Organic geochemistry of sediments from sapropel 94 of ODP Hole 161-974C

Analysis of the molecular composition of the organic matter (OM) from whole sediment samples can avoid analytical bias that might result from isolation of components from the sediment matrix, but has its own analytical challenges. We evaluated the use of GC * GC-ToFMS to analyze the pyrolysis products of six whole sediment samples obtained from above, within and below a 1 million year old OM-rich Mediterranean sapropel layer. We found differences in pyrolysis products

(Table 1) Concentrations of neutral and phenolic organohalogen compounds in adipose tissue, blood, brain and liver of polar bears (Ursus maritimus) from East Greenland

The tissue-specific composition of sum classes of brominated and chlorinated contaminants and metabolic/degradation byproducts was determined in adult male and female polar bears from East Greenland. Significantly (p < 0.05) higher concentrations of SUM-PCBs, various other organochlorines such as SUM-CHL, p,p'-DDE, SUM-CBz, SUM-HCHs, octachlorostyrene (OCS),SUM-mirex, dieldrin, the flame retardants SUM-PBDEs, and total-(R)-hexabromocyclododecane (HBCD), SUM-methylsulfonyl (MeSO2)-PCBs and 3-MeSO2-p,p'-DDE, were found in the adipose and liver tissues relative to whole blood and brain. In contrast, SUM-hydroxyl (OH)-PCB, 4-OH-heptachlorostyrene and SUM-OH-PBDE concentrations were significantly highest (p < 0.05) in whole blood, whereas the highest concentrations of SUM-OH-PBBs were found in the adipose tissue. Based on the total concentrations of all organohalogens in all three tissues and blood, the combined body burden was estimated to be 1.34 ± 0.12 g, where >91% of this amount was accounted for by the adipose tissue alone, followed by the liver, whole blood, and brain. These results show that factors such as protein association and lipid solubility appear to be differentially influencing the toxicokinetics, in terms of tissue composition/localization and burden, of organohalogen classes with respect to chemical structure and properties such as the type of halogenation (e.g., chlorination or bromination), and the presence or absence of additional phenyl group substituents (e.g., MeO and OH groups). The tissue- and blood-specific accumulation (or retention) among organohalogen classes indicates that exposure and any potential contaminant-mediated effects in these polar bears are likely tissue or blood specific.

(Table 1) Diatom abundance and preservation in ODP Hole 130-806B samples

We report on diatom abundance and preservation stratigraphy in the uppermost four cores of Ocean Drilling Program Hole 806B, which span the Quaternary period. Changes in diatom abundance and preservation show a rather complicated pattern, with much noise at high frequencies. However, in the cycles corresponding to eccentricity and obliquity variations, the picture is quite clear. Abundance and preservation follow glacial-interglacial cycles, with lowest abundances and poorest preservation observed in sediments that correspond to glacial stages. Seventy taxa compose the diatom assemblage of Hole 806B (from Samples 130-806B-1H-1, 8-9 cm, to -4H-7, 73-74 cm) with Azpeitia nodulifera as the dominant member. This species exhibits significant size variations related to glacial and interglacial stages during the Pleistocene. The distribution of power in the Fourier spectrum of the diatom signal (in the time domain) displays the expected Milankovitch frequencies (at 100,41, and 24-18 k.y.). It also shows concentration at various "odd" frequencies, especially at 62 k.y., suggesting a complicated response of productivity (and silicate chemistry) to climatic forcing.

(Table 1) Ratio of hydroxy-GDGT vs. the total core GDGT was calculated based on the detection of hydroxy-GDGT

Hydroxylated glycerol dialkyl glycerol tetraethers (hydroxy-GDGTs) were detected in marine sediments of diverse depositional regimes and ages. Mass spectrometric evidence, complemented by information gleaned from two-dimensional (2D) 1H-13C nuclear magnetic resonance (NMR) spectroscopy on minute quantities of target analyte isolated from marine sediment, allowed us to identify one major compound as a monohydroxy-GDGT with acyclic biphytanyl moieties (OH-GDGT-0). NMR spectroscopic and mass spectrometric data indicate the presence of a tertiary hydroxyl group suggesting the compounds are the tetraether analogues of the widespread hydroxylated archaeol derivatives that have received great attention in geochemical studies of the last two decades. Three other related compounds were assigned as acyclic dihydroxy-GDGT (2OH-GDGT-0) and monohydroxy-GDGT with one (OH-GDGT-1) and two cyclopentane rings (OH-GDGT-2). Based on the identification of hydroxy-GDGT core lipids, a group of previously reported unknown intact polar lipids (IPLs), including the ubiquitously distributed H341-GDGT (Lipp J. S. and Hinrichs K. -U. (2009) Structural diversity and fate of intact polar lipids in marine sediments. Geochim. Cosmochim. Acta 73, 6816-6833), and its analogues were tentatively identified as glycosidic hydroxy-GDGTs. In addition to marine sediments, we also detected hydroxy-GDGTs in a culture of Methanothermococcus thermolithotrophicus. Given the previous finding of the putative polar precursor H341-GDGT in the planktonic marine crenarchaeon Nitrosopumilus maritimus, these compounds are synthesized by representatives of both cren- and euryarchaeota. The ubiquitous distribution and apparent substantial abundance of hydroxy-GDGT core lipids in marine sediments (up to 8% of total isoprenoid core GDGTs) point to their potential as proxies.