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Porewater nutrients (phosphate, ammonia and silicate) in the eastern part of the southern Baltic Sea

Graca B., Witek Z., Burska D., Białkowska I., Pawelec A., Bolałek J.

Oceanological and Hydrobiological Studies

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2006

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Vol. 35, No.3

237-256

EN

In the present work, results of studies concerning phosphate, ammonia and silicate in porewaters of the eastern part of the southern Baltic sediments are presented. A strong interaction was observed between the investigated compound concentrations and the sea bottom type, defined by means of the sediment water content (W) and loss on ignition (LOI) values. High concentrations and an exponential increase in concentration downwards in the sediment depth profile was observed in regions named here transport/accumulation bottom (LOI?4%, W?50%). Lower concentrations and irregular changes in concentration with depth occurred in regions designated as erosion bottom type (LOI<4, W<50%). Only in areas under strong anthropogenic influence (Vistula river mouth, the vicinity of Gdynia harbour), in the erosion type bottom concentration periodically raised to the level observed in the transport/accumulation bottom areas. The mass of nutrients accumulated in porewaters in the 10 cm thick layer of surface sediments of the Gulf of Gdańsk in September 2000 was estimated to be 910 t P-PO43-, 2780 t N-NH4+ and 5430 t DSi, while in March/April of 2001 estimated values equalled 908 t P-PO43-, 1860 t N-NH4+ and 3080 t DSi. In the erosion bottom areas, approximately 12 t, 210 t and 650 t of P-PO43-, N-NH4+ and DSi, respectively, were flushed out of the sediments during the intensive autumn-winter mixing.

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Interdependence between phosphorus forms in sediments and iron in interstitial waters in the Gulf of Gdańsk

Matuszewska K., Białkowska I., Bolałek J.

Oceanological and Hydrobiological Studies

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2003

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Vol. 32, No. 1

5-14

EN

The content of various phosphorus forms in sediments and the content of iron in interstitial waters were measured in sediment samples collected in the Gulf of Gdańsk in March 2001. The studies showed that the greatest amounts of the total phosphorus and total dissolved iron were present in the uppermost sediment layer, and their respective concentrations ranged from 203.99 žmol g-1 d.w. to 1894.02 μmol g-1 d.w., and from 0.02 μmol dm-3 to 4.68 μmol dm-3. The contents of these parameters were directly connected with the type of sediment – the greatest concentrations were measured in fine sediments. The analysis of multiple correlation coefficients demonstrated that in over 90% of cases the concentration of phosphorus bound with iron depended on: the sediment type and its humidity, the content of organic matter, and the concentration of the total iron dissolved in the interstitial waters.

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Distribution of the Fe (II) and Fe (III) dissolved in the interstitial water of the Gulf of Gdańsk

Białkowska I., Bolałek J.

Oceanological Studies

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2000

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Vol. 29, No. 4

43-54

EN

A sediment environment of the Gulf of Gdańsk is reductive to the iron (III). The iron (II) is a dominant form of this element in the interstitial water, and a total reduction takes place in a sediment layer of up to 20 cm. A speciation of a dissolved iron as well as a total iron concentration is related to types of sediments in a measuring point. It could also be noted that a concentration of each iron form in the above-bottom water layer is much lower than in the interstitial water of the top sediment layer. To illustrate redox conditions in the environment a ratio Fe(III) : Fe(II) was introduced. In the waters, the iron (III) dominates and the Fe(III) : Fe(II) ratio is much higher than the relevant value in the interstitial water.