Effects of Access Tube Material and Grout on Neutron Probe Measurements in the Vadose Zone

A test-stand experiment was conducted on neutron probe measurements using steel and Schedule 40 PVC access tubes to determine the effect of backfill grout in boreholes. The experiment used a moveable simulated vadose zone. Access tubes and grout do have masking effects on vadose zone measurements, but vadose zone moisture was detected through all configurations tested. Steel tubing has a smaller masking effect than PVC tubing. The masking effect of grout increased with borehole diameter. Although this experiment produced numerical results, conclusions drawn are qualitative in nature, rather than a quantitative calibration of the technique.     

Morphology and sedimentary processes in and around Tortugas and Agassiz Sea Valleys,southern Straits of Florida

Continuous seismic reflection profiling and new bathymetry data in the southern Straits of Florida over an area dominated by the Tortugas and Agassiz Valley systems have allowed a more detailed analysis of the morphology and sedimentary processes active in this region. Four dives in the submersible DSV “Alvin” supplement the seismic and bathymetric data.The continental slope in the study area can be divided into two physiographic provinces: (I) an irregular topography controlled by the Florida Escarpment west of Tortugas Valley; and (II) the remainder of the continental slope which contains the majority of features under investigation. Seismic data indicate that the valleys are being filled shoreward of 290 fathoms (530 m) by a wedge of prograding sediments derived from the Florida shelf.The morphology of the two valley systems reflects probable differences of origin. Tortugas Valley appears to have originated coincident with the eastern terminus of the Florida Escarpment and province-I-type topography. The Agassiz valleys may have an origin associated with jointing patterns observed by divers aboard DSV “Alvin”. Current meter readings and bottom photographs from “Alvin” indicate that currents are relatively sluggish and not very effective in the transport of sediment within the valleys. An area of undulations west of Pourtales Terrace was investigated and concluded to be erosional in origin.Slumping appears to have played a large part in shaping many features in the study area. The bottom morphology and sediment distribution on the continental slope and in the axis of the Straits of Florida suggest that bottom currents are active in shaping the entire area.     

Habitat temperature ranges of azooxantellate scleractinian corals in the World Ocean

Based on the study of the scleractinian azooxantellate corals sampled during many marine expeditions of Russian research vessels in the Pacific, Indian, and Atlantic oceans, habitat temperature ranges of their species were first estimated with compiling of temperature series according to the growing thermophility. The temperature series compiled for these oceanic basins consist of 35, 17 and 10 species, respectively. The confinement of scleractinian species to particular water masses is revealed. These data are thought to be useful for reconstructing ecological and oceanological characteristics in the past geological epochs, since coral species exist for millions years. For example, the temperature series established for scleractinian species may be used for reconstructing water temperatures in Cenozoic oceans and, probably, for determining geological ages for some coral species.     

Scleractinian Corals of the Arctic and High Latitudes of the North Atlantic Ocean

Oceanology - Only two species of scleractinian corals were found in the high latitudes of the Arctic Ocean west of the Barents Sea: Lophelia pertusa (Linné, 1758) and Flabellum macandrewi...     

Acoustic thermometry data compared with two ocean models: the importance of Rossby waves and ENSO in modifying the ocean interior

An interpretation is made of interannual changes in acoustic travel time between Oahu and seven receivers at distances of 3000–4000 km. Measurements were made in late 1983, and over two 5-month intervals between 1987 and 1989. Previous publications demonstrated that these changes stem from variations in temperature. Two hydrodynamic ocean models are used to identify plausible oceanic features that could cause these variations. They are from the Naval Research Laboratory and the Florida State University at (1/8)° and (1/6)° resolution, respectively, and are forced with different interannual wind sets for more than a decade. Modelled El Niño's and La Niña's generate poleward travelling Kelvin waves on the eastern boundary of the Pacific. These excite Rossby waves that propagate westward at mid-latitudes. Rossby waves are the dominant model features which affect the modelled acoustic travel times, and hence section-averaged temperatures in the eastern North Pacific. These waves yield travel times whose standard deviations and rates of changes are similar to the measurements. In the observations, some sections separated by less than 500 km exhibit trends in heat content with opposite signs. Similar variability can be explained with modelled Rossby waves. Model wavelengths less than 500 km, eddies, and seasonal cycles induced by seasonal winds yield travel times that are two orders of magnitude too small to account for the data.     

The Paleocene–Eocene transition in the marginal northeastern Tethys (Kazakhstan and Uzbekistan)

We studied two sections that accumulated during the Paleocene–Eocene transition in shelf waters in the northeastern Tethys. Stable carbon isotopic compositions of marine and terrestrial biomarkers are consistent with a ¹³C depletion in the oceanic and atmospheric carbon dioxide pools during the Late Paleocene Thermal Maximum (LPTM; Subzone P5b). The 2–3‰ negative δ ¹³C excursion in planktic foraminifera coincides with minimum δ ¹⁸O values, an incursion of transient subtropical planktic foraminiferal fauna, and the occurrence of an organic-rich sapropelite unit in Uzbekistan, which accumulated at the onset of a transgressive event. Biomarker distributions and hydrogen indices indicate that marine algae and bacteria were the major organic matter sources. During the Late Paleocene (Subzones P4 and P5a), the marginal northeastern Tethys experienced a temperate to warm climate with wet and arid seasons. Most likely, warm and humid climate initiated during the LPTM (Subzone P5b) and subsequently extended during the Eocene (Zone P6) onto adjacent land areas of the marginal northeastern Tethys. Received: 18 May 1999 / Accepted: 2 February 2000     

New initiatives for synoptic observations

Several new synoptic facilities for long-term studies of the Sun will become operational within the next few years. This paper summarizes information on some of these projects, in particular GONG+, ISOON, GOES/SXI, and SOLIS. SOLIS, the Synoptic Optical Long-Term Investigations of the Sun, is currently being built by the National Solar Observatory and will become operational in 2001. It consists of a 50-cm vector spectromagnetograph, a 14-cm full-disk patrol, and an 8-mm sun-as-a-star spectrometer.