Water chemistry and hydrometeorology in a glacierized catchment in the Polar Urals,Russia

This study aims to determine the relationships between local meteorological conditions,proglacial river discharge and biogeochemical processes operating in a periglacial basin located in the Polar Ural mountain range, Russia. Fieldwork was conducted in the catchment of Obruchev Glacier(13 km2) during the summer peak flow period in 2008. River discharge was dominated by snowmelt and changed from 3300 l s-1 to less than 1000 l s-1. The mean daily air temperatures of stations situated in the mountain tundra and near Obruchev Glacier from July 11 th to August 1st 2008 were 14.4°C and 10.3°C, respectively. The glacial river had low total dissolved solids varying from 4.5 to 9 mg l-1 and coefficients of correlation between Na+ and Cl-, K+ and Cl-, as well as NH4+ and Cl- were 0.94, 0.90 and 0.84, respectively. Rainfall events affected the snowmelt initiation and provided an essential part of the discharge during the intense snowmelt period, which occurred from July 11 th to July 18 th 2008. Data showed that Na+ and K+ in the surface water derived from snowmelt rather than chemical weathering of silicates. Also, it was obtained that NO3- derived from the melting snowpack, whereas ammonification occurring under the snowpacks was the primary source for NH4+.     

Short and medium term dynamics of the carbon exchange between the Baltic Sea and the North Sea

A detailed analysis of the short and medium term dynamics of the carbon exchange between the Baltic Sea and the North Sea is presented. To quantify the carbon fluxes distinguishing the Baltic and North Sea water masses, the salinity-based End Members (EM) method was successfully applied. The results of 0.63±0.25×10¹² mol C year⁻¹ identify the Baltic Sea as a net source of carbon for the North Sea. Dissolved organic carbon (DOC) was found to contribute significantly (22%) to the bulk of exported carbon. The levels determined suggest the hydrology-dependence of the carbon fluxes in the Danish Straits, which stimulates the high variability of carbon fluxes at both interseasonal and interannual scales.     

Evolution of the East Philippine Arc: experimental constraints on magmatic phase relations and adakitic melt formation

Piston-cylinder experiments on a Pleistocene adakite from Mindanao in the Philippines have been used to establish near-liquidus and sub-liquidus phase relationships relevant to conditions in the East Philippines subduction zone. The experimental starting material belongs to a consanguineous suite of adakitic andesites. Experiments were conducted at pressures from 0.5 to 2 GPa and temperatures from 950 to 1,150°C. With 5 wt. % of dissolved H₂O in the starting mix, garnet, clinopyroxene and orthopyroxene are liquidus phases at pressures above 1.5 GPa, whereas clinopyroxene and orthopyroxene are liquidus (or near-liquidus) phases at pressures <1.5 GPa. Although amphibole is not a liquidus phase under any of the conditions examined, it is stable under sub-liquidus conditions at temperature ≤1,050°C and pressures up to 1.5 GPa. When combined with petrographic observations and bulk rock chemical data for the Mindanao adakites, these findings are consistent with polybaric fractionation that initially involved garnet (at pressures >1.5 GPa) and subsequently involved the lower pressure fractionation of amphibole, plagioclase and subordinate clinopyroxene. Thus, the distinctive Y and HREE depletions of the andesitic adakites (which distinguish them from associated non-adakitic andesites) must be established relatively early in the fractionation process. Our experiments show that this early fractionation must have occurred at pressures >1.5 GPa and, thus, deeper than the Mindanao Moho. Published thermal models of the Philippine Sea Plate preclude a direct origin by melting of the subducting ocean crust. Thus, our results favour a model whereby basaltic arc melt underwent high-pressure crystal fractionation while stalled beneath immature arc lithosphere. This produced residual magma of adakitic character which underwent further fractionation at relatively low (i.e. crustal) pressures before being erupted.     

