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Kyle S Boodoo, Nico Trauth, Christian Schmidt, Jakob Schelker, Tom J Battin
Streams are significant sources of CO2 to the atmosphere. Estimates of CO2 evasion fluxes (f CO2) from streams typically relate to the free flowing water but exclude geomorphological structures within the stream corridor. We found that gravel bars (GBs) are important sources of CO2 to the atmosphere, with on average more than twice as high f CO2 as those from the streamwater, affecting f CO2 at the level of entire headwater networks. Vertical temperature gradients resulting from the interplay between advective heat transfer and mixing with groundwater within GBs explained the observed variation in f CO2 from the GBs reasonably well...
October 31, 2017: Scientific Reports
Alejandro Tejedor, Anthony Longjas, Douglas A Edmonds, Ilya Zaliapin, Tryphon T Georgiou, Andrea Rinaldo, Efi Foufoula-Georgiou
The form and function of river deltas is intricately linked to the evolving structure of their channel networks, which controls how effectively deltas are nourished with sediments and nutrients. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. To date, however, a unified theory explaining how deltas self-organize to distribute water and sediment up to the shoreline remains elusive...
October 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
Sébastien Terrat, Walid Horrigue, Samuel Dequietd, Nicolas P A Saby, Mélanie Lelièvre, Virginie Nowak, Julie Tripied, Tiffanie Régnier, Claudy Jolivet, Dominique Arrouays, Patrick Wincker, Corinne Cruaud, Battle Karimi, Antonio Bispo, Pierre Alain Maron, Nicolas Chemidlin Prévost-Bouré, Lionel Ranjard
Although numerous studies have demonstrated the key role of bacterial diversity in soil functions and ecosystem services, little is known about the variations and determinants of such diversity on a nationwide scale. The overall objectives of this study were i) to describe the bacterial taxonomic richness variations across France, ii) to identify the ecological processes (i.e. selection by the environment and dispersal limitation) influencing this distribution, and iii) to develop a statistical predictive model of soil bacterial richness...
2017: PloS One
Chun Liu, Zhongwu Li, Xiaofeng Chang, Xiaodong Nie, Lin Liu, Haibing Xiao, Danyang Wang, Hao Peng, Guangming Zeng
Understanding the dynamics of organic matter (OM) at global and local scales is one of the challenges in the environmental sciences and i.e. terrestrial biogeochemistry. The accurate identification of OM is an essential element to achieve this goal. In our study, a novel application for quantitatively apportioning sources of eroded sedimentary OM from an eco-geomorphologic perspective was shown successfully via a coupled molecular n-alkane biomarkers and stable isotopic signatures ((13)C and (15)N) along with elemental compositions (TOC and TN) using a Bayesian mixing model (SIAR)...
October 17, 2017: Science of the Total Environment
Deng-Feng Xie, Min-Jie Li, Jin-Bo Tan, Megan Price, Qun-Ying Xiao, Song-Dong Zhou, Yan Yu, Xing-Jin He
Urophysa is a Chinese endemic genus with only two species (U. rockii and U. henryi) distributed in Yungui Plateau (Guizhou Province) and adjacent regions (i.e., Provinces of Hunan, Hubei, Chongqing and Sichuan). The aim of this study was to determine the genetic diversity and population differentiation within Urophysa and investigate the effect of the Yungui Plateau uplift and climate oscillations on evolution of Urophysa. In this study, micro-morphological characteristics, nine microsatellite loci (SSR), two nuclear loci (ITS and ETS) and two chloroplast fragments (psbA-trnH and trnL-trnF) were used to analyze the phylogenetic relationships and assess genetic and phylogeographical structure of Urophysa...
2017: PloS One
Francesco Gabrielli, Alessia Amato, Susanna Balducci, Lorenzo Magi Galluzzi, Francesca Beolchini
The geomorphology of the Italian territory causes the incidence of many disasters like earthquakes and floods, with the consequent production of large volumes of waste. The management of such huge flows, produced in a very short time, may have a high impact on the whole emergency response. Moreover, historical data related to disaster waste management are often not easily accessible; on the other hand, the availability of data concerning previous events could support the emergency managers, that have to take a decision in a very short time...
