Wyniki wyszukiwania - BazTech

1

Subfossil chironomid assemblages as paleoenvironmental indicators in lake faulersee (Germany)

Rohrig R., Beug H., Trettin R., Morgenstern P.

Studia Quaternaria

|

2004

|

Vol. 21

117-127

EN

Remains of chironomid larvae from cores of the ancient Lake Faulersee in northern Germany were examined. Pollen, radiocarbon datings, and geochemical data were used to develop the chronology of the Late-Glacial Period in Lake Faulersee and to validate interpretations made by chironomid data. Factors influencing the composition of the subfossil chironomid assemblages were assessed. Our data indicate fluctuations of temperature, lake-level, and trophic state in the Late-Glacial. Furthermore, we explain a discontinuous sequence found in the cores of Lake Faulersee pertaining to a refilling event about 5,800 cal years before present (BP).

2

Sediment cores from river dams as flood archives

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

Studia Quaternaria

|

2004

|

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.

3

Influence of pellet composition in IR-laser ablation inductively coupled plasma atomic emission and mass spectrometry

Wennrich R., Morgenstern P., Liebergeld G., Werner G.

Chemia Analityczna

|

1999

|

Vol. 44, No. 3B

523-538

EN

Aspects of infrared laser ablation as sampling tool for the analysis of pellet materials using inductively coupled plasma atomic emission and mass spectrometry have been inves-tigated. The sensitivity for Ca, Fe, La, Mg, Mn, Sr, V and Zn in targets prepared from powders of geological reference materials depends on the kind of additives applied. For understanding this phenomenon the behaviour of selected elements was studied. Trace el-ement fractionation is prevalently effected by repeated irradiance of a target. There are significant differences in the impoverishing of analytes -as the result of fractionation -out of pellets by subsequent laser ablation in dependence on the analytes and their con-centrations. The use of an internal standard was studied to reduce the serious problems caused by fractionation. The application of an internal standard is only partly successful for the improvement of the correlation coefficient of calibration plots. The use of suitable binding materials leads to diminish differences in the ablation behaviour of analytes and the internal standard associated with the variation of chemical and physical properties of the geological matrices. The matched pellets (SiO(2) + carbon + binder) were used to study the influence of the binding of Zn, Bi, Cu, Mn, Fe and Ni on the ablation behavior. The results indicate significant differences in the sensitivity when the analytes were added as oxides, sulfates or in a metallic form. To demonstrate these analyte specific phenomena normalized sensitivity values (sensitivity in laser ablation divided by sensitivity in pneu-matic nebulization) have been used. An explanation of the analyte specific behaviour has been supported by comparing the normalized values with thermodynamic data.

PL

Badano wpływ ablacji, jako metody próbkowania, za pomocą lasera IR na wyniki oznaczeń w spektrometrii mas z indukcyjnie sprzężoną plazmą. Czułość oznaczania Ca, Fe, La, Mg, Mn, Sr, V, i Z n w próbkach geologicznych materiałów odniesienia zależy od rodzaju stosowanych dodatków. Frakcjonowanie pierwiastków śladowych zależy od wielokrotnego naświetlania obiektu. Występują znaczące różnice w zubożeniu analitów w wyniku frakcjonowania, w pastylkach w zależności od rodzaju analitów i ich stężeń. Badano zastosowanie wewnętrznego standardu w celu zredukowania trudności wynikających z frakcjonowania. Wewnętrzny standard jedynie częściowo poprawia współczynnik korelacji krzywych kalibrowania. Zastosowanie odpowiednich środków wiążących powoduje zmniejszenie różnic w zachowaniu się analitów i wewnętrznego standardu związanych ze zmiennością chemicznych i fizycznych właściwości matryc geologicznych. Zastosowano pastylki zawierające SiO2 + węgiel + środek wiążący, w badaniu wpływu czynnika wiążącego na ablację Zn, Bi, Cu, Mn, F e i Ni. Wyniki wskazuj ą na znaczne różnice czułości w zależności od tego, czy anality dodawane były w postaci tlenków, siarczanów czy wolnych metali. Aby wykazać te specyficzne dla analitów zjawiska zastosowano normalizowane wartości czułości ( czułość przy stosowaniu ablacji las6rowej podzielona przez czułość w nebulizatorze pneumatycznym). Wyjaśnienie specyficznego zachowania się analitów potwierdza porównanie tych znormalizowanych wartości z danymi termodynamicznymi.