Lowland Plains Research Articles

Basin characterization and determination of hydraulic connectivity of mega basins using integrated methods: (The case of Baro-Akobo and mega watershed beyond)

Despite being the longest river and the fourth in drainage area, Nile River has the lowest discharge per unit areas among the top ten rivers of the world. Understanding the hydrologic significance of the regional litho-stratigraphy and structures help to better understand the hydrodynamics. This work is aimed at characterizing the Baro-Akobo-Sobbat sub-basin of Nile and determine trans-basin flows. Integrated method is used to characterize the basin and determine the Baro-Akobo-Sobbat sub-basin's relationship with African Mesozoic Rifts. Oil and water well drilling logs; aeromagnetic, gravity and vertical electrical sounding data; and various study reports are used to establish regional lithostratigraphic correlations and determine trans-regional hydrogeological connectivity. A total of 633 samples collected from wells, springs, rivers, lakes, swamps and rain water are analysed for their chemical, stable isotopes, tritium and radon properties. The Baro-Akobo river basin is commonly presumed to have good groundwater potential, particularly in its lowland plain. However, it has poor exploitable groundwater potential and recharge rate due to the extensive clay cover, limited retention capacity and the loss of the bulk of the groundwaters through regional geological structures to the deep seated continental sediments; presumably reaching the hydraulically connected African Mesozoic Rifts; mainly Melut and Muglad. The deep underground northward flows, along Nile River is, presumably, retarded by Central African Shear Zone in the Sudan.

Microhabitat estimation of an imperiled headwater fish, the Yazoo darter (Etheostoma raneyi), in coastal plain streams

Headwater fishes in the southeastern United States make up much of the fish biodiversity of the region yet many are imperiled. Despite this, the specific habitat requirements of imperiled headwater fishes in lowland Coastal Plain streams have rarely been quantified. Using data collected over three years of seasonal sampling we provide estimates of the microhabitat requirements of the imperiled Yazoo darter (Etheostoma raneyi Suttkus and Bart), a small benthic insectivore. Our results indicate that the species is a microhabitat specialist and that optimum microhabitat within degraded contemporary streams consists of a narrow range of water depths (about 20–30 cm), current velocity ≥ 0.25 m·s−1, complex stable debris piles, rooted macrophytes, and likely coarse substrate. No pronounced or generalized seasonal shifts in microhabitat use occurs, and no evidence exists for intraspecific partitioning of microhabitat. Though stable and complex instream cover is one of the most important variables explaining variation in microhabitat use by Yazoo darters, such cover is rare in the degraded streams within the range of the species. Current conservation classifications of the Yazoo darter by governmental agencies and nongovernmental organizations as well as associated management plans that are based on the assumption that Yazoo darters are habitat generalists should be reviewed in recognition of the increased risk of decline because Yazoo darters are microhabitat specialists. These considerations should also be extended to other closely related imperiled species of snubnose darters.

Basin hydrogeological characterization using remote sensing, hydrogeochemical and isotope methods (the case of Baro-Akobo, Eastern Nile, Ethiopia)

Hydrogeochemical and isotopic signatures of the waters of the Baro-Akobo River Basin show deviation from signatures in other Ethiopian river basins. In this study, hydrogeochemical and isotope methods were employed to determine regional and local hydrogeology and characteristics of the basin. Optical, thermal and radar remote sensing products were used to update geological and structural maps of the basin and determine sampling points using the judgment sampling method. A total of 363 samples from wells, springs, rivers, lakes, swamps and rain were collected for this study, and an additional 270 water quality data sets were added from previous studies. These data were analyzed for their hydrogeochemical characteristics and isotope signatures. Analysis of the oxygen, deuterium and tritium isotopes shows the groundwater of the basin is modern water. Among all basins in Ethiopia, the Baro-Akobo Basin shows the highest enrichment. This indicates the proximity of the rainfall sources, which presumably are the Sudd and other wetlands in South Sudan. The hydrochemical properties of the waters show evapotranspiration is the dominant hydrologic process in the basin and explains the large amount of water that is lost in the lowland plain. Analysis of radon-222 shows no significant groundwater flux over the wetlands, which are part of Machar Marshes. This shows evaporation to be dominant hydrologic process in this zone. Results from all analyses help explain the limited holding capacity of the aquifers in the recharge zone and their vulnerability to anthropogenic impacts and climate variability. There is a trend of decreasing surface flow and rainfall and increasing water soil erosion.

