(Table 1) Water chemistry of groundwater and snow samples from three sites in Ontario, Canada

Snow samples collected from hand-dug pits at two sites in Simcoe County, Ontario, Canada were analysed for major and trace elements using the clean lab methods established for polar ice. Potentially toxic, chalcophile elements are highly enriched in snow, relative to their natural abundance in crustal rocks, with enrichment factor (EF) values (calculated using Sc) in the range 107 to 1081 for Ag, As, Bi, Cd, Cu, Mo, Pb, Sb, Te, and Zn. Relative to M/Sc ratios in snow, water samples collected at two artesian flows in this area are significantly depleted in Ag, Al, Be, Bi, Cd, Cr, Cu, Ni, Pb, Sb, Tl, V, and Zn at both sites, and in Co, Th and Tl at one of the sites. The removal from the waters of these elements is presumably due to such processes as physical retention (filtration) of metal-bearing atmospheric aerosols by organic and mineral soil components as well as adsorption and surface complexation of ionic species onto organic, metal oxyhydroxide and clay mineral surfaces. In the case of Pb, the removal processes are so effective that apparently ''natural'' ratios of Pb to Sc are found in the groundwaters. Tritium measurements show that the groundwater at one of the sites is modern (ie not more than 30 years old) meaning that the inputs of Pb and other trace elements to the groundwaters may originally have been much higher than they are today; the M/Sc ratios measured in the groundwaters today, therefore, represent a conservative estimate of the extent of metal removal along the flow path. Lithogenic elements significantly enriched in the groundwaters at both sites include Ba, Ca, Li, Mg, Mn, Na, Rb, S, Si, Sr, and Ti. The abundance of these elements can largely be explained in terms of weathering of the dominant silicate (plagioclase, potassium feldspar, amphibole and biotite) and carbonate minerals (calcite, dolomite and ankerite) in the soils and sediments of the watershed. Arsenic, Mo, Te, and especially U are also highly enriched in the groundwaters, due to chemical weathering: these could easily be explained if there are small amounts of sulfides (As, Mo, Te) and apatite (U) in the soils of the source area. Elements neither significantly enriched nor depleted at both sites include Fe, Ga, Ge, and P.

Argon, uranium, thorium and lead composition and ages of ODP Leg 180 sites

During Ocean Drilling Program (ODP) Leg 180, 11 sites were drilled in the vicinity of the Moresby Seamount to study processes associated with the transition from continental rifting to seafloor spreading in the Woodlark Basin. This paper presents thermochronologic (40Ar/39Ar, 238U/206Pb, and fission track) results from igneous rocks recovered during ODP Leg 180 that help constrain the latest Cretaceous to present-day tectonic development of the Woodlark Basin. Igneous rocks recovered (primarily from Sites 1109, 1114, 1117, and 1118) consist of predominantly diabase and metadiabase, with minor basalt and gabbro. Zircon ion microprobe analyses gave a 238U/206Pb age of 66.4 ± 1.5 Ma, interpreted to date crystallization of the diabase. 40Ar/39Ar plagioclase apparent ages vary considerably according to the degree to which the diabase was altered subsequent to crystallization. The least altered sample (from Site 1109) yielded a plagioclase isochron age of 58.9 ± 5.8 Ma, interpreted to represent cooling following intrusion. The most altered sample (from Site 1117) yielded an isochron age of 31.0 ± 0.9 Ma, interpreted to represent a maximum age for the timing of subsequent hydrothermal alteration. The diabase has not been thermally affected by Miocene-Pliocene rift-related events, supporting our inference that these rocks have remained at shallow and cool levels in the crust (i.e., upper plate) since they were partially reset as a result of middle Oligocene hydrothermal alteration. These results suggest that crustal extension in the vicinity of the Moresby Seamount, immediately west of the active seafloor spreading tip, is being accommodated by normal faulting within latest Cretaceous to early Paleocene oceanic crust. Felsic clasts provide additional evidence for middle Miocene and Pliocene magmatic events in the region. Two rhyolitic clasts (from Sites 1110 and 1111) gave zircon 238U/206Pb ages of 15.7 ± 0.4 Ma and provide evidence for Miocene volcanism in the region. 40Ar/39Ar total fusion ages on single grains of K-feldspar from these clasts yielded younger apparent ages of 12.5 ± 0.2 and 14.4 ± 0.6 Ma due to variable sericitization of K-feldspar phenocrysts. 238U/206Pb zircon, 40Ar/39Ar K-feldspar and biotite total fusion, and apatite fission track analysis of a microgranite clast (from Site 1108) provide evidence for the existence of a rapidly cooled 3.0 to 1.8 Ma granitic protolith. The clast may have been transported longitudinally from the west (e.g., from the D'Entrecasteaux Islands). Alternatively, it may have been derived from a more proximal, but presently unknown, source in the vicinity of the Moresby Seamount.

