Porosity and sound velocity measured in sediment core CIROS-1

The CIROS-1 drillhole, which in 1986 reached a depth of 700 m below the seafloor, is still the only deep hole that can provide information on the velocity structure of the upper crust in McMurdo Sound and the Ross Sea, Antarctica. A careful review and quality control of the downhole logging data of CIROS-1 resulted in a new porosity depth function that is consistent with porosity data from the MSSTS-1 and CRP-1 drillholes. Using existing porosity-velocity equations, it was possible for the first time to obtain reliable velocity information for the upper 700 m of strata off the Victoria Land coast. The calculated synthetic seismograms, based on downhole velocity and density data, fit very well with the existing seismic lines IT90A-71, PD90-12, and NBP9601-89. The quality of the correlation confirms that the average velocity of the top 700 m of strata is about 2 000-2 300 m/s, and not 2 800-3 000 m/s, as was previously assumed. In consequence, these distinctly lower velocities result in shallower depths for the seismic unconformities V3/V4 andV4/V5 and thus may have important implications for further drilling off Cape Roberts.

Soil porosity along a plant diversity gradient in the Jena Experiment (Main Experiment, 2013)

Soil porosity is the fraction of total volume occupied by pores or voids measured at matric potential 0. To measure soil porosity, soil samples were taken from each plot using sample rings with an internal diameter of 57 mm and height of 40.5 mm (inner volume of Vs=100 cm3). The samples were placed on a sand bed box with water level set to allow saturation of the samples with water. After 48 h the samples were weighed (ms), oven dried at 105 °C and weighed again to determine the dry weight (md). We calculated soil porosity (n [%]) using the density of water (?w=1 g cm?3), n=100 ? (mw-md) / (?w?Vs). To account for the spatial variation of soil properties, three replicates were taken per plot, approximately 2, 3 and 4 weeks after the flood that occurred at the field site during June 2013. Data are the average soil porosity values per plot. All data where measured in the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown in the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, or 4 functional groups). Plots were maintained by bi-annual weeding and mowing.