La arqueología neolítica en el Abrigo de Penedo dos Mouros (Gouveia, Portugal): la evidencia de prácticas de trashumancia primitiva en la Sierra de la Estrella

Located in the foothills of the north-western sector of the Estrela Mountain (Beira Alta province in central-north Portugal), Penedo dos Mouros Rock-shelter revealed a succession of three distinct archaeological horizons datable to the evolved Early Neolithic and initial Middle Neolithic, thus partially coinciding with the onset of the regional Megalithism. The find of a few caprine remains at least one possible sheep, among a large spectrum of species –swine, rabbit, hare, Iberian lynx and toad–, makes this site the oldest in the region to provide direct evidence for herding practices. Small-sized pots, expedient use of local lithic raw materials together with curated use of exogenous flint, and low density of artefacts indicate a strategy of residential mobility in line with similar evidence observed elsewhere in Beira Alta. Given previous claims of Neolithic vertical transhumance between montane plateaux –in the summer– and lowland plains –in the winter–, this hypothesis is here discussed –and refuted– based on spatial analysis of Neolithic sites, economic characterization of the period and local orographic and bioclimatic constraints.

Using geomorphic understanding of catchment-scale process relationships to support the management of river futures: Macaé Basin, Brazil

Impacts of colonial settlement upon catchment-scale fluvial geomorphic relationships are reported for a relatively small catchment in northern Rio de Janeiro State, Brazil. Structural controls have induced the type and patterns of rivers in Macaé Basin. Fault block activity has resulted in steep, incised headwater streams above the escarpment. Confined and partly confined rivers in mid-catchment reaches of the rounded foothills have limited potential for geomorphic adjustment. Fluvial, estuarine and marine sediments in low relief landscapes of the lowland plain have supported the development of meandering sand bed rivers, with many cut-and-fill (intact valley fill) deposits in tributary systems. Indigenous people exerted relatively minor, localized impacts upon the geomorphology of this river system. Portuguese settlement since the sixteenth century brought about clearance of much of the Atlantic Forest of lowland reaches, and subsequent establishment of sugar cane and coffee plantations. Lowland reaches were channelized from the 1940s-1980s for flood protection and to support the expansion of pastoral agriculture. Significant adjustments have occurred to these geomorphologically sensitive reaches. In contrast, although rivers in the rounded foothills were impacted by forest clearance, the limited availability of sediment stores along these reaches has limited the extent of geomorphic responses to human disturbance. Relatively inaccessible upland reaches were even less impacted, and are now major conservation areas. Building on principles of the River Styles framework, catchment-scale evolutionary trajectories of rivers in the Macaé Basin are assessed based on analysis of patterns of river types, their capacity for adjustment and connectivity relationships, and responses to disturbance events. From this, three future scenarios of prospective evolutionary traits are developed: a ‘steady as she goes’ scenario, an optimistic (effective, proactive management) scenario, and a ‘doomsday’ scenario.

