Research Article| May 01, 1972 Geochemistry of Ferromanganese Oxide Concretions and Associated Deposits in Lake Ontario D. S CRONAN; D. S CRONAN Department of Geology, University of Ottawa, Ottawa, Ontario, Canada Search for other works by this author on: GSW Google Scholar R. L THOMAS R. L THOMAS Canada Centre for Inland Waters, Burlington, Ontario, Canada Search for other works by this author on: GSW Google Scholar GSA Bulletin (1972) 83 (5): 1493–1502. https://doi.org/10.1130/0016-7606(1972)83[1493:GOFOCA]2.0.CO;2 Article history received: 14 Jun 1971 rev-recd: 16 Nov 1971 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D. S CRONAN, R. L THOMAS; Geochemistry of Ferromanganese Oxide Concretions and Associated Deposits in Lake Ontario. GSA Bulletin 1972;; 83 (5): 1493–1502. doi: https://doi.org/10.1130/0016-7606(1972)83[1493:GOFOCA]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A large deposit of ferromanganese oxide coated sands and scattered manganese nodules occurs in the northern portion of Lake Ontario. The Mn and Fe contents of the concretions are similar to those in concretions from other environments, while their Ni, Cu, and Co contents are lower than in deep-sea nodules, but higher than in most previously described lacustrine concretions. Pb and Zn are high in the coatings and exceed the concentrations found in many previously analyzed Mn deposits. Within the deposit, Mn, Ni, Co, and Zn contents are correlated, and they vary inversely with Fe. Mn, Fe, Ni, Cu, and Pb are present in the interstitial waters of the sediments underlying the deposit in higher concentrations than in the overlying lake waters, thus providing a potential source of metals for concretion formation.The origin and compositional variations in the deposit possibly can be explained in terms of the fractionation and precipitation of Fe and Mn as a result of redox variations in the lake sediments. Eh increases from south to north across the deposit in such a way that iron may be selectively oxidized and precipitated in the south and manganese, in the north. The upward diffusion of Mn, Fe, and associated elements from the underlying sediments probably provides the principal source of the metals in the south of the deposit, while metal-enriched bottom waters are probably the principal source in the north. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Carbon partitioning and rhizodeposition by corn (Zea mays L.) and bromegrass (Bromus inermis Leyss.) were evaluated after 1 and 2 yr of cropping. 14 C-labelled CO 2 was used as a tracer of assimilated C. Most of the 14 C assimilated by corn was translocated to the aboveground plant (nearly 90%), whereas the amounts located above and below ground in bromegrasss were approximately 60 and 40%, respectively. The total amount of rhizodeposition by bromegrass was twice that of corn after both 1 and 2 yr of cropping. A model was developed to predict the amount of carbon input by the below-ground systems of both crops on a field scale. The model indicates that the annual carbon rhizodeposition by bromegrass would be nearly five times higher than the below-ground carbon input under corn. Key words: Carbon partitioning, rhizodeposition, soil structure, root exudates
Abstract The activity of soluble and immobilized pronase in the presence of montmorillonite was examined using a differential spectrophotometric technique over a 100‐sec incubation period. On the basis of equivalent amounts of enzyme protein, the immobile enzyme had only 28% of the activity of the soluble pronase in the absence of clay. However, in the presence of clay, the immobile pronase was much less inhibited, retaining an average of 75% of its activity while the soluble pronase retained only 31% of its activity. The differential spectrophotometric procedure was satisfactory for monitoring the enzyme action in the presence of suspended clay.
Ninety-six samples of the uppermost 3 cm of sediment were taken from the Big Bay section of the Bay of Quinte. The samples were analyzed for grain size, Eh, pH, organic C, and inorganic C. The Big Bay section contains three depositional basins and has a mean depth of 4.7 m. The sediment distribution was mapped by conventional echosounding and showed that the coarser sediments, sands and gravels, occurred on the northern shore and in the eastern part of the study area, with clayey silts and silty clays offshore in the three depositional basins. This distribution was confirmed by the grain size analyses.The textural properties of the sediments, mean grain size, standard deviation, skewness, and kurtosis, are related to the variable mixing of three populations comprising gravel, sand, and silt/clay. Trends in the grain-size statistics related to sediment distribution suggested that the distribution observed is a result of increasing energy levels downwind under prevailing westerly and southwesterly winds.
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