Gold and copper partitioning in magmatic-hydrothermal systems at 800 °C and 100 MPa

Porphyry-type ore deposits sometimes contain fluid inclusion compositions consistent with the partitioning of copper and gold into vapor relative to coexisting brine at the depositional stage. However, this has not been reproduced experimentally at magmatic conditions. In an attempt to determine the conditions under which copper and gold may partition preferentially into vapor relative to brine at temperatures above the solidus of granitic magmas, we performed experiments at 800 °C, 100 MPa, oxygen fugacity () buffered by Ni-NiO, and fixed at either 3.5 × 10⁻² by using intermediate solid solution-pyrrhotite, or 1.2 × 10⁻⁴ by using intermediate solid solution-pyrrhotite-bornite. The coexisting vapor (∼3 wt.% NaCl eq.) and brine (∼68 wt.% NaCl eq.) were composed initially of NaCl + KCl + HCl + H₂O, with starting HCl set to <1000 μg/g in the aqueous mixture. Synthetic vapor and brine fluid inclusions were trapped at run conditions and subsequently analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Our experiments demonstrate that copper and gold partitioned strongly into the magmatic volatile phase(s) (MVP) (i.e., vapor or brine) relative to a silicate melt over the entire imposed range of . Nernst style partition coefficients between coexisting brine (b) and melt (m), D^b/m (±1σ), range from 3.6(±2.2) × 10¹ to 4(±2) × 10² for copper and from 1.2(±0.6) × 10² to 2.4(±2.4) × 10³ for gold. Partition coefficients between coexisting vapor (v) and melt, D^v/m range from 2.1 ± 0.7 to 18 ± 5 and 7(±3) × 10¹ to 1.6(±1.6) × 10² for copper and gold, respectively. Partition coefficients for all experiments between coexisting brine and vapor, D^b/v (±1σ), range from 7(±2) to 1.0(±0.4) × 10² and 1.7(±0.2) to 15(±2) for copper and gold, respectively. Observed average D^b/v at an of 1.2 × 10⁻⁴ were elevated, 95(±5) and 15 ± 1 for copper and gold, respectively, relative to those at the higher of 3.5 × 10⁻² where D^b/v were 10(±5) for copper and 7(±6) for gold. Thus, there is an inverse relationship between the and the D^b/v for both copper and gold with increasing resulting in a decrease in the D^b/v signifying increased importance of the vapor phase for copper and gold transport. This suggests that copper and gold may complex with volatile S-species as well as Cl-species at magmatic conditions, however, none of the experiments of our study at 800 °C and 100 MPa had a D^b/v ? 1. We did not directly determine speciation, but infer the existence of some metal-sulfur complexes based on the reported data. We suggest that copper and gold partition preferentially into the brine in most instances at or above the wet solidus. However, in most systems, the mass of vapor is greater than the mass of brine, and vapor transport of copper and gold may become more important in the magmatic environment at higher , lower , or near the critical point in a salt-water system. A D^b/v ? 1 at subsolidus hydrothermal conditions may also occur in response to changes in temperature, , , and/or acidity.Additionally, both copper and gold were observed to partition into intermediate solid solution and bornite much more strongly than into vapor, brine or silicate melt. This suggests that, although vapor and brine are both efficient at removing copper and gold from a silicate melt, the presence of Cu-Fe sulfides can sequester a substantial portion of the copper and gold contained within a silicate melt if the Cu-Fe sulfides are abundant.     

The soluble organic compounds of the Bells meteorite: Not a unique or unusual composition

The Bells meteorite is a CM2 chondrite that has long been considered anomalous for having mineralogical and isotopic differences with CMs together with an overall affinity to CIs in its matrix. We extracted a fragment of the only Bells stone collected unweathered with water and solvents and studied the meteorite’s soluble organic composition. We found Bells to contain abundant organic compounds, which are predominantly O-containing such as hydroxy- and di-carboxylic acids, and a scarcity of amino acids and other N-containing compounds. Amines were not detected and ammonia is less abundant than in both the Murchison and Ivuna meteorites. Overall, Bells’ soluble organic composition is more similar to that of Ivuna than of Murchison. The observation that Bells’ amino acid suite shares a distinct distribution of characteristic molecular species with other stones that are thought to have experienced extensive parent body aqueous alteration, such as the Orgueil, Ivuna and recently analyzed GRO 95577 CR1 meteorites, seems to allow the suggestion that such a composition is secondary to prolonged aqueous alteration processes that superseded some of the initial compositional distinctions determined by the asteroidal environments.     