Molecular epidemiology of Crimean–Congo hemorrhagic fever virus in ticks collected from western Iran

Background: Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral disease that is endemic in Africa, southeastern Europe, and Asia. Ticks are both the reservoir and the vector of the CCHF virus (CCHFV). Determining the virus infection rate of the tick population in different geographical regions is necessary todesign public health policies to prevent CCHF outbreaks. Objectives: To determine the prevalence, seasonal activity, and the frequency of CCHFV infection of the tick population in Hamadan province of west Iran. Methods: This cross-sectional study was conducted in 3 counties of Hamadan Province from June 2013 to May 2014. The study areas included both lowland (plains) and highland (mountains) and covered 5% of the villages where 10 herds per village of sheep and goats were randomly selected for hard tick collection. Results: We examined 983 sheep and goats, and 881 ticks were collected and identified before being preserved for molecular tests. The collected ticks belonged to 3 genera including, Rhipicephalus (95.6%, n = 842), Hyalomma (4.1%, n = 36) and Haemaphysalis (0.4%, n = 4). After species identification, 100 randomly selected ticks were analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR) to detect viral infection. CCHFV infection was observed in 7 collected ticks, of which 4 belonged to R. sanguineus, 2 belonged to R. bursa, and one Hy. asiaticum. Conclusions: Hyalomma and Rhipicephalus ticks are the main vectors of CCHFV in Hamadan province where CCHF is focal and endemic. Keywords: Crimean-Congo hemorrhagic fever, Hamadan, Iran, molecular epidemiology, tick-borne diseases, zoonotic viral disease

Comprehensive species set revealing the phylogeny and biogeography of Feliformia (Mammalia, Carnivora) based on mitochondrial DNA.

Extant Feliformia species are one of the most diverse radiations of Carnivora (~123 species). Despite substantial recent interest in their conservation, diversification, and systematic study, no previous phylogeny contains a comprehensive species set, and no biogeography of this group is available. Here, we present a phylogenetic estimate for Feliformia with a comprehensive species set and establish a historical biogeography based on mitochondrial DNA. Both the Bayesian and maximum likelihood phylogeny for Feliformia are elucidated in our analyses and are strongly consistent with many groups recognized in previous studies. The mitochondrial phylogenetic relationships of Felidae were for the first time successfully reconstructed in our analyses with strong supported. When divergence times and dispersal/vicariance histories were compared with historical sea level changes, four dispersal and six vicariance events were identified. These vicariance events were closely related with global sea level changes. The transgression of sea into the lowland plains between Eurasia and Africa may have caused the vicariance in these regions. A fall in the sea level during late Miocene to Pliocene produced the Bering strait land bridge, which assisted the migration of American Feliformia ancestors from Asia to North America. In contrast with the ‘sweepstakes hypothesis’, our results suggest that the climate cooling during 30–27 Ma assisted Feliformia migration from the African mainland to Madagascar by creating a short-lived ice bridge across the Mozambique Channel. Lineages-through-time plots revealed a large increase in lineages since the Mid-Miocene. During the Mid-Miocene Climatic Optimum, the ecosystems and population of Feliformia rapidly expanded. Subsequent climate cooling catalyzed immigration, speciation, and the extinction of Feliformia.

Lacustrine-fluvial interactions in Australia's Riverine Plains

Climatic forcing of fluvial systems has been a pre-occupation of geomorphological studies in Australia since the 1940s. In the Riverine Plain, southeastern Australia, the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world. Surficial sediments and landforms exceed 140,000 yr in age, and geomorphological change recorded in the fluvial, fluvio-lacustrine and aeolian features have provided a well-studied record of Quaternary environmental change over the last glacial cycle. The region includes the Willandra Lakes, whose distinctive lunette lakes preserve a history of water-level variations and ecological change that is the cornerstone of Australian Quaternary chronostratigraphy. The lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the Australian continent. To date, the lake-level and palaeochannel records in the Lachlan-Willandra system have not been fully integrated, making it difficult to establish the regional significance of hydrological change. Here, we compare the Willandra Lakes environmental record with the morphology and location of fluvial systems in the lower Lachlan. An ancient channel belt of the Lachlan, Willandra Creek, acted as the main feeder channel to Willandra Lakes before channel avulsion caused the lakes to dry out in the late Pleistocene. Electromagnetic surveys, geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion. Single grain optical dating of floodplain sediments indicates that sedimentation in the new Middle Billabong Palaeochannel had commenced before 18.4 ± 1.1 ka. A second avulsion shifted its upper reaches to the location of the present Lachlan River by 16.2 ± 0.9 ka. The timing of these events is consistent with palaeohydrological records reconstructed from Willandra Lakes and with the record of palaeochannels on the Lachlan River upstream. Willandra Lakes shows high inflows during the Last Glacial Maximum (∼22 ka), but their subsequent drying between 20.5 ka and 19 ka was caused by river avulsion rather than regional aridity. This case study highlights the benefits of combining fluvial with lacustrine archives to build complementary records of hydrological change in lowland riverine plains.

