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1

The Puck Bay as an example of deep dredging unvaforably affecting the aquatic environment

Graca B.

Oceanological and Hydrobiological Studies

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2009

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Vol. 38, No.2

109-127

EN

The presented study is a review of available geochemical data concerning a dredge area in the Puck Bay. It is a small, semi-closed and degraded water body on the Polish Baltic coast. In this region very deep dredging was conducted in the years 1989-95. Five dredge pits were created in the bottom of the bay. Only two of them have been geochemically investigated so far. In the deepwater parts of both the dredge pits organic matter accumulation resulted in sulfate reduction and subsequent hydrogen sulfide production in the sediment, as well as elevated nutrient concentrations in the interstitial waters. Moreover, temporal oxygen deficits in the near bottom waters were observed. Such conditions favor nitrogen and phosphorus release to the water column and potentially enhance the eutrophication. The impact of deep dredging on the chemical conditions in the dredged area seems to be controlled by a complex interplay of the season, phytoplankton biomass production and hydrodynamic conditions. Areas with high biomass production and low water dynamic are probably more vulnerable to environmental degradation due to deep dredging. This implies that some of the dredge pits require different methods of recultivation than others. However the decision if, and with which methods, to remediate dredge pits in the Puck Bay requires successive research including all the pits in all four seasons.

2

Microbiological changes in the environment caused by deep dredging. A case study: post-dredging pit Kuźnica II (Puck Bay)

Graca B., Dudkowiak M.

Oceanological and Hydrobiological Studies

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2007

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Vol. 36, No.1

17-27

EN

In this study psychrophilic, mesophilic and denitrifying bacterial abundances were studied seasonally (summer, autumn, winter and spring) in the water column and surface sediment layer (0-5 cm) in the post dredging pit Kuźnica II and natural areas of Puck Bay. The research was conducted between VI 2001 and III 2003. In the pit area an increase in mesophilic bacteria and a decrease in denitrifying bacteria numbers were observed, when compared to the natural areas. In the case of the mesophilic bacteria, the increase was visible in the near-bottom waters and surficial sediments during the period of well developed vegetation – in summer and autumn. In the case of denitrifying bacteria, the decrease of number concerned the sediments. Numbers of psychrophilic bacteria in both the natural and dredged areas did not differ significantly over the course of the study. These results suggest that deep dredging can cause the self-purification potential of the ecosystem to be diminished and induce strong bacteriological pollution.

3

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.

4

Monitoring stacji fotowoltaicznych w świetle norm europejskich

Zaremba A., Rodziewicz T., Graca B., Wacławek M.

Chemistry-Didactics-Ecology-Metrology

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2005

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R. 10, NR 1-2

51--55

PL

Przedstawiono założenia nowej normy europejskiej dotyczącej monitoringu stacji fotowoltaicznych (IEC 61724). Pokazano jej zastosowanie na przykładzie ministacji pracującej na dachu Uniwersytetu Opolskiego.

EN

The new European standard IEC 61724 (concerned with photovoltaic monitoring) was presented. Application of this standard to mini photovoltaic system working on the roof of the Opole University was given.

5

Denitrification in the sediments of the inner Puck Bay -preliminary results

Graca B.

Oceanological and Hydrobiological Studies

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2004

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Vol. 33, No. 4

73--91

EN

Denitrification was measured in the sediments of the Inner Puck Bay using the acetylene inhibition technique and pertinent environmental data. This process was not found to be particularly significant for the nitrogen budget of the ecosystem. The rate ranged from 0 to 40.2 μmol N m-2 h-1, which is equivalent to 151 t N per year. This constitutes 6.5% of the external nitrogen input to the investigated water body. The denitrification rate reached the highest values in spring, after the first algal blooms, when relatively fresh organic matter had amassed in the sediments and nitrate concentrations in interstitial waters peaked. The rates were almost sixfold lower than the maximal value in summer and fall. The main nitrogen source for denitrification in the investigated area was nitrification within the sediments. The deciding parameter determining the variability of the denitrification rate was the nitrate concentration in interstitial waters.

6

Temporal variations in phosphorus species in the surface layer of bottom sediments from the Gulf of Gdańsk - preliminary research

Graca B., Bolałek J.

Oceanological Studies

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2000

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Vol. 29, No. 4

55-66

EN

Temporal variations in phosphorus species [total phosphorus (Ptot), organic phosphorus (Porg), total inorganic phosphorus (Pmin), phosphorus bound to calcium (PCa), aluminium (PAl) and iron (PFe)] were studied in the surface layer of bottom sediments from the Gulf of Gdańsk. These changes were caused mainly by variability in Porg, PAl and PFe concentrations and were closely related to the growth cycle in the basin. The phosphorus concentration was higher in the spring and summer (April - September) that in the autumn and winter (November-March). For much of the year concentrations of Pmin were higher than those of organic phosphorus. The prevalent form of inorganic phosphorus was PCa, whose concentrations exceeded those of iron- and aluminium-bound phosphorus.