Bioindicative potential of shell abnormalities occurring in the clam Macoma balthica (L.) from the Baltic Sea

This study reports the occurrence of shell deformities in the Baltic clam Macoma balthica from the Northern Baltic Sea (Trösa Archipelago, Sweden). The functional significance and the bioindicative potential of observed exoskeleton’ anomalies was assessed using a suite of physiological and morphological biomarkers.Analyzed shell deformations (SD) included damages of the dorsal margin visible as shell excavations, destruction of the beak, umbo and hinge ligament and decreased shell’ transparency. Deformed clams exhibited worse physiological conditions and increased frequency of micronuclei. Skewed sex ratio towards male domination was observed in all studied populations. Spatial differences in the occurrence of deformed clams are reported, with more than 50% of deformed clams inhabiting polluted locations and 8% the reference station. These results are encouraging for the use of described SDs as initial and cost effective indicators of environmental health.     

Protomylonite evolution potentially revealed by the 3D depiction and fractal analysis of chemical data from a feldspar

Tourmalinization associated with peraluminous granitic intrusions in metapelitic host-rocks has been widely recorded in the Iberian Peninsula, given the importance of tourmaline as a tracer of granite magma evolution and potential indicator of Sn-W mineralizations. In the Penamacor-Monsanto granite pluton (Central Eastern Portugal, Central Iberian Zone), tourmaline occurs: (1) as accessory phase in two-mica granitic rocks, muscovite-granites and aplites, (2) in quartz (±mica)-tourmaline rocks (tourmalinites) in several exocontact locations, and (3) as a rare detrital phase in contact zone hornfels and metapelitic host-rocks. Electron microprobe and stable isotope (δ¹⁸O, δD, δ¹¹B) data provide clear distinctions between tourmaline populations from these different settings: (a) schorl–oxyschorl tourmalines from granitic rocks have variable foititic component (^X□ = 17–57 %) and Mg/(Mg + Fe) ratios (0.19–0.50 in two-mica granitic rocks, and 0.05–0.19 in the more differentiated muscovite-granite and aplites); granitic tourmalines have constant δ¹⁸O values (12.1 ± 0.1 ‰), with wider-ranging δD (?78.2 ± 4.7 ‰) and δ¹¹B (?10.7 to ?9.0 ‰) values; (b) vein/breccia oxyschorl [Mg/(Mg + Fe) = 0.31–0.44] results from late, B- and Fe-enriched magma-derived fluids and is characterized by δ¹⁸O = 12.4 ‰, δD = ?29.5 ‰, and δ¹¹B = ?9.3 ‰, while replacement tourmalines have more dravitic compositions [Mg/(Mg + Fe) = 0.26–0.64], close to that of detrital tourmaline in the surrounding metapelitic rocks, and yield relatively constant δ¹⁸O values (13.1–13.3 ‰), though wider-ranging δD (?58.5 to ?36.5 ‰) and δ¹¹B (?10.2 to ?8.8 ‰) values; and (c) detrital tourmaline in contact rocks and regional host metasediments is mainly dravite [Mg/(Mg + Fe) = 0.35–0.78] and oxydravite [Mg/(Mg + Fe) = 0.51–0.58], respectively. Boron contents of the granitic rocks are low (<650 ppm) compared to the minimum B contents normally required for tourmaline saturation in granitic melts, implying loss of B and other volatiles to the surrounding host-rocks during the late-magmatic stages. This process was responsible for tourmalinization at the exocontact of the Penamacor-Monsanto pluton, either as direct tourmaline precipitation in cavities and fractures crossing the pluton margin (vein/breccia tourmalinites), or as replacement of mafic minerals (chlorite or biotite) in the host-rocks (replacement tourmalinites) along the exocontact of the granite. Thermometry based on ¹⁸O equilibrium fractionation between tourmaline and fluid indicates that a late, B-enriched magmatic aqueous fluid (av. δ¹⁸O ~12.1 ‰, at ~600 °C) precipitated the vein/breccia tourmaline (δ¹⁸O ~12.4 ‰) at ~500–550 °C, and later interacted with the cooler surrounding host-rocks to produce tourmaline at lower temperatures (400–450 °C), and an average δ¹⁸O ~13.2 ‰, closer to the values for the host-rock. Although B-metasomatism associated with some granitic plutons in the Iberian Peninsula seems to be relatively confined in space, extending integrated studies such as this to a larger number of granitic plutons may afford us a better understanding of Variscan magmatism and related mineralizations.     

