Mechanical properties and comparisons of dynamic and static Young's moduli at DSDP Holes 69-504B, 70-504B and 83-504B

From laboratory tests under simulated downhole conditions we tentatively conclude that the higher the triaxial-compressive strength, the lower the drilling rate of basalts from DSDP Hole 504B. Because strength is roughly proportional to Young's modulus of elasticity, which is related in turn to seismic-wave velocities, one may be able to estimate drilling rates from routine shipboard measurements. However, further research is needed to verify that P-wave velocity is a generally useful predictor of relative drilling rate.

Oxygen contents, sulfate concentrations, and changes of IPLs under different storage conditions of samples from ODP Leg 204 and IODP Expedition 311

We have studied the effects of slow infiltration of oxygen on microbial communities in refrigerated legacy samples from ocean drilling expeditions. Storage was in heat-sealed, laminated foil bags with a N2 headspace for geomicrobiological studies. Analysis of microbial lipids suggests that Bacteria were barely detectable in situ but increased remarkably during storage. Detailed molecular examination of a methane-rich sediment horizon showed that refrigeration triggered selective growth of ANME-2 archaea and a drastic change in the bacterial community. Subsequent enrichment targeting methanogens yielded exclusively methylotrophs, which were probably selected for by high sulfate levels caused by oxidation of reduced sulfur species. We provide recommendations for sample storage in future ocean drilling expeditions.

Static GPS measurements and elevation model in the vicinity of the EDML deep-drilling site

Interpretation of ice-core records requires accurate knowledge of the past and present surface topography and stress-strain fields. The European Project for Ice Coring in Antarctica (EPICA) drilling site (0.0684° E and 75.0025° S, 2891.7 m) in Dronning Maud Land, Antarctica, is located in the immediate vicinity of a transient and splitting ice divide. A digital elevation model is determined from the combination of kinematic GPS measurements with the GLAS12 data sets from the ICESat satellite. Based on a network of stakes, surveyed with static GPS, the velocity field around the EDML drilling site is calculated. The annual mean velocity magnitude of 12 survey points amounts to 0.74 m/a. Flow directions mainly vary according to their distance from the ice divide. Surface strain rates are determined from a pentagon-shaped stake network with one center point, close to the drilling site. The strain field is characterised by along flow compression, lateral dilatation, and vertical layer thinning.

Static GPS measurements in the vicinity of EDML and an elevation model for Dronning Maud Land

The knowledge of ice sheet surface topography and the location of the ice divides are essential for ice dynamic modeling. An improved digital elevation model (DEM) of Dronning Maud Land (DML), Antarctica, is presented in this paper. It is based on ground-based kinematic GPS profiles, airborne radar altimetry, and data of the airborne radio-echo sounding system, as well as spaceborne laser altimetry from NASA's Ice, Cloud and land Elevation Satellite (ICESat). The accuracy of ICESat ice sheet altimetry data in the area of investigation is discussed. The location of the ice divides is derived from aspect calculation of the topography and is verified with several velocity data derived from repeated static GPS measurements.

Literature review of elasmobranch bycatch and retention rate

To address growing concern over the effects of fisheries non-target catch on elasmobranchs worldwide, the accurate reporting of elasmobranch catch is essential. This requires data on a combination of measures, including reported landings, retained and discarded non-target catch, and post-discard survival. Identification of the factors influencing discard vs. retention is needed to improve catch estimates and to determine wasteful fishing practices. To do this we compared retention rates of elasmobranch non-target catch in a broad subset of fisheries throughout the world by taxon, fishing country, and gear. A regression tree and random forest analysis indicated that taxon was the most important determinant of retention in this dataset, but all three factors together explained 59% of the variance. Estimates of total elasmobranch removals were calculated by dividing the FAO global elasmobranch landings by average retention rates and suggest that total elasmobranch removals may exceed FAO reported landings by as much as 400%. This analysis is the first effort to directly characterize global drivers of discards for elasmobranch non-target catch. Our results highlight the importance of accurate quantification of retention and discard rates to improve assessments of the potential impacts of fisheries on these species.

