Oceanologia No. 47 (3) / 05






Attenuation of wave-induced groundwater pressure in shallow water. Part 2. Theory
Oceanologia 2005, 47(3), 291-323

Stanisław R. Massel, Anna Przyborska, Michał Przyborski
Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: smas@iopan.gda.pl

Keywords: surface wave, pore water pressure, sandy beach, filtration, mathematical modelling

Received 11 March 2005, revised 14 July 2005, accepted 17 August 2005.
In this Part 2 of the paper (Part 1 was published by Massel et al. 2004) an exact close-form solution for the pore-water pressure component and velocity circulation pattern induced by surface waves is developed. This comprehensive theoretical model, based on Biot's theory, takes into account soil deformations, volume change and pore-water flow. The calculations indicate that for the stiffness ratio G/E'w ≥ 100, the vertical distribution of the pore pressure becomes very close to the Moshagen & Tørum (1975) approach, when the soil is rigid and the fluid is incompressible.
    The theoretical results of the paper have been compared with the experimental data collected during the laboratory experiment in the Large Wave Channel in Hannover (see Massel et al. 2004) and showed very good agreement. The apparent bulk modulus of pore water was not determined in the experiment but was estimated from the best fit of the experimental pore-water pressure with the theoretical one. In the paper only a horizontal bottom is considered and the case of an undulating bottom will be dealt with in another paper.

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Fluxes and balance of mercury in the inner Bay of Puck, southern Baltic, Poland: an overview
Oceanologia 2005, 47(3), 325-350

Leonard Boszke
Collegium Polonicum, Adam Mickiewicz University,
Kościuszki 1, PL-69-100 Słubice, Poland;
e-mail: boszke@euv-frankfurt-o.de

Keywords: total mercury, fluxes, balance, environmental fate, Bay of Puck, Baltic Sea, Poland

Received 19 April 2005, revised 6 May 2005, accepted 5 July 2005.
The aim of the study was to analyse the balance of mercury (Hg), i.e. the content of this metal, its inflow and outflow, in the ecosystem of the Bay of Puck. Based on literature data and the results of the author's own study, this analysis has shown that the main source of Hg pollution is the atmosphere. An estimated 1.1-3.8 kg of Hg enters annually from the atmosphere, whereas the mass of Hg carried there by river waters per annum is about 7 times lower (0.13-0.44 kg year-1). The 0.9-2.7 kg year-1 of Hg released from Bay of Puck waters to the atmosphere is of the same order as the quantity deposited from the atmosphere. The total amount of Hg deposited in the upper (0-5 cm deep) layer of the sediments has been estimated at 240-320 kg, its rate of entry being c. 2.25-2.81 kg year-1. 0.25-1.25 kg year-1 of Hg are released from the bottom sediments to bulk water, while 0.61-0.97 kg remains confined in aquatic organisms, including 133 g in the phytobenthos, 2.6 g in the zooplankton, 420-781 g in the macrozoobenthos and 34 g in fish.
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Trophodynamic variations on microtidal North Mediterranean sandy beaches
Oceanologia 2005, 47(3), 351-364

Paolo Vassallo, Mauro Fabiano
Department for the Study of the Territory and its Resources,
University of Genoa,
Corso Europa 26, IT-16132 Genova, Italy;
e-mail: vassallo@fisica.unige.it

Keywords: beach environment, trophodynamics, swash zone

Received 19 January 2005, revised 10 June 2005, accepted 5 July 2005.
Trophic models of the micro and meiobenthic community of six sandy beaches on the Ligurian coast (north-western Mediterranean Sea) have been performed to assess variations in structure and function of the ecosystem. A novel approach based on the determination of the feeding predisposition of the benthic community revealed that there is a significant shift in the trophodynamics of the system with respect to environmental constraints. Along an emerged-submerged gradient the benthic community displayed a clear trend from a fundamentally detritus-dependent structure to an autotrophic, more balanced and diversified one. The trends analysed focus on the importance of the swash zone as a transitional area between the land and the sea that is characterised by a high diversity and activity of the trophic network.
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Hydrology and morphology of two river mouth regions (temperate Vistula Delta and subtropical Red River Delta)
Oceanologia 2005, 47(3), 365-385

