Seismic hazard impact of the Lower Tagus Valley Fault Zone (SW Iberia)

The seismic hazard of SW Iberia is composed of two contributions: offshore, large to very large events on the plate boundary between Africa and Eurasia such as the Lisbon earthquake of 1755 or the Gorringe Bank earthquake of 1969; and onshore, moderate to strong intraplate earthquakes on inherited crustal fractures. One of these zones of crustal weakness is the Lower Tagus Valley (LTV) fault zone, which displays the highest level of seismic hazard in Western Iberia. In this paper we review the active tectonics and seismicity of the LTV, integrating previous geophysical data with recent results of paleoseismological investigations, and discuss its impact on the seismic hazard of SW Iberia. We conclude that the seismic zonation for hazard assessment currently in force in the building code is biased towards the scenario of distant offshore rupture, and does not take adequately into account the LTV seismic source.     

Field-scale Variations in Plant and Grasshopper Communities: A GIS-based Assessment

GIS technology allowed us to examine species-specific occurrence and abundance patterns of important grassland herbivore species through the use of appropriate statistical methods and the superior spatial representation commonly available in existing GIS packages. The study was conducted on a 254 ha grassland area located 10 km south of Three Forks, Gallatin County, Montana, in the Agropyron spicatum province of the western steppe region of the U.S.A. From an ecological perspective, grasshopper species distribution and abundance patterns observed on a local, non-uniform landscape (2.6 km 2) were consistent with results found in other studies at the valley (≈1,400 km 2) and state-level (≈237,000 km 2) scales. Our observations at the local scale further demonstrate the importance of vegetation type and specific local stand physiognomies in structuring grasshopper populations. The application of results from studies conducted at various scales to the development of decision support tools for resource managers is also discussed.     

Fluid seepage along the San Clemente Fault scarp: basin-wide impact on barium cycling

Material fluxes associated with fluid expulsion at cold seeps and their contribution to oceanographic budgets have not been accurately constrained. Here we present evidence that the barium released at cold seeps along the San Clemente Fault zone may significantly impact the geochemical budget of barium within the basin. Barium fluxes at seep localities on the fault scarp, measured with benthic chambers, reach values as high as 5 mmol m⁻² day⁻¹. This is the largest dissolved barium flux measured to date at a cold seep. The discharge of barium-rich fluids results in formation of massive barite deposits along the escarpment wall. The deposits are young (approximately 8 yr) and appear to grow at a minimum rate of 0.2 cm yr⁻¹. This rapid growth rate requires a barium efflux rate that is about two orders of magnitude higher than the measured dissolved flux. We believe that the discrepancy reflects a highly localized seepage system and that chambers positioned as close as possible to the growing chimneys did not sample the foci of fluid discharge. Transport of fine barite particles from the seeps may be responsible for excess rates of barium accumulation throughout the San Clemente Basin, relative to other basins in the California Margin. Based on a preliminary budget, we estimate that cold-seep barite is accumulating at the basin floor in San Clemente at a rate of 2 μmol m⁻² day⁻¹, a value that is comparable to the total barium accumulation rates driven by detrital and biogenic components in neighboring basins. Remobilization of cold-seep barite on the basin floor adds to that driven by the biogenic barium flux and results in benthic barium recycling rates (effluxes) within the San Clemente Basin that are as much as seven times higher than the effluxes from surrounding borderland basins. Our estimates imply that processes associated with fluid seepage along the San Clemente Fault significantly contribute to the basin’s barium cycle. The strontium isotopic composition of the seep barite is significantly different from marine ‘biogenic’ barite, which is known to accurately record seawater composition. In addition, the seep deposits are depleted in ²²⁶Ra relative to their modern biogenic counterparts, and are likely to be a source of radium-depleted particulate barium to the basin. Thus the impact of barite transport from seeps on the San Clemente escarpment to the basin floor might also have implications for the geochemistry of elements other than barium.     