October 16, 2017: Waste Management
Paul C Kusnierz, Christopher M Holbrook
Bed stability is an important stream habitat attribute because it affects geomorphology and biotic communities. Natural resource managers desire indices of bed stability that can be used under a wide range of geomorphic conditions, are biologically meaningful, and are easily incorporated into sampling protocols. To eliminate potential bias due to presence of instream wood and increase precision of stability values, we modified a stream bed instability index (ISI) to include measurements of bankfull depth (d bf) and median particle diameter (D 50) only in riffles and increased the pebble count to decrease variability (i...
October 16, 2017: Environmental Monitoring and Assessment
Daniel Magnone, Laura A Richards, David A Polya, Charlotte Bryant, Merren Jones, Bart E van Dongen
The poisoning of rural populations in South and Southeast Asia due to high groundwater arsenic concentrations is one of the world's largest ongoing natural disasters. It is important to consider environmental processes related to the release of geogenic arsenic, including geomorphological and organic geochemical processes. Arsenic is released from sediments when iron-oxide minerals, onto which arsenic is adsorbed or incorporated, react with organic carbon (OC) and the OC is oxidised. In this study we build a new geomorphological framework for Kandal Province, a highly studied arsenic affected region of Cambodia, and tie this into wider regional environmental change throughout the Holocene...
October 12, 2017: Scientific Reports
Molly K Welsh, Sara K McMillan, Philippe G Vidon
Although floodplain restoration may improve stream-riparian connectivity and increase channel stability through cross-vane installation, stream bank regrading, and buffer revegetation, the impact of these geomorphic alterations on denitrification across the aquatic-terrestrial interface is poorly understood. Seasonal denitrification enzyme activity (DEA) was compared in stream-riparian ecotones of four streams with varying hydrologic connection, riparian vegetation composition, and agricultural influence. Riparian and stream DEA was generally higher in sites adjacent to agricultural fields due to proximity to nitrate source...
September 2017: Journal of Environmental Quality
Bahram Choubin, Hamid Darabi, Omid Rahmati, Farzaneh Sajedi-Hosseini, Bjørn Kløve
Suspended sediment load (SSL) modelling is an important issue in integrated environmental and water resources management, as sediment affects water quality and aquatic habitats. Although classification and regression tree (CART) algorithms have been applied successfully to ecological and geomorphological modelling, their applicability to SSL estimation in rivers has not yet been investigated. In this study, we evaluated use of a CART model to estimate SSL based on hydro-meteorological data. We also compared the accuracy of the CART model with that of the four most commonly used models for time series modelling of SSL, i...
February 15, 2018: Science of the Total Environment
Josef Bryja, Danila Kostin, Yonas Meheretu, Radim Šumbera, Anna Bryjová, Mohammed Kasso, Ondřej Mikula, Leonid A Lavrenchenko
The Ethiopian highlands are the most extensive complex of mountainous habitats in Africa. The presence of the Great Rift Valley (GRV) and the striking elevational ecological gradients inhabited by recently radiated Ethiopian endemics, provide a wide spectrum of model situations for evolutionary studies. The extant species of endemic rodents, often markedly phenotypically differentiated, are expected to possess complex genetic features which evolved asa consequence of the interplay between geomorphology and past climatic changes...
September 27, 2017: Molecular Phylogenetics and Evolution
Ali Fadaie Kermani, Reza Derakhshani, Shahram Shafiei Bafti
Morphotectonic indices by representing the longer period of time than recorded earthquake data, are useful in evaluating the tectonic activity of a region. Dashtkhak area is located in Kerman province of Iran, where one of the most active faults, Kouhbanan strike slip fault, passes through. This data article provides a precise level data on mountain fronts and valleys of Dashtkhak region that is fundamental for morphotectonic investigations of the relationship among geomorphology and tectonic activity. This data is valuable in the field of geology and geography...
October 2017: Data in Brief
M Rogger, M Agnoletti, A Alaoui, J C Bathurst, G Bodner, M Borga, V Chaplot, F Gallart, G Glatzel, J Hall, J Holden, L Holko, R Horn, A Kiss, S Kohnová, G Leitinger, B Lennartz, J Parajka, R Perdigão, S Peth, L Plavcová, J N Quinton, M Robinson, J L Salinas, A Santoro, J Szolgay, S Tron, J J H van den Akker, A Viglione, G Blöschl
Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage, and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long-term experiments on physical-chemical-biological process interactions, and a focus on connectivity and patterns across spatial scales. It is suggested that these strategies will stimulate new research that coherently addresses the issues across hydrology, soil and agricultural sciences, forest engineering, forest ecology, and geomorphology...
