Impact of In-channel Organic Debris on Fluvial Process and Channel Form

Author(s):  
Nick Wallerstein ◽  
C. R. Thorne
Author(s):  
John M. Wehrung ◽  
Richard J. Harniman

Water tables in aquifer regions of the southwest United States are dropping off at a rate which is greater than can be replaced by natural means. It is estimated that by 1985 wells will run dry in this region unless adequate artificial recharging can be accomplished. Recharging with surface water is limited by the plugging of permeable rock formations underground by clay particles and organic debris.A controlled study was initiated in which sand grains were used as the rock formation and water with known clay concentrations as the recharge media. The plugging mechanism was investigated by direct observation in the SEM of frozen hydrated sand samples from selected depths.


2020 ◽  
Author(s):  
Alice Hinzmann ◽  
◽  
Trent Foky ◽  
Chantal Iosso ◽  
April I. Phinney ◽  
...  
Keyword(s):  

1988 ◽  
Vol 23 (2) ◽  
pp. 1135-1141 ◽  
Author(s):  
Lars O. Hedin ◽  
Marilyn S. Mayer ◽  
Gene E. Likens
Keyword(s):  

2010 ◽  
Vol 10 (4) ◽  
pp. 195-203 ◽  
Author(s):  
Ivan Sazima ◽  
Cristina Sazima

Several bird species feed on a variety of external parasites and epibionts, organic debris, dead and wounded tissue, clots and blood, and secretions from the body of other vertebrates (hosts or clients). We present an overview of so called cleaner birds from the Neotropics based on field records, literature, and photo survey. We found that 33 bird species in 16 families practice cleaning even if some of them do so very occasionally. The birds range from the Galápagos ground finch Geospiza fuliginosa to the widespread black vulture Coragyps atratus. Clients mostly are large herbivores such as capybaras, deer, and livestock, but also include medium-sized herbivores such as iguanas and tortoises, and carnivores such as boobies and seals - a few bird species associate with these latter marine mammals. No carnivorous terrestrial mammal client is recorded to date except for a domestic dog, from whose hair black vultures picked organic debris. Some clients adopt particular inviting postures while being cleaned, whereas others are indifferent or even disturbed by the activity of cleaner birds. Capybaras, giant tortoises, and iguanas are among the inviting clients, whereas boobies try to dislodge the 'vampire' finch Geospiza difficilis. Most of the Neotropical cleaner birds may be lumped in one broad category (omnivores that dwell in open areas and associate with large to medium-sized herbivores). A second, restricted category accommodates some species from Patagonia and the Galápagos Islands (omnivores that dwell in open areas and associate with carnivorous marine mammals, or seabirds and marine reptiles). Two still more restricted categories accommodate the following: 1) forest-dwelling cleaner birds; and 2) marine coastal cleaners. Additional records of Neotropical cleaner birds will mostly fall in the broad category.


2017 ◽  
Vol 65 (4) ◽  
pp. 678-694 ◽  
Author(s):  
Leonardo Rubi Rörig ◽  
Maevi Ottonelli ◽  
Ana Gabriela Itokazu ◽  
Marcelo Maraschin ◽  
João Vitor Heberle Lins ◽  
...  

Abstract Balneário Camboriu (SC - Brazil) is a touristic city where the disordered growth of the urban population and the implementation of coastal works without proper evaluation generated environmental impacts and affected the sanitary quality of water and sediment of Camboriu River and marine adjacent area. One of the most recent and alarming phenomena observed are the blooms of invasive bryozoans (Arboscuspis bellula and Membraniporopsis tubigera) associated with epibenthic diatoms (Amphitetras antediluviana and Biddulphia biddulphiana). Several clues associate these phenomena, started in 2003, with the excess of nutrients and organic matter in the Camboriú cove and large coastal works such as dredging, landfills and construction of jetties, leading to changes in benthic ecological structure. Being an aesthetic and environmental health problem, the concern of the scientific community and government agencies intensified as the occurrences become more frequent and persistent. This research addresses this issue through environmental and experimental studies. Samplings of the benthic material collected by boat and diving, and blooms monitoring were the environmental approach. The laboratory work included the algal isolation and culture, in addition to growth conditions assessment and chemical biomass analysis. Monitoring data showed a seasonal trend in the blooms, with more conspicuous events in warmer months. Diatoms increase in abundance in colder months and bryozoans in the warmer ones. The diatom A. antediluviana, predominant in the blooms, grew satisfactorily in laboratory cultivation, showing better growth in media with higher concentrations of silicate and phosphate. Bryozoans showed slow growth in laboratory conditions. The deposited material collected in the environment showed low concentrations of saturated fatty acids, but the high biomass suggest a possible use for biofuels production. Biomass samples dominated by bryozoans showed moderate antimicrobial activity against Klebsiella pneumoniae. The explanation for the occurrence of these blooms are still inconclusive, but there is considerable evidence that it is a synergistic effect between the high concentration of bacteria and organic debris in the water related to local pollution and the elimination of natural competitors by coastal works.


2017 ◽  
Vol 10 (1) ◽  
pp. 21
Author(s):  
Shirin Malek ◽  
Mozammal Hossain ◽  
Md. Abdul Gafur ◽  
Md. Shahjalal Rana ◽  
Md. Ali Asgor Moral

<p>The purpose of the present study was to compare the marginal integrity of resin modified glass ionomer cement with that of resin sealant, <em>in vitro</em>. Forty artificial pit and fissure cavities were prepared in occlusal surface of extracted premolar teeth by using ¼ round carbide bur. Cavities were condensed with artificial organic debris followed by cleaning with prophylaxis pumice brush and paste and then separated into two treatment groups. In Group A, 15 fissure cavities were sealed by resin sealant and in Group B, 15 fissure cavities were sealed by resin modified glass ionomer sealant. These specimens were subjected to thermo-cycling followed by dye penetration test. The remaining 5 cavities from each group were analyzed for debris score by the SEM. The results of the microleakage test showed that the efficacy of preventing microleakage of samples sealed by resin modified glass ionomer sealant was higher than the samples sealed by resin sealant. However, no significant differences were found. It can be concluded that use of resin modified glass ionomer sealant is a good alternative for sealing pits and fissures.</p>


Author(s):  
Carl Legleiter

The Snake River is a central component of Grand Teton National Park, and this dynamic fluvial system plays a key role in shaping the landscape and creating diverse aquatic and terrestrial habitat. The river’s complexity and propensity for change make effective characterization of this resource difficult, however, and conventional, ground-based methods are simply inadequate. Remote sensing provides an appealing alternative approach that could facilitate resource management while providing novel insight on the factors controlling channel form and behavior. In this study, we evaluate the potential to measure the morphology and dynamics of a large, complex river system such as the Snake using optical image data. Initially, we made use of existing, publicly available images and basic digital aerial photography acquired in August 2010. Analysis to date has focused on estimating flow depths from these data, and preliminary results indicate that remote bathymetric mapping is feasible but not highly accurate, with important constraints related to the limited radiometric resolution of these data sets. Additional, more sophisticated hyperspectral data are scheduled for collection in 2011, along with further field work.


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