Effect of isolation temperature on the characteristics of extracellular proteases produced by Antarctic bacteria

Protease-producing psychrotolerant bacteria were isolated from Antarctic biotopes on casein agar plates using different incubation temperatures. Most of the isolates were non-spore-forming Gram-negative motile rods with catalase activity, 30% were pigmented and none of them were glucose fermenters. All the strains were grown in liquid cultures at 20°C and protease secretion was tested using the azocasein method. Despite their capacity for production of a clear zone of hydrolysis in agar plates, some strains did not produce detectable levels of proteolytic activity in liquid cultures. The lowest apparent optimum temperature for protease activity found in culture supernatants was 40°C. Almost all the strains showed activation energy values about 10-20 kJ-mol⁻¹ lower than that observed for a mesophilic Subtilisin. Most of the proteases showed optimal activity at neutral or alkaline pH values and developed a multiple-band profile on gelatine-SDS-PAGE. It was observed that the lower the strain isolation temperature was, the more stongly cold-adapted–in terms of optimal temperature and activation energy–were the proteases produced by them. This dependence of the characteristics of the proteases on the isolation temperature is an important factor to take into account in the design of screening programmes directed towards the isolation of psychrotolerant bacteria able to produce proteases strongly or weakly adapted to work in the cold. The Antarctic area explored proved to be a promising source of proteolytic bacteria with potential use in industrial processes to be carried out at low or moderate temperatures.     

Individual and Synergistic Effects of Metronidazole,Amoxicillin, and Ciprofloxacin on Methane Fermentation with Sewage Sludge

Methane fermentation is widely used to dispose of sewage sludge at wastewater treatment plants (WWTPs), due to production of renewable energy in the form of biogas. Antibiotics present in wastewater may accumulate in a sewage sludge. The aim of the present study is to investigate the impact of three antibiotics from different classes in three different doses on methane production from sewage sludge. For this purpose, metronidazole (MET), amoxicillin (AMO), and ciprofloxacin (CIP) are individually added to anaerobic reactors with sewage sludge collected from municipal WWTP. The antibiotics’ highest concentration (1024 mg kg^?1 of AMO; 512 mg kg^?1 of MET and CIP) lowers methane production and methane content in biogas. MET exerts the most marked effect and lowers methane production to 36.8 ± 3.7 mL CH₄ kg^?1 volatile solids. Tested antibiotics probably inhibit methanogenic archaea, which results in volatile fatty acids (VFAs) accumulation. Addition of MET results in accumulation of many kinds of VFAs with the highest concentration of acetic acid (17.52 ± 1.85 g L^?1). The addition of of AMO results in accumulation of butyric acid only (253.00 ± 15.89 g L^?1). However, addition of CIP results in accumulation of mainly acetic acid (7.58 ± 0.82 g L^?1) and isovaleric acid (2.01 ± 0.41 g L^?1). Next, synergistic effect of these antibiotics in a low concentration of 16 mg kg^?1 of AMO, 8 mg kg^?1 of MET, and 2 mg kg^?1 of CIP is measured in semi‐continuous conditions and causes inbibition of methane production and accumulation of VFAs.     

The use of the slope–area function to analyse process domains in complex badland landscapes