Distributary channels in the fluvial to tidal transition zone

Coastal lowland plains under mixed fluvial‐tidal influence may form complex, composite channel networks, where distributaries blend the characteristics of mouth bar channels, avulsion channels, and tidal creeks. The Kapuas coastal plain exemplifies such a coastal plain, where several narrow distributaries branch off the Kapuas River at highly asymmetric bifurcations. A comprehensive geomorphological analysis shows that trends in the channel geometry of all Kapuas distributaries are similar. They consist of a short, converging reach near the sea and a nonconverging reach upstream. The two parts are separated by a clear break in scaling of geometrical properties. Such a break in scaling was previously established in the Mahakam Delta, which suggests that this may be a general characteristic in the fluvial to tidal transition zone. In contrast to the geometrical trend similarities, a clear difference in bed material between the main and side distributaries is found. In the main distributary, a continuous trend of downstream fining is established, similar to what is often found in lowland rivers. In the side distributaries, bed material coarsens in the downstream direction. This indicates an undersupply of sediment to the side distributaries, which may contribute to their long‐term stability as established from historical maps. Tides may be the main agent preventing fine sediment to settle, promoting residual transport of fine material to the coastal ocean.

Chapter 20 Current tectonic activity along the Sagaing Fault, Myanmar indicated by alluvial fans

In the area to the north of Sagaing, fault-parallel ridges, alluvial fans, sag ponds, scarp lines, fault furrows, offset streams, a lowland plain hosting a lacustrine basin, river terraces and elevated flat-surfaces are the striking geomorphic features adjacent to the Sagaing Fault. The present study concentrates on the nature and development of the younger alluvial fans and the older fanglomerates located along the fault, in order to document the tectonic history of the Sagaing Fault. Alluvial fans and associated features can be a valuable record of tectonic activity (Nemec & Kazanci 1999) as they commonly develop along fault scarps, and thick sequences of syntectonic sediments have frequently been deposited on the actively subsiding side of the major fault (Reineck & Singh 1980; Collinson 1981). This chapter ties field-based geological studies, associated with satellite-image observations and interpretation of sedimentological data, to reconstruct the history of the alluvial fans along the Sagaing Fault in the area of Sagaing. Located between the Ayeyarwady (Irrawaddy) River and the Yemyet Inn (Lake) in Sagaing township, Central Myanmar, the study area extends northwards from Sagaing for a distance of 40 km. Topographically, the area consists of two fault-parallel north–south ridges: the Minwun Ridge in the west, and the Sagaing Ridge in the east. The latter, about 30 km long and studded with religious edifices, is much broader and higher than the former, the highest point at Mingun Taung (Hill) is 406 m above sea level. The two ridges, often considered as transpressive features (Win Swe 1981; Bertrand & Rangin 2003), are divided by a wide fault valley; just north of Kyaukta Village is the Yega Inn, a sag pond 1.2 km long. North of this lake, the valley becomes less conspicuous as the Minwun Ridge plunges beneath and locally emerges from the alluvial fan …

Acid weathering of basalt and basaltic glass: 2. Effects of microscopic alteration textures on spectral properties

