Beach sediments from two beaches at the Polish coast of the Baltic Sea were collected and analyzed. The sediments were collected in two seasons – winter and summer – at two stations, depending on the influence of the sea water on the examined sediments. At each station, surface sediments (0-5 cm) were collected as well as sediments at the depth of 10-15 cm. The results of the conducted tests reveal, that anthropopressure, the depth where the collected sediments were taken and the direct influence of the sea water on the sediments have impact on the chemical composition of beach sediments and their food quality for the inhabiting psammon. The conducted tests disclose that there is more organic matter and its labile forms in the sediments originating from Ustka. Strong anthropogenic pressure found at the beach in Ustka also contributes to higher concentration of uncharacterized fraction of organic carbon in the area. Analyzing alimentary usefulness of the organic matter there, it seems to be higher at the beach in Czołpino.
Heavy mineral assemblages were studied in onshore sandy deposits from the 26 December 2004 tsunami on Kho Khao Island, southern Thailand. The most common minerals included tourmalines, zircon, muscovite, biotite, limonites and opaque minerals. An abundance of micas and depletion in tourmalines allowed us to distinguish the tsunami deposits from modern beach sediments and pre-tsunami soils. Major lateral and vertical changes in the studied profiles were related to an increase in flake-shaped micas upward in the tsunami sequence as well as landward. These variations, although documented for one grain size fraction, corresponded well with changes in the grain size distributions of the whole samples. The observed changes probably reflect wave hydrodynamics and a change in the sedimentation mode from bed-load deposition to settling of the suspended load.
Grain size studies of sediments from beaches in the region from Mandapam to Kanyakumari, divided into 5 sectors, indicate that sediments are unimodal to polymodal in nature, coarse to fine grained, moderately to poorly sorted, and positively-negatively skewed in character. The inference to be drawn from these studies is that the variation in sedimentological parameters is governed by fluvial input, wave dynamics, and littoral transport of the sediments. Bivariant plots show that the Mandapam and Kanyakumari sectors can be classified as beach environments, whereas the Tuticorin and Valinokkam sectors come under the influence of riverine environments and the dune environment in the Manappad sector. The CM pattern of all five sectors shows a clustered distribution of sediments in the PQ and QR segments, indicating a graded mode of deposition. Visher diagrams depict a wave shadow environment for the Mandapam sector, whereas the Valinokkam, Tuticorin and Manappad sectors show double saltation populations characteristic of beaches, and the Kanyakumari sector is characterized by a more truncated population characteristic of a plunge zone, which is a high-energy environment.
Potential capability of heterotrophic bacteria for extracellular enzyme synthesis and their activity were determined in a transect from dunes to a water depth of 1 m in a sandy beach near Sopot on the southern Baltic coast. Among studied enzymes, alkaline phosphatase, esterase lipase, and leucine arylaminase were synthesized in a higher degree, whereas α-fucosidase, βglucouronidase and α-galactosidase had only low levels. No clear horizontal gradients were observed in the transect from dune to water. The enzyme activities of bacteria isolated from the surface and subsurface did not differ in their height and composition. Bacteria isolated form the sand of studied beach in different seasons, as a rule, synthesized the tested hydrolytic enzymes with similar intensity.
Tsunami deposits are often characterized by specific diatom assemblages, which may indicate sediment provenance and help identify paleotsunami deposits. In the present study diatom assemblages were studied in tsunami deposits left by the 2004 tsunami in Thailand, as well as in beach sediments, inner shelf marine sediments and freshwater ponds and streams. The assemblages in tsunami deposits had chaotic structure and consisted of species found in all the studied habitats, suggesting erosion of terrestrial and marine sediments by tsunami. The diatom frustules in tsunami deposits were generally rare and often damaged due to excessive wave force. The most common identified species were Amphora turgida Gregory, Cocconeis scutellum Ehrenberg, Diplomenora cocconeiformis (Schmidt) Blazé, Eunotogramma marinum (W. Smith) Peragallo (typical for benthos of marine and brackish environments), and taxa common in freshwaters, including Cyclotella ocellata Pantocsek, Cocconeis placentula Ehrenberg and Encyonema silesiacum (Bleish) D.G. Mann.
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