A simple method for the rapid determination of biogenic opal in pelagic marine sediments

Mortlock, Richard A.; Froelich, Philip N.

doi:10.1016/0198-0149(89)90092-7

Cited by 1,155 publications

(589 citation statements)

References 21 publications

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“…Organic carbon was determined using a Costech 410 elemental analyzer at the Mass Spectrometry Laboratory (CICIMAR-IPN), and carbonates were determined using a UIC CM5014 carbon dioxide coulometer at the School of Marine Sciences (UABC). Biogenic silica was determined by molybdenum blue spectrophotometry (Mortlock and Froelich 1989).…”

Section: Methodsmentioning

confidence: 99%

Variability of marine biological productivity in the northeastern Pacific over the past millennium

Juárez¹,

Sánchez²,

González-Yajimovich³

2015

Cienc. Mar.

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ABSTRACT. In this study we present new data of biogenic opal (BO), organic carbon (OC), and calcium carbonate (CaCO 3 ) in a highresolution record from the western coast of Baja California Sur, Mexico. The variability of marine biological productivity in this area is dominated by El Niño and La Niña events on different time scales. The BO and OC contents showed a decrease between AD 1100 and 1400. From AD 1400 to the present, BO and OC showed a significant increase, indicating permanent upwelling conditions. The CaCO 3 content showed an inverse correlation with OC, which suggests that the exported OC fluxes are a significant factor controlling CaCO 3 dissolution in the sediment. The increase in BO and OC was synchronic with a decline in the number of El Niño events (6 ± 4 every 100 years) over the last 600 years of the millennium.Key words: biogenic opal, organic carbon, El Niño, La Niña, upwelling. RESUMEN.En este trabajo se presentan nuevos datos de un registro de alta resolución de ópalo biogénico (OB), carbono orgánico (CO) y carbonato de calcio (CaCO 3 ) en la costa occidental de Baja California Sur, México. En esta región, la variabilidad de la productividad biológica marina es dominada por la intensidad de los eventos El Niño y La Niña en diversas escalas de tiempo. Los contenidos de OB y CO disminuyeron durante el periodo de AD 1100 a 1400. En el periodo de AD 1400 al presente, el OB y CO aumentaron significativamente, lo cual indica condiciones permanentes de surgencia. El contenido de CaCO 3 se correlacionó inversamente con el CO, y esto sugiere que los flujos de CO exportado son un factor significativo que controla la disolución de CaCO 3 en el sedimento. El incremento en el OB y CO fue sincrónico con la disminución en el número de eventos de El Niño (6 ± 4 cada 100 años) para los últimos 600 años del milenio.Palabras clave: ópalo biogénico, carbono orgánico, El Niño, La Niña, surgencia.

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Section: Methodsmentioning

confidence: 99%

Variability of marine biological productivity in the northeastern Pacific over the past millennium

Juárez¹,

Sánchez²,

González-Yajimovich³

2015

Cienc. Mar.

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“…Percent biogenic opal was measured by alkaline extraction after Mortlock and Froelich [1989]. Carbonate was measured by coulometry on a UIC CM5130 Acidification Module.…”

Section: Study Area and Methodsmentioning

confidence: 99%

Opal burial in the equatorial Atlantic Ocean over the last 30 ka: Implications for glacial‐interglacial changes in the ocean silicon cycle

