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87:6235 Modeling solute transport and sulfate reduction in marsh sediments
948
C. Chemical Oceanography
C150. Particulate matter 87:6231 Yanagi, Tetsuo, Kumiko Azetsu, Katsuhisa Honda and. Ryo Tatsukawa, 1986. A numerical simulation of suspended sediments flocculation in the estuary. Mer, Tokyo, 24(4):202-209. A steady state numerical model has been developed which includes the flocculation process of suspended sediments. The turbidity maximum of suspended sediments in the middle layer at the central part of the estuary is formed only in the case where the model includes the flocculation process. The age and residence time of each suspended sediment are also discussed. Dept. of Ocean Engng, Ehime Univ., Bunkyo 3, Maysuyama, 790, Japan.
OLR (1987) 34 (1])
flat was taking up P near the maximal rate measured in the laboratory. The rate of P uptake was slow compared to the advection of P across most barrier reef flats and compared to the rate of C fixation. Dept. of Zool., Univ. of Western Australia, Nedlands, WA 6009, Australia. 87:6234 Atkinson, M.J. and D.F. Smith, 1987. Slow uptake of 32p over a barrier reef flat. Limnol. Oceanogr., 32(2):436-441.
(see also D-SUBMARINE GEOLOGY AND GEOPHYSICS)
A double-label experiment with 32p and 3H was conducted over a reef flat dominated by algae in the Indian Ocean. Very little 32p was removed relative to 3H, demonstrating relatively slow exchange of P between the benthos and the water column. The best estimate of the constant of proportionality (k) between the rate of respiration-normalized P uptake (P*/R*) and concentration of P([P]) was 9.2 L (mmol 02) t, about the same value reported for two other reef flats. Dept. of Zool., Univ. of Western Australia, Nedlands, WA 6009, Australia.
87:6232 Anderson, L.G., David Dyrssen and Jens Skei, 1987. Formation of chemogenic calcite in super-anoxic seawatermFramvaren, southern Norway. Mar. Chem., 20(4):361-376.
87:6235 Casey, W.H. and A.C. Lasaga, 1987. Modeling solute transport and suffate reduction in marsh sediments. Geochim. cosmochim..4cta, 51(5): 11091120.
Framvaren contains 7-8 mmol L ~of sulphide and a total carbonate concentration of 18.5 mmol k g ~ in the bottom water. The chemistry of calcium has been studied, considering sources, biogenic and chemical processes and sedimentary sinks. Calcium associated with the bacteria biomass at the redox interface (18 m depth) appears to be the primary source of dissolved calcium in the deep, anoxic water. Excess calcium and high total carbonate cause supersaturation of calcite, which is precipitated chemogenically. Calcite is identified in sediment trap material and bottom sediments below the depth of supersaturation. Dept. of Analytical and Mar. Chem., Chalmers Univ. of Tech., S-412 96 Gothenburg, Sweden.
Diffusion models of salinity can account for the observed profiles but only as long as the marsh is inundated. Complexities introduced to the solute transport equations by sediment desiccation invalidate steady-state modeling. Concentration profiles of dissolved products of sulfate reduction, such as bicarbonate, require months to reestablish a steady state after being disrupted. If the profiles of dissolved products of sulfate reduction are disrupted seasonally, as by fluctuation in the water table, they may remain transient throughout the year. Sandia Natl. Lab., Geochem. Div. 1543, Albuquerque, NM 87185, USA.
C180. Geochemistry, biogeochemistry
87:6233 Atkinson, M.J., 1987. Rates of phosphate uptake by coral reef flat communities. Limnol. Oceanogr., 32(2):426-435.
87:6236 Chanton, J.P., C.S. Martens and M.B. Goldhaber, 1987. Biogeochemical cycling in an organic-rich coastal marine basin. 7. Sulfur mass balance, oxygen uptake and sulfide retention. Geochim. cosmochim. Acta, 51(5): 1187-1199.
