Trace metals in contemporary and seventeenth-century Galapagos coral: Records of seasonal and annual variations

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

DOI:https://doi.org/10.1016/0016-7037(90)90327-H· OSTI ID:7188929

Linn, L J; Delaney, M L; Druffel, E R.M. ^[1]

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1. Univ. of California, Santa Cruz (USA)

The authors report trace element/calcium ratios for modern (Cu/Ca, Mn/Ca, Cd/Ca and Pb/Ca) and seventeenth-century (Cu/Ca, Mn/Ca, and Pb/Ca) specimens of Pavona clavus collected in the Galapagos Islands. These data include the first reliable measurements of Cu/Ca ratios in coralline aragonite. They estimate that the ratio of Cu/Ca in the lattice to that in seawater (i.e., the effective distribution coefficient) is {approx} 0.3, lower than the value of 1 observed for several other divalent elements; they estimate the effective distribution coefficient for Mn is {approx} 1. Distribution coefficients in coral aragonite for 8 divalent metals are near unity despite different ionic radii and chemical speciation in seawater. In a modern Hood Island coral, quarter-annually sampled from 1964-73, Cu/Ca ratios decrease twofold from the late 1960s to early 1970s. Mn/Ca and Cd/Ca ratios vary seasonally with upwelling and the generic El Nino. The El Nino Southern Oscillation (ENSO) events of 1965, 1969, and 1972 are marked by suppression of Cd/Ca ratios by about 2.5 nmol/mol, while the Mn/Ca ratio is highest during the strong 1972 ENSO. Pb/Ca ratios were relatively constant throughout this period. From the Cu/Ca record of a seventeenth-century Urvina Bay coral annually sampled from 1600-1725 and the estimated Cu distribution coefficient, surface seawater Cu concentrations at Galapagos during the seventeenth century were similar to present day at 0.7-1.4 nmol/kg. Estimated Pb concentrations were lower at 5-20 pmol/kg, and Mn concentrations were slightly higher at 1.6-2.8 nmol/kg.

• OSTI ID: 7188929
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:2; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
ARAGONITE
BIOGEOCHEMISTRY
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMICAL COMPOSITION
CHEMISTRY
CNIDARIA
COELENTERATA
CONCENTRATION RATIO
COPPER COMPOUNDS
CORALS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
GEOCHEMISTRY
GEOLOGIC HISTORY
HYDROGEN COMPOUNDS
INVERTEBRATES
MINERALS
OXYGEN COMPOUNDS
SEASONAL VARIATIONS
SEAWATER
TRACE AMOUNTS
TRANSITION ELEMENT COMPOUNDS
VARIATIONS
WATER
WATER CHEMISTRY