Zbigniew Pruszak1, Pham van Ninh2, Marek Szmytkiewicz1, Nguyen Manh Hung2, Rafał Ostrowski1*
1Institute of Hydroengineering, Polish Academy of Sciences,
Kościerska 7, PL-80-953 Gdańsk, Poland;
e-mail: rafi@ibwpan.gda.pl
*corresponding author
2Institute of Mechanics,
Center for Marine Environment, Survey, Research and Consultation,
264 Don Can, Hanoi, Vietnam

Keywords: river mouth, delta, sedimentation, discharge, waves, coastal currents

Received 7 February 2005, revised 3 August 2005, accepted 29 August 2005.
The paper presents a comparative analysis of two different river mouths from two different geographical zones (subtropical and temperate climatic regions). One is the multi-branch and multi-spit mouth of the Red River on the Gulf of Tonkin (Vietnam), the other is the smaller delta of the river Vistula on a bay of the Baltic Sea (Poland). The analysis focuses on the similarities and differences in the hydrodynamics between these estuaries and the adjacent coastal zones, the features of sediment transport, and the long-term morphodynamics of the river outlets. Salinity and water level are also discussed, the latter also in the context of the anticipated global effect of accelerated sea level rise. The analysis shows that the climatic and environmental conditions associated with geographical zones give rise to fundamental differences in the generation and dynamic evolution of the river mouths.
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Comparison of two models in the estimation of nitrogen uptake rates using data from 15-N incubation experiments
Oceanologia 2005, 47(3), 387-403

Clavery Tungaraza*, Natacha Brion, Willy Baeyens
Laboratory for Analytical and Environmental Chemistry,
Vrije Universiteit Brussel,
Pleinlaan 2, BE-1050 Brussel, Belgium
*current contact address:
Faculty of Sience, Sokoine University of Agriculture,
PO Box 3038, Morogoro, Tanzania;
e-mail: tungaraza@suanet.ac.tz

Keywords: model validity, nitrogenous nutrients, uptake rates

Received 13 May 2005, revised 1 August 2005, accepted 16 August 2005.

This study was supported by the EC research programme COMWEB (Comparative Analysis of Food Webs Based on Flow Network) and the Belgian national research programme (CT960052) "Sustainable Management of the North Sea".
This paper compares two uptake rate models, Dugdale & Goering's (D&G) model and Elskens' model. The aim is to provide an insight into how estimates of uptake processes, i.e. regeneration and loss rates from both dissolved and particulate nitrogen pools, influence the total uptake rates when the two models are compared. The uptake rates of three nitrogenous nutrients (nitrate, ammonium and urea) from 15-N incubation experimental data were compared. The comparison indicated that the D&G model underestimated nitrate uptake rates by about 34%, implying a significant regeneration and loss rates of the nutrient. Elskens' model further showed that the loss rates from the dissolved phase were about 40% and 25% for the ammonium and urea pools, respectively, indicating that the D&G model underestimated the experimental uptake rates of the nutrients. On average, nitrification made up about 30% of the total ammonium uptake flux, whereas the sinks from particulate nitrogen and dissolved nitrogen were estimated at 36% and 56%, respectively. The D&G model sometimes overestimated the f-ratio values to about 60% and higher as a result of ammonium and urea uptake rates underestimation. This paper also shows that detritus adsorption, bacterial uptake and cell lysis are equally important processes.
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Hemimysis anomala G. O. Sars, 1907 (Crustacea, Mysidacea) - first record in the Gulf of Gdańsk
Oceanologia 2005, 47(3), 405-408

Urszula Janas, Piotr Wysocki
Department of Experimental Ecology of Marine Organisms,
Institute of Oceanography, University of Gdańsk,
al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: ula@sat.ocean.univ.gda.pl

Keywords: Hemimysis anomala, non-indigenous species, Southern Baltic

Received 19 May 2005, revised 1 September 2005, accepted 5 September 2005.

The project was carried out within the framework of the MarBEF Network of Excellence "Marine Biodiversity and Ecosystem Functioning" which is funded by the European Community's Sixth Framework Programme (contract No GOCE-CT-2003-505446). This paper is contribution number MPS-05017 of MarBEF.
The present paper reports on the occurrence of Hemimysis anomala G. O. Sars, 1907 (Crustacea, Mysidacea) in the coastal waters of the Gulf of Gdańsk in the years 2002-2005.
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5th Baltic Sea Science Congress. "The Baltic Sea - a changing ecosystem" (Sopot, Poland, 20-24 June 2005). Brief report
Oceanologia 2005, 47(3), 409-411

Jan Piechura
Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: piechura@iopan.gda.pl

Manuscript received 6 September 2005.
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