Spectral reflectance of ODP Leg 178 holes

The routine use of spectrophotometry on the sediment surfaces of archive halves of each section during the onboard sedimentological core description process is a great stride toward development of real-time noninvasive characterization of deep-sea sediments. Spectral reflectance data have been used so far for mineral composition studies as well as for lithostratigraphic correlation between sites (Balsam and Deaton, 1991; Balsam et al., 1997; Mix et al., 1995; Ortiz et al., 1999). Their results demonstrate that spectrophotometry can estimate CaCO3 content by using the 4.65-, 5.25-, and 5.55-µm wavelength spectrums. A detailed overview of various other noninvasive methods is given in Ortiz and Rack (1999). The purpose of this study is to test whether spectrophotometry in the visible band can be used as a tool to gather further information about grain-size variation, sorting, compaction, and porosity, which are directly linked to the sedimentation process. From remote sensing data analyses, it is known that diffuse spectral reflectance data in the visible band in the wavelength window of 7.0-6.5 µm are sensitive to grain-size variations. It appears that a relationship between grain size and signal absorption exists only in this wavelength window. (e.g., Clark, 1999; Gaffey, 1986; Gaffey et al., 1993). Variations in grain size during a sedimentation process are linked to depositional energy, which affects sorting, compaction, and porosity of sediment deposits. As an example, we study here the spectrophotometric data of the sedimentary sequence of Hole 1098C, which was deposited under widely varying environmental conditions. Alternating turbidite and finely laminated sediments were recovered from Hole 1098C. The turbidites are related to a high depositional energy environment; the finely laminated sediments are related to a low depositional energy environment. Data from Hole 1098C were therefore used to test whether the spectral reflectance data can provide a proxy for these different depositional environments.

Graphs of experimental results given in concentration of trace metals versus time in days

The impact of CO2 leakage on solubility and distribution of trace metals in seawater and sediment has been studied in lab scale chambers. Seven metals (Al, Cr, Ni, Pb, Cd, Cu, and Zn) were investigated in membrane-filtered seawater samples, and DGT samplers were deployed in water and sediment during the experiment. During the first phase (16 days), "dissolved" (<0.2 µm) concentrations of all elements increased substantially in the water. The increase in dissolved fractions of Al, Cr, Ni, Cu, Zn, Cd and Pb in the CO2 seepage chamber was respectively 5.1, 3.8, 4.5, 3.2, 1.4, 2.3 and 1.3 times higher than the dissolved concentrations of these metals in the control. During the second phase of the experiment (10 days) with the same sediment but replenished seawater, the dissolved fractions of Al, Cr, Cd, and Zn were partly removed from the water column in the CO2 chamber. DNi and DCu still increased but at reduced rates, while DPb increased faster than that was observed during the first phase. DGT-labile fractions (MeDGT) of all metals increased substantially during the first phase of CO2 seepage. DGT-labile fractions of Al, Cr, Ni, Cu, Zn, Cd and Pb were respectively 7.9, 2.0, 3.6, 1.7, 2.1, 1.9 and 2.3 times higher in the CO2 chamber than that of in the control chamber. AlDGT, CrDGT, NiDGT, and PbDGT continued to increase during the second phase of the experiment. There was no change in CdDGT during the second phase, while CuDGT and ZnDGT decreased by 30% and 25%, respectively in the CO2 chamber. In the sediment pore water, DGT labile fractions of all the seven elements increased substantially in the CO2 chamber. Our results show that CO2 leakage affected the solubility, particle reactivity and transformation rates of the studied metals in sediment and at the sediment-water interface. The metal species released due to CO2 acidification may have sufficiently long residence time in the seawater to affect bioavailability and toxicity of the metals to biota.

Radiosonde profiles and meteorological observations during Atlantic Expedition M2 in 1965 (IQSY) of RV "Meteor"

A radiosonde is described for measuring the upward and downward fluxes of visible light in the atmosphere. Photoresistors are used as sensors, the optical center of the spectral range beeing at 0.55 µ. The results of these flux-measurements obtained during the Atlantic Expedition 1965 with the research vessel "Meteor" are presented. The datas have been divided into three groups according to the amount of cloudiness. In group a) (small cloudiness) the extinction coefficient of the prevailing linear radiation is derived as a function of the height. Characteristics of airmasses of maritime or continental origin are shown. In group b) (cloud covered sky) microphysical quantities are determined from the radiative lapse rate in the clouds. The average radius of droplets is found to lie between 5.5 µm and 14.4 µm. The albedo of cloud surfaces varies between 25% and 54%, the transmission values are between 58% and 73%. One ascent through a Cirrus cloud of considerable vertical thickness is treated seperately. The observed distribution of extinction is compared with theoretical values in water clouds leading to the same order of magnitude. The relation between the albedo of the surface of the sea and the amount of cloudiness is discussed.