Influence of temperature on the accumulation and retention of 11 radionuclides by the marine alga Fucus vesiculosus (L.)

Accumulation of the radionuclides ²⁴¹Am, ^110mAg, ¹³³Ba, ¹⁰⁹Cd, ⁵⁷Co-cobalamine, ⁶⁰Co, ¹³⁴Cs, ¹⁵²Eu, ⁵⁴Mn, ¹⁰⁶Ru and ⁶⁵Zn in the brown macroalga Fucus vesiculosus (L.) Phaeophyceae, was compared at 2°C and 12°C in a series of laboratory radiotracer experiments. Concentration factors in the thallus were temperature-dependent and significantly decreased at 2°C for ^110mAg, ¹⁰⁹Cd, ⁶⁰Co, ⁵⁴Mn and ⁶⁵Zn (CF = 439, 51, 101, 92 and 162, respectively) but not for ²⁴¹Am, ¹³³Ba, ¹³⁴Cs, ¹⁵²Eu and organic ⁵⁷Co (CF = 329, 210, 3.3, 470 and 214, respectively); hence, for these last isotopes concentration factors in this species derived from temperate latitude (12°C) studies can probably be applied to radiological assessments made under Arctic conditions. Between 2 and 14 days of depuration, the radionuclides, except ¹³³Ba and ¹³⁴Cs, remained tightly bound to the alga. Our results suggest that: 1. temperature must be considered when modelling the radiological impact of radioactive waste dumping in the Arctic Seas; and 2. Fucus spp. would be excellent bioindicators of radionuclide contamination and dispersion in the Barents and Kara Seas.     

2,3-Dimethylbiphenyl: Kinetics of its cyclisation reaction and effects of maturation upon its relative concentration in sediments

The rate constants of the cyclisation reaction of 2,3-dimethylbiphenyl to give 1-methylfluorene under non-catalytic conditions have been obtained at five temperatures between 460 and 500°C. The activation energy, activation entropy and frequency factor for the reaction have been determined from the experimental data. These kinetic parameters were then used to calculate the temperature ranges where the reaction occurs under natural conditions in sedimentary sequences which have experienced different heating rates. The coincidence of the measured and calculated values has been taken as evidence that the cyclisation reaction occurs in sediments under non-catalytic conditions.     

The effects of a gas well blow out on groundwater chemistry

Water wells were sampled near North Madison, Ohio, following a gas well blow out that injected large amounts of CH₄ into near-surface groundwater Chemical analyses showed elevated levels of Fe⁺², Mn⁺², Ca⁺², sulfide, alkalinity, and pH, and low levels of dissolved oxygen, SO₄ ⁻², and NO₃ ⁻ in CH₄-affected wells compared to unaffected wells. Sulfate reduction is quantitatively the most important vehicle for CH₄ oxidation Equilibrium thermodynamic computer models were used to simulate groundwaters from the North Madison area Model results showed that CH₄ is oxidized to HCO₃ ⁻, SO₄ ⁻² is reduced, iron and manganese oxides are reduced and dissolved, and pH increases These simulations are in excellent agreement with trends observed in the field data A laboratory experiment was designed to simulate CH₄ ⁻ perturbed groundwater in the methane-perturbed system, sulfide increased significantly, providing direct evidence for methane oxidation by sulfate reduction Although suitable anaerobic methane-oxidizing bacteria have not been isolated from groundwater aquifers, the combination of field data, laboratory experiment, and computer simulation form a convincing argument that CH₄ perturbation of aquifers can and does affect groundwater chemistry     

Basal layered deposits of the Peach Springs Tuff,northwestern Arizona,USA

Basal layered deposits of the large-volume Peach Springs Tuff occur beneath the main pyroclastic flow deposit over a minimum lateral distance of 70 km in northwestern Arizona (USA). The basal deposits are interpreted to record initial blasting and pyroclastic surge events at the beginning of the eruption; the pyroclastic surges traveled a minimum of 100 km from the (as yet unknown) source. Changes in bedding structures with increasing flow distance are related to the decreasing sediment load of the surges. Some bed forms in the most proximal part of the study area (Kingman, Arizona) can be interpreted as being shock induced, reflecting a blast origin for the surges. Component analyses support a hydrovolcanic origin for some of the blasting and subsequent pyroclastic surges. The eruption apparently began with magmatic blasts, which were replaced by hydrovolcanic blasts. Hydrovolcanic activity may be partially related to failure of the conduit walls that temporarily plugged the vent. A single large-volume pyroclastic flow immediately followed the blast phase, and no evidence has been observed for a Plinian eruption column. The stratigraphic sequence indicates that powerful hydrovolcanic blasting rapidly widened the vent, thus bypassing a Plinian fallout phase and causing rapid evolution to a collapsing eruption column. Similar processes may occur in other large-volume ignimbrite eruptions, which commonly lack significant Plinian fallout deposits.     