This paper explores the effectiveness of the widely-used functional relationship between drainage area (A in m²) and slope (S in m/m) to identify local process domains and aid interpretation of process interactions in a complex badland landscape. In order to perform this investigation, a series of sub-basins tributary to the Formone River in the Orcia catchment (central Italy) were selected as a suitable study area within which to explore our questions, given these basins' general representativeness of local terrain, the availability of a high resolution digital terrain model and previous extensive geomorphological research. Eroding basins containing both calanchi and landslides are common in the sub-humid badland landscape of central Italy, where field observation identifies a complex pattern of erosive processes associated with a history of uplift, despite which parts of the local landscape appear disconnected. Results reveal that the shape of all S–A curves (plotted using S data binned on log A) is comparable with that described in the literature, although sub-basins containing calanchi generally plot with higher S values than non-calanchi ones, except in the ‘fluvial’ section of the plots. Second, when viewed on total data (non-binned) S–A plots, landslide source area domains and calanchi domains are entirely coincident in all basins, supporting a cause–effect relationship. Additional plotting of the frequency characteristics of the raw data in a new way supports the interpretation that calanchi frequently initiate in landslide scars. In general though, although the S–A plots can contribute to the disentanglement of geomorphological behaviour in some complex erosional landscapes, it became apparent that in this landscape, process domains do not separate out with clarity along the A axis as suggested by theory. Despite this, an alternative, broader-scale morphoevolutive model can be proposed for the development of within-landslide calanchi, driven by changes to basin connectivity to the base channel. © 2018 John Wiley & Sons, Ltd.     

Stochastic evaluation of the impact of sewer inlets’ hydraulic capacity on urban pluvial flooding

Sewer inlet structures are vital components of urban drainage systems and their operational conditions can largely affect the overall performance of the system. However, their hydraulic behaviour and the way in which it is affected by clogging is often overlooked in urban drainage models, thus leading to misrepresentation of system performance and, in particular, of flooding occurrence. In the present paper, a novel methodology is proposed to stochastically model stormwater urban drainage systems, taking the impact of sewer inlet operational conditions (e.g. clogging due to debris accumulation) on urban pluvial flooding into account. The proposed methodology comprises three main steps: (i) identification of sewer inlets most prone to clogging based upon a spatial analysis of their proximity to trees and evaluation of sewer inlet locations; (ii) Monte Carlo simulation of the capacity of inlets prone to clogging and subsequent simulation of flooding for each sewer inlet capacity scenario, and (iii) delineation of stochastic flood hazard maps. The proposed methodology was demonstrated using as case study design storms as well as two real storm events observed in the city of Coimbra (Portugal), which reportedly led to flooding in different areas of the catchment. The results show that sewer inlet capacity can indeed have a large impact on the occurrence of urban pluvial flooding and that it is essential to account for variations in sewer inlet capacity in urban drainage models. Overall, the stochastic methodology proposed in this study constitutes a useful tool for dealing with uncertainties in sewer inlet operational conditions and, as compared to more traditional deterministic approaches, it allows a more comprehensive assessment of urban pluvial flood hazard, which in turn enables better-informed flood risk assessment and management decisions.     

Status and outlook of hiking trails in the central part of the Low Tatra Mountains in Slovakia between 1980–1981 and 2013–2014

This study presents a methodology for assessment of the condition of hiking trails (HTs) and their impact zones in the central part of the Low Tatra mountain range, based on comparison of two complex data sets gathered in 33 years apart. The first field investigation was performed in 1980 and 1981, and the second in 2013 and 2014. The main goal was to perform a landscape typology in order to assess the susceptibility of landscape complexes to occurrence of anthropogenic and natural destruction processes and to assess the condition and prospects of HTs and their impacts on the adjacent alpine environment. Landscape complexes were characterised by selected abiotic, biotic and technical parameters of HTs and their impact zones. Due to the high variability of these parameters over the length of the HTs, we had to decide on how to map them. This was done using a square grid with 100 m-sized cells. For each cell with HT, the parameters were assigned the typical value within that cell. In total, 26.3 km of HT were studied, stretching over 266 grid cells. On comparison of the two data sets, it was seen that, 64% (171 grid cells) display a generally positive condition, with 54% (143 grid cells) even exhibiting significant improvement or continuously positive state of their condition. 36% (95 grid cells) were in bad condition, including 3% (9 grid cells) whose state had deteriorated, and 2% (6 grid cells) whose state had significantly deteriorated, in the time between the two assessments.     

