Ground Truthing Chemostratigraphic Correlations in Fluvial Systems

2018 ◽  
Author(s):  
T, K Ratcliffe,
2017 ◽  
Author(s):  
Rebecca Anne Tisherman ◽  
◽  
Daniel J. Bain
Keyword(s):  

2020 ◽  
Author(s):  
Nathan A. Niemi ◽  
◽  
Adda Athanasopoulos-Zekkos ◽  
Cassandra Champagne ◽  
Marin K. Clark ◽  
...  

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1608
Author(s):  
Salvatore Ivo Giano

This Special Issue deals with the role of fluvial geomorphology in landscape evolution and the impact of human activities on fluvial systems, which require river restoration and management [...]


Author(s):  
Jose B. Rosales Chavez ◽  
Meg Bruening ◽  
Punam Ohri-Vachaspati ◽  
Rebecca E. Lee ◽  
Megan Jehn

Street food stands (SFS) are an understudied element of the food environment. Previous SFS studies have not used a rigorous approach to document the availability, density, and distribution of SFS across neighborhood income levels and points of access in Mexico City. A random sample (n = 761) of street segments representing 20 low-, middle-, and high-income neighborhoods were assessed using geographic information system (GIS) and ground-truthing methods. All three income levels contained SFS. However, SFS availability and density were higher in middle-income neighborhoods. The distribution of SFS showed that SFS were most often found near homes, transportation centers, and worksites. SFS availability near schools may have been limited by local school policies. Additional studies are needed to further document relationships between SFS availability, density, and distribution, and current structures and processes.


2021 ◽  
pp. 1-13
Author(s):  
Anna Belcher ◽  
Sophie Fielding ◽  
Andrew Gray ◽  
Lauren Biermann ◽  
Gabriele Stowasser ◽  
...  

Abstract Antarctic krill are the dominant metazoan in the Southern Ocean in terms of biomass; however, their wide and patchy distribution means that estimates of their biomass are still uncertain. Most currently employed methods do not sample the upper surface layers, yet historical records indicate that large surface swarms can change the water colour. Ocean colour satellites are able to measure the surface ocean synoptically and should theoretically provide a means for detecting and measuring surface krill swarms. Before we can assess the feasibility of remote detection, more must be known about the reflectance spectra of krill. Here, we measure the reflectance spectral signature of Antarctic krill collected in situ from the Scotia Sea and compare it to that of in situ water. Using a spectroradiometer, we measure a strong absorption feature between 500 and 550 nm, which corresponds to the pigment astaxanthin, and high reflectance in the 600–700 nm range due to the krill's red colouration. We find that the spectra of seawater containing krill is significantly different from seawater only. We conclude that it is tractable to detect high-density swarms of krill remotely using platforms such as optical satellites and unmanned aerial vehicles, and further steps to carry out ground-truthing campaigns are now warranted.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andreas Buerkert ◽  
Bryan Adam Dix ◽  
Mohamed Nasser Al Rawahi ◽  
Eva Schlecht

AbstractThe millenia-old oasis systems in the Western Hajar Mountains of Northern Oman have received widespread attention as models of sustainable irrigated agriculture in hyperarid Arabia. Given Oman’s rampant urbanization, growing scarcity of water and skilled labour, we quantified chances in water use, land use, and land cover between 2007 and 2018 using a rare time-series approach of detailed GIS-based crop mapping. Results from satellite image analysis and comprehensive ground truthing showed that urban areas grew from 206 ha in 2009 to 230 ha in 2014 and 252 ha in 2018. Throughout this decade, irrigated areas in backyards and front-house gardens of the town, planted largely to tree crops and vegetables, increased from 13.5 to 23.3 ha. Between 2007 and 2018 the actively used area of the studied oasis systems declined by 2.0% and the share of perennial crops without underplanting by 5.1%, while land under agroforestry increased by 2.1% and fallow land by 3.5%. Rising water demand of the sprawling town Sayh Qatanah led to terraces of Al ‘Ayn and Ash Sharayjah now being partly irrigated with treated wastewater which accelerated the abandonment of the old settlement structures. The labour- and water use efficiency-driven transformation of the Al Jabal Al Akhdar oasis agriculture into increasingly market-oriented landuse systems questions its function as example of sustainable, bio-cultural heritage of Arabia.


Author(s):  
Laura Barral-Fraga ◽  
María Teresa Barral ◽  
Keeley L. MacNeill ◽  
Diego Martiñá-Prieto ◽  
Soizic Morin ◽  
...  

This review is focused on the biogeochemistry of arsenic in freshwaters and, especially, on the key role that benthic microalgae and prokaryotic communities from biofilms play together in through speciation, distribution, and cycling. These microorganisms incorporate the dominant iAs (inorganic arsenic) form and may transform it to other arsenic forms through metabolic or detoxifying processes. These transformations have a big impact on the environmental behavior of arsenic because different chemical forms exhibit differences in mobility and toxicity. Moreover, exposure to toxicants may alter the physiology and structure of biofilms, leading to changes in ecosystem function and trophic relations. In this review we also explain how microorganisms (i.e., biofilms) can influence the effects of arsenic exposure on other key constituents of aquatic ecosystems such as fish. At the end, we present two real cases of fluvial systems with different origins of arsenic exposure (natural vs. anthropogenic) that have improved our comprehension of arsenic biogeochemistry and toxicity in freshwaters, the Pampean streams (Argentina) and the Anllóns River (Galicia, Spain). We finish with a briefly discussion of what we consider as future research needs on this topic. This work especially contributes to the general understanding of biofilms influencing arsenic biogeochemistry and highlights the strong impact of nutrient availability on arsenic toxicity for freshwater (micro) organisms.


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