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The weathering-modified iridium record of a new Cretaceous–Palaeogene site at Lechowka near Chelm, SE Poland, and its palaeobiologic implications

100%

Racki G., Michalski M., Koeberl C., Harasimiuk M.

Acta Palaeontologica Polonica

2011

tom 56

nr 1

In the light of integrated biostratigraphic and geochemical data, a complete shallow−marine succession across the Cretaceous–Palaeogene (K–Pg) boundary, with the critical boundary clay coupled with a burrowed siliceous chalk (“opoka” in Polish geological literature), possibly equivalent of the basal Danian Cerithium Limestone in Denmark, has been discovered at Lechówka near Chełm, SE Poland. An extraterrestrial signature marking the K–Pg boundary is confirmed by anomalously high amounts of iridium (up to 9.8 ppb) and other siderophile elements (especially Au and Ni), as well as by an elevated Ir/Au ratio consistent with a chondrite meteoritic composition. The major positive iridium spike surprisingly occurs in Maastrichtian marls, 10 cm below the boundary clay interval, which can be explained by diagenetic mobilisation and re−concentration of the impact−derived components. Thus, intensively infiltrating, humic acid−rich ground waters during the long−lasting Palaeogene weathering in tropical humid regimes were probably responsible not only for the large−scale decalcification of the Lechówka section, but also for both downward displaced position of the iridium enrichment, a dispersed profile of this anomaly and its significantly lessened value, but still approaching an increase by a factor of 100. This modified record of the K–Pg boundary event points to a careful reconsideration of the iridium anomaly as a trustworthy marker for studying the extinction patterns across the K–Pg boundary, as supported by the recent data from New Jersey, USA.

Platinum group elements: a challenge for environmental analytics

100%

Dubiella-Jackowska A., Polkowska Z., Namiesnik J.

Polish Journal of Environmental Studies

2007

tom 16

nr 3

329-345

An increased worldwide usage of platinum group elements (PGE) has been observed during recent decades. High amounts of PGE are applied in such areas as chemical industry and jewellery production, but the increased demand for these metals primarily depends on the introduction of automobile catalytic converter systems. Catalytic converters have also been considered to be a major source of PGE pollution. The similar Pt:Rh ratio, which is used in these autocatalysts, was found in various environmental samples as well. The present literature review indicates that the concentration of these metals has increased considerably in the last twenty years in different environmental matrices, resulting in ecological and human health risks. Because of the importance of PGE and their trace levels in environmental and biological matrices, sensitive methods are required for reliable determination. Details of the particular steps of analytical procedures for PGE quantification in environmental samples such as road dust, airborne particulate matter, soil, benthic sediments, water, wastewater and biological samples are discussed. Sampling and sample storage and preservation techniques are presented. Moreover, the most frequently used extraction, enrichment, detection and determination procedures for PGE are described.

Ograniczanie wyników

1 Acta Palaeontologica Polonica

1 Polish Journal of Environmental Studies

1 Dubiella-Jackowska A.

1 Harasimiuk M.

1 Koeberl C.

1 Michalski M.

1 Namiesnik J.

1 Polkowska Z.

1 Racki G.

1 2011

1 2007

Wyniki wyszukiwania

The weathering-modified iridium record of a new Cretaceous–Palaeogene site at Lechowka near Chelm, SE Poland, and its palaeobiologic implications

Platinum group elements: a challenge for environmental analytics