly be felt also in the surface water.

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Water Transport and Water Retention in Five Connected Subbasins in the Baltic Sea—Simulations using a General Mass-Balance Modeling Approach for Salt and Substances

Cited by 6 publications

References 24 publications

Baltic Sea transparency from ships and satellites: centennial trends

Baltic Sea transparency from ships and satellites: centennial trends

Modeling Multiple Interacting Nutrient Stocks:Application to the Baltic Sea

Estimating the Pool of Mobile Phosphorus in Offshore Soft Sediments of the Baltic Proper

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