Bio-volatilization of polonium: Results from laboratory analyses

Polonium, like other elements in the Group VI Oxygen series (S, Se, Te), has the potential to form volatile alkyl derivatives. This may be evident in its pervasive radioactive excesses in the atmosphere and coastal waters, and its deficiency in surface open ocean waters. We present evidence for the formation of volatile polonium species. The first evidence comes from duplicating experiments that proved the existence of volatile tellurium, its Group VI congener. Cultures of bread mold at room temperature spiked with polonium tracers showed a significant and reproducible loss of about 0.5% per day of volatile polonium species. In another set of experiments, between 30–50% loss of²¹⁰Po was observed from Floridan groundwater when nitrogen was bubbled through it over durations of 5–30 minutes. Polonium volatility is highly relevant for biogeochemical studies because it may provide a natural radiochemical tracer for recycling of similar volatile sulfur and other Group VI metal species between the geosphere, atmosphere, and hydrosphere.     

Response of oil shale to fragmentation by cylindrical charges

Summary This paper describes an experimental program that was conducted in 1981 through 1983 in the Anvil Points Oil Shale Mine near Rifle, Colorado. The objective was to examine the response of the kerogen rich oil shale to explosive charges in relatively large scale tests. Due to an alleged shortage of oil at that time the price per barrel of crude oil had reached nearly $40 and the United States was looking at oil shale as a possible source of hydrocarbon fuels.It was the intention of the fragmentation program to develop a modified in situ retort to recover the oil from the fragmented shale. Programs were already underway wherein the oil shale was being mined, transported to the surface, and retorted to remove the oil. This surface retorting resulted in a tremendous amount of spent shale (shale with the kerogen removed) which had to be handled and it was felt that this would lead to serious environmental problems. The scheme being investigated in the program at Anvil Points was one in which about 25% of the shale is mined, moved to the surface, and retorted. The remaining 75% of the shale was to be fragmented in place and an underground retort formed so that the oil could be removed without the necessity of transporting the shale to the surface.A successful method was not developed but the results of the program did provide information on the response of shale to both single hole and multiple hole explosive charges.     

Dye trace and bacteriological testing of sinkholes: Sulphur Springs,Tampa, Florida

This paper summarizes over four years of studies and testing of a sinkhole/spring system in north Tampa. Sulphur Springs Pool delivers an average of 95 million l/d to the Hillsborough River, which is tributary to Tampa Bay. In 1986, owing to increasingly erratic bacterial levels at the natural bathing area adjacent to Sulphur Springs, the Hillsborough County Health Department closed the pool for swimming. The City of Tampa, Southwest Florida Water Management District (SWFWMD), Hillsborough County Environmental Protection Commission, and the United States Geological Survey have gathered data in an attempt to better understand the system and possible sources of contamination. The Sulphur Springs Action League is a civic group in the area, which has an objective of reopening the pool for recreational purposes. Environmental Engineering Consultants, Inc. provided pro bono technical assistance and expertise in assisting the Action League with its goal. The Action League obtained a grant from SWFWMD to outfit underwater divers for sinkhole exploration as well as water quality and dye trace analysis. The main suspects for bacterial contamination of the pool were two significant sinkholes located 1950 and 2300 m north of the spring. A series of dye tests and water-quality tests were performed. It was estimated that the underground velocity of water was between 90–100 m/h. Using a dye trace, bacteria testing, and travel time estimating, a new source of contamination was found in a Department of Transportation (DOT) stormwater retention basin in which a sinkhole had opened up and was receiving stormwater. The two significant sinkholes received stormwater from commercial and residential areas, and this stormwater brings a large amount of bacteria into the sinkhole, which funnels into the underground system and induces a bacteria spike at Sulphur Springs pool that exceeds the bathing water standards. The City of Tampa has constructed an experimental initial flush capture basin that will sand-filter stormwater to see if this will favorably affect bacteria levels. A mayor's task force in Tampa has recommended ultraviolet disinfection as an interim solution to the contamination problem.     

