Flux and dispersion of gases from the “Drachenschlund” hydrothermal vent at 8°18' S, 13°30' W on the Mid-Atlantic Ridge

Hydrothermal emission of mantle helium appears to be directly related to magma production rate, but other processes can generate methane and hydrogen on mid-ocean ridges. In an on-going effort to characterize these processes in the South Atlantic, the flux and distribution of these gases were investigated in the vicinity of a powerful black smoker recently discovered at 8°17.9' S, 13°30.4' W. The vent lies on the shoulder of an oblique offset in the Mid-Atlantic Ridge and discharges high concentrations of methane and hydrogen. Measurements during expeditions in 2004 and 2006 show that the ratio of CH₄ to ³He in the neutrally buoyant plume is quite high, 4 × 10⁸. The CTD stations were accompanied by velocity measurements with lowered acoustic Doppler current profilers (LADCP), and from these data we estimate the methane transport to have been 0.5 mol s^− 1 in a WSW-trending plume that seems to develop during the ebb tidal phase. This transport is an order of magnitude greater than the source of CH₄ calculated from its concentration in the vent fluid and the rise height of the plume. From this range of methane fluxes, the source of ³He is estimated to be between 0.14 and 1.2 nmol s^− 1. In either case, the ³He source is significantly lower than expected from the spreading rate of the Mid-Atlantic Ridge. From the inventory of methane in the rift valley adjacent to the vent, it appears that the average specific rate of oxidation is 2.6 to 23 yr^− 1, corresponding to a turnover time between 140 and 16 days. Vertical profiles of methane in the surrounding region often exhibited Gaussian-like distributions, and the variances appear to increase with distance from the vent. Using a Gaussian plume model, we obtained a range of vertical eddy diffusivities between 0.009 and 0.08 m²m² s^− 1. These high values may be due to tidally driven internal waves across the promontory on which the vent is located.     

Seasonal changes in imposex and tissue burden of butyltin compounds in Thais clavigera populations along the coastal area of Mirs Bay, China

We assessed the current status of tributyltin (TBT) contamination of Thais clavigera (Gastropoda) along the coastal area of Mirs Bay, China for the first time. The snail samples were collected from 10 different sites in the summer (June) and winter (December) of 2006, respectively. They were analyzed for imposex status, i.e. relative penis size index (RPSI) and vas deferens sequence index (VDSI), followed by quantification of butyltins in their tissues. Most of the collected females suffered from imposex, but the level of butyltin contamination varied with the distance from Yantian Port, which is currently the fourth busiest container port in the world. The tissue concentration of TBT varied with season. For a particular site, the winter samples in general contained much higher concentration of TBT than the summer samples. RPSI, VDSI and organotin concentrations were higher in T. clavigera collected from sites closer to the Port, such as the Seafood Street and Kat O. Both RPSI and VDSI were positively correlated with the tissue burden of tributyltin. VDSI exhibited little seasonal variability, whereas RPSI showed marked seasonal variability, with lower values in the summer samples. The current results will serve as an important reference for long-term monitoring of butyltin contamination in this area.     

Electrical structure of the upper mantle beneath Central Europe: Results of the CEMES project

In the years 2001–2003, we accomplished the experimental phase of the project CEMES by collecting long-period magnetotelluric data at positions of eleven permanent geomagnetic observatories situated within few hundreds kilometers along the south-west margin of the East European Craton. Five teams were engaged in estimating independently the magnetotelluric responses by using different data processing procedures. The conductance distributions at the depths of the upper mantle have been derived individually beneath each observatory. By averaging the individual cross-sections, we have designed the final model of the geoelectrical structure of the upper mantle beneath the CEMES region. The results indicate systematic trends in the deep electrical structure of the two European tectonic plates and give evidence that the electrical structure of the upper mantle differs between the East European Craton and the Phanerozoic plate of west Europe, with a separating transition zone that generally coincides with the Trans-European Suture Zone.     

Arguments for ionic nature of the Carpathian electric conductivity anomaly

This publication is a contribution to discussion on the geometry and petrography of the rock complex responsible for the Carpathian conductivity anomaly. We analysed arguments showing that this anomaly is caused by induction in the sedimentary basin, and make a critical review of various data to find out whether the good conductivity is connected with a rock complex containing graphite or mineralized water. We conclude that a more likely mechanism is the ionic one, i.e., the existence of fluids, although a final decision can only be made on the basis of deep drillings.     