AbstractAcid alteration has long been proposed for the Martian surface, and so it is important to understand how the resulting alteration textures affect surface spectra. Two basaltic materials of varying crystallinity were altered in two different H2SO4 solutions (pH 1 and pH 3) for 220 days. The unaltered and altered samples were studied in the visible and near infrared (VNIR) and thermal infrared (TIR), and select samples were chosen for scanning electron microscopy analysis. Materials altered in pH 3 solutions showed little to no physical alteration, and their spectral signatures changed very little. In contrast, all materials altered in pH 1 acid displayed silica‐rich alteration textures, and the morphology differed based on starting material crystallinity. The more crystalline material displayed extensive alteration reaching into the sample interiors and had weaker silica spectral features. The glass sample developed alteration layers tens of microns thick, exhibiting amorphous silica‐rich spectral features that completely obscured the substrate. Thus, the strong absorption coefficient of silica effectively decreases the penetration depth of TIR spectral measurements, causing silica abundances to be grossly overestimated in remote sensing data. Additionally, glass samples with silica layers exhibited distinct concave up blue spectral slopes in the VNIR. Spectra from the northern lowland plains of Mars are modeled with high abundances of amorphous silica and exhibit concave up blue spectral slopes and are thus consistent with acid altered basaltic glass. Therefore, we conclude that large regions of the Martian surface may have formed through the interaction of basaltic glass with strongly acidic fluids.

Between mountain and plain: new evidence for the Middle Palaeolithic in the northern Susiana Plain, Khuzestan, Iran

The Middle East generally (Bar-Yosef 1994) and Iran specifically (Vahdati Nasab et al. 2013) have become a focus for the study of human migration between South-west Asia and Central and Eastern Asia during the Pleistocene (Asgari Khaneghah et al.2005; Biglari & Shidrang 2006; Heydari Guran 2012). In Iran, studies of the Palaeolithic have concentrated on the Zagros and Alborz areas, but recent work in the sub-montane areas, desert margins and lowland plains have also revealed interesting results regarding the activities of hunter-gatherer societies (Biglari et al. 2000; Dashtizadeh 2009; Vahdati Nasab et al. 2009, 2010, 2013; Darabi et al. 2012).

Analysis of the interaction between neotectonic and surface processes in a low-land intracratonic setting of South America

Abstract The Quaternary sedimentary record in the continental interiors has generally been studied taking into consideration the climatic forcing. However, episodes of uplift controlling the development of landforms have often been dismissed. The interiors of continents are typically considered to have low deformation rates, lower than the rates of exogenous processes. Deformation in the middle of the Pampean plains, an intracratonic setting of South America, has been observed to have generated an elevated area surrounded by lowland plains. This elevated area is susceptible to fluvial erosion. From this fact we developed a geomorphologic modelling constrained from geomorphic markers in order to estimate the relative incidence of the different factors that control erosion in lowland landscapes. An adapted erosion code was employed, which combines fluvial incision equation (the stream power law), an uplift function spatially distributed and the hillslope diffusion equation. A low-DEM was achieved for restoring an initial non-deformed topography affected by low fluvial incision. It represents a palaeosurface chrono-stratigraphically constrained. The estimation of the model parameters was achieved by applying the inversion method. The best-fit between the numerical solution (calculated topography) and the measured topography (simulated by means a DEM) was approached by comparison of the stream longitudinal profiles. The yield numerical approach suggests that a geomorphological modelling based on the stream power law is possible to be applied in low-land landscapes. For this, a large scale change of the magnitude of the processes modelling the landscape should be expected in comparison with mountain erosional environments. Remarkably low K empirical values ( K = 5 × 10 −6 –6 × 10 −6 yr −1 ) suggest that the extremely low slopes exert a larger influence on the stream power in low-land landscapes. Also the diffusion coefficient D values resulted largely lower (3 × 10 −4 –1.9 × 10 −3 cm 2 /yr) than presented in tectonically active landscapes (>0.03 cm 2 /yr). Regional uplift rates can be higher (0.35 mm/yr) than it is generally expected in low uplift rate settings (0.1–0.25 mm/yr). These estimations evidence highly dynamic surface and tectonic processes controlling the landscape evolution over intermediate time scales in an intracratonic setting.

