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500 years of ecological changes recorded in subfossil Cladocera in a high-altitude, tropical Lake Lago de la Luna, central Mexico

Zawisza E., Caballero M, Ruiz-Fernandez C

Studia Quaternaria

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2012

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Vol. 29

23--29

EN

We present the last 500 years of history of a high-altitude tropical lake Lago de la Luna located at Nevado de Toluca crater, Central Mexico, based on subfossil Cladocera analysis. Through the studied sedimentary sequence only five Cladocera species were present. Cladocera community was dominated by littoral species (4) and among them one (Ilyocryptus nevadensis) is endemic. The detailed analysis of the sediments (every 1 cm) allowed us to track contemporary climatic and anthropogenic changes. Our results showed that Lago de la Luna is a very sensitive ecosystem and has strong response to climatic changes. The most remarkable change in the Cladocera community was observed between 1683-1780 yr, which was well correlated with the Little Ice Age. PCA results implied that modern state of the lake Lago de la Luna is very similar to one 400-500 yr ago. Only one period was identified when human impact was of importance. This period seemed to correlate with changes in the lake ecosystem due to fish introduction in the 1950s.

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Sediment cores from river dams as flood archives

Frank W., Jendryschik K., Morgenstern P., Treutler H.Ch., Zerling L.

Studia Quaternaria

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2004

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Vol. 21

187-195

EN

Studies of sediment cores originating from a dam of the River Mulde near Bitterfeld (Saxony-Anhalt, Germany) confirmed that river dams act as excellent archives of flood events. The records were performed by significant changes of the composition and quality of suspended matter and sediment. To combine the investigated sediment core with a reliable time scale, suitable reference data (e.g. radionuclides, geochemical markers) were included into the study. Subsequently, flow data of the Mulde (from 1975 up to now) were used to assign specific floods (>300 m3/s) to the event layers detected in the sediment cores. In addition to this, further time markers were inspected towards a more reliable adjustment of the time scale. In detail we made use of the 137Cs activity maximum (caused by Chernobyl fallout), as well as of the drop in organic pollution (following the collapse of East Germany's industrial sector 1989/90), and finally of the decrease in the concentration levels of elements and isotopes (a consequence of the reduced activities of mines and metallurgical plants in the River Mulde catchment). Exemplarily we present the results for a short sediment core, which originates from the Friedersdorf basin of the Mulde river dam (sampled in September 2002). The most recent such layer occurring in this sediment core was caused by the flood in August 2002. This event proved to be an outstanding flood time marker with regard to its thickness and geochemical properties.

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Variation of Cs-137 deposition in soil and lakes in the north-east region of Poland

Zalewski M., Kapała J., Mnich Z., Zalewski P.

Nukleonika

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2002

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Vol. 47, nr 2

75-78

EN

The aim of this work is to assess the current deposits of Cs-137 in soil and in lakes in the Poland's north-eastern lake district (12-14 years after Chernobyl accident) a dozen or so years after the Chernobyl disaster. Caesium content in soil and sediment was determined by gamma spectrometry (in 79 soil samples and 136 sediment samples). The soil samples were collected in summer 1998-2000. The sediment from 29 lakes were sampled in May 2000. The highest surface activity was found in soil with the arithmetic mean (AM) 3.13 kBq m-2 and median (M) 2.37 kBq m-2. For lakes, the respective values were 1.89 kBq m-2 and 1.5 kBq m-2. In the case of the soil samples collected from forests, fields, lake shores and arable lands, the mean values of caesium deposition were: 4.37, 2.56, 3.42 and 1.52 kBq m-2, respectively. The mean surface activity of sedimentary samples (AM) from oligotrophic, mesotrophic and eutrophics lakes was found to have different values, viz. 1.48, 2.23 and 1.86 kBq m-2, respectively.

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Evaluation of the results of metal analyses for lake sediment samples: a multivariate statistical approach

Tokalıoğlu Ş., Kartal Ş.

Chemia Analityczna

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2002

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Vol. 47, No. 4

627-638

EN

The 28 sediment samples were collected from the lakes of a water-laden area of Sultansazligi, Kayseri (Turkey). The metal contents such as chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium (below the detection limit), and lead in the sediment sample fractions were examined by using fractionation procedure, for example, the Community Bureau of Reference (BCR) method including sequential extraction. The determination of extrac-table heavy metals mentioned above in the sediment samples was carried out by flame atomic absorption spectrometry (FAAS) using an injection method. In order to evaluate the analytical data by multivariate statistical techniques, principal components analysis (PCA), cluster analysis (CA), correlation analysis, and enrichment factors (EF.) were used. In order to determine the possible sources of metals, the results obtained with the multivariate techniques which use the data base containing the total elemental concentrations identified the four distinct heavy metal sources, namely soil-industrial, industrial-traffic, soil-combustion, and agricultural.

PL

Z terenu Sultansazligi, Kayseri (Turcja) pobrano 28 próbek osadów. Zawartość metali: chromu, manganu, żelaza, kobaltu, niklu, miedzi, cynku, kadmu i ołowiu, oznaczano we frakcjach próbek stosując procedurę frakcjonowania, np. metodę Community Bureau of Reference, polegającą na sekwencyjnej ekstrakcji. Do oznaczania zawartości metali we frakcjach stosowano płomieniową spektrometrię absorpcyjną, w układzie wstrzykowym. Ocenę otrzymanych wyników przeprowadzono metodami statystyki wielowymiarowej, analizą głównych składników, analizą skupień, analizą korelacyjną i faktorów zatężania. W celu określenia prawdopodobnych źródeł zanieczyszczeń, otrzymane wyniki, oparte na bazie danych dotyczącej całkowitych zawartości metali, określono cztery wyraźne źródła metali: gleba-przemysł, przemysł-transport, gleba-spalanie i rolnictwo.