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Articles 1 - 4 of 4
Full-Text Articles in Earth Sciences
Assessing Ageing At Beaver Reservoir, Northwest Arkansas: Limnological, Geochemical & Paleolimnological Approach, Byron Anthony Winston
Assessing Ageing At Beaver Reservoir, Northwest Arkansas: Limnological, Geochemical & Paleolimnological Approach, Byron Anthony Winston
Graduate Theses and Dissertations
Access to potable water has been arguably one of the most important requisites for the advancement of human civilization on earth. As a result, man in his infinite wisdom devised the dam and formed reservoirs, (man- made lakes), to exploit water resources at will. In all natural lakes and reservoirs changes occur in the water quality parameters as it relates to chemical nutrients, temperature and turbidity over time. These changes are collectively referred to as "Reservoir Ageing", of which sedimentation and eutrophication are primary. Reservoir Ageing has consequences which adversely affect and defeat many of the intended uses of the …
Subaerial Freshwater Stromatolites In Deer Cave, Sarawak – A Unique Geobiological Cave Formation, Joyce Lundberg, Donald A. Mcfarlane
Subaerial Freshwater Stromatolites In Deer Cave, Sarawak – A Unique Geobiological Cave Formation, Joyce Lundberg, Donald A. Mcfarlane
WM Keck Science Faculty Papers
A suite of distinctive freshwater subaerial phosphatic stromatolites is developed close to the northeastern entrance of Deer Cave, Gunung Mulu National Park, Sarawak, Borneo, in conditions of very low light but ample supply of nutrients from guano. These stromatolites are not particulate; they are composed of alternating layers of more porous and more dense amorphous hydroxylapatite. This biomineralization occurs as moulds of coccoid (the majority) and filamentous (less abundant) cyanobacteria. Mineralization occurs at a pH of ~ 7.0 in the extracellular sheaths and in micro-domains of varying carbonate content in the surrounding mucus of the biofilm. The most recent surfaces …
A Note On The Occurrence Of A Crayback Stalagmite At Niah Caves, Borneo, Joyce Lundberg, Donald A. Mcfarlane
A Note On The Occurrence Of A Crayback Stalagmite At Niah Caves, Borneo, Joyce Lundberg, Donald A. Mcfarlane
International Journal of Speleology
Crayback stalagmites have mainly been reported from New South Wales, Australia. Here we document a small crayback in the entrance of Painted Cave (Kain Hitam), part of the Niah Caves complex in Sarawak, Borneo. Measuring some 65 cm in length and 18 cm in height, this deposit is elongate in the direction of the dominant wind and thus oriented towards the natural tunnel entrance. It shows the classic humpbacked long profile, made up of small transverse segments or plates, in this case the tail extending towards the entrance. The dark blue-green colour down the centre suggests that cyanobacterial growth follows …
In Situ Acetylene Reduction Activity Of Scytonema Julianum In Vapor Cave (Spain), Antonia Dolores Asencio, Marina Aboal
In Situ Acetylene Reduction Activity Of Scytonema Julianum In Vapor Cave (Spain), Antonia Dolores Asencio, Marina Aboal
International Journal of Speleology
Nitrogen fixation was measured in situ for the first time by acetylene reduction for a greyish mat composed of Scytonema julianum in cave-like environments. Mat-specific rates (129.9-215.7 nmol C2 H4 m-2 s-1 for daytime fixation and 65.1-120.6 nmol C2 H4 m-2 s-1 for nighttime fixation) recorded in the Vapor cave differed considerably due to the energy reserves stored during photosynthesis being exhausted and used in the dark phase. The most influential environmental parameter for nitrogen fixation in the Vapor cave is temperature in the daytime and nighttime fixations. Nitrogen fixation by cyanobacteria may contribute considerably to the overall nitrogen cycle …