Estimates of Sediment Fluxes in Long Island Sound

Kim, Byung-Hwan; Bokuniewicz, Henry

doi:10.2307/1351659

Cited by 15 publications

(8 citation statements)

References 12 publications

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“…In Long Island Sound, continentally derived 32 Si can account for a maximum of 0.11–0.13 dpm/kg of the recovered 32 Si activity, ~20% of total 32 Si activity at this study site. All of these environments also import water, sediment, and marine biogenic Si, from offshore due to estuarine flow (Kim & Bokuniewicz, ; Shiller & Boyle, ; Sun et al, ; Turner & Rabalais, ; Wolanski et al, ; Aller, Blair, et al, ). From these calculations, it is evident that the majority of the 32 Si bulk activity measured in the Gulf of Papua, the Mississippi Delta, and Long Island Sound deposits must have a marine biogenic Si source rather than a continental one.…”

Section: Discussionmentioning

confidence: 99%

“…The estuary consists of three major basins, and the site sampled in this study comes from Smithtown Bay, located in the Central Basin and representative of silty/clay sediments which cover~60% of the total area of the sound (Sun et al, 1994;Latimer et al, 2014). Modeling of fluvial inputs to the Sound suggests that about 45% of the total sediment supply has a source in the neighboring coastal ocean (Kim & Bokuniewicz, 1991), with the majority of muddy sediment accumulating in the western and central sound (Kim & Bokuniewicz, 1991;Latimer et al, 2014). The top few centimeters to decimeters of deposits in the sound are rapidly reworked by bioturbation and are underlain by a slower reworked layer down to 1-2 m (Aller & Cochran, 1976;Goldhaber et al, 1977;Benninger et al, 1979).…”

Section: Study Sitesmentioning

confidence: 99%

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The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic ³²Si

Rahman

Aller

Cochran

2017

Global Biogeochemical Cycles

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Burial of biogenic silica (bSitotal) in high sedimentation rate continental margins remains highly uncertain. Cosmogenic 32Si (t1/2~140 years) can be used to trace the fates of bSitotal postdeposition, including as opal (bSiopal) and diagenetically altered opal (bSialtered), the latter dominantly authigenic clay (bSiclay). To determine the magnitude and form of bSitotal storage in coastal sediments, conventional operational leaches targeting bSiopal and bSialtered (including bSiclay) were modified for large‐scale samples necessary for measurement of 32Si. The 32Si activity was used to estimate total biogenic silica burial (bSitotal = bSiopal + bSialtered) in several depositional settings: Gulf of Papua, Gulf of Mexico, Long Island Sound, and in the previously studied Amazon‐Guianas deltaic system. In subtropical and temperate regions, 32Si was detected in both traditional biogenic silica leaches (bSiopal) and residual authigenic clays. Traditional bSiopal and modified operational leaches designed to target the most reactive authigenic silicates (~bSialtered) consistently underestimate authigenic clay formation (bSiclay) and thus the magnitude of bSitotal burial in temperate coastal zones and subtropical deltas by 2–4‐fold. In tropical deltas, 32Si activities in the residual fraction after removal of bSiopal demonstrate rapid and almost complete alteration of initial bSiopal to new forms, most likely bSiclay. Globally, 4.5–4.9 Tmol/yr Si may be trapped in marine nearshore deposits as rapidly formed clay (bSiclay), 100% of the “missing silica sink” in the marine silica budget.

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Section: Discussionmentioning

confidence: 99%

Section: Study Sitesmentioning

confidence: 99%

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic ³²Si

Rahman

Aller

Cochran

2017

Global Biogeochemical Cycles

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“…Mineral fluxes decreased to nearby Hudson River marshes after 1875, as farmlands were reforested [Pederson et al, 2005], and a similar transition likely occurred in the marshes along Long Island's north and eastern shores that are surrounded by young forests. A separate study in Long Island Sound used a box-modeling approach incorporating suspended sediment concentrations, settling rates, temperature, salinity, and water velocities and diffusion rates during 1988 and 1989 [Kim and Bokuniewicz, 1991] to calculate average sediment accumulation rates to the sounds benthos as 0.92 mm yr −1 [Kim and Bokuniewicz, 1991]. These rates are very close to rates determined from 210 Pb and 14 C in sediment cores in the sound (0.7 ± 0.1 mm yr −1 ), suggesting little centennialscale change in regional sediment availability [Kim and Bokuniewicz, 1991, and references therein].…”

Section: Chronologies Of Sediment Accretion and Mineral Depositionmentioning

confidence: 99%

Global climate changes recorded in coastal wetland sediments: Empirical observations linked to theoretical predictions