Vulnerability and adaptation to climate-related fire impacts in rural and urban interior Alaska

This paper explores whether fundamental differences exist between urban and rural vulnerability to climate-induced changes in the fire regime of interior Alaska. We further examine how communities and fire managers have responded to these changes and what additional adaptations could be put in place. We engage a variety of social science methods, including demographic analysis, semi-structured interviews, surveys, workshops and observations of public meetings. This work is part of an interdisciplinary study of feedback and interactions between climate, vegetation, fire and human components of the Boreal forest social–ecological system of interior Alaska. We have learned that although urban and rural communities in interior Alaska face similar increased exposure to wildfire as a result of climate change, important differences exist in their sensitivity to these biophysical, climate-induced changes. In particular, reliance on wild foods, delayed suppression response, financial resources and institutional connections vary between urban and rural communities. These differences depend largely on social, economic and institutional factors, and are not necessarily related to biophysical climate impacts per se. Fire management and suppression action motivated by political, economic or other pressures can serve as unintentional or indirect adaptation to climate change. However, this indirect response alone may not sufficiently reduce vulnerability to a changing fire regime. More deliberate and strategic responses may be required, given the magnitude of the expected climate change and the likelihood of an intensification of the fire regime in interior Alaska.     

On the way to a better state? The role of NGOs in the planning and implementation of protected areas in Brazil

Protected areas are considered some of the most versatile as well as important instruments of nature conservation and environmental policies. The `classic' model of nature conservation aims at the isolation of large areas in order to preserve their `pristine' nature from human interference. However, the transfer of this model to developing countries led to serious conflicts with local people. From a socio-geographical viewpoint, protected areas can be understood as regulative tools for the shaping and controlling of space. This approach helps to recognise the influence of distinct modes of appropriation of space and nature on the emergence and course of conflicts. In the present article it is used to analyse the leading role played by Brazilian NGOs in the transformation of the classic model of protected area management at the beginning of the nineties. Two case studies – dealing with the implementation of the Amazonian Mamirauá Reserve and with the reform of the Brazilian protected area legislation – are used to illustrate not only the success of the new approaches, but also the expectations and contradictions which surround the future development of protected areas in Brazil.     

Consequences of change and variability in sea ice on marine ecosystem and biogeochemical processes during the 2007–2008 Canadian International Polar Year program

Change and variability in the timing and magnitude of sea ice geophysical and thermodynamic state have consequences on many aspects of the arctic marine system. The changes in both the geophysical and thermodynamic state, and in particular the timing of the development of these states, have consequences throughout the marine system. In this paper we review the ??consequences?? of change in sea ice state on primary productivity, marine mammal habitats, and sea ice as a medium for storage and transport of contaminants and carbon exchange across the ocean-sea-ice-atmosphere interface based upon results from the International Polar Year. Pertinent results include: 1) conditions along ice edges can bring deep nutrient-rich ??pacific?? waters into nutrient-poor surface waters along the arctic coast, affecting local food webs; 2) both sea ice thermodynamic and dynamic processes ultimately affect ringed seal/polar bear habitats by controlling the timing, location and amount of surface deformation required for ringed seal and polar bear preferred habitat 3) the ice edges bordering open waters of flaw leads are areas of high biological production and are observed to be important beluga habitat. 4) exchange of climate-active gases, including CO₂, is extremely active in sea ice environments, and the overall question of whether the Arctic Ocean is (or will be) a source or sink for CO₂ will be dependent on the balance of competing climate-change feedbacks.     

Permafrost occurrence during the Last Permafrost Maximum in the Western Carpathian Mountains of Slovakia as inferred from cryogenic cave carbonate

Coarse crystalline cryogenic cave carbonate (CCC) forms during the slow freezing of standing water pools and represents indirect proof of freezing temperature in the past. The dating by U‐series of CCC deposits from nine caves in the Western Carpathians Mountains of Slovakia suggests that freezing conditions, and possible permafrost conditions, occurred during the Last Permafrost Maximum (LPM, c. 20–18 ka BP). The CCC deposits occur in caves at elevations of between 800 and 1800 m a.s.l. They point to widespread alpine permafrost, the lower limit of discontinuous/sporadic permafrost being approximately 800 m a.s.l. The thickness of permafrost probably varied between 30 and 180 m. In the Vysoké Tatry Mountains at altitudes of ～1800 m a.s.l., one occurrence of CCC suggests that subzero temperatures may have penetrated to a depth of over 285 m.     

The perseids 1995 in Poland

Visual observations of 1995 Perseid meteor stream made by Polish astronomy amateurs are reported. Using this material we obtained new accurate points in the activity profile during maximum. The Zenithal Hourly Rates (ZHRs) for the whole period of activity are presented. We also discuss the magnitude, the colour and the velocity distributions of Perseids.