Benthic foraminiferal denitrification rates and nitrate storage

The discovery that foraminifera are able to use nitrate instead of oxygen as energy source for their metabolism has challenged our understanding of nitrogen cycling in the ocean. It was evident before that only prokaryotes and fungi are able to denitrify. Rate estimates of foraminiferal denitrification were very sparse on a regional scale. Here, we present estimates of benthic foraminiferal denitrification rates from six stations at intermediate water depths in and below the Peruvian oxygen minimum zone (OMZ). Foraminiferal denitrification rates were calculated from abundance and assemblage composition of the total living fauna in both, surface and subsurface sediments, as well as from individual species specific denitrification rates. A comparison with total benthic denitrification rates as inferred by biogeochemical models revealed that benthic foraminifera account for the total denitrification on the shelf between 80 and 250 m water depth. They are still important denitrifiers in the centre of the OMZ around 320 m (29-56% of the benthic denitrification) but play only a minor role at the lower OMZ boundary and below the OMZ between 465 and 700 m (3-7% of total benthic denitrification). Furthermore, foraminiferal denitrification was compared to the total benthic nitrate loss measured during benthic chamber experiments. Foraminiferal denitrification contributes 1 to 50% to the total nitrate loss across a depth transect from 80 to 700 m, respectively. Flux rate estimates ranged from 0.01 to 1.3 mmol m?2 d?1. Furthermore we show that the amount of nitrate stored in living benthic foraminifera (3 to 705 µmol L?1) can be higher by three orders of magnitude as compared to the ambient pore waters in near surface sediments sustaining an important nitrate reservoir in Peruvian OMZ sediments. The substantial contribution of foraminiferal nitrate respiration to total benthic nitrate loss at the Peruvian margin, which is one of the main nitrate sink regions in the world oceans, underpins the importance of previously underestimated role of benthic foraminifera in global biochemical cycles.

Shifts in the microbial community structure in different temperatures during sample storage from IODP Hole 325-M0058A

The objective of this study was to determine shifts in the microbial community structure and potential function based on standard Integrated Ocean Drilling Program (IODP) storage procedures for sediment cores. Standard long-term storage protocols maintain sediment temperature at 4°C for mineralogy, geochemical, and/or geotechnical analysis whereas standard microbiological sampling immediately preserves sediments at -80°C. Storage at 4°C does not take into account populations may remain active over geologic time scales at temperatures similar to storage conditions. Identification of active populations within the stored core would suggest geochemical and geophysical conditions within the core change over time. To test this potential, the metabolically active fraction of the total microbial community was characterized from IODP Expedition 325 Great Barrier Reef sediment cores prior to and following a 3-month storage period. Total RNA was extracted from complementary 2, 20, and 40 m below sea floor sediment samples, reverse transcribed to complementary DNA and then sequenced using 454 FLX sequencing technology, yielding over 14,800 sequences from the six samples. Interestingly, 97.3% of the sequences detected were associated with lineages that changed in detection frequency during the storage period including key biogeochemically relevant lineages associated with nitrogen, iron, and sulfur cycling. These lineages have the potential to permanently alter the physical and chemical characteristics of the sediment promoting misleading conclusions about the in situ biogeochemical environment. In addition, the detection of new lineages after storage increases the potential for a wider range of viable lineages within the subsurface that may be underestimated during standard community characterizations.

(Table 1) Water storage changes of the 33 world's largest river basins between 2002-2009

Global change in land water storage and its effect on sea level is estimated over a 7-year time span (August 2002 to July 2009) using space gravimetry data from GRACE. The 33 World largest river basins are considered. We focus on the year-to-year variability and construct a total land water storage time series that we further express in equivalent sea level time series. The short-term trend in total water storage adjusted over this 7-year time span is positive and amounts to 80.6 ± 15.7 km**3/yr (net water storage excess). Most of the positive contribution arises from the Amazon and Siberian basins (Lena and Yenisei), followed by the Zambezi, Orinoco and Ob basins. The largest negative contributions (water deficit) come from the Mississippi, Ganges, Brahmaputra, Aral, Euphrates, Indus and Parana. Expressed in terms of equivalent sea level, total water volume change over 2002-2009 leads to a small negative contribution to sea level of -0.22 ± 0.05 mm/yr. The time series for each basin clearly show that year-to-year variability dominates so that the value estimated in this study cannot be considered as representative of a long-term trend. We also compare the interannual variability of total land water storage (removing the mean trend over the studied time span) with interannual variability in sea level (corrected for thermal expansion). A correlation of ~0.6 is found. Phasing, in particular, is correct. Thus, at least part of the interannual variability of the global mean sea level can be attributed to land water storage fluctuations.