23 research outputs found
Submarine Geologie am Kontinentalhang Mittel-Amerikas: Forschungsfahrt SO-76 Abschlussbericht
SIGLEAvailable from TIB Hannover: F95B1199+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman
Temporal and spatial changes of cadmium in the near-bottom suspended matter of the Pomeranian Bay - Arkona Deep system
Owing to the high toxicity of cadmium (Cd) towards biota and the considerable
quantities of this element entering the environment from anthropogenic sources,
interest in its biogeochemistry is increasing. This is also true for the marine
environment, which serves as a sink for both natural and anthropogenic Cd
loads entering the hydrosphere and the atmosphere. The distribution of Cd in
the coastal zone of the marine environment is governed primarily by the flux of the so-called fluffy layer suspended matter (FLSM), which spreads across the top
of the sea floor as a several-centimetre-thick layer containing highly concentrated
suspended matter.
Both total contents and solid speciation of Cd was measured in FLSM collected
in the Pomeranian Bay – Arkona Deep system (Western Baltic Proper) in the course
of the three-year-long study.
Seasonal changes in the total Cd content (0.5–1.8 μg g−1 dry matter) were
attributed to the contribution of organic suspensions originating from algal blooms.
The decreasing content of Cd in FLSM offshore is due to the input of Cd-rich
suspended matter from the River Odra (Oder), and the decreasing organic matter
content in FLSM with increasing depth. The contribution of labile fractions
(adsorbed and bound to iron(III) hydroxides) was found to be from 50 to 75%
of the total content. In view of the substantial mobility and bioavailability of the
fractions, this is a highly alarming feature
The contribution of the fine sediment fraction to the Fluffy Layer Suspended Matter (FLSM)
Fluffy Layer Suspended Matter (FLSM) is a layer of fairly concentrated suspended
matter resting on the sea floor. Its passage to the depositional basins in the
Pomeranian Bay – Arkona Deep System of the Baltic Sea is estimated to take
around six months. In the course of this migration, the properties of FLSM change
as a result of ageing and the influx of fresh particles from the water column,
and possibly also because of mass exchange with the uppermost sediment layers.
Measurements of radioisotopes (210Po, 210Pb, 137Cs) have demonstrated that in
shallow water this topmost layer of sediments, from 8 cm to 3 cm in thickness, is
subject to mixing. This creates redox profiles favourable to biota and bioturbation. Basing on 210Pb/210Po disequilibria and the 210Po excess, it was estimated that
under steady state conditions from 1.5 to 2.2% of fine fraction (FSF) in the mixed
layer of sediments is freshly imported from FLSM. This implies replacement of
FSF from the sediments and its incorporation into FLSM. On the assumption that
the surface density of FLSM is 10 mg cm−2, FSF freshly exported from sediments
actually comprises up to 15% of FLSM. Therefore, the properties of FLSM are
strongly influenced by the processes taking place in the sediments, although FLSM
by definition is independent of sediments
Coccolithophorid ecostratigraphy and multi-proxy paleoceanographic reconstruction in the Southern Adriatic Sea during the last deglacial time (Core AD91-17)
International audienc