An examination of internally generated variability in long climate simulations

General circulation model experiments designed to estimate the magnitude and structure of internally generated variability and to help understand the mechanisms underlying this variability are described. The experiments consist of three multi-century integrations of a rhomboidal 15, 9 level, version of the Center for Ocean-Land-Atmosphere Studies atmospheric general circulation model: a run with fixed sea surface temperatures and equinox solar radiation, a run with seasonally varying climatological sea surface temperatures and seasonally varying solar forcing, and a run with seasonally varying solar forcing in which the state of the ocean is predicted by a 3° by 3°, 16 vertical level, nearly global domain version of the Geophysical Fluid Dynamics Laboratory Modular Ocean Model. No flux correction is used in the coupled model integration. Selected surface fields of the three runs are compared to each other as well as to the observed climate. Statistical properties of variability on interannual time scales are compared between the runs. Evidence is presented that climate time scale variability in the simulations is produced by random weather time scale forcing due to the integrating effect of elements of the system with long memories. The importance of ocean variability for land climate variability is demonstrated and attributed to both the memory effect and coupled atmosphere-ocean instability.     

Freshwater ice rafting: an additional mechanism for the formation of some high-latitude submarine pockmarks

 Submarine pockmarks are common features on high-latitude continental shelves, yet the mechanisms for their formation are poorly understood. Here we propose an additional mechanism for the formation of high-latitude pockmarks involving freshwater ice rafting. Freshwater seeping upward through the sediments freezes at the sediment–water interface when bottom waters are below 0°C. Thin layers of the frozen water containing some sediment are buoyant and can rise off the bottom as small ice rafts, thereby excavating a seafloor depression over time. Sediment in the ice rafts becomes entrained in bottom currents and is dispersed over a wide area.     

Near-Infrared Spectrophotometry of Phobos and Deimos

We have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 μm and Deimos from 1.65 to 3.12 μm near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24±0.06 magnitude at 1.65 μm and brighter than Deimos by 0.98±0.07 magnitude at 1.65 μm. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 μm. We find no 3-μm absorption feature due to hydrated minerals on either hemisphere to a level of ∼5-10% on Phobos and ∼20% on Deimos. When the infrared data are joined to visible and near-IR data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-μm absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior (F. P. Fanale and J. R. Salvail 1989, Geophys. Res. Lett.16, 287-290; Icarus88, 380-395).     

Error analysis of an acoustic current meter

Accuracies of the benthic acoustic stress sensor (BASS) and the proposed modular acoustic velocity sensor (MAVS) are evaluated. A simple model of the hydrodynamic sources of error for acoustic current meters is presented and compared with the measured performance of BASS in a tow-tank and in field deployments. The sources of error addressed include those due to ideal flow around the sensor cage, wake effects from the support structure and transducers, vortex shedding from the cage, and electronic zero-point offsets. Electronic error dominates at velocities less than 5-10 cm/s, while flow disturbance dominates at higher speeds     

Apollo drill core depth relationships

Preliminary depth relationships are presented for the Apollo 15, 16 and 17 drill core samples. For a given depth in any of these drill stems, thein situ lunar surface depth can be estimated. Ranges of uncertainty are also established, based on percent core recovery and degree of sample disturbance. The most likely explanation for the sample disturbance observed in the top three sections of the Apollo 16 drill stem is sample migration after the stem was capped on the lunar surface; essentially no sample was lost. Similar disturbance occurred in the Apollo 17 drill core, although to a lesser degree. The average original bulk densities (i.e., before any disturbance occurred) of the Apollo 15, 16 and 17 drill cores are 1.76, 1.59, and 1.87 g cm^?3, respectively. The Apollo 15 and 17 values are probably close to thein situ values; but the Apollo 16 averagein situ density could be as much as 13% less than the already low density in the drill core.