Estimating Flood Quantiles on the Basis of Multi-Event Rainfall Simulation — Case Study

This paper presents an approach to estimating the probability distribution of annual discharges Q based on rainfall-runoff modelling using multiple rainfall events. The approach is based on the prior knowledge about the probability distribution of annual maximum daily totals of rainfall P in a natural catchment, random disaggregation of the totals into hourly values, and rainfall-runoff modelling. The presented Multi-Event Simulation of Extreme Flood method (MESEF) combines design event method based on single-rainfall event modelling, and continuous simulation method used for estimating the maximum discharges of a given exceedance probability using rainfall-runoff models. In the paper, the flood quantiles were estimated using the MESEF method, and then compared to the flood quantiles estimated using classical statistical method based on observed data.     

Magnetic mineralogy and paleomagnetism of serpentinized ultramafic rocks from the Braszowice-Brzeźnica fragment of sudetic paleozoic ophiolite

Complex paleomagnetic, rock-magnetic and mineralogical studies were performed on serpentinized utramafic rocks from Braszowice-Brze?nica massif (BB) situated at the southern extremity of the Niemcza Shear Zone, close to the Sudetic Marginal Fault. Studies of magnetic minerals revealed presence of several varieties of magnetite grains, and partly altered Cr-spinels. Paleomagnetic studies revealed stable component HS of natural remanence carried by magnetite formed probably during the initial serpentinization. The directions of HS have good grouping within each locality, but differ between localities. Studies of anisotropy of magnetic susceptibility (AMS) have shown that directions of anisotropy axes are steep instead of horizontal as is common within the Niemcza Shear Zone. Taking advantage of the directions of AMS we rotated the directions of HS and brought them to the reference direction for the Sudetes for 372 Ma. We suggest that after acquiring AMS and HS during the Upper Devonian, the BB became divided into multiple units due to tectonic activity in the region.     

Impact of climate change on zooplankton communities, seabird populations and arctic terrestrial ecosystem—A scenario

Many arctic terrestrial ecosystems suffer from a permanent deficiency of nutrients. Marine birds that forage at sea and breed on land can transport organic matter from the sea to land, and thus help to initiate and sustain terrestrial ecosystems. This organic matter initiates the emergence of local tundra communities, increasing primary and secondary production and species diversity. Climate change will influence ocean circulation and the hydrologic regime, which will consequently lead to a restructuring of zooplankton communities between cold arctic waters, with a dominance of large zooplankton species, and Atlantic waters in which small species predominate. The dominance of large zooplankton favours plankton-eating seabirds, such as the little auk (Alle alle), while the presence of small zooplankton redirects the food chain to plankton-eating fish, up through to fish-eating birds (e.g., guillemots Uria sp.). Thus, in regions where the two water masses compete for dominance, such as in the Barents Sea, plankton-eating birds should dominate the avifauna in cold periods and recess in warmer periods, when fish-eaters should prevail. Therefore under future anthropogenic climate scenarios, there could be serious consequences for the structure and functioning of the terrestrial part of arctic ecosystems, due in part to changes in the arctic marine avifauna. Large colonies of plankton-eating little auks are located on mild mountain slopes, usually a few kilometres from the shore, whereas colonies of fish-eating guillemots are situated on rocky cliffs at the coast. The impact of guillemots on the terrestrial ecosystems is therefore much smaller than for little auks because of the rapid washing-out to sea of the guano deposited on the seabird cliffs. These characteristics of seabird nesting sites dramatically limit the range of occurrence of ornithogenic soils, and the accompanying flora and fauna, to locations where talus-breeding species occur. As a result of climate warming favoring the increase of ichthyiofagous cliff-nesting seabirds, we can expect that large areas of ornithogenic tundra around the colonies of plankton-eating seabirds situated far from the sea may disappear, while areas of tundra in the vicinity of cliffs inhabited by fish-eating seabirds, with low total production and supporting few large herbivores, will likely increase, but only imperceptibly. This may lead to habitat fragmentation with negative consequences for populations of tundra-dependent birds and mammals, and the possibility of a substantial decrease in biodiversity of tundra plant and animal communities.     

Plumbotectonic aspects of polymetallic vein mineralization in Paleozoic sediments and Proterozoic basement of Moravia (Czech Republic)

