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The role of air masses on iron concentrations in wet atmospheric deposition over the urbanized coastal zone of the Gulf of Gdańsk

Falkowska L., Lewandowska A., Sikorowicz G., Bełdowska M., Madeja J.H.

Oceanological and Hydrobiological Studies

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2008

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Vol. 37, No.2

21-37

EN

This paper describes the role of air masses in transporting iron to the coastal zone of the Gulf of Gdansk. Fe(II) concentrations in rainfall were measured between 19th January and 30th November 2005 in Gdynia, during which time they varied from 0.74 žmol dm-3 to 97.45 žmol dm-3. The relationship between iron concentrations and precipitation amount, including during preceding rainless periods, was calculated. The effectiveness of washing iron out of the atmosphere is described by the exponential function of precipitation duration. Air masses arriving from west of the area transport terrigenous iron to the coastal zone of the Gulf of Gdańsk, while anthropogenic sources in Western Europe and Pomerania hardly affected the iron concentrations.

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The impact of solar radiation on changes in chlorophyll a concentration in the sea surface microlayer in the southern Baltic

Falkowska L., Pryputniewicz D., Magulski R., Dunajska D., Sikorowicz G., Kowacz M.

Oceanological and Hydrobiological Studies

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2005

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Vol. 34, No.3

109--123

EN

The potential effect of an increase in ultraviolet radiation on organic matter in the sea surface microlayer and subsurface bulk seawater was evaluated in spring during three sampling periods in 1997, 1998, and 2000. The phytoplankton concentration is high in the water of the southern Baltic during this period. The results of temporal changes in chlorophyll a, phaeopigments, and oxygen concentrations were taken into account. An inhibitory effect (expressed as a decline in chlorophyll a concentrations) on biological processes in the sea surface microlayer as well as in the subsurface layer occurred around noon and in the early afternoon. High levels of ultraviolet radiation intensified chlorophyll a reduction. The measurements conducted in the microlayer and the subsurface layer indicated the possibility of photodamage to phytoplankton under natural conditions when there is an excessive increase of UV-B radiation in comparison to PAR. A significant increase in the phaeophytin a concentration and a decrease in the chlorophyll a concentration was observed at noon when the UV-B/PAR ratio was high.

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Diurnal variations in nitrogen, phosphorus and iron compounds in the southern Baltic Sea

Sikorowicz G., Falkowska L., Burska D., Dunajska D., Pryputniewicz D., Magulski R., Lewandowska A.

Oceanologia

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2005

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No. 47 (2)

243-263

EN

In order to assess their short-term variability, nutrient concentrations were measured at standard depths at 2 h intervals in the deepest region of the Gdańsk Deep during the first ten days of June 2001. The mean concentrations of nutrients in the euphotic zone were: NN (NO_2-, NO_3-, NH_4+) - 1.93 žmol dm^-3, PO_4^3- - 0.12 žmol dm^-3 and Fetot - 0.11 žmol dm^-3. During daylight hours, when the rate of assimilation was fastest, concentrations of nitrogen, phosphorus and iron compounds were very low. The phosphate concentration fell to a minimum (0.03 žmol dm^-3) between 04:00 and 10:00 hrs, while total iron dropped to 0.01 žmol dm^-3 between 10:00 and 16:00 hrs. Both levels were below the limiting values for phosphorus and iron. At night, concentrations of NO_3- and PO_4^3- rose by 25%, those of NH_4+ and Fetot by 35%. The mean molar ratios of N_N:PO_4^3- and Fetot:PO_4^3- in the surface layer were subject to significant daily fluctuations. The molar N_N:PO_4^3- ratio was higher than the optimum value established for the Baltic Sea. Below the halocline, the concentrations of dissolved iron and phosphorus rose as a result of diffusion from sediments in response to changing redox conditions.

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Short-term fluctuations of chlorophyll α fluorescence versus diurnal variations of solar radiation in the surface water of the Gdańsk Basin

Magulski R., Falkowska L., Dunajska D., Pryputniewicz D., Sikorowicz G.

Oceanological and Hydrobiological Studies

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2004

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Vol. 33, No. 3

57--68

EN

Measurements of chlorophyll α fluorescence accompanied by solar radiation measurements were carried out during two spring cruises in the region of the Gdańsk Basin. Chlorophyll α fluorescence, similarly to that of chlorophyll a concentration in the seawater, showed considerable diurnal variability. The measurements provided statistically significant negative correlation coefficients that indicated that chlorophyll α fluorescence is inhibited as solar PAR and UV radiation intensity increases. The approximate range of radiation intensity that corresponded to a clearly marked decline in chlorophyll α fluorescence and chlorophyll α concentration was determined. It was revealed that the decline in chlorophyll a concentration in the surface water layer resulted from the photodegradation of chlorophyll α as well as phytoplankton grazing. In both cases, the resulting observation was an increase of pheophytine a concentration. The vertical migration of phytoplankton was identified as an additional process induced by high radiation levels.