Meteorological effects on seasonal displacements of the ?knes rockslide, western Norway

In the alpine topography along one of the long fjords with steep and high mountain sides in western Norway the large ?knes rockslide area is defined by a distinct back scarp rising from 800 to 1,000 m a.s.l. In 2004, an extensive monitoring program started, including establishment of a meteorological station above the upper tension crack, 900 m a.s.l. This paper evaluates the significance of meteorological conditions affecting the displacements recorded by five extensometers and two laser sensors in the tension crack from November 2004 to August 2008. Meteorological factors of importance for the recorded activity in the tension crack are found to be melt water in spring and large temperature fluctuations around the freezing point in spring, autumn, and early winter. The records show less acceleration phases in the measured distance across the tension crack in the second half of the analyzed period even though annual displacements are increasing, indicating that other processes, like disintegration of irregularities along unfilled joints and disintegration of intact rock bridges in the sliding plane have become more important.     

Mixed layer depth (MLD) variability in the southern Bay of Biscay. Deepening of winter MLDs concurrent with generalized upper water warming trends?

Mixed layer depth (MLD) variability from seasonal to decadal time scales in the Bay of Biscay is studied in this work. A hydrographic time series running since 1991 in the study area, a climatology of the upper layer vertical structure based on the topology of this temperature profile time series and a one-dimensional water column model have been used for this purpose. The prevailing factors driving MLD variability have been determined with detail, and agreement with observations is achieved. Tests carried out to investigate climatological profile skill to reproduce the upper layer temporal evolution have demonstrated its ability to simulate variability at seasonal time scales and reproduce the most conspicuous events observed. This has enabled us to carry out a reconstruction of the MLD variability for the last 60 years in the study area. Favourable sequence of intense mixing events explains interannual differences and cases of extraordinary deepening of winter mixed layer. The negative phase of the Eastern Atlantic pattern seems to determine important interannual variability through intense episodes of cooling and mixing as in winter 2005 in the Bay of Biscay. Low-frequency variability is also observed. A very striking and unexpected shallower winter MLD during the 1970s and 1980s than those observed from 1995 has been found. Simulation results support this counter-intuitive outcome of shallower winter mixed layers concurrent with generalized upper water warming trends reported on several occasions for the area. The long-term trends in MLD seem related with decadal variability in the North Atlantic Oscillation, being in phase and opposition with other deepening-shallowing cycles found from subtropical-to-subpolar areas in the North Atlantic.     

Dynamical parameter analysis of continuous seismic signals of Popocatépetl volcano (Central Mexico): A case of tectonic earthquakes influencing volcanic activity

The continuous background seismic activity contains information on the internal state of a volcanic system. Here, we report the influence of major regional tectonic earthquakes (M > 5 in most cases) on such state, reflected as changes in the spectral and dynamical parameters of the volcano continuous seismic data. Although changes do not always occur, analysis of five cases of earthquake-induced variations in the signals recorded at Popocatépetl volcano in central México reveal significant fluctuations following the tectonic earthquakes. External visible volcanic activity, such as small to moderate explosions and ash emissions, were related to those fluctuations. We briefly discuss possible causes of the variations. We conclude that recognition of fluctuations in the dynamical parameters in volcano monitoring seismic signals after tectonic earthquakes, even those located in the far field, hundreds of kilometers away, may provide an additional criterion for eruption forecasting, and for decision making in the definition of volcanic alert levels.     

Geochemical mobility of arsenic in the surficial waters from Argentina

The presence of arsenic (As) in surface water constitutes an important environmental risk, where mobility and adsorption processes are responsible for its behavior in the sediment–water interface. Therefore, the assessment of adsorption, mobility and water availability of arsenic in freshwater sediments, with agricultural, livestock and urban soil uses was performed. Arsenic concentrations in sediments ranged from 5.4 to 15.9 mg kg^?1 (total) and 2.8 to 6.5 mg kg^?1 (labile), and those of iron and manganese were 11,563–23,500 and 140.6–662.1 mg kg^?1, respectively. The As levels in water were significantly lower than those of sediments. Results would suggest that As co-precipitation and adsorption on Fe oxides are probably the major route of immobilization, determining its low lability. Manganese did not present an outstanding contribution to the retention, and cation-exchange capacity, pH and organic matter of sediments did not show an influence on the mobility of As.     

