Wyniki wyszukiwania - Biblioteka Nauki

1

Checklist and annotated bibliography of Recent Foraminiferida from the German Baltic Sea coast

100%

Frenzel P. , Tech T. , Bartholdy J.

Studia Geologica Polonica

|

2005

|

tom Vol. 124

67-86

EN

There are 96 Recent foraminiferal species reported from the German sector of the Baltic Sea. All are benthic taxa. Most species are agglutinated forms, reflecting the brackish water conditions of the southern Baltic Sea. Decreasing diversity is visible following the salinity gradient along the coast from the west to the east. The associations of the deeper water below the halocline and of shallow water above are very different with higher diversity in the deeper water. A complete species list and annotated bibliography for Recent foraminiferal species from the brackish water of the German Baltic Sea coast are presented.

2

High resolution Single Particle Analysis by scanning electron microscopy : a new tool to investigate the mineral composition of agglutinated foraminifers

88%

Bartholdy J. , Leipe T. , Frenzel P. , Tauber F. , Bahlo R.

Studia Geologica Polonica

|

2005

|

tom Vol. 124

35-65

EN

A high resolution Single Particle Analysis by scanning electron microscopy (SEM) and X-ray microanalysis is introduced as a new technique to investigate components of tests of aggluti- nated foraminifers. In a feasibility study, specimens of Nodulina dentaliniformis (Brady, 1881) from surface sediment of the Lübeck Bight (southwestern Baltic Sea) were investigated. A chemical mapping of a selected part of the surface of the last chamber as well as analysis of isolated foraminiferal shell grains and the ambient sediment were carried out. The investigations point to the non-selectivity of the foraminifer to use specific minerals but a selectivity to use specific grain sizes and shapes.

3

Environmental changes in the central Baltic Sea during the past 1000 years: inferences from sedimentary records, hydrography and climate

75%

Leipe T. , Dippner J. W. , Hille S. , Voss M. , Christiansen C. , Bartholdy J.

Oceanologia

|

2008

|

tom 50

|

nr 1

23-41

EN

Short sediment cores from the eastern Gotland Basin were investigated using a multi-proxy approach in order to reconstruct the environmental conditions of the area during the past 1000 years. Sediment data and facies were discussed in relation to hydrographic features (salinity, oxygen) and climate change. During the medieval warm period (MWP), from about 900 to 1250 AD, the hydrographic and environmental conditions were similar to those of the present time (modern warm period, since about 1850): a temporally stable halocline, caused by regular saline water inflows from the North Sea, prevents vertical mixing and leads to bottom water anoxia and the deposition of laminated, organic-rich sapropels. During the period from about 1250 to 1850, referred to as the cold phase (including the Little Ice Age), the environmental conditions of the central Baltic Sea were distinctly different: the lower salinity, resulting from reduced North Sea water inflows, allowed vertical convection of the water column and long-term stable ventilation of the sea bed (oxic stage). Both the productivity of the planktonic ecosystem as well as the preservation of organic matter in the sediments improved during the warm periods. The anthropogenic impact can be identified within the recent laminated sequence by a temporal reconstruction of pollutant deposition. Our findings imply a climate-change driven shift in the environmental conditions and the ecosystem of the Baltic from the north to the south and back to the north.

4

Environmental changes in the central Baltic Sea during the past 1000 years: inferences from sedimentary records, hydrography and climate

75%

Leipe T. , Dippner J. W. , Hille S. , Voss M. , Christiansen C. , Bartholdy J.

Oceanologia

|

2008

|

tom No. 50 (1)

23-41

EN

Short sediment cores from the eastern Gotland Basin were investigated using a multi-proxy approach in order to reconstruct the environmental conditions of the area during the past 1000 years. Sediment data and facies were discussed in relation to hydrographic features (salinity, oxygen) and climate change. During the medieval warm period (MWP), from about 900 to 1250 AD, the hydrographic and environmental conditions were similar to those of the present time (modern warm period, since about 1850): a temporally stable halocline, caused by regular saline water inflows from the North Sea, prevents vertical mixing and leads to bottom water anoxia and the deposition of laminated, organic-rich sapropels. During the period from about 1250 to 1850, referred to as the cold phase (including the Little Ice Age), the environmental conditions of the central Baltic Sea were distinctly different: the lower salinity, resulting from reduced North Sea water inflows, allowed vertical convection of the water column and long-term stable ventilation of the sea bed (oxic stage). Both the productivity of the planktonic ecosystem as well as the preservation of organic matter in the sediments improved during the warm periods. The anthropogenic impact can be identified within the recent laminated sequence by a temporal reconstruction of pollutant deposition. Our findings imply a climate-change driven shift in the environmental conditions and the ecosystem of the Baltic from the north to the south and back to the north.