Venus’ radar-bright highlands: Different signatures and materials on Ovda Regio and on Maxwell Montes

Venus’ highlands appear much brighter than its lowland plains in reflected radar, which has been explained by several conflicting hypotheses. We study this transition at higher spatial and elevation resolution than previously possible by combining Magellan synthetic aperture radar (SAR) images with Magellan SAR stereo elevations. We confirm that SAR backscatter over Ovda Regio (5°N to 15°S) grades from low to high as elevation increases (2–4.5km above the datum), and then drops precipitously above ∼4.5km (T= ∼702K). This pattern is consistent with presence of a substance that undergoes a phase transition from ferroelectric to normal dielectric at ∼700K; the mineral chlorapatite is a likely candidate. This pattern is seen across Ovda, on other near-equatorial highlands, and on some shield volcanoes like the Tepev Montes. We also confirm that Maxwell Montes (60–68°N) shows a different pattern; its surface transitions abruptly from low backscatter to high backscatter at ∼4.5km above the datum, and remains so to nearly its highest elevations (∼10km). This pattern is consistent with the presence of a semiconductor material either precipitated from the atmosphere (e.g., a frost) or produced by atmosphere–surface interaction. If a ferroelectric substance were in the rock at Maxwell (as at Ovda), it could be invisible beneath the coating of semiconductor material. However, the absence of a semiconductor material on Ovda requires either that [1] the atmosphere compositions at Maxwell and Ovda are substantially different, or [2] that the semiconductor at Maxwell forms by atmosphere–surface reaction (not as an atmospheric precipitate) and that the surface materials at Ovda and Maxwell are substantially different.

Identifying and mapping the tourists⿿ perception of cultural ecosystem services: A case study from an Alpine region

Landscapes provide an array of services to society, from the provision of food and material, to the provision of cultural ecosystem services such as recreation, aesthetics or spirituality. Studies on cultural ecosystem services, however, remain rare and little is known about the spatial localisation of these services. In this study, we adopt and test a framework to identify and map the provision of cultural ecosystem services as perceived by tourists in an Alpine region, i.e. the region of South Tyrol in Italy. A photo-based questionnaire survey is combined with cartographical representations of landscape types to elicit hot and coldspot areas of cultural ecosystem service provision. We statistically test for influences of the land use type and the respondents' socio-demographic background on the tourists' perception of these services. The results show that different spatial patterns emerge for each of the investigated cultural ecosystem services depending on the distribution and extent of the landscape types to which they are related. In particular traditionally managed landscapes, small in extent and mainly scattered over large areas between 1000 and 2200m a.s.l., are hotspot areas of aesthetic beauty, leisure activities and spirituality. In contrast, intensively managed landscapes, mainly located in the lowland plains of the study site, are considered to be more important for the provision of cultural heritage values. While the results suggest that land use type exerts the strongest influence upon tourists' perception, factors such as the respondents' perceived importance of the services, their gender, cultural background, environmental engagement and experience with the landscape play a significant but subordinate role. We conclude that the spatially explicit information about the provision of cultural ecosystem services can serve as a helpful basis for the design and further implementation of land use policies that acknowledge the high touristic value of traditionally used landscapes in mountain regions.

River networks system changes and its impact on storage and flood control capacity under rapid urbanization

AbstractUrbanization significantly affects both the drainage network structure and the storage capacity of river channels in lowland plain river networks. The Yangtze River Delta region has experienced a rapid and profound urbanization of any region worldwide in the past 30 years. The southeast Yinfeng plain in the Yangtze River Delta region was used as the study area to assess changes in the river network structure from 1990 to 2010, using river feature parameter analyses and GIS spatial analysis. The elastic method was adopted to analyse river network pattern response to both urbanization and climate change, and the rates at which these factors contributed to changes in the river network pattern were investigated. Changes in the storage capacity and flood control capacity of the channel network over the past 21 years were then analysed. The results indicated that: (1) the number of river networks, and the complexity of the river network spatial structures were reduced, the drainage density decreased by 20%, the water surface ratio by 36%, the river area–length ratio by nearly 18% and the fractal dimension of the river networks by 4.5%; (2) the river network changes were due more to human activities than to climate change in this study period. Limited changes occurred in the structure of the river system, as indicated by an urbanization variability rate of less than 20% and precipitation variability range of −5% to −15%, although the stream structure gradually decreased with increasing urbanization variability; and (3) the storage capacity of the main river network decreased earlier (1990–2003) and was restored later (2003–2010) because of dredging and widening activities. In addition, the number of lower‐order rivers decreased, which resulted in significant decreases in the storage and flood control capacities of the river networks. Copyright © 2016 John Wiley & Sons, Ltd.