Glacial and periglacial floodplain sediments regulate hydrologic transfer of reactive iron to a high arctic fjord

The transport of reactive iron (i.e. colloidal and dissolved) by a glacier‐fed stream system draining a high relief periglacial landscape in the high Arctic archipelago of Svalbard is described. A negative, non‐linear relationship between discharge and iron concentration is found, indicative of increased iron acquisition along baseflow pathways. Because the glaciers are cold‐based and there are no intra‐ or sub‐permafrost groundwater springs, baseflow is principally supplied by the active layer and the colluvial and alluvial sediments in the lower valley. Collectively, these environments increase the flux of iron in the stream by 40% over a floodplain length of just 8 km, resulting in 6 kg Fe km^?2a^?1 of reactive iron export for a 20% glacierized watershed. We show that pyrite oxidation in shallow‐groundwater flowpaths of the floodplain is the most important source of reactive iron, although it is far less influential in the upper parts of the catchment where other sources are significant (including ironstone and secondary oxide coatings). Microbial catalysis of the pyrite oxidation occurs in the floodplain, enabling rapid, hyporheic water exchange to enhance the iron fluxes at high discharge and cause the non‐linear relationship between discharge and reactive iron concentrations. Furthermore, because the pyrite oxidation is tightly coupled to carbonate and silicate mineral weathering, other nutrients such as base cations and silica are also released to the stream system. Our work therefore shows that high Arctic floodplains should be regarded as critically important regulators of terrestrial nutrient fluxes to coastal ecosystems from glacial and periglacial sources. Copyright © 2015 John Wiley & Sons, Ltd.     

Solar influence and hydrological variability during the Holocene from a speleothem annual record (Molinos Cave,NE Spain)

We present a multi‐proxy approach to reconstructing Holocene climate conditions in northeastern Spain based on an excellent correlation among the lamina thickness, colour parameters and isotope (δ¹⁸O and δ¹³C) variations recorded in a speleothem. An age model constructed from five U/Th dates and annual lamina counting suggests that the uppermost 14.7 cm of the MO‐7 stalagmite grew between 7.2 and 2.5 ka before present but experienced a growth hiatus from 4.9 to 4.3 ka. Three spectral analysis methods were applied to 11 time series. The results reveal common solar periodicities on decennial (Gleissberg cycle) and centennial (De Vries‐Suess cycle) scales. The onset of Holocene carbonate precipitation in the MO‐7 stalagmite appears to be associated with a cold, wet period, whereas the hiatus and the end of growth are related to warm, dry periods. This environmental trend fits well within the regional Holocene climate.     

Possible interaction between tectonic events and seismic noise at Las Cañadas Volcanic Caldera,Tenerife, Spain

Continuous seismic noise is recorded in the volcanic island of Tenerife (Canary Islands, Spain). The origin of this noise, strongly augmented by anthropogenic contamination, is still under debate. In this paper, we discuss the relationship between this noise and the occurrence of local tectonic events in the same area. In particular, transitions are sought in the time evolution of dynamic parameters computed on the seismic noise, and examples are shown where abrupt transitions may be associated with the occurrence of tectonic events. These transitions provide further evidence of the existence of a natural origin for at least part of the seismic noise, which is strongly contaminated—if not dominated—by anthropogenic sources.     

Contrasting perspectives on mangroves in arid Northwestern Mexico: Implications for integrated coastal management

Mangroves in Northwestern Mexico are vital to maintain coastal environments healthy, to provide nutrients for several food chains, and to supply valuable goods and services that sustain and improve human livelihoods. Many of these values offer a range of opportunities for economic development that attract workers, investors and developers. Recently, federal privatization policies have promoted an accelerated coastal development of this region to obtain large profits in short times, creating competing and overlapping interests to use coastal environments and control key resources. Such intense developments are modifying the ecological conditions of many coastal areas, threatening the provision of important ecosystem services to society. After years of centralized decisions, new paradigms are needed to achieve a coastal management that ensures long-term ecosystem maintenance, fair resource use and social equity. Recognizing the multiplicity of actors involved in coastal management and using a qualitative research methodology, we identified and explored the perspectives of different key stakeholders in the states of Baja California Sur and Sonora, Mexico, to better understand their views on mangroves use and management as well as the interaction among them. We discuss similarities and/or discrepancies found among stakeholders’ perceptions by describing their central ideas and identifying overlapping interests that may create conflicts when defining development and conservation programs or formulating policies. This information also intends to encourage further research on the social-ecological system of the coasts in Northwestern Mexico and to contribute to address coastal management issues in integrated ways that consider the social dimension through documenting stakeholders’ narratives in the future.     

The first high-amplitude δ Scuti star in an eclipsing binary system

Consider radar ranging of a distant galaxy in a Friedman–Lemaître cosmological model. In this model the comoving coordinate of the galaxy is constant; hence, the equations of null geodesics for photons travelling to the distant galaxy and back imply Here, τ_e, τ_r and τ_o are, respectively, the times of emission, reflection and observation of the reflected photons, and a (τ) is the scalefactor. Since the Universe is expanding, a (τ) is a monotonically increasing function, so the return traveltime, τ_o−τ_r, must be greater than the forward traveltime, τ_r−τ_e. Clearly, space expands, and on their way back, the photons must travel a longer distance! This paper explains why this argument for the Expansion of Space (EoS) is wrong. We argue that, unlike the expansion of the cosmic substratum, the EoS is unobservable. We therefore propose to apply to it – just like to the ether – Ockham's razor.