July 2017: Water Resources Research
Kim Birnie-Gauvin, Jeroen S Tummers, Martyn C Lucas, Kim Aarestrup
Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures - such as hydroelectric dams, weirs, culverts and bridges - are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations...
December 15, 2017: Journal of Environmental Management
Elizabeth M Palmer, Essam Heggy, Wlodek Kofman
We present orbital bistatic radar observations of a small-body, acquired during occultation by the Dawn spacecraft at asteroid Vesta. The radar forward-scattering properties of different reflection sites are used to assess the textural properties of Vesta's surface at centimeter-to-decimeter scales and are compared to subsurface hydrogen concentrations observed by Dawn's Gamma Ray and Neutron Detector to assess potential volatile occurrence in the surface and shallow subsurface. We observe significant differences in surface radar reflectivity, implying substantial spatial variations in centimeter-to-decimeter-scale surface roughness...
September 12, 2017: Nature Communications
Carolina Peña-Alonso, Pablo Fraile-Jurado, Luis Hernández-Calvento, Emma Pérez-Chacón, Eduard Ariza
A system of indicators has been developed to evaluate beach geomorphological vulnerability (GVI) through: intrinsic susceptibility, the agents that model them, and their ability to remain stable over time. The method is applied to 34 beaches on the island of Gran Canaria (Spain) that experience different levels and conditions of human occupation, marine incidence, landforms and sediments, and spatial evolution that have been recorded since 1960. In contrast with other studies, the analysis of these dimensions (and their relationships) allows a diagnosis of the geomorphology of the beaches with an integrated approach...
December 15, 2017: Journal of Environmental Management
Rodrigo I Cerri, Fábio A G V Reis, Marcelo F Gramani, Lucilia C Giordano, José Eduardo Zaine
This paper presents a new approach of landslides zonation hazard studies, based on an integrated study of structural data along with geomorphological and external factors, in a hilly regions of Brazil, covered by a tropical humid rain-forest, called Serra do Mar. The Serra do Mar consists of a hilly region along the east coast of Brazil, with high slopes and many geological structures in a gneiss - migmatitic terrain. In contrast to traditional approaches, this method proposes that structural data (foliation, fractures and bedding planes) and its relation with the slope geometry, is important to be consider in the landslide zonation hazard, along with declivity, relative relief, soil and rock properties, land use and vegetation cover and hydrogeological and climate factors...
August 31, 2017: Anais da Academia Brasileira de Ciências
Kristen M Harrigan, Paul A Moore
In flowing systems, fluctuations in the frequency, magnitude, and duration of exposure occurs due to turbulence and geomorphology, causing spatial and temporal variations in chemical exposure at the scale of the organism. Spatial models representing toxicant distribution at the appropriate scales of stream organisms are noticeably missing from the literature. To characterize the fine scale distribution of pollutants in freshwater streams at the scale of a benthic organism, nine artificial stream habitats were created (riffle, pool, run, bend, woody debris) with either sand or gravel substrate...
September 5, 2017: Archives of Environmental Contamination and Toxicology
Thomas R Barnum, Donald E Weller, Meghan Williams
More than half the world's population lives in urban areas, so quantifying the effects of urbanization on ecological communities is important for understanding whether anthropogenic stressors homogenize communities across environmental and climatic gradients. We examined the relationship of impervious surface coverage (a marker of urbanization) and the structure of stream macroinvertebrate communities across the state of Maryland and within each of Maryland's three ecoregions: Coastal Plain, Piedmont, and Appalachian, which differ in stream geomorphology and community composition...
September 5, 2017: Ecological Applications: a Publication of the Ecological Society of America
Sarah L Murfitt, Blake M Allan, Alecia Bellgrove, Alex Rattray, Mary A Young, Daniel Ierodiaconou
Monitoring of intertidal reefs is traditionally undertaken by on-ground survey methods which have assisted in understanding these complex habitats; however, often only a small spatial footprint of the reef is observed. Recent developments in unmanned aerial vehicles (UAVs) provide new opportunities for monitoring broad scale coastal ecosystems through the ability to capture centimetre resolution imagery and topographic data not possible with conventional approaches. This study compares UAV remote sensing of intertidal reefs to traditional on-ground monitoring surveys, and investigates the role of UAV derived geomorphological variables in explaining observed intertidal algal and invertebrate assemblages...
August 31, 2017: Scientific Reports
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