Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 7

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
During the period May-October 1991 a hydrochemical investigation was carried out in the Waksmundzka Valley lying on the granite substratum of the High Tatra Mountains. An acidification of the Waksmundzki Stream dependent on precipitation was observed in spring, while heavy late summer and autumn rainfall reduced the quantity of the acidic substances. Differences in the stream chemistry between the upper and lower part of the catchment were also observed. The small amount of groundwater entering the lower part of the stream is believed to be responsible for it.
Nitrate reductase activity (NRA) was studied in the invasive alien plant F. japonica (Japanese knotweed) during the vegetation season and among natural, semi-natural, and human-made habitats and compared with NRA in selected native species. NRA was measured directly in the field from the beginning of May until the beginning of October. NRA was much higher than in the plant’s native range, i.e., East Asia, and showed a high degree of variation over time with the highest values being reached at the stage of fast vegetative growth and at the beginning of fruiting. NRA was highest on dumping sites probably due to the high nitrogen input into soils and near traffic and the emission of NOx by vehicles. A comparison of the enzyme activity in four selected native plant species indicated that NRA in F. japonica was the highest with the exception of Urtica dioica, which exhibited a similar activity of the enzyme. A detailed comparison with this species showed that differences between these species on particular dates were influenced by differences in the phenology of both plants. The initial results that were obtained suggest that nitrogen pollution in an environment can contribute to habitat invasibility and a high level of NRA, which in addition to the many plant traits that are commonly accepted as characteristic of invasiveness features, may be an important factor that enhances invasion success.
Background. Fish are often used as indicators of pollution levels in water environments. The omnivorous chub inhabiting rivers of Europe, including their more polluted parts, is a potentially suitable indicator. The information published, however, on the metal accumulation in the tissues of chub living in varyingly polluted waters (both polluted and unpolluted environments) is scarce. The presently reported study was conducted to examine the metal concentrations in selected tissues of chub living in a natural submontane river. Materials and Methods. Sediment samples (0–5 cm layer) and chub, Leuciscus cephalus (L.), were collected from the upper (stations 1–4) and lower (stations 5–8) sections of the Biała Tarnowska River in summer 2003. Fish age was determined from the otoliths. The AAS method was used to determine metal concentrations (Cd, Pb, Cu, and Zn) in sediment and chub tissues (spleen, liver, and muscle). Results. According to the values of the geochemical index (Igeo), the river sediments were not polluted by Pb, Cu, and Zn, while in various degrees polluted by Cd. Despite the low metal concentrations, the mean Cd and Cu concentrations were higher (c. 2× and 4×, respectively) in the upper part of the river compared to the lower section, while concentration of Pb and Zn were similar in the two areas. Chub accumulated the greatest amount of Cu in the liver, while the bulk of Cd, Pb, and Zn was found in the spleen. In the upper part of the river, elevated concentrations of trace elements in selected tissues of chub were found: Cu (spleen, muscle), Cd (spleen), Zn (muscle). The pollution status of the river, on the basis of trace element contents in the sediment, was also determined. Conclusion. The obtained results indicated tissue-specific metal accumulation in chub. Selected chub tissues are sensitive to Cd and Cu contents in the river sediment.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.