Eutrophication in the Baltic Sea

Håkanson, Lars; Bryhn, Andreas C.

doi:10.1007/978-3-540-70909-1

Cited by 44 publications

(22 citation statements)

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“…The theoreti-cal wave base is also an important divider for sediments; above this depth, sediments are generally affected by erosion and transportation processes, while sediment accumulation dominates bottom areas below the theoretical wave base. The theoretical wave base is located at 41.1 m depth in the BB, at 42.5 m in the BS, at 43.8 m in the BP, at 43.8 m in the GF, and at 39.2 m in the GR [11]. It should be noted that the actual wave base could be located at quite different depths than these during extreme meteorological events such as major storms or long calm periods.…”

Section: Methodsmentioning

confidence: 93%

“…At present, there are no such models available for nitrogen but only for phosphorus [9,11]. Furthermore, the very fact that it has been possible to construct a general dynamic phosphorus model which does not take nitrogen loadings into account but which uses a unitary set of equations and model constants and gives good predictions of recent TP concentrations in all of the five subbasins investigated in this work contradicts hypothesis number six [11]. Finally, riverine nitrogen loads peaked in the 1980s [3] and have been stable since the mid-1990s [12] while a stable atmospheric nitrogen deposition has also been noted since the mid-1990s [26] which makes it difficult to present comprehensive empirical support for this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

“…Surface waters were defined as being located above the theoretical wave base [11]. This is the depth below which wind and wave action normally do not reach and the depth at which the thermocline may typically be found.…”

Section: Methodsmentioning

confidence: 99%

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Trends in Total Phosphorus Loadings and Concentrations Regarding Surface Waters of the Baltic Sea, 1968-2007

Bryhn

2010

TOOCEAJ

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Abstract:The Baltic Sea, a large estuarine sea in northern Europe, has for many decades displayed obvious signs of anthropogenic eutrophication. This study relates long-term trends in total phosphorus (TP) loadings and TP concentrations in surface waters regarding five major sub-basins of the Baltic Sea; the Bothnian Bay, the Bothnian Sea, the Baltic Proper, the Gulf of Finland and the Gulf of Riga. The longest time series ever published on these variables was developed and used for this purpose. TP loadings to these waters have decreased greatly and significantly since the 1980s. However, TP concentrations have only decreased slightly in one of the sub-basins while concentrations have increased in the other four basins. Four possible hypotheses about the weak connection between TP loadings and concentrations are 1) increasing TP concentration is a delayed effect from many decades of intensive TP loading, 2) fewer saline inflows of high intensity have decreased sedimentation rates and increased TP concentrations, 3) fewer oxygen-rich saline inflows of high intensity have increased TP diffusion from deep sediments to the whole water column and 4) less ice in the winter has increased the erosion and resuspension of shallow sediments and increased TP concentrations.

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Section: Methodsmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

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Trends in Total Phosphorus Loadings and Concentrations Regarding Surface Waters of the Baltic Sea, 1968-2007

Bryhn

2010

TOOCEAJ

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“…The rating of trophic condition is based on Carlson and Håkansson trophic status classification criteria based on Secchi depth measurements and calculation of the Carlson index on Secchi distance [8][9][10][11]. Carlson trophic state index is used for comparison of different water bodies within an area as well as to compare trophic level changes over time [13][14][15][16].…”

Section: Evaluate Of Trophic Conditionmentioning

confidence: 99%

“…From the lowest to the highest biologic activity: Oligotrophic (water clear and translucent, with low levels of nutrients and algae), Mesotrophic (green waters with easy, yet clear, the average amount of nutrients and algae), Eutrophic (water with a dark green color, high concentration of nutrients and algae), Hypertrophic (enriched in phosphorus and nitrogen, low phytoplankton development, polluted waters). Body of water with low value of trophic index may also be considered Hipertrophic [8,9]. Trophic state index (TSI) [10] is a different classification system.…”

Section: Introductionmentioning

confidence: 99%

Water Turbidity as One of the Trophic State Indices in Butrinti Lake

Çako¹,

Baci²,

Shena³

2013

JWARP

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In this paper we are presenting observations, data and some conclusions regarding the water turbidity and transparency of the aquatic ecosystem of Butrinti Lake in southern Albania. Located amidst a major tourist attraction area, Butrinti Lake is fed by fresh waters from surrounding areas and discharges into Ionian Sea. Although development is preset in the area, it is still minor as part of the area is a National Park. Turbidity, as an optical property which describes the cloudiness of the water, is a measure of the degree to which the water becomes less transparent due to the presence of suspended particulates, including sediments and phytoplankton. The water turbidity parameters were measured every two weeks over a year, monitoring three selected stations in this water ecosystem. Turbidity of water in such ecosystems is measured in FTU (Formazin Turbidity Units) using a portable turbid meter (in our case type HANNA HI 93703-11), which measures the intensity of light scattered at 90 degrees, as a beam of light passes through a water sample. In addition, turbidity is evaluated using a Secchi disk. The depth (Secchi depth) until the disk can be no longer seen by the observer is recorded as a measure of the transparency of the water (inversely related to turbidity). The Secchi disk has the advantages of integrating turbidity over depth (where variable turbidity layers are present). The relationship between the depth of the viewing disk and the turbidity can be characterized by an inverse curvilinear one. The defined trend line can be expressed by the same curve related to the data of Butrinti Lake. An R2 Value of 0.85 was calculated for the above equation. Variations were observed on turbidity level of the selected stations in this ecosystem. These differences on the turbidity values of selected stations of water body can be explained by the communications sea-lagoon, fresh water supply as well as by the pollution due to human activity near a certain station. The monitored water ecosystem can be characterized by certain level of turbidity, based on the trophic state classification by Hakanson and Carlson. Furthermore, relationship between turbidity and trophic state evaluated by other bio-indicators of the monitored ecosystems is analyzed.

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