The aim of the present paper was to determine the effect of the extraction time on the alkaline extracts of humic substances from organic and mineral lake bottom sediments. The extraction was performed with the use of 0.5 M NaOH. Both for organic and mineral sediments, the ratio during extraction was 1:10 and 1:50 (w/v). In both variants the extraction time was, respectively 1, 5, 12, 24 and 48 h. In the mixtures of humic and fulvic acids obtained, the following were determined: the content of carbon and the spectrometric properties for the UV-VIS range. Based on the present results, the values of absorbance ratios and extraction efficiency were calculated. The results demonstrate, most of all, that the extraction time has a significant effect on the properties of extracts. It was observed that the extracts after a longer extraction time, in general, showed a higher content of carbon. The present research revealed that in the case of sediments, the extraction performed in the ratio of 1:50 (w/v) is more efficient as compared with the extraction in the ratio of 1:10 (w/v).
The objective of the present study was to compare the content of polyphenolic compounds in sediments of lakes with different types of catchment. Sediment samples for analysis were collected from the littoral and profundal zones of lakes with field or forest catchments. The study material was supplemented with select aquatic plant species. Basic physicochemical properties and the content of polyphenolic compounds were determined in the material applying the Folin-Ciocalteu method. The results reveal that bottom sediments of forest lakes were distinguished by a higher content of polyphenols compared to sediments of field lakes (0.290 and 0.200%om). Aquatic plants were characterized by a highly diverse content of polyphenols (0.74-2.67%om); shining pondweed had the highest content.
Do badań wytypowano 10 jezior o zróżnicowanym użytkowaniu zlewni - grunty orne i lasy. Próby z warstwy powierzchniowej i naddennej jezior oraz wód dopływających i odpływających z badanych jezior, pobrano w trzech terminach: podczas cyrkulacji wiosennej i jesiennej oraz podczas stagnacji letniej. W pobranych próbach oznaczono zawartość azotu ogółem, azotanów, jonów amonowych i fosforanów oraz pH. Stwierdzono, że wody jezior o rolniczym zagospodarowaniu zlewni charakteryzują się wyższą zawartością azotanów niż porównawcze jeziora śródleśne. Zawartość różnych form azotu w wodach jezior wykazuje zmienność sezonową w ciągu roku.
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