Bitumen and n-alkanes in organic matter from sedimentary rocks sampled in DSDP Holes 47-397A and 47-398

A study of samples from DSDP Leg 47 shows that transformation of organic matter in deep sea sediments is completly analogous to evolution of organic matter in sedimentary sequences on continents and depends on the same factors. Crucial among these factors are: genesis of organic matter, nature of its diagenetic changes, and current stage of catagenesis.

(Table 2) Carbon and nitrogen isotopic ratios in blood sampled from arctic foxes (Vulpes lagopus) on Bylot Island between 2003-2008

Inter-individual variation in diet within generalist animal populations is thought to be a widespread phenomenon but its potential causes are poorly known. Inter-individual variation can be amplified by the availability and use of allochthonous resources, i.e., resources coming from spatially distinct ecosystems. Using a wild population of arctic fox as a study model, we tested hypotheses that could explain variation in both population and individual isotopic niches, used here as proxy for the trophic niche. The arctic fox is an opportunistic forager, dwelling in terrestrial and marine environments characterized by strong spatial (arctic-nesting birds) and temporal (cyclic lemmings) fluctuations in resource abundance. First, we tested the hypothesis that generalist foraging habits, in association with temporal variation in prey accessibility, should induce temporal changes in isotopic niche width and diet. Second, we investigated whether within-population variation in the isotopic niche could be explained by individual characteristics (sex and breeding status) and environmental factors (spatiotemporal variation in prey availability). We addressed these questions using isotopic analysis and Bayesian mixing models in conjunction with linear mixed-effects models. We found that: i) arctic fox populations can simultaneously undergo short-term (i.e., within a few months) reduction in both isotopic niche width and inter-individual variability in isotopic ratios, ii) individual isotopic ratios were higher and more representative of a marine-based diet for non-breeding than breeding foxes early in spring, and iii) lemming population cycles did not appear to directly influence the diet of individual foxes after taking their breeding status into account. However, lemming abundance was correlated to proportion of breeding foxes, and could thus indirectly affect the diet at the population scale.

Fish biometry and concentration of volatile siloxanes in liver of Atlantic cod (Gadus morhua) and shorthorn sculpin (Myxocephalus scorpius) sampled during RV Lance cruise COPOL in 2009

The purpose of this study was to investigate presence and potential accumulation of cyclic volatile methyl siloxanes (cVMS) in the Arctic environment. Octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcy-clohexasiloxane (D6) were analyzed in sediment, Zooplankton, Atlantic cod (Gadus morhua), shorthorn sculpin (Myxocephalus scorpius), and bearded seal (Erignathus barbatus) collected from the Svalbard archipelago within the European Arctic in July 2009. Highest levels were found for D5 in fish collected from Adventfjorden, with average concentrations of 176 and 531 ng/g lipid in Atlantic cod and shorthorn sculpin, respectively. Decreasing concentration of D5 in sediment collected away from waste water outlet in Adventfjorden indicates that the local settlement of Longyearbyen is a point source to the local aquatic environment. Median biota sediment accumulation factors (BSAFs) calculated for D5 in Adventfjorden were 2.1 and 1.5 for Atlantic cod and shorthorn sculpin, respectively. Biota concentrations of D5 were lower or below detection limits in remote and sparsely populated regions (Kongsfjorden and Liefdefjorden) compared to Adventfjorden. The levels of cVMS were found to be low or below detection limits in bearded seal blubber and indicate a low risk for cVMS accumulation within mammals. Accumulation of cVMS in fish appears to be influenced by local exposure from human settlements within the Arctic.