Lead isotope ratios of basalts from DSDP Leg 37 (Table 1)

Analyses of Pb from mid-ocean ridge basalts obtained from DSDP Leg 37 lie on a line of near-zero-age slope. The data seem consistent with an evolutionary model of three stages, the beginning of the second stage being at about 600 m.y. - the model age obtained for the least radiogenic Pb. The beginning of the third stage of evolution at the time of formation of the rocks apparently did not change the average Th/U ratio since measured values are consistent with the ratio deduced from Pb isotope ratios. Ratios of U/Pb are not consistent with Pb isotope ratios, however, thus ruling out a simple two-stage evolutionary model.

Lead (pb) toxicity in saccharomyces cerevisiae: the role of cell wall

O chumbo é utilizado em muitos produtos, tais como baterias, gasolina, tintas e corantes, resultando na sua libertação no meio ambiente. Neste trabalho, foi examinado o papel da parede celular da levedura Saccharomyces cerevisiae como uma barreira ou como alvo da toxicidade do chumbo. A biodisponibilidade do Pb é muito reduzida pelos componentes do meio de cultura YEPD, o que dificulta a avaliação da toxicidade deste elemento em concentrações ambientalmente realistas. Para avaliar a toxicidade de Pb em S. cerevisiae, em condições de crescimento, foram efetuadas diferentes diluições (10-100 vezes) do meio YEPD, as quais foram misturadas com várias concentrações de Pb (0,1-1,0 mmol/l). Observou-se que o YEPD diluído 25 vezes constituía a melhor condição de compromisso entre o crescimento celular e a precipitação de Pb. Os genes CWP1 e CWP2 codificam para duas grandes manoproteínas da parede celular da levedura S. cerevisiae; a deleção destes genes CWP aumenta a permeabilidade da parede celular. A suscetibilidade de células de levedura interrompidas no gene CWP1 (estirpe cwp1Δ) ou CWP2 (estirpe cwp2Δ) foi comparada com a da estirpe, isogénica, selvagem (WT). Verificou-se que o crescimento das estirpes cwp1Δ e cwp2Δ, no meio de cultura YEPD 25 vezes diluído, na presença de Pb, não diferiu do crescimento da estirpe WT. Este resultado sugere que a alteração da permeabilidade da parede celular não altera a sensibilidade de células de levedura ao Pb. Foi investigada o impacto do Pb na parede celular de levedura. Para este efeito, comparou-se a suscetibilidade ao dodecil sulfato de sódio (SDS), ao calcofluor (CFW) e a uma enzima que degrada a parede da célula (liticase), em células da estirpe WT não expostas ou expostas a Pb durante 4, 8 ou 24 h. Além disso, o conteúdo de quitina da parede celular de levedura foi investigada por coloração das células com CFW. Os resultados não mostraram uma alteração da suscetibilidade ao SDS e ao CFW, nas células tratadas com Pb; contudo, nas células tratadas durante 24 h com Pb, observou-se um aumento da sensibilidade à liticase e um aumento da coloração com CFW. Estes resultados sugerem que o chumbo interage com a parede celular da levedura e influencia a sua composição. Deve ser levado a cabo trabalho adicional a fim de confirmar estes resultados.

Geochemistry and mineralogy of a silica chimney from an inactive seafloor hydrothermal field (East Pacific Rise, 18°S)

An inactive vent field comprised of dead chimneys was discovered on the ultrafast East Pacific Rise (EPR) at 18°S during the research campaign NAUDUR with the R/V Le Nadir in December 1993. One of these chimneys was sampled, studied and found to be largely composed of silica-mineralized bacterial-like filaments. The filaments are inferred to be the result of microbial activity leading to silica (± Fe-oxyhydroxide) precipitation. The chimney grew from the most external layer (precipitated 226 ± 4 yr. B.P.) towards the central chimney conduit. Hydrothermal activity ceased 154 ± 13 yr. B.P. and the chimney conduit was completely sealed. Mixing between an end-member hydrothermal fluid and seawater explains the Sr–Nd isotopic composition of the chimney. Seawater was the major source of Sr to the chimney, whereas the dominant Nd source was the local mid-ocean ridge basalt (MORB) leached by the hydrothermal fluids. The mixing scenarios point to a dynamic hydrothermal system with fluctuating fluid compositions. The proportion of seawater within the venting fluid responsible for the precipitation of the silica chimney layers varied between 94 and 85%. Pb-isotope data indicates that all of the Pb in the chimney was derived from the underlying MORB. The precipitation temperatures of the chimney layers varied between 55 and 71 °C, and were a function of the seawater/end-member hydrothermal fluid mixing ratio. δ30Si correlates with the temperature of precipitation implying that temperature is one of the major controls of the Si-isotope composition of the chimney. Concentrations of elements across the chimney wall were a function of this mixing ratio and the composition of the end-member hydrothermal fluid. The inward growth of the chimney wall and accompanying decrease in wall permeability resulted in an inward decrease in the seawater/hydrothermal fluid mixing ratio, which in turn exerted a control on the concentrations of the elements supplied mainly by the hydrothermal fluids. The silica chimney is significantly enriched in U, likely a result of bacterial concentration of U from the seawater-dominated vent fluid. The chimney is poor in rare earth elements (REE). It inherited its REE distribution patterns from the parent end-member hydrothermal fluids. The dilution of the hydrothermal fluid with over 85% seawater could not obliterate the particular REE features (positive Eu anomaly) of the hydrothermal fluids.

