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Geological, geochemical and bacteriological conditions in a post- dredging pit in Puck Bay (Southern Baltic, Poland)

100%

Bolalek J., Piekarek-Jankowska H., Leczynski L., Frankowski L., Podg?rska B.

Oceanological Studies

1996

vol. 25

issue 3

111-122

The paper presents the results of geological and geochemical studies carried out in an artificial pit which was formed after dredging the sediments up from the bottom of Puck Bay in 1991. It was found out that fine-grained classic sediments (d50 = 0.2 - 0.08 mm) as well as a great amount of organic matter (Pilayella littoralis) were deposited in the pit. The proc-esses of organic matter mineralization brought about reducing conditions. Ammonia concen-trations in near-bottom waters were higher than in the areas surrounding the pit 191.0 mmol?dm-3 compared to 3.97 mmol?dm-3. Phosphate concentrations in the waters and sedi-ments were elevated and reached values up to 1 mmol?dm-3. Intensive processes of organic matter mineralization caused both the temporary decline in sulphate concentration in near-bottom waters down to the value of 272 mg?dm3 (almost twice lower than the average concen-tration in Puck Bay waters) as well as sulphate deficiency in interstitial water. Below the 5 - metre isobath, the concentration of hydrogen sulphide varied between 0.11 and 0.49 mmol?kg-1w.w. The total number of bacteria in 1 cm3 of near-bottom water amounted to 107 and the number of sulphate-reducing bacteria ranged from 240-46000. The number of sulphate-reducing bacteria in 1 g d.w. of surface bottom sediments was estimated as 104 to 106.

Anthropogenic factors, sedimentation rates, vertical movements and the prognoses of the east Baltic Sea development according to the data of comparative sedimentological analysis

100%

Pustelnikovas O.

Oceanological Studies

2000

vol. 29

issue 1

101-116

In the process of sea development, the water level fluctuations, neotectonic movements, sedimentation rates and anthropogenic factors play an important role. Water level fluctuation and vertical movements determine the rates of long-term sedimentation. The sea level rises South of 56?N, its amplitude has been increasing from 1.5 mm y-1 (at the beginning of the 20th century) to 3-4 mm y-1 (predicted for the 22nd century). The rise of land is evident in the Central and Northern Baltic (1-9 mm y-1). These factors speed up the erosion of shallowing areas, eutrophication and accumulation of sedimentary matter in local basins. The latter processes complicate the ecological situation in the river mouth areas. The chemical composition of sediments reflect the nature of ground rocks in the denudation basin and change climatic conditions. The anthro-pogenic activity takes place in the river mouth areas, lagoons and other geochemical barriers. The mentioned factors influence the rates of sedimentation (0.6-7.5 mm y-1) which reach their maximum in the shallow areas of the East Baltic (2.5-7.5 mm y-1).

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2 Oceanological Studies

1 2000

1 1996

1 Bolalek J.

1 Frankowski L.

1 Leczynski L.

1 Piekarek-Jankowska H.

1 Podg?rska B.

1 Pustelnikovas O.

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Geological, geochemical and bacteriological conditions in a post- dredging pit in Puck Bay (Southern Baltic, Poland)

Anthropogenic factors, sedimentation rates, vertical movements and the prognoses of the east Baltic Sea development according to the data of comparative sedimentological analysis