Rates of P" uptake for subsamples of a barrier reef community were determined in aquaria and compared to the net rate of P uptake measured in the field for the entire reef flat. Constants of proportionality between rate of P uptake (per respiration rate) and concentration of P were the same for the experimental communities and the reef flat. The reef
Sulfur and oxygen fluxes were quantified in the seasonally varying anoxic marine sedimentary system of Cape Lookout Bight, N.C., U.S.A. The mean annual sulfate reduction rate was 18.2_ + 1.6 molesm 2 . y ~, which added to the estimate of the detrital sulfur input of 1.2_+4.4 gave a total sulfur input of 19.4___4.7 moles.m2-y-L The sulfide flux to the
C. Chemical Oceanography
C150. Particulate matter 87:6231 Yanagi, Tetsuo, Kumiko Azetsu, Katsuhisa Honda and. Ryo Tatsukawa, 1986. A numerical simulation of suspended sediments flocculation in the estuary. Mer, Tokyo, 24(4):202-209. A steady state numerical model has been developed which includes the flocculation process of suspended sediments. The turbidity maximum of suspended sediments in the middle layer at the central part of the estuary is formed only in the case where the model includes the flocculation process. The age and residence time of each suspended sediment are also discussed. Dept. of Ocean Engng, Ehime Univ., Bunkyo 3, Maysuyama, 790, Japan.
OLR (1987) 34 (1])
flat was taking up P near the maximal rate measured in the laboratory. The rate of P uptake was slow compared to the advection of P across most barrier reef flats and compared to the rate of C fixation. Dept. of Zool., Univ. of Western Australia, Nedlands, WA 6009, Australia. 87:6234 Atkinson, M.J. and D.F. Smith, 1987. Slow uptake of 32p over a barrier reef flat. Limnol. Oceanogr., 32(2):436-441.
(see also D-SUBMARINE GEOLOGY AND GEOPHYSICS)
A double-label experiment with 32p and 3H was conducted over a reef flat dominated by algae in the Indian Ocean. Very little 32p was removed relative to 3H, demonstrating relatively slow exchange of P between the benthos and the water column. The best estimate of the constant of proportionality (k) between the rate of respiration-normalized P uptake (P*/R*) and concentration of P([P]) was 9.2 L (mmol 02) t, about the same value reported for two other reef flats. Dept. of Zool., Univ. of Western Australia, Nedlands, WA 6009, Australia.
87:6232 Anderson, L.G., David Dyrssen and Jens Skei, 1987. Formation of chemogenic calcite in super-anoxic seawatermFramvaren, southern Norway. Mar. Chem., 20(4):361-376.
87:6235 Casey, W.H. and A.C. Lasaga, 1987. Modeling solute transport and suffate reduction in marsh sediments. Geochim. cosmochim..4cta, 51(5): 11091120.
Framvaren contains 7-8 mmol L ~of sulphide and a total carbonate concentration of 18.5 mmol k g ~ in the bottom water. The chemistry of calcium has been studied, considering sources, biogenic and chemical processes and sedimentary sinks. Calcium associated with the bacteria biomass at the redox interface (18 m depth) appears to be the primary source of dissolved calcium in the deep, anoxic water. Excess calcium and high total carbonate cause supersaturation of calcite, which is precipitated chemogenically. Calcite is identified in sediment trap material and bottom sediments below the depth of supersaturation. Dept. of Analytical and Mar. Chem., Chalmers Univ. of Tech., S-412 96 Gothenburg, Sweden.
Diffusion models of salinity can account for the observed profiles but only as long as the marsh is inundated. Complexities introduced to the solute transport equations by sediment desiccation invalidate steady-state modeling. Concentration profiles of dissolved products of sulfate reduction, such as bicarbonate, require months to reestablish a steady state after being disrupted. If the profiles of dissolved products of sulfate reduction are disrupted seasonally, as by fluctuation in the water table, they may remain transient throughout the year. Sandia Natl. Lab., Geochem. Div. 1543, Albuquerque, NM 87185, USA.
C180. Geochemistry, biogeochemistry
87:6233 Atkinson, M.J., 1987. Rates of phosphate uptake by coral reef flat communities. Limnol. Oceanogr., 32(2):426-435.
87:6236 Chanton, J.P., C.S. Martens and M.B. Goldhaber, 1987. Biogeochemical cycling in an organic-rich coastal marine basin. 7. Sulfur mass balance, oxygen uptake and sulfide retention. Geochim. cosmochim. Acta, 51(5): 1187-1199.
Rates of P" uptake for subsamples of a barrier reef community were determined in aquaria and compared to the net rate of P uptake measured in the field for the entire reef flat. Constants of proportionality between rate of P uptake (per respiration rate) and concentration of P were the same for the experimental communities and the reef flat. The reef
Sulfur and oxygen fluxes were quantified in the seasonally varying anoxic marine sedimentary system of Cape Lookout Bight, N.C., U.S.A. The mean annual sulfate reduction rate was 18.2_ + 1.6 molesm 2 . y ~, which added to the estimate of the detrital sulfur input of 1.2_+4.4 gave a total sulfur input of 19.4___4.7 moles.m2-y-L The sulfide flux to the