Implicaciones geodinámicas del complejo metamórfico paleozoico de la Sierra Madre Oriental en el Noreste de México

Dataciones geocronológicas U-Pb en circones detríticos, edades 40Ar/ 39Ar en mica blanca, análisis estructurales, texturales, la composición química de elementos mayores, traza y tierras raras (REE) así como la composición química mineral de las rocas metamáficas, metultramáficas y metasedimentarias, fueron determinadas con el fin de determinar las condiciones metamórficas, el ambiente tectónico y la procedencia del Esquisto Granjeno en el noreste de México (Nuevo León y Tamaulipas). En el país existen rocas metamórficas paleozoicas que están relacionados con los procesos que dieron lugar a la colisión entre Laurentia y Gondwana durante la formación Pangea. Vestigios de la configuración continental paleozoica de México se encuentran en el Esquisto Granjeno, que forma parte del basamento metamórfico de la Sierra Madre Oriental. Relaciones de campo y análisis petrográficos indican que el Esquisto Granjeno consiste de rocas metamórficas con protolitos sedimentarios (psamita, pelita, turbidita, conglomerado, lutita negra) e ígneos (toba, flujos de lava, lava meta-almohadillada y cuerpos ultramáficos). El geotermómetro de clorita, el geobarómetro de fengita y la edad 40Ar/ 39Ar calculada indican que el Esquisto Granjeno fue afectado por metamorfismo en facies de sub-esquistos verdes a facies de esquistos verdes-anfibolita, (165-410°C y 2.5-4 kbar ) durante el Carbonífero (330±30 Ma). Las rocas metamáficas del Esquisto Granjeno tienen una afinidad sub-alcalina a alcalina y se caracterizan por un bajo contenido de SiO2 (40-50 wt%), alto contenido de Al2O3 (19 wt%) y #MgO de 48-67. La abundancia de tierras raras (∑REE) varía de 51-167 ppm. Estas rocas presentan patrones de REE normalizados a condrita moderadamente fraccionados, con valores de LaN/YbN 0.74-8.88. La anomalía de europio es variable (Eu/Eu* 0.80- 1.09) y presenta una tendencia ligeramente negativa (Eu/Eu* 0.96). Las rocas metamáficas tienen composiciones correspondientes a basaltos de cresta (MORB) e isla oceánica (OIB), de acuerdo a los valores en las relaciones Zr/Y=6-8 y Zr/Nb=4-9 para OIB y 0.9-3; 14-53 para MORB. Los protolitos de la serpentinita y el metacumulato corresponden a dunita y harzburgita. La serpentina y el metacumulato tienen un contenido de MgO (16-39 wt%), SiO2 (36-45 wt%), FeO (2-11 wt%), Al2O3 (0.76-13 wt%), CaO (< 22wt%) y #MgO (85-98, 69). Las rocas de talco presentan contenido de MgO (26-33wt%), SiO2 (31- 61wt%), FeO (3.7-9.8wt%), Al2O3 (1.2-19wt%), CaO (0.25-2.0wt%), y #Mg (83-93). Los patrones de tierras raras casi horizontals (LaN/YbN=0.51-19.95 y la relación LaN/SmN=0.72-9.08 sugieren un origen vinculado a un ambiente de dorsal oceánica y de suprasubducción para las rocas ultramáficas. Las serpentinitas contienen cromita rica en Al, ferrit-cromita y magnetita. La cromita rica en Al tiene #Cr 0.48-0.55 que indica que este mineral fue formado a partir de una fuente tipo MORB y que fue afectada hasta un 18% fusión parcial durante su formación. La ferritchromita tiene #Cr 0.93-1.00 que indica un origen metamórfico. La composición química de roca total indica que los protolitos de las rocas metasedimentarias consisten de lutita, grauvaca y arenita. La metapelita y metapsamita tienen un contenido de SiO2 (69-78% y 80-96% ) y de Al2O3 (9-13% y 1-8%). La abundancia de ∑REE son variables en los metasedimentos (9-178 ppm). Presentan patrones de REE normalizados a condrita con una tendencia más fraccionada que los de las rocas metamáficas, con valores en las relaciones LaN/YbN de 3-16. Las rocas metasedimentarias tienen anomalías de europio negativa (Eu/Eu* 0.67). Los datos obtenidos sugieren que los protolitos de las rocas metasedimentarias derivan de fuentes mixtas con una composición ígnea félsica-básica. (Ti/Nb 200-400). Según los valores de las relaciones de los elementos traza Th/Sc y Zr/Sc de 0.2-3.6 y 0.2-220, respectivamente se sugiere un ambiente de depósito para los protolitos de margen continental activo.

