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The paper presents the results of determinations of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in 24 samples of bottom sediments collected in six gauging cross-sections along the course of the Mała Wełna river (western Poland). The samples were collected once a month from May to August 2006. The determinations were made separately in the following granulometric fractions: >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.25, 0.25-0.1, 0.1-0.063, and <0.063 mm, using 3M HCl as the extraction agent. The concentrations of the heavy metals studied were lowest in the 0.5-0.25 and 0.25-0.1 mm fractions, and the highest in the 0.1-0.063 and <0.063 mm fractions, and also in the larger fraction. The determinations were made using atomic absorption spectrometry with flame atomization (F-AAS).
Our study presents the results of determining labile aluminium form in samples from the 2004 tsunamiaffected coastal zone of Thailand. The samples were collected from tsunami deposits, beach sediments, sediments underlying the tsunami deposits (pre 2004 tsunami soil), as well as from soils from areas, that were not flooded. The extraction of the labile form of aluminium was performed using 3 mol L⁻¹ HCl in twelve grain size fractions. In the surface layer samples the highest concentrations were determined in the tsunami deposits in fractions <0.063 mm (5850 mg kg⁻¹). The highest determined concentration in the whole set of investigated samples occurred in soil sample in fractions 0.09-0.125 mm (19770 mg kg⁻¹). An increase in concentration of labile aluminium form, along with decreasing grain diameter, was observed in samples from all the studied settings. In general, concentrations were higher in soil samples not affected by the tsunami. This is probably due to steady weathering of minerals during soil forming processes and removal of sediment grain surface coatings potentially enriched in labile Al during high energy transport by tsunami.
The photosynthetic activity of phytoplankton (in pelagial) and macrophytes (in littoral) is considered to be one of the main factors affecting the carbon cycle in lakes. This concerns in particular hardwater ecosystems, where most of the carbon is available in the form of Ca- or Mg-bicarbonates. In such ecosystems charophytes (macroscopic green algae, forming dense meadows) are regarded as the most effective carbonate producer due to the HCO3— utilization and the formation of thick CaCO3 encrustations.Calcium carbonate and biomass production of charophytes were studied in a small and shallow charophyte-dominated Lake Jasne (Western Poland). Fresh and dry weight of plants, percentage contribution of calcium carbonate and production of CaCO3 per 1 m2 were studied at three depths (1, 3 and 5 m) in three sample sites (each sampled area −0.04 m2). Additionally, physical-chemical parameters of water samples were studied. It was found that the dry weight of charophytes and the values of calcium carbonate were similar for all sites but varied for depth of sampling. The dry weight exceeded 2000 g m-2 (average 1165 g m-2) at the most shallow sample sites. CaCO3 encrustations constituted from 39.5% at the depth of 5m, to over 82% of the charophyte dry weight at the depth of 1m. The maximum and average values of carbonates precipitated by charophytes were 1696 g m-2 and 891 g m -2, respectively, and exceeded results reported so far. The results of physical-chemical analyses revealed no statistically significant differences between all the sample sites. Nevertheless, distinct correlations were found between dry weight of charophytes, carbonates precipitated by charophytes and some physical-chemical properties of water from the sample sites. The results highlight the habitat engineering role of charophytes, evidenced in particular by great amounts of biomass influencing sedimentary processes and biogeochemical cycle within littoral zone.
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