Diversity of terrestrial avifauna in response to distance from the shoreline of the Salton Sea

Large aquatic bodies influence surrounding terrestrial ecosystems by providing water and nutrients. In arid landscapes, the increased primary productivity that results may greatly enhance vertebrate biodiversity. The Salton Sea, a large saline lake in the Colorado Desert of southern California, provides nutrients in the form of hundreds of thousands of dead fish carcasses, brine flies, and chemical compounds through windborne salt sea spray. We performed point counts for landbirds and shorebirds monthly or every other month between March 2001 and February 2002 across a sampling grid of 35 points along the west edge of Salton Sea. We found that avian diversity (numbers of species and numbers per species) was dependent on proximity to the Sea. Diversity was at a maximum nearest the shore, and was significantly lower away from the Sea's edge, at all surveyed distances up to 1 km from the shore. Cover by the dominant shrubs on the study site also corresponded to proximity to the water's edge. Whereas one may hypothesize that the avian diversity patterns are caused by these differences in vegetation structure, our data did not support this. Future studies should further investigate this potential correlation between vegetation and bird patterns. Until more is understood about the relationship between elevated avian diversity and the physical environment of the land-shore interface, our results suggest that the Sea's surface be stabilized near its present level. Future management schemes at the Salton Sea that include reductions of water sources should be carefully analyzed, so as to not jeopardize the terrestrial avifauna at this unique ecosystem.     

Lessons learned in remediation and restoration in the Oklahoma prairie: A review

For almost a decade the Tallgrass Prairie Preserve in Oklahoma has been used as a field laboratory for the investigation of aspects of the remediation and restoration of oil and brine spills. Objectives of this work have included: (1) simplification of the remediation process and lowering the cost of remediation; (2) the development of methods to accelerate or jump-start the restoration process; and (3) determining appropriate metrics for assessing the status of soil ecosystem recovery. This research has resulted in a number of lessons learned that will be presented here which can be exported to other exploration and production sites, especially sites located in sensitive ecosystems. Key observations have included the role of a fertilizer amendment in linking the remediation and restoration process at an oil-impacted site, the use of nematodes as ecological indicators in the restoration of oil- and brine-impacted sites, and the development of a two-stage process for remediation of brine impacted sites that does not include significant use of gypsum.     

Lunar rock magnetism

The relationship between the magnetization and temperature in a high constant magnetic field for a temperature range between 5 K and 1100 K was examined for Apollo 11, 12 and 14 lunar materials. The average value of Curie point temperature is (768.2 ± 3.5)°C for the lunar igneous rocks and (762.5 ± 3.4)°C for the lunar fines and breccias. A tentative conclusion about the ferromagnetic substance in the lunar materials would be that Fe is absolutely dominant with a slight association of Ni and Co, and probably Si also, in the lunar native irons.The antiferromagnetic phase of ilmenite and the paramagnetic phase of pyroxenes are considerably abundant in all lunar materials. However, a discrepancy of observed magnetization from a simulated value based on known magnetic elements for the temperature range between 10 and 40 K suggests that pyroxene phase represented by (M _x Fe_1-x ) SiO₃ (whereM = Ca²⁺, Mg²⁺, etc and 0 x 1/4) also may behave antiferromagnetically.Magnetic hysteresis curves are obtained at 5 K and 300 K, and the viscous magnetic properties also are examined for a number of lunar materials. The superparamagnetically viscous magnetization has been experimentally proven as due to fine grains of metallic iron less than 200 Å in mean diameter. The viscous magnetization is dominant in the lunar fines and breccias which is classified into Type II, while it is much smaller than the stable magnetic component in lunar igneous rocks (Type I). The superparamagnetically fine particles of metallic iron are mostly blocked at 5 K in temperature; thus coercive force (H _c ) and saturation remanent magnetization (I _R ) become much large at 5 K as compared with the corresponding values at 300 K.Strongly impact-metamorphosed parts of lunar breccias have an extremely stable NRM which could be attributed to TRM. NRM of the lunar igneous rocks and majority of breccias (or clastic rocks) are intermediately stable, but their stability is considerably higher than that of IRM of the same intensity. This result may imply that some mechanism which causes an appreciable magnitude of NRM and the higher stability, such as the shock effect, may take place on the lunar surface in addition to TRM mechanism for special cases.A particular igneous rock (Sample 14053) is found to have an unusually strong magnetism owing to a high content of metallic iron (about 1 weight percent), and its NRM amounts to 2 × 10^–3 emu/g. The abundance of such highly magnetic rocks is not known as yet but it seems that the observed magnetic anomalies on the lunar surface could be related to such highly magnetized rock masses.     

Spatial analysis of two-dimensional orientation data

A frequently encountered problem in structural geology is the analysis and interpretation of directional data with a geographical distribution. Such data may arise, for example, as samples of fracture strikes collected at a number of locations (rocky outcrops, road cuttings, etc.), trends of geological structures mapped in underground mines where they are exposed in the tunnel roof, or as lineaments annotated on aerial or satellite photographs. From such data, it is of interest to determine the structural domains in the area, that is, to partition the area into subareas of homogeneous structural pattern. This paper presents a method for performing such an analysis, and applies it to a data set collected from an underground coal mine.