Identifying and implementing adaptive strategy in the U.S. military

Changes in the environment, including increased environmental complexity, require military supply units to employ a more adaptive strategy in order to enhance military agility. We extend the Lumpkin and Dess (1996) model and develop propositions that explore the interrelationships between/amongst entrepreneurial orientation (EO); opportunity recognition, evaluation and exploitation; environmental and organizational factors; and organizational performance. We propose that the innovativeness, proactiveness, and risk-taking dimensions of EO are of primary importance in identifying adaptive solutions and that these relationships are moderated by environmental factors. The autonomy and competitive aggressiveness dimensions of EO are important in implementing solutions as adaptive strategies, especially in a military context, and these relationships are moderated by organizational factors. This chapter extends existing theory developed primarily for the civilian sector to the military. Military organizations are more rigid hierarchical structures, and have different measures of performance. At an applied level, this research provides insights for military commanders that can potentially enhance agility and adaptability.

The role of timber plantations in U.K. investment portfolios

Although timber plantations and forests are classified as forms of agricultural production, the ownership of this land classification is not limited to rural producers. Timber plantations and forests are now regarded as a long-term investment with both institutional and absentee owners. While the NCREIF property indices have been the benchmarks for the measurement of the performance of the commercial property market in the UK, for many years the IPD timberland index has recently emerged as the U.K. forest and timberland performance indicator. The IPD Forest index incorporates 126 properties over five regions in the U.K. This paper will utilise the IPD Forestry Index to examine the performance of U.K. timber plantations and forests over the period 1981-2004. In particular, issues to be critically assessed include plantation and forest performance analysis, comparative investment analysis, and the role of plantations and forests in investment portfolios, the risk reduction and portfolio benefits of plantations and forests in mixed-asset portfolios and the strategic investment significance of U.K. timberlands.

Dislodgement of commercial property public debt markets : the case of U.S. and Australia

The paper investigates if there are any discernible trends in the U.S. and Australian commercial property public debt markets with the onset of the global financial crisis (GFC). Commercial mortgage-backed securities and unsecured bonds issued by real estate investment trusts for the period 2000 to Q3:2009 are reviewed. It is shown that events in the equity markets have an impact on the pricing of these two instruments. Furthermore, the impact of subdued activity in these financing instruments on the commercial property market is discussed.

Australian student reactions to U.S. tourism advertising : a test of advertising as public diplomacy

A study among Australian college students gauged their reactions to a television commercial produced for the U.S. Commerce Department to bolster sagging tourism numbers among international visitors. In addition to using traditional measures applied to tourism advertisements, the student also concluded items to measure attitudes toward the U.S. government and its people Pre- and post-viewing results indicated that while the Hollywood-movie-themed commercial was not well received by the Australian students as a tourism message, it did result in more favorable attitudes toward the U.S. government, though not the U.S. people. The findings lend partial support for the potential of tourism advertising efforts to exert a "bleed-over effect" in terms of their contributions to overall attitudes toward a country, regardless of whether viewers plan to visit the country whose travel advertisements they see.

The role of U.S. timberland in real estate portfolios

Timberland is seen as a long-term investment which has recently received increased institutional investor attention in many countries and potentially provides added value in a mixed-asset portfolio. Using the National Council of Real Estate Investment Fiduciaries (NCREIF) timberland series, this paper analyses the risk-adjusted performance and portfolio diversification benefits of timberland in the United States over the period of 1987-2007. U.S. timberland is seen to have been a strongly performed asset class with significant portfolio diversification benefits over this period; with a significant portfolio role separate to that of real estate. However, recent years have seen reduced risk-adjusted returns, with some loss of portfolio diversification benefits of timberland with stocks and real estate. Global drivers are likely to see increased future demand for timberland investment.