Vapor-phase interactions and diffusion of organic solvents in the unsaturated zone

This article presents an analysis of the interactions and static movement of 37 organic solvents as vapors through the unsaturated soil zone. The physicochemical interactions of the organic vapors with unsaturated soil materials were emphasized with focus on diffusive, and adsorptive interactions. Fick's Law and porous media diffusion coefficients for most of the solvent vapors were either compiled or estimated; coefficients were not available for some of the fluorinated solvents. The adsorption of some of the solvent vapors by silica was concluded to be due to hydrogen bond formation with surface silanol groups. Heats of adsorption data for different adsorbents were also compiled. There were very few data on the adsorption of these solvent vapors by soils, but it appears that the magnitude of adsorption of nonpolar solvents is reduced as the relative humidity of the vapor-solid system is increased. Consequently, the interaction of the vapors may then separated into two processes; (1) gas-water partitioning described by Henry's Law constants, and (2) solid-water adsorption coefficients which may be estimated from liquid-solid partition coefficients (K _d values).     

Analyzing Animal Movement Characteristics From Location Data

When individuals of a species utilize an environment, they generate movement patterns at a variety of spatial and temporal scales. Field observations coupled with location technologies (e.g. GPS tags) enable the capture of detailed spatio‐temporal data regarding these movement patterns. These patterns contain information about species‐specific preferences regarding individual decision‐making, locational choices and the characteristics of the habitat in which the animal resides. Spatial Data Mining approaches can be used to extract repeated spatio‐temporal patterns and additional habitat preferences hidden within large spatially explicit movement datasets. We describe a method to determine the periodicity and directionality in movement exhibited by a migratory bird species. Results using a High Arctic‐nesting Svalbard Barnacle Goose movement data yielded undetected patterns that were secondarily corroborated with expert field knowledge. Individual revisits by the geese to specific locations in the breeding and wintering grounds of Svalbard, Norway and Solway, Scotland, occurred with a periodicity of 334 days . Further, the orientation of this movement was detected to be mostly north‐south. During long‐range migration the geese use the north‐south oriented Norwegian islands as “stepping stones”, Short‐range movement between mudbank roosts to feeding fields in Solway also retained a north‐south orientation.     

Analysis of multiple enteric viral targets as sewage markers in coral reefs

Water and coral mucus samples were collected from throughout the Florida Keys National Marine Sanctuary and the Dry Tortugas for three years and were analyzed for human enteric viruses (enteroviruses, noroviruses, hepatitis A virus and adenoviruses) as conservative markers of human sewage using molecular methods. Of the 100 coral and water samples collected, 40 contained genetic material from one or more human enteric viruses. DNA-based adenoviruses were detected widely, in 37.8% of samples and at 91% of stations, including ‘pristine’ reefs in the Dry Tortugas; however, the detection rate was 12% for the RNA-based enteroviruses and noroviruses (hepatitis A virus was never detected). The disparity between the prevalence of RNA- and DNA-based viruses suggests the need for additional work to determine the utility of adenovirus as marker of human sewage.     

Composite spectra Paper 15: HD 216572, a triple system containing a short-period, double-lined secondary

We analyse 81 optical spectra of the composite-spectrum binary HD 216572, and show that the primary is a cool giant of type G8 III while the secondary is a double-lined binary consisting of two nearly identical B9 dwarfs in a 1.18-d orbit. The inner system undergoes partial eclipses, whose photometry we model to derive the physical parameters of both secondary stars. The outer system does not eclipse. We isolate the combined spectrum of the secondary by spectral subtraction, and from 48 separate radial-velocity measurements of both secondary components we obtain a triple-lined orbit solution from which we determine the individual masses of all three stars and the inclinations of both the inner and the outer orbits. The period of the outer system is 55 d, which is surprisingly short for a giant star, and our detection of small but non-negligible amounts of variable chromospheric emission in the Ca  ii K line is not unlike that detected in other systems with comparably short periods. The secondary components are in a circular orbit and are rotating at about  95 ± 10 km s⁻¹  ; although their surface-to-surface separation is only  4 R_⊙  the stars are not noticeably distorted geometrically by such close proximity. All three stars appear to be in synchronous rotation in their respective orbits. We derive fairly accurate Hertzsprung–Russell diagram positions for all three stars and compare them to evolutionary tracks calculated for the respective stellar masses, but cannot reconcile the age of the cool giant with that of the B stars.     