Kolker

Kirwan

Goodbred

et al. 2010

Geophysical Research Letters

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[1] Whether coastal areas are experiencing, and responding to, an accelerated rate of global sea-level rise (GSLR) is critically important for the ∼2 billion people living near Ea rth' s o cea ns. A cc retion rate s from a s uite of physiographically diverse coastal wetlands surrounding Long Island, NY accelerated during the 20th century at 2.3 ± 0.2 × 10 −2 mm yr −2 , which is comparable to reported rates of GSLR acceleration and global temperature changes. Wetlands varied in tidal range, salinity and geomorphic setting, and were located in embayments with limited human impacts in a region with limited and constant rates of subsidence. From geochronologies with temporal resolutions of 2-5 yr, we constructed new composite histories of sediment accretion and mineral deposition. Wetland dynamics are consistent with predictions from sedimentology and a numerical model of ecogeomorphic response, suggesting that these systems, and likely others worldwide, are responding to accelerated GSLR and related climatic changes. Citation: Kolker, A. S., M. L. Kirwan, S. L. Goodbred, and J. K. Cochran (2010), Global climate changes recorded in coastal wetland sediments: Empirical observations linked to theoretical predictions, Geophys. Res. Lett.,

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“…Net sedimentation rates are variable (up to -1.8 mm yr-') are found in the deep trough of the southern central basin (Kim and Bokuniewicz, 1991). Surfacemost (co.1 mm) sediments are resuspended frequently by tidal currents.…”

Section: Study Areamentioning

confidence: 99%

The sedimentary Mn cycle in Long Island Sound: Its role as intermediate oxidant and the influence of bioturbation, O<SUB>2</SUB>, and C<SUB>org</SUB> flux on diagenetic reaction balances

Aller¹

1994

issn: 0022-2402

212

111

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The potential importance of sedimentary Mn as a secondary oxidant and redox intermediate between O2 and Corg is often discounted in nearshore sediments. Study of the Mn cycle at 19 stations in Long Island Sound (LIS) demonstrates that sedimentary Mn can be a significant redox intermediate, accounting in many cases for 30-50% of the benthic O2 flux (annual mean-40 + 35%). At some sites and times, the import of solid oxidant as Mn in suspended matter is also apparently greater than the dissolved O2 flux to the bottom. The relative importance of the Mn cycle as redox intermediate varies substantially both seasonally (summer > fall > spring > winter) and spatially as a function of biogenic reworking, Corg flux, and O2 concentration in the overlying water. During warmer seasons, the net flux of Mn++ from the bottom decreases (-5-10x) generally from west to east, correlating directly with the benthic flux of planktonic debris and storage of residual Corg. Average fluxes are-0.003,0.43-0.94,2.2, and 0.43 mmol Mn/m2/d during winter, spring, summer, and fall respectively. Mn++ fluxes are relatively elevated during the spring bloom despite low temperatures. At most sites and times, surface sediments are enriched in excess Mn (4-17 kmol/g) above lithogenic background, with exponentially decreasing concentrations to 2-3 cm depth. A regular seasonal and spatial cycle of excess Mn occurs. Excess Mn inventories are often-5-10 tr,mol/cm2 but range from-0-25 umol/cm2. The highest inventories are found in mid LIS, in the transition area between high Corg flux and seasonally low O2 regions of the western Sound and the lower Corg flux, better oxygenated regions of central LIS. Excess Mn decreases at most sites following the spring plankton bloom and is lost entirely from westernmost sediments of highest Corg flux, several months before noticeable O2 depletion in overlying water. The bloom is a major factor in mobilization of metals into suspended matter and promotes lateral redistribution of Mn. Destratification and oxygenation of the water column in the fall results in the capture and reestablishment of excess sedimentary Mn in all regions of the Sound. Bioturbation transports Mn and Corg into anoxic sediment zones. When overlying water is well-oxygenated, the resulting Mn ++ is efficiently irreversibly adsorbed or reoxidized (-SO-90%, during summerfall), closing the sedimentary Mn cycle and inhibiting net Mn ++ fluxes. The internal Mn cycle is therefore most important as an intermediate oxidant during warm periods of high bioturbation, well-oxygenated overlying water, and moderate Corg flux. S species apparently dominate the direct reduction of Mn.

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Estimates of Sediment Fluxes in Long Island Sound

Cited by 15 publications

References 12 publications

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic ³²Si

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic ³²Si

Global climate changes recorded in coastal wetland sediments: Empirical observations linked to theoretical predictions

The sedimentary Mn cycle in Long Island Sound: Its role as intermediate oxidant and the influence of bioturbation, O<SUB>2</SUB>, and C<SUB>org</SUB> flux on diagenetic reaction balances

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Estimates of Sediment Fluxes in Long Island Sound

Cited by 15 publications

References 12 publications

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic 32Si

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic 32Si

Global climate changes recorded in coastal wetland sediments: Empirical observations linked to theoretical predictions

The sedimentary Mn cycle in Long Island Sound: Its role as intermediate oxidant and the influence of bioturbation, O<SUB>2</SUB>, and C<SUB>org</SUB> flux on diagenetic reaction balances

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The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic ³²Si

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic ³²Si