IMAGING ORGANOMINERALISATION OF THE VERMELHA MICROBIAL ALGAL MAT

2018 ◽  
Author(s):  
Maurice P. Testa ◽  
◽  
Brenda E. Kirkland
Keyword(s):  
1997 ◽  
Vol 33 (4) ◽  
pp. 179-186 ◽  
Author(s):  
NOBUTADA NAKAMOTO ◽  
NORIYASU IWASE ◽  
KENTARO NOZAKI ◽  
MASASHI SAKAI

Ecology ◽  
1969 ◽  
Vol 50 (4) ◽  
pp. 645-652 ◽  
Author(s):  
Jerry L. Wilhm ◽  
Joseph Long
Keyword(s):  

2013 ◽  
Vol 9 (3) ◽  
pp. 243-250

In coastal marine environments, with shallow, warm and calm waters, it is sometimes possible to observe the presence of organosedimentary structures that are commonly flat and laminar in shape. These structures are called algal mats or recent stromatolites due to their remarkable similarities to fossil stromatolites. The aim of this work was the study of the distribution of the various forms of Cu and Cd in the main layers of coastal algal mats in a closed bay at Anavissos, on the coast of Saronikos Gulf. Small sediment cores were collected from one point inside the cove on a seasonal basis and the trace metals extracted according to the BCR sequential extraction method. The main results of the study were: Most of the labile Cd was associated with small inorganic grains or lime particles. The contribution of the fraction associated with Mn and Fe oxides, was similar to that adsorbed to organic compounds and sulfides. The high contribution of the labile Cd to the total element (over 85%) was a strong indication of anthropogenic origin. On the other hand, most of the Cu in the sediment was associated with the crystal lattice (74%). Cu showed increased seasonal fluctuation; most of its labile forms were associated with organic compounds and sulfides whereas the less abundant form was that associated with Mn and Fe oxides. On the whole, the sediments were slightly enriched in Cd, while the concentrations of Cu were normal for the region.


1991 ◽  
Vol 35 (3-Part1) ◽  
pp. 438-450 ◽  
Author(s):  
C. Vance Haynes

AbstractAt the Murray Springs Clovis site in southeastern Arizona, stratigraphic and geomorphic evidence indicates that an abnormally low water table 10,900 yr B.P. was followed soon thereafter by a water-table rise accompanied by the deposition of an algal mat (the “black mat”) that buried mammoth tracks, Clovis artifacts, and a well. This water-table fluctuation correlates with pluvial lake fluctuations in the Great Basin during and immediately following Clovis occupation of that region. Many elements of Pleistocene megafauna in North America became extinct during the dry period. Oxygen isotope records show a marked decrease in δ18O correlated with the Younger Dryas cold-dry event of northern Europe which ended 10,750 yr B.P., essentially the same time as the water table began to rise in southeastern Arizona. Clovis hunters may have found large game animals easier prey when concentrated at water holes and under stress. If so, both climate and human predation contributed to Pleistocene extinction in America.


1981 ◽  
Vol 27 (95) ◽  
pp. 11-18 ◽  
Author(s):  
Howard Thomas Brady ◽  
Barry Batts

AbstractAn extensive system of mirabilite (Na2SO4· 10H2O) beds has been mapped on the Ross Ice Shelf near Black Island. The salt beds are normally underlain by a thin layer of mud and their surface is covered by a non-marine algal mat and boulder lag. These authors suggest the salt has been formed by the displacement of sub-ice-shelf brines to the ice-shelf surface. Evidence also suggests that other terrestrial mirabilite beds in the McMurdo Sound area were formed in the same manner and deposited by the Ross Ice Shelf during its Wisconsin retreat from McMurdo Sound. Mirabilite salt in the dry valleys, southern Victoria Land, may have also originated from melt waters which dissolved ice-shelf mirabilite beds.


1986 ◽  
Vol 43 (6) ◽  
pp. 1156-1162 ◽  
Author(s):  
Michael A. Reiter ◽  
Robert E. Carlson

Water velocity is commonly accepted as a factor in the development of benthic algal mats in streams. Within a stream, two different zones of velocity are observed: the free-water velocity of the open water and the local velocity near the stream substrate. A closed laboratory flume system was used to observe the taxonomic composition of benthic algal mats and corresponding changes in the local velocities under different free-water velocities. As the algal mat developed under each experimental velocity, local velocities diminished and eventually became equal in all sections, while free-water velocities remained different. After a period of maximum taxonomic diversity during the first 2 wk of mat development, taxonomic composition, relative abundance of the taxa, and dry weight biomass became increasingly similar in the three velocity regimes, although the mats appeared different upon casual observation. Differences in composition and morphology in natural algal mats may not result from differences in current velocity, and the idea of a "closed monolayer" algal mat may not be appropriate in all situations.


2019 ◽  
Vol 21 (11) ◽  
pp. 4283-4299 ◽  
Author(s):  
Martin Rippin ◽  
Martina Pichrtová ◽  
Erwann Arc ◽  
Ilse Kranner ◽  
Burkhard Becker ◽  
...  

2017 ◽  
Vol 74 ◽  
pp. 1-9 ◽  
Author(s):  
Marta Pikosz ◽  
Beata Messyasz ◽  
Maciej Gąbka

1998 ◽  
Vol 10 (1) ◽  
pp. 39-44 ◽  
Author(s):  
A. McMinn ◽  
C. Ashworth

Oxygen microelectrodes were used to measure the photosynthetic rates of Antarctic fast ice algal mats. Using the oxygen flux across the diffusive boundary layer below the fast ice at Davis, a productivity range of 0–1.78 mg C m−2 h−1 was measured. This is at the lower end of fast ice productivity estimates and suggests that conventional 14C techniques may overestimate sea ice algal mat productivity. Photosynthetic capacity (P max) approached 0.05 mg C. (mg chl a)−1 h −1. Onset of photosynthesis saturation, E k, was found at c. 14 μmol photons m −2 s −1. The irradiance of photoinhibition onset, E inh, was c. 20 μmol photons m −2 s −1 and the irradiance at the compensation point, E c, was 4 μmol photons m −2 s −1.


Nature ◽  
1983 ◽  
Vol 305 (5934) ◽  
pp. 520-523 ◽  
Author(s):  
Adolfo G. Requejo ◽  
James G. Quinn

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