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A Berner cascade impactor was used for the separation of solid urban aerosols in two localities of the Baltic coastal macro-region – Słupsk and Hel – in different seasons and weathers. Ten ranges of aerodynamic diameters between 0.009 and 8.11 μm were used. The elementary composition for each diameter was obtained in a complex procedure consisting of laser ablation of deposits, then their successive ionization in an inductively coupled plasma generator, and finally, mass selection in a quadrupole spectrometer. Despite its complexity, the chemical element analysis method proved to be versatile, allowing the identification air pollution from natural and industrial sources, and road traffic.
Aerosol samples were collected in May 1997 at a routine off-shore measurement station in the Gdańsk Deep region and at Hel, the latter being a coastal station situated at the tip of the Hel Peninsula. Concentrations of NO− 3 , Cl−, Na+, Mg2+, K+ and Ca2+ were measured simultaneously at both stations. The sea influences the chemical composition of aerosols in the coastal zone of the Gulf of Gdańsk regardless of season, time of day or direction of advection. Sodium chloride was always present in aerosols in the form of large particles originating from seawater. Besides the marine chloride and nitrate, additional amounts of these ions could have been of terrigenous origin. Sodium and chloride concentrations were dominant in the total mass of aerosols at both stations; however, these concentrations were three times higher at the marine station. Similarly, the concentrations of ions originating from seawater, like magnesium and calcium, were, on average, three times higher at the marine station. The chemical composition of aerosols and air over the Gulf of Gdańsk was modified through the evaporation of chloride from the marine salt particles in reactions with gaseous nitric and sulphuric acids. A certain deficit of chloride versus sodium ions was noted. At the marine station the Cl−/Na+ ratio reached 0.89 ± 0.2, on average, while over the land station it was 0.93 ± 0.25, i.e. lower than the seawater standard.
This paper evaluates the second part of a three-year field study to investigate the effects of the beach macro- and meiofauna community structure on the decay of stranded wrack on Hel Beach (see Jędrzejczak 2002),f ocusing on successional changes and the colonisation of wrack by beach fauna. The investigation enabled the associated faunal assemblages to be characterised. Zostera marina tissue was colonised by the supralittoral fauna in two distinct phases. The macrofauna, including the talitrid amphipod Talitrus saltator,ad ult Diptera and Coleoptera, colonised the wrack within a day,with maximum numbers being recorded after 3 days. Thereafter,their numbers in the samples declined and the meiofauna, consisting of nematodes, oligochaetes,tur bellarians and dipteran larvae, became increasingly abundant. After 18 days,the wrack surface was dominated by meiofauna. This faunal succession was not directly related to the degradation of the seagrass tissue,whic h proceeded linearly throughout the study period. Exclusion of macrofauna from the wrack by the use of < 1 mm mesh litterbags had no appreciable effect on the rate of dry matter loss. Therefore,the major macrofaunal wrack consumers,including T. saltator and Coleoptera,d id not affect the rate of seagrass disintegration. The effect of meiofaunal nematodes, oligochaetes,gast rotrichs and turbellarians on wrack breakdown could not be accurately determined. However,the development of the meiofaunal community suggested that changes in the fauna community were linked more closely to successional changes in the chemistry and/or microflora of the beach wrack than to its physical breakdown.
The effects of the beach community structure of macro- and meiofauna on the process of beach wrack decay were investigated by means of a simple field colonisation experiment in a temperate, fine quartz sediment, sandy beach at the end of the Hel Peninsula in Poland. 1260 replicate litterbags of three mesh sizes (12 mm, 0.5 mm, 48 μm) containing fresh wrack were used to assess the role of faunal and non-faunal components in the breakdown of stranded Zostera marina. Wrack breakdown was determined during a three-year field study. This paper presents the first part of the results of this field experiment, which refer to the effects of fragmentation detritivory, leaching and decay rates. Material was lost from the bags at a rapid rate, with only 22–32% of the original dry mass remaining after 27 days in the field. This degradation was not directly related to the faunal succession of the eelgrass tissue, which proceeded in two distinct phases throughout the study period. Exclusion of macrofauna from the wrack by the use of finer-mesh litterbags (< 1 mm) had no appreciable effect on the rate of dry matter loss. Microbial decay, and abiotic leaching and fragmentation are probably the major causes of seagrass weight loss from the litterbags.
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