A regional isotopic study of Pb and S in hydrothermal galenas and U–Pb and S in potential source rocks was carried out for part of Moravia, Czech Republic. Two major generations of veins, (syn-) Variscan and post-Variscan, are defined based on the Pb-isotope system together with structural constraints (local structures and regional trends). The Pb-isotopic compositions of galena plot in two distinct populations with outliers in ²⁰⁶Pb/²⁰⁴Pb–²⁰⁷Pb/²⁰⁴Pb space. Galena from veins hosted in greywackes provides a cluster with the lowest Pb–Pb ratios: ²⁰⁶Pb/²⁰⁴Pb = 18.15–18.27, ²⁰⁷Pb/²⁰⁴Pb = 15.59–15.61, ²⁰⁸Pb/²⁰⁴Pb = 38.11–38.23. Those hosted in both limestones and greywackes provide the second cluster: ²⁰⁶Pb/²⁰⁴Pb = 18.37–18.44, ²⁰⁷Pb/²⁰⁴Pb = 15.60–15.63, ²⁰⁸Pb/²⁰⁴Pb = 38.14–38.32. These clusters suggest model Pb ages as Early Carboniferous and Triassic–Jurassic, the latter associated with MVT-like deposits. Two samples from veins hosted in Proterozoic rocks lie outside the two clusters: in metagranitoid (²⁰⁶Pb/²⁰⁴Pb = 18.55, ²⁰⁷Pb/²⁰⁴Pb = 15.64, ²⁰⁸Pb/²⁰⁴Pb = 38.29) and in orthogneiss (²⁰⁶Pb/²⁰⁴Pb = 18.79, ²⁰⁷Pb/²⁰⁴Pb = 15.73, ²⁰⁸Pb/²⁰⁴Pb = 38.54). The results from these two samples suggest an interaction of mineralizing fluids with the radiogenic Pb-rich source (basement?). The values of δ³⁴S suggest the Paleozoic host rocks (mostly ?6.7 to +5.2‰ CDT) as the source of S for hydrothermal sulfides (mostly ?4.8 to +2.5‰ CDT). U–Pb data and Pb isotope evolutionary curves indicate that Late Devonian and Early Carboniferous sediments, especially siliciclastics, are the general dominant contributor of Pb for galena mineralization developed in sedimentary rocks. Plumbotectonic mixing occurred, it is deduced, only between the lower and the upper crust (the latter involving Proterozoic basement containing heterogeneous radiogenic Pb), without any significant input from the mantle. It is concluded that in the Moravo–Silesian and Rhenohercynian zones (including proximal districts in Poland) lead and sulfur have been mobilized from the adjacent rocks during multiple hydrothermal events in processes that are remarkably comparable in timing, geochemistry of fluids and nature of sources.     

Aluminium in glacial meltwater demonstrates an association with nutrient export (Werenskiöldbreen,Svalbard)

The aluminium (Al) cycle in glacierised basins has not received a great deal of attention in studies of biogeochemical cycles. As Al may be toxic for biota, it is important to investigate the processes leading to its release into the environment. It has not yet been ascertained whether filterable Al (passing through a pore size of 0.45 μm) is incorporated into biogeochemical cycles in glacierised basins. Our study aims to determine the relationship between the processes bringing filterable Al and glacier‐derived filterable nutrients (particularly Fe and Si) into glacierised basins. We investigated the Werenskiöldbreen basin (44.1 km², 60% glacierised) situated in SW Spitsbergen, Svalbard. In 2011, we collected meltwater from a subglacial portal at the glacier front and at a downstream hydrometric station throughout the ablation season. The Al concentration, unchanged between the subglacial system and proglacial zone, reveals that aluminosilicate weathering is a dominant source of filterable Al under subglacial conditions. By examining the Al:Fe ratio compared with pH and the sulphate mass fraction index, we found that the proton source for subglacial aluminosilicate weathering is mainly associated with sulphide oxidation and, to a lesser degree, with hydrolysis and carbonation. In subglacial outflows and in the glacial river, Al and Fe are primarily in the forms of Al(OH)₄^‐ and Fe(OH)₃. The annual filterable Al yield (2.7 mmol m^‐2) was of a magnitude similar to that of nutrients such as filterable Fe (3.0 mmol m^‐2) and lower than that of dissolved Si (18.5 mmol m^‐2). Our results show that filterable Al concentrations in meltwater are significantly correlated to filterable and dissolved glacier‐derived nutrients (Fe and Si, respectively) concentrations in glaciers worldwide. We conclude that a potential bioavailable Al pool derived from glacierised basins may be incorporated in biogeochemical cycles, as it is strongly related to the concentrations and yields of glacier‐derived nutrients.     

Seasonal and annual variability of days with strong winds and wind damage in Krakow (Poland) during the period 2000�C2007

The study analyses the numbers of days with strong winds in Krakow during the period 2000?C2007 using anemometric records and fire department data. Patterns are identified in the seasonal and annual variation of strong winds. Particular attention is devoted to extreme events. Based on measurements, the study finds that strong winds mostly occurred in winter. Fire department call-out data show that repair of damage caused by strong winds and gusts of wind was needed equally as frequently in summertime. Strong winds accompanying summer storms are often of a local nature and are not always recorded by weather stations. Wind damage was mapped using requests for fire department assistance.