Enzymatic activities in spermatozoa and butyltin concentrations in Baltic turbot (Scophthalmus maximus)

Spermatozoal enzymes of fish (NAD+- and NADP-dependent dehydrogenases and creatine kinase (CK)) were previously determined to be sensitive to tributyltin (TBT) in laboratory experiments and were thus indicated for use as biomarkers for TBT exposure. However, the potential ability of spermatozoal enzymes as biomarkers of TBT exposure has never been recapitulated in a field study. For this purpose, the kinetic activities of spermatozoal enzymes of the natural turbot Scophthalmus maximus population from the Gulf of Gdańsk (GDA) and the Pomeranian Bay (POM) in the southern Baltic Sea were measured. Gas chromatography/high-resolution mass spectrometry was used to determine the concentrations of TBT and its breakdown products, dibutyltin (DBT) and monobutyltin (MBT), in the muscle, liver and testes of the male turbot. Males from GDA had significantly higher enzymatic activities and butyltin (BT) content in tissues than those from POM. A general linear model (GLM) showed that lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PDH) and CK activities increased significantly with BT concentration in the testes and liver. We indicate the potential effects of TBT pollution on the spermatozoal enzymes of Baltic turbot.     

Burial of organic carbon in Holocene sediments of the Zhujiang (Pearl River) and Changjiang (Yangtze River) estuaries

The East Asian marginal seas are important sinks of terrigenous materials transported by large rivers. In this study two cores from the Changjiang (Yangtze River) and Zhujiang (Pearl River) estuaries and one core from the inner shelf off of Hong Kong were investigated to examine the burial of organic matter during the postglacial period and its possible links with paleoenvironmental changes. Based on a simple two end-member mixing model, the terrestrial organic matter supplied primarily from the Zhujiang and Changjiang dominates the estuarine areas while marine organic matter contributes more to the inner-mid shelf. The competing contributions of terrestrial and marine organic matter are responsible for the downcore variations of organic elemental compositions. The overall decreasing shifts of total organic carbon concentrations and total organic carbon to total nitrogen ratios in the Zhujiang estuarine sediments since 6.5 kaBP seems to support the notion that depth profiles of organic matter compositions deposited in the Zhujiang Estuary can aid in the reconstruction of monsoon history in the Holocene. Nevertheless, organic matter compositions in the Changjiang Estuary and inner shelf off of southeastern Hong Kong respond in a different and more complex way to freshwater discharges or precipitation changes (monsoon variability) in the catchments, owing to complex controls of deposition and preservation of organic matter in these estuarine and shelf environments. Caution is therefore needed in using organic elemental and isotopic compositions to decipher paleoenvironmental changes in East Asian continental shelves where intense river–sea interactions occur and sedimentary environments change drastically.     

Volume and mass distribution in selected asteroid families

The main focus of this paper is calculation of the diameters of asteroids belonging to five families (Vesta, Eos, Eunomia, Koronis, and Themis). To do that, we used the HCM algorithm applied for a data set containing 292,003 numbered asteroids, and a numerical procedure for choosing the crucial parameter of the HCM, called “the cutting velocity” v_cut. It was established with a precision as high as 1 m s^?1. Thereafter, we used the WISE (Wide‐field Infrared Survey Explorer) catalog to set a range of albedo for the largest members of each family considered. The albedo data were supported by the data concerning color classification (SDSS MOC4). The asteroids with albedo out of this range were classified as interlopers and were therefore disqualified as family members. Sizes were calculated for the asteroids with albedo within the acceptable range. For the other asteroids (those chosen by means of the HCM, but with albedo not listed in the WISE), the value of albedo of the largest member of the family was adopted. Results are given in a set of figures showing the families on the planes (a, e), (a, i), (e, i). Diameters and volumes of the asteroids that are the individual members of a family were calculated on the basis of their known or assumed albedo and on their absolute magnitude. Volumes of the parent bodies of the families were found on the basis of the cumulative volume distribution of these families. We also studied the secular resonances of the family members. We have shown that the locations of members of the considered asteroid families are related to the lines of secular resonances z₁, z₂, and z₃ with Saturn.