Phylogeography and evolution of the Red Salamander (Pseudotriton ruber)

Phylogeographic studies frequently result in the elevation of subspecific taxa to species given monophyly, or the synonymy of subspecies that are not monophyletic. However, given limited or incongruent datasets, retention of subspecies can be useful to describe hypothesized incipient species or to illustrate interesting biological phenomena driving morphological diversity. Four subspecific taxa have been used to describe largely allopatric geographic variation within the species Pseudotriton ruber, a plethodontid salamander occupying stream and spring habitats across eastern North America: P. r. vioscai occurs in lowland Coastal Plain habitats, while P. r. ruber, P. r. nitidus, and P. r. schencki occupy upland regions in and around the Appalachian Mountains. Pseudotriton ruber co-occurs through its distribution with the aposematic newt Notophthalmus viridescens, and both species are hypothesized to be part of a Müllerian mimicry complex. In this study, we sequenced regions of two mitochondrial (cytochrome b, NADH dehydrogenase subunit 2) and one single copy nuclear protein-coding gene (pro-opiomelanocortin) from individuals sampled across much of the distribution of P. ruber and then used maximum-likelihood and Bayesian phylogenetic inference to test the monophyly of subspecies, reconstruct biogeographic history, and make inferences about morphological evolution. Phylogeographic hypotheses from mitochondrial and nuclear datasets described structure among populations of P. ruber which separated Coastal Plain and upland Appalachian populations, but subspecies were not monophyletic. Biogeographic reconstruction estimated the ancestor of all populations to have occupied and initially diverged in the Coastal Plain during the Pliocene (∼3.6mya), before one lineage subsequently invaded upland areas of Appalachia. Bold bright coloration of high elevation subspecies P. r. nitidus and P. r. schencki appears to have evolved twice. We hypothesize that the Müllerian mimicry complex with N. viridescens and P. ruber may provide a selective mechanism driving the co-evolution of striking bright and dull morphological variation among populations of both species. While P. ruber subspecies were not consistent with our criteria for diagnosing species (monophyly) and therefore could not be elevated to species, we advocate for the retention of subspecies because they describe hypotheses about an incipient species (P. r. vioscai) and how Müllerian mimicry may shape morphological diversity of species.

Monsoonal influence on variation of hydrochemistry and isotopic signatures: Implications for associated arsenic release in groundwater

Summary The present study examines the groundwater and surface water geochemistry of two different geomorphic domains within the Chakdaha block, West Bengal, in an attempt to decipher potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer, the effect of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and concomitant As release. A low-land flood plain and a natural levee have been selected for this purpose. Although the stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) are largely controlled by local precipitation, the isotopic composition falls sub-parallel to the Global Meteoric Water Line (GMWL). The Cl/Br molar ratio indicates vertical recharge into the wells within the flood plain area, especially during the post-monsoon season, while influences of both evaporation and vertical mixing are visible within the natural levee wells. Increase in mean DOC concentrations (from 1.33 to 6.29 mg/L), from pre- to post-monsoon season, indicates possible inflow of organic carbon to the aquifer during the monsoonal recharge. Concomitant increase in AsT, Fe(II) and HCO3− highlights a possible initial episode of reductive dissolution of As-rich Fe-oxyhydroxides. The subsequent sharp increase in the mean As(III) proportions (by 223%), particularly in the flood plain samples during the post-monsoon season, which is accompanied by a slight increase in mean AsT (7%) may refer to anaerobic microbial degradation of DOC coupled with the reduction of As(V) to As(III) without triggering additional As release from the aquifer sediments.

