Chloride, phosphate, sulphate, ammonia, hydrogen carbonate concentrations, the redox potential Eh and the pH of bottom sediments were determined. The spatial distribution and profiles of selected species are presented. These parameters showed great variability (e.g. potential redox values ranged from -358 to 223 mV), which depended mainly on the penetration of underground waters and station location, and but only to an insignificant extent on the bottom type. Higher redox potentials were recorded for samples with low PO43-, NH4+, HCO3- and Cl- concentrations and with high SO42- concentrations. The relationship between redox potential and the concentration of species originating from the oxidation of organic matter, e.g. PO43-, NH4+ and HCO3-, was found.
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.
The paper presents results of analytical investigation on possible sources of hydrogen sulphide occuring in seawater supplied to marine laboratories of the Marine Station of Gdansk University in Hel.Seawater is pumped to aquaria system from the Puck Bay.Hydrogen sulphide concentration in pumped water was about o.25 mmol/ml, while in sediments surrounding the water intake it reached 2.64 mmol/ml.It turned out that hydrogen sulphide was produced in sediments by sulphste reducing bacterai from anthropogenic wastes.
Differences between the species composition and total resources of bottom macrofauna in two areas of Puck Bay were analysed in 1962-63 and 1984-85. These areas were the shallow Puck Lagoon, originally overgrown by luxuriant multi-specific submerged meadows which later un-derwent serious degradation, and the outer Puck Bay with its very limited extent of underwater meadows. In the first area the total resources were found to have decreased, whereas in the second the bottom macrofauna had increased. Both regions saw a four-fold increase in polychaete bio-mass, that of Hediste diversicolor in particular. In the outer Puck Bay the mollusc biomass in-creased, especially that of Mytilus trossulus, Macoma balthica, and the crustacean Gammarus sp., Balanus improvisus, and especially Corophium volutator. The biomass of most taxonomic groups decreased, which in the Puck Lagoon is evidence for the degradation of the bottom macroflora.
Certain ice-related processes and phenomena associated with formation and disintegration of grounded ice hummocks in sheltered areas are discussed. The descriptions and discussion are based on the author?s research carried out over many years in the southern Baltic coastal lagoons. The first part of the paper focuses on the hummocking process which may be invoked to explain the formation of high (up to 10 m above the water level) hummocks. Conditions necessary for hummocking are described and the areas and seasons during which hummocks occur are indicated. In the second part of the paper, the rate at which the hummock height is being reduced during: 1. windless weather with below-zero air temperature, and 2. windy weather (strong wave action) and above-zero air temperature, is discussed. The formation of the so-called ice depression around a hummock is described as well. In the concluding part, attention is being paid to destructive effects of ice in the area affected by hummocking
The subject of the study were the benthic diatom communities of the Puck Bay littoral zone. Samples of the sediments were taken from sites situated near the sewage treatment plant at Swarzewo from June 1998 to May 1999. The analysis of the species composition and the relative percentages of the diatom indicative groups were used to evaluate water quality. The following ecological factors were taken into consideration: salinity, trophic status and saprobity. Following Lange?Bertalot (1979), water quality was classified based on a 5-degree scale of saprobity. It was correlated to the percentages of the sensitive, tolerant and resistant diatoms taxa and their reaction to organic matter content. The water quality evaluation was tested with the diatom indices using Omnidia 3 software. The results of the diatom studies indicate that the dominating groups were the oligohalobous and mesohalobous taxa, which are characteristic of eutrophic waters and contain biogenic compounds, mainly nitrogen and phosphorus. The most abundant groups in the saprobic spectrum were the resistant (-mesosaprobic, polysaprobic) and tolerant (-mesosaprobic, /-mesosaprobic) diatoms, which are indicators of water purity class II (III), and in summer, predominantly class III. The comparison of the results of diatom analysis of the Puck Bay microphytobenthos obtained with the Lange?Bertalot (1979) method and the those acquired with Omnidia 3 software demonstrates the possibility of applying it to evaluate environmental status and assess polluted brackish waters.