Seasonal variations in sup 7 Be activity in the sediments of Cape Lookout Bight, North Carolina

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90211-3· OSTI ID:6692239

Canuel, E A; Martens, C S; Benninger, L K ^[1]

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1. Univ. of North Carolina, Chapel Hill (USA)

Short-term sediment accumulation rates were determined using activity distribution of {sup 7}Be in the surficial sediments of a station (A-1) in Cape Lookout Bight, North Carolina (USA). This semi-enclosed coastal marine basin is characterized by high annual accumulation rates. Protected from high energy conditions by its geomorphology, the relatively quiescent waters of the bight's interior cause it to act as an efficient settling trap for fine-grained sediment. Lack of bioturbation in the surface sediments allowed for variations in depth-integrated activity profiles of {sup 7}Be to be interpreted as short-term accumulation events. Beryllium-7 inventories exhibited seasonal cyclicity with maxima occurring during spring (February through June). The inventory of {sup 7}Be ranged from 5.8 to 32.6 dpm cm{sup {minus}2} and was always well in excess of the atmospherically supported value ({bar x} = 3.8 dpm cm{sup {minus}2}; n = 15). Accumulation rates calculated from {sup 7}Be activity profiles indicate that the delivery of particulate matter to the sediments of Cape Lookout Bight is not constant throughout an annual cycle. The highest monthly accumulation rates appeared to be associated with north/northeastern storm activity. Inputs were generally highest during late winter/early spring when storm frequency is greatest. Short-term accumulation rates derived from this study agree with {sup 210}Pb rates calculated for a ten-year period of accumulation. The annual sediment accumulation rates for each of the two years over which the study was conducted was found to be 4.8 {plus minus} 0.8 g cm{sup {minus}2}y{sup {minus}1} and 3.7 {plus minus} 1.2 g cm{sup {minus}2}y{sup {minus}1}.

• OSTI ID: 6692239
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:1; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
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CHEMICAL COMPOSITION
CHEMISTRY
COASTAL REGIONS
CONTINENTAL MARGIN
CONTINENTAL SHELF
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EVEN-ODD NUCLEI
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GEOCHEMISTRY
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ISOTOPE RATIO
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NUCLEI
RADIOISOTOPES
SEAS
SEASONAL VARIATIONS
SEDIMENT-WATER INTERFACES
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VARIATIONS