Modified compressibility of cohesive sediments induced by thermal anomalies due to a borehole heat exchanger

In Ground Source Heat Pump systems (GSHP) a continuous circulation of a fluid inside the exchangers installed in the ground transfers heat between the ground and the building's conditioning system. Often the carrier fluids are brines consisting of a mixture of water and anti-freezing solutions, which lower their working temperature in order to improve the heat extraction from the ground during the cold season. The international community has already pointed out the importance of assessing a minimum temperature threshold for the brines inside the probes, in order to constrain the thermal anomalies induced in the soil.This paper analyzes how a borehole heat exchanger could affect the natural consolidation processes of surrounding cohesive layers, if the thermal anomaly induces freezing and subsequent heating processes.The study case of Venice (Italy) is considered, where GSHP systems could be a very interesting solution for the issues related to the particular configuration of the city center, the density of historical buildings and the local regulations. Venice represents an example of a densely urbanized area with a subsoil characterized by a continuous alternation between cohesive and coarser layers, as in most coastal lowland plains. The induced thermal settlement and the increased stiffness are measured in a silty-clay sampled in the area by means of a special device consisting in a thermostatically controlled oedometer. The obtained results contribute to the definition of the environmental hazards connected with the use of GSHP systems.

AEOLIAN-ACCUMULATIVE COMPLEX SARYKUM AS A UNIQUE GEOMORPHIC OBJECT OF RUSSIA: STRUCTURE, GENESIS AND SANDS SOURCES

Aeolian-accumulative complex Sarykum is one of the highest isolated (i.e. formed away from the deserts) sandy landforms in Eurasia, located within the Terek-Sulak lowland plain at the north-eastern foothill of the Caucasus Mountains, 16–17 km towards WNW of the Makhachkala City port of Caspian Sea (Republic of Dagestan, Russia). On the basis of particle size distribution and mineralogical analysis of 59 sandy samples, the heterogeneous structure of the complex is defined. The coarsest sandy material (modal values are 352 micron and more) composes the central dune-ridge segment of Sarykum (of so-called Great (or West) Sarykum). The further from the dune constructions to the periphery, the thinner the average dimension of the sand particles and smaller the modal values (249 micron and less) of their granulometric spectra. This grain size distribution can be explained not only by windy sorting of the sands and further aeolian recast of dune-ridge segment, but also by spatial features of the facial changes during the period of initial sandy accumulation, and also by the differences in composition of rocks, which were the sources of denudation. In the vertical structure of Sarykum the heterogeneity is also expressed. It is associated with temporary changes of sandy sedimentation conditions in the region. So, the dune-ridge segment of Great Sarykum can be represented as a system of consistently accumulated sandy layers (lenses?) (which includes the gravelly sands), which differ in composition and age, having apparently the coarsest content in the middle part of its vertical geological cross-section. The material of overwhelming majority of the selected samples belongs to mineral group of quartz sands (quartz content is over 90%) and subgroup of quartz subarkose (quartz content is 80–90%). Moreover, the aeolian (defl ated) sands of the dune-ridge segment and its underlying cross-bedded sands of Great Sarykum entirely belong to the first group; the hilly and peripheral sands, which characterized by fine granulometry, refer to the second mineral subgroup. The Sarykum’s structure is due to the combination of gravelly sands, formed by the river Shura-Ozen’ deltaic accumulation in the Late Quaternary, and sandy (with gravels and pebbees) deposits proluvially and deluvially dislocated to the recent Sarykum massif territory from the slopes of the nearby Narat-Tube mountain range. The mixing of originally and compositionally different sediments that formed the Sarykum complex, likely have the complicated history, following by the staged changes of the periglacial landscape-climatic conditions in the Late Quaternary.