Regional scenarios of sea level rise and impacts on Basque (Bay of Biscay) coastal habitats,throughout the 21st century

Global climate models have predicted a rise on mean sea level of between 0.18 m and 0.59 m by the end of the 21st Century, with high regional variability. The objectives of this study are to estimate sea level changes in the Bay of Biscay during this century, and to assess the impacts of any change on Basque coastal habitats and infrastructures. Hence, ocean temperature projections for three climate scenarios, provided by several atmosphere–ocean coupled general climate models, have been extracted for the Bay of Biscay; these are used to estimate thermosteric sea level variations. The results show that, from 2001 to 2099, sea level within the Bay of Biscay will increase by between 28.5 and 48.7 cm, as a result of regional thermal expansion and global ice-melting, under scenarios A1B and A2 of the Intergovernmental Panel on Climate Change. A high-resolution digital terrain model, extracted from LiDAR, data was used to evaluate the potential impact of the estimated sea level rise to 9 coastal and estuarine habitats: sandy beaches and muds, vegetated dunes, shingle beaches, sea cliffs and supralittoral rock, wetlands and saltmarshes, terrestrial habitats, artificial land, piers, and water surfaces. The projected sea level rise of 48.7 cm was added to the high tide level of the coast studied, to generate a flood risk map of the coastal and estuarine areas. The results indicate that 110.8 ha of the supralittoral area will be affected by the end of the 21st Century; these are concentrated within the estuaries, with terrestrial and artificial habitats being the most affected. Sandy beaches are expected to undergo mean shoreline retreats of between 25% and 40%, of their width. The risk assessment of the areas and habitats that will be affected, as a consequence of the sea level rise, is potentially useful for local management to adopt adaptation measures to global climate change.     

Spatial and temporal distribution of cadmium and copper in water and zooplankton in the Bahía Blanca estuary,Argentina

Cadmium and copper in the dissolved and particulate phase and in zooplankton were determined in the Bahía Blanca estuary during six surveys from March to December 2005. Temperature, pH, salinity, dissolved oxygen, suspended particulate matter, particulate organic matter and chlorophyll-a were also considered. Dissolved Cd was below the detection limit (0.2 μg L⁻¹) for almost the entire study period whereas Cu concentrations (0.5–2.4 μg L⁻¹) indicated a continuous dissolved Cu input. Particulate Cd concentrations ranged from below the detection limit (<0.01) to 28.6 μg g⁻¹ d.w. while particulate Cu ranged from below the detection limit (<0.04) to 53.5 μg g⁻¹ d.w. Cd in mesozooplankton ranged from below the detection limit (<0.01) to 37.4 μg g⁻¹ d.w. Some of the Cd levels were higher than those reported for other aquatic ecosystems. Cu in the mesozooplankton ranged from 1.3 to 89.3 μg g⁻¹ d.w., values which were within the reported values or higher than other studies. The log of the partition coefficients (log (K_d)) of Cd was 0.04, while log (K_d) for Cu ranged from −0.39 to 2.79. These values were lower than both those calculated for other estuaries and the typical coefficients for marine environments. The log of the bioconcentration factor (log BCF) of Cd was 1.78, indicating that Cd concentration was higher in the zooplankton than in the dissolved phase. Log BCF of Cu ranged from 1.15 to 3. The logs of the biomagnification factors (log BMF) of Cd were low, with a range between −3.45 and 2.21 and those for Cu ranged from −0.1 to 3.35. Positive values indicate biomagnification while negative values indicate biodiminution. In general, no significant dissolved Cd concentration appeared to be present in the Bahía Blanca estuary and Cu values did not indicate a critical environmental status. The particulate phase seemed to be the major carrier for Cd and Cu and TPCu values were within the normal values for an anthropogenically stressed estuary but not for a strongly polluted system. This fraction was the most important metal source for the mesozooplankton. Moreover, the highest metal concentrations were in the mesozooplankton since most of the bioconcentration and biomagnification factors were positive, especially for Cu.