Metal accumulation rates in sediments from the Southwestern Pacific Basin.

Schmitz, W.; Glasby, G. P.; Stoffers, Peter; Mangini, Augusto

doi:10.2343/geochemj.33.79

Cited by 2 publications

(2 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other solid phases include CaCO 3 and SiO 2 , which dissolve using first‐order dissolution kinetics, and nonreactive clay. The model does not currently simulate time‐dependent behavior, such as the generation of relict manganese layers [ Berger et al , 1983; Schmitz et al , 1999].…”

Section: Model Formulationmentioning

confidence: 99%

A model of suboxic sedimentary diagenesis suitable for automatic tuning and gridded global domains

Archer

Morford

Emerson

2002

Global Biogeochemical Cycles

121

147

View full text Add to dashboard Cite

[1] We present a new model for oxic and anoxic diagenesis of shallow and deep-sea sediments based on an efficient solver for steady state pore water and solid phase diffusion/reaction/advection equations. The model, called ''Muds'', is orders of magnitude faster than solvers of the corresponding time-dependent equations. The model resolves Mn and Fe/S geochemistry as well as pore water pH and CaCO 3 dissolution. The model speed opens application possibilities that are impossible for time-dependent models, including automatic tuning of uncertain parameters, and deployment of the model in gridded global domains. The kinetic rate constants for respiration and bioturbation are parameterized as functions of the organic carbon rain to the seafloor, based on existing parameterizations in the literature. Seven uncertain model parameters, including many of the rate constant parameterizations, were tuned to minimize the misfit to observations from 53 sedimentary locations throughout the ocean. The model tuning knobs were the fractions of labile and refractory organic matter in the sedimenting material, the NO 3 À , Mn, Fe, and S respiration rate constant parameterizations, and the depth scales of respiration and of pore water irrigation. We searched for adequate fit values of these parameterizations using a simulated annealing method. The cost function (degree of misfit) was based on a comparison of pore water (NO 3 À , NH 4 + , Mn 2+ , and Fe 2+ ) and solid phase (organic carbon and MnO 2 ) model results with data. Many of the tuning parameters are constrained to ±50% or better. The model is most skillful at predicting organic carbon concentration, depth of NO 3 À penetration, and pore water Fe 2+ , and less so for Mn 2+ , NH 4 + , and solid phase MnO 2 . The model misses some of the very high sediment surface MnO 2 concentrations observed in, for example, the California Borderlands. We believe that these sites must receive a higher input of reactive Mn than the crustal abundance of the clay rain. The model was deployed on every 2°Â 2°grid point below 1000 m of the global seafloor, using gridded maps of organic carbon rain to the seafloor and overlying water chemistry. The deep-sea carbon burial efficiency is 7%, with 95% of respiration by oxic metabolism. The model was also run against a new depth-oxygen hypsometry of the global ocean, with sediment area as a function of overlying oxygen concentration and average depth related to carbon fluxes, to include the effects of shallow water sediments. This analysis predicts that shallow waters (<1000 m) account for 88% of respiration, and oxygen accounts for 66% of respiration overall. Denitrification is closely coupled to organic nitrogen fluxes to the sediment, and the global rate is estimated to be 1.4 Â 10 14 mol yr À1 , a factor of 6 -8 higher than the corresponding estimate from Middelburg et al. [1996], throwing the nitrogen cycle in the ocean into imbalance.

show abstract

Section: Model Formulationmentioning

confidence: 99%

A model of suboxic sedimentary diagenesis suitable for automatic tuning and gridded global domains

Archer

Morford

Emerson

2002

Global Biogeochemical Cycles

121

147

View full text Add to dashboard Cite

show abstract

“…The climatic and oceanographic evolution of the northwest Pacific Ocean throughout the Cenozoic Era has been studied for many years [e.g., Bischoff et al , 1979; Marchig et al , 1982; Rea and Dixon , 1983; Janecek and Rea , 1985; Rea et al , 1985; Yamamoto , 1988; Theyer et al , 1989; Hovan et al , 1989, 1991; Krissek and Janecek , 1993; Nakai et al , 1993; Jones et al , 1994; Rea , 1994; Rea and Hovan , 1995; Aoki and Kohyama , 1998; Rea et al , 1998; Asahara et al , 1999; Bralower et al , 2006; Thomas , 2004]. In particular, chemical studies that have examined changes in lithogenic, authigenic/hydrogenous/hydrothermal (AHH), and biogenic sedimentary components, and their possible end‐member source compositions, provide valuable insight into changes in climate and ocean conditions in the past [ Heath and Dymond , 1977; Dymond , 1981; Leinen and Heath , 1981; Clauer et al , 1982; Lyle , 1983; Marchig and Erzinger , 1986; Leinen and Pisias , 1984; Heath et al , 1985; Matsumoto et al , 1985; Nohara and Kato , 1985; Lyle et al , 1986; Marchig and Erzinger , 1986; Leinen , 1987; Piper et al , 1988; Leinen , 1989; Kyte et al , 1993; Bailey , 1993; Aoki and Kohyama , 1998; Schmitz et al , 1999; Dubinin and Sval'nov , 2001; Zhou and Kyte , 1992].…”

Section: Introductionmentioning

confidence: 99%

Geochemical evolution of the central Pacific Ocean over the past 56 Myr

Ziegler

Murray

2007

Paleoceanography

View full text Add to dashboard Cite

[1] We measured the elemental concentrations of 69 sediment samples collected at Ocean Drilling Program Site 1215 and employed a suite of statistical methods and elemental ratios to quantify the lithogenic, biogenic, and authigenic/hydrogenous/hydrothermal (AHH) components. We show that the changes in their abundance record (1) northwestward migration of the Pacific Plate, (2) changes in climatic and oceanographic processes associated with the transition from the Eocene ''greenhouse'' into the Oligocene ''icehouse,'' and (3) changes in Pacific spreading rates and plate reorganization. The distributions of three separate lithogenic end-members depend on the latitudinal positioning of the site underneath the different wind belts. Locations north of 22°N received material from Asia, which was transported to the central Pacific via the westerlies. Locations between 20°and 22°N display a silicic volcanic composition and may reflect the boundary between westerlies and northeast trade winds. Locations south of 20°N are geochemically (e.g., Cr/Ta, Sc/Th, etc.) distinct from locations north of 22°N and suggest a North American origin. Rb/Sc significantly increases from values of 2.8 g g À1 at $20-22 Ma to 5.7 g g À1 in the modern, recording the development of the east Asian monsoon and formation of Asian loess. During the early to mid-Eocene (53-54 Ma), when Site 1215 was located at $11°-13°N and was above the carbonate compensation depth, export production increased by 40-55% and was $25% greater than the modern value at 9°N. The AHH component dominated from late Eocene to the late Miocene and during the late Eocene may have been driven by elevated hydrothermal activity during increased seafloor spreading.

show abstract

Metal accumulation rates in sediments from the Southwestern Pacific Basin.

Cited by 2 publications

References 27 publications

A model of suboxic sedimentary diagenesis suitable for automatic tuning and gridded global domains

A model of suboxic sedimentary diagenesis suitable for automatic tuning and gridded global domains

Geochemical evolution of the central Pacific Ocean over the past 56 Myr

Contact Info

Product

Resources

About