Kimberlitic sources of super-deep diamonds in the Juina area,Mato Grosso State,Brazil

The Juina diamond field, in the 1970–80s, was producing up to 5–6 million carats per year from rich placer deposits, but no economic primary deposits had been found in the area. In 2006–2007, Diagem Inc. discovered a group of diamondiferous kimberlitic pipes within the Chapadão Plateau (Chapadão, or Pandrea cluster), at the head of a drainage system which has produced most of the alluvial diamonds mined in the Juina area. Diamonds from placer deposits and newly discovered kimberlites are identical; they have super-deep origins from the upper-mantle and transition zone. Field observations and petrographic studies have identified crater-facies kimberlitic material at seven separate localities. Kimberlitic material is represented by tuffs, tuffisites and various epiclastic sediments containing chrome spinel, picroilmenite, manganoan ilmenite, zircon and diamond. The diamond grade varies from 0.2–1.8 ct/m³. Chrome spinel has 30–61 wt.% Cr₂O₃. Picroilmenite contains 6–14 wt.% MgO and 0.2–4 wt.% Cr₂O₃. Manganoan ilmenite has less than 3 wt.% MgO and 0.38–1.41 wt.% MnO. The ¹⁷⁶Hf/¹⁷⁷Hf ratio in kimberlitic zircons is 0.028288–0.28295 with ε_Hf = 5.9–8.3, and lies on the average kimberlite trend between depleted mantle and CHUR. The previously known barren and weakly diamondiferous kimberlites in the Juina area have ages of 79–80 Ma. In contrast, zircons from the newly discovered Chapadão kimberlites have a mean ²⁰⁶Pb/²³⁸U age of 93.6 ± 0.4 Ma, corresponding to a time of magmatic activity related to the opening of the southern part of the Atlantic Ocean. The most likely mechanism of the origin of kimberlitic magma is super-deep subduction process that initiated partial melting of zones in lower mantle with subsequent ascent of proto-kimberlitic magma.     

The first results of U/Pb dating and isotope geochemical studies of detrital zircons from the neoproterozoic sandstones of the Southern Timan (Djejim-Parma Hill)

This report presents the first results of U/Pb dating, isotope-geochemical, and geochemical studies of detrital zircons from the Neoproterozoic clastic rocks of the Southern Timan. Sixty-one zircon grains were treated, including 51 from red-colored sandstones and 10 grains from aleurosandstones of the Djejim Formation of the southern Chetlas-Djejim zone (Djejim-Parma Hill). It was found that the U/Pb-ages of zircons from the rocks of the Djejim Formation, varied from ∼2.97 to ∼1.20 Ga. The studies of microelement composition in 47 grains (of 61 U/Pb isotope ages obtained), on the basis of several empirical regularities found formerly, show that the detrital zircons had originated from “granites” (22 grains), “diorites” (12 grains), or their volcanic analogues, or more rarely, from “syenites” and “basites” (5 and 8 grains, respectively). The Lu/Hf isotope system of zircons allows one to estimate the model ages (T _DM^C) of the substrate magmatic rocks being parental to the zircons considered. In particular, Archean zircons are characterized by ∼2.84–3.36 Ga model ages of magmaforming rocks. For some of the grains, their model ages (∼2.84 Ga) are close to those of zircons as such (∼2.7–2.8 Ga), which points to the juvenile character of the substrate from which the parent magma of the zircons treated was fused. For Proterozoic (to Middle Riphean) zircons, the Lu/Hf isotope system allows one to estimate the model age of the substrate of their parental rocks within ∼2.00–3.36 Ga, which shows that these rocks were formed under the recycling of the Archean and Early-Proterozoic crust. The ages obtained for detrital zircons, as well as model ages of the substrate of the corresponding parental magmatic rocks, are quite comparable to the age of crystalline complexes of the ancient framework of the East European Platform (EEP), formed in the course of the Archean, Early-Proterozoic, and Early-Middle Riphean tectonomagmatic events. This permits us to conclude that the Neoproterozoic detrital complexes of the Timan were formed owing to the erosion of earlier Neoproterozoic and Early Precambrian complexes constituting the Neoproterozoic Baltica continent, presenting complexes of the passive margin of this continent. A variety of ages of detrital zircons from sandstones and aleurosandstones from the Djejim Formation of Djejim-Parma Hill, and of the estimates of magmatic rocks parental to these zircons, may be characterized as a Baltic Provenance signal.     