et al. 2007

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The Silicic Acid Leakage Hypothesis (SALH) suggests that, during glacial periods, excess silicic acid was transported from the Southern Ocean to lower latitudes, which favored diatom production over coccolithophorid production and caused a drawdown of atmospheric CO2. Downcore records of 230Th‐normalized opal fluxes and 231Pa/230Th ratios from seven equatorial Atlantic cores were used to reconstruct diatom productivity over the past 30 ka (where a is years) and to test the SALH. Downcore records of 231Pa/230Th ratios and opal fluxes are highly correlated, suggesting that they constitute a production‐based record of opal flux. Opal flux records support the SALH in that glacial opal burial exceeded Holocene burial by 1.8 Gt opal/ka in the area 0°–40°W and 5°N–5°S. Earlier results from the eastern equatorial Pacific Ocean showed the opposite trend, with greater Holocene than glacial opal burial, but approximately the same magnitude of difference between glacial and interglacial opal burial. We suggest four (nonexclusive) scenarios to explain the data from both basins: (1) Increased upwelling in the equatorial Atlantic and El Niño–like conditions suppressing upwelling in the eastern equatorial Pacific altered the overall nutrient supply to both basins; (2) Si leaked from the Southern Ocean because of Fe fertilization, but was prevented from upwelling in the equatorial Pacific because of El Niño–like conditions during the LGM; (3) Si leaked from the Southern Ocean because diatom productivity was limited by increased sea ice extent and was again prevented from upwelling in the equatorial Pacific; or (4) changes in ocean circulation related to the decreased input of Agulhas water to the glacial South Atlantic provided excess dissolved Si to the equatorial Atlantic Ocean. A deglacial opal pulse is seen in both the Atlantic and Pacific Oceans. All four scenarios and the presence of the common deglacial opal pulse suggest a common driver in the Southern Ocean.

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“…Biogenic silica was determined by the methods for opal extraction described by Mortlach and Froelich (1989). Opal contents were corrected for Al 2 O 3 content measured in the extraction solute to account for silica liberated from the dissolution of clay.…”

Section: Methodsmentioning

confidence: 99%

Record of Late Pleistocene Glaciation and Deglaciation in the Southern Cascade Range. I. Petrological Evidence from Lacustrine Sediment in Upper Klamath Lake, Southern Oregon

Reynolds

Rosenbaum

Rapp

et al. 2004

Journal of Paleolimnology

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Petrological and textural properties of lacustrine sediments from Upper Klamath Lake, Oregon, reflect changing input volumes of glacial flour and thus reveal a detailed glacial history for the southern Cascade Range between about 37 and 15 ka. Magnetic properties vary as a result of mixing different amounts of the highly magnetic, glacially generated detritus with less magnetic, more weathered detritus derived from unglaciated parts of the large catchment. Evidence that the magnetic properties record glacial flour input is based mainly on the strong correlation between bulk sediment particle size and parameters that measure the magnetite content and magnetic mineral freshness. High magnetization corresponds to relatively fine particle size and lower magnetization to coarser particle size. This relation is not found in the Buck Lake core in a nearby, unglaciated catchment. Angular silt-sized volcanic rock fragments containing unaltered magnetite dominate the magnetic fraction in the late Pleistocene sediments but are absent in younger, low magnetization sediments. The finer grained, highly magnetic sediments contain high proportions of planktic diatoms indicative of cold, oligotrophic limnic conditions. Sediment with lower magnetite content contains populations of diatoms indicative of warmer, eutrophic limnic conditions. During the latter part of oxygen isotope stage 3 (about 37-25 ka), the magnetic properties record millennial-scale variations in glacial-flour content. The input of glacial flour was uniformly high during the Last Glacial Maximum, between about 21 and 16 ka. At about 16 ka, magnetite input, both absolute and relative to hematite, decreased abruptly, reflecting a rapid decline in glacially derived detritus. The decrease in magnetite transport into the lake preceded declines in pollen from both grass and sagebrush. A more gradual decrease in heavy mineral content over this interval records sediment starvation with the growth of marshes at the margins of the lake and dilution of detrital material by biogenic silica and other organic matter.

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A simple method for the rapid determination of biogenic opal in pelagic marine sediments

Cited by 1,155 publications

References 21 publications

Variability of marine biological productivity in the northeastern Pacific over the past millennium

Variability of marine biological productivity in the northeastern Pacific over the past millennium

Opal burial in the equatorial Atlantic Ocean over the last 30 ka: Implications for glacial‐interglacial changes in the ocean silicon cycle

Record of Late Pleistocene Glaciation and Deglaciation in the Southern Cascade Range. I. Petrological Evidence from Lacustrine Sediment in Upper Klamath Lake, Southern Oregon

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