In-situ hafnium and lead isotope analyses of detrital zircons from the Devonian sedimentary basin of NE Greenland: a record of repeated crustal reworking

An intramontane collapse basin developed within the hanging wall above the large-scale extensional Fjord Regional Detachment of NE Greenland in middle to late Devonian times. The continental clastic sediments within the basin are derived locally from Laurentian source rocks, which makes them well suited for a study of the crustal evolution of the source terrain. This is the first integrated in-situ Pb and Hf isotope study to be presented, and zircon data on a selected sandstone from the basin are combined with Sm-Nd whole-rock data on sand/siltstones. Nd whole-rock ages of two samples of sandstones and a siltstone are 2.0-2.1 Ga. Peak frequencies of zircon ²⁰⁷Pb/²⁰⁶Pb ages at 1,764-1,912 Ma, and ¹⁷⁶Hf/¹⁷⁷Hf values at 0.28142-0.28163 (t_DM=2.47 to 2.06) for the sandstone suggest the generation of a considerable volume of juvenile continental crust in the ultimate zircon provenance at 1.9-2.0 Ga. The Hf isotopic compositions of Archaean zircons in the sandstone are distinct from those of the source materials of Proterozoic protocrust at 1.9-2.0 Ga, but zircons with elevated Hf-t_DM ages of up to 2.47 Ga can be related to a component of Archaean crust or reworked Archaean material in the ultimate zircon source area. Zircon ²⁰⁷Pb/²⁰⁶Pb ages are also recorded at 1,480-1,572, 1,318 and 1,014 Ma (Grenvillian). The Hf isotope compositions of these zircons are consistent with reworking of the Proterozoic protocrust at these times, with little or no juvenile input. The Proterozoic zircons form two distinct groups defined by ¹⁷⁶Yb/¹⁷⁷Hf>0.05055 and ¹⁷⁶Yb/¹⁷⁷Hf<0.03301, and the latter group overlaps with Yb-Hf isotope data on the Archaean zircons. The two groups may represent zircons derived from evolved granites and intermediate to mildly felsic rocks, respectively. The repeated reworking of the continental crust also comprised erosion and deposition of sediments in the Proterozoic (the Krummedal sequence and the Eleonore Bay Supergroup, EBS) and intrusion of Caledonian anatectic granites in the EBS, which both represent provenance components to the Devonian sediments. No discrete Caledonian Pb-Pb zircon ages are recorded, but Caledonian magmatism may be represented by strongly discordant zircons which form arrays with a lower intercept age at ca. 400 Ma and an upper intercept at 1,600-2,000 Ma. One undated zircon records a ¹⁷⁶Hf/¹⁷⁷Hf ratio of 0.282218, higher than that of the Proterozoic protocrust in Caledonian/late-Caledonian times (380-450 Ma) which may represent a Caledonian mantle contribution.     

Petrological implications of some corona structures

Reactions between olivine and plagioclase, and between pyroxenes and plagioclase, commonly produce corona assemblages of lower volume and entropy. These coronas imply that assemblages representative of intermediate-and high-pressure granulite facies, and of eclogite facies (emphacite + garnet), can be produced by the cooling of dry olivine + plagioclase and pyroxene + plagioclase assemblages from igneous temperatures within the continental crust. They further imply that eclogite is a stable assemblage within the deeper parts of the continental crust; this in turn requires that dP/dT > 0 for the equilibrium curves for the relevant reactions. The general relations between T and rates of nucleation, growth and diffusion suggest that these coronas will only be formed in relatively deep-seated rocks (P > 6 kb ?). The formation of such coronasby regional or contact metamorphism, or by metasomatism, is unlikely; they are best regarded as retrograde features.     

Zoning in eclogite garnets from Nordfjord,West Norway

Some of the garnets in eclogites within the quartzo-feldspathic gneisses of Nordfjord, West Norway, are zoned with higher calcium, iron and manganese in the cores and more magnesium at the rims. The zoning is discussed in terms of the apparent distribution coefficients of Fe²⁺/Mg between garnet and clinopyroxene (which will be aberrantly high for the garnet cores) and in terms of the metamorphic evolution of the eclogites.Publication nr. 32 in The Norwegian geotraverse project.