Source of trace element variability in Great Barrier Reef corals affected by the Burdekin flood plumes

Chantal Alibert*, Les Kinsley, Stewart J. Fallon, Malcolm T. McCulloch, Ray Berkelmans, Felicity McAllister

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    146 Citations (Scopus)

    Abstract

    Massive corals in the Great Barrier Reef, analyzed at high-resolution for Sr/Ca (thermal ionization mass spectrometry) and trace elements such as Ba and Mn (laser ablation inductively coupled plasma mass spectrometry), can provide continuous proxy records of dissolved seawater concentrations, as well as sea surface temperature (SST). A 10-yr record (1989 to 1998) from Pandora Reef, an inshore reef regularly impacted by the freshwater plumes of the Burdekin River, is compared with an overlapping record from a midshelf reef, away from runoff influences. Surface seawater samples, taken away from river plumes, show little variability for Sr/Ca (8484 ± 10 μmol/mol) and Ba (33.7 ± 0.7 nmol/kg). Discrete Ba/Ca peaks in the inshore coral coincide with flood events. The magnitude of this Ba/Ca enrichment is most likely controlled by the amount of suspended sediments delivered to the estuary, which remains difficult to monitor. The maximum flow rate at peak river discharge is used here as a proxy for the sediment load and is shown to be strongly correlated with coral Ba/Ca (r = 0.97). After the wet summer of 1991, the coral Ba/Ca flood peak is followed by a plateau that lingers for several months after dissipation of plume waters, signifying an additional flux of Ba that may originate from submarine groundwater seeps and/or mangrove reservoirs. Both Mn and Y are enriched by a factor of ∼ 5 in inshore relative to midshelf corals. Mn/Ca ratios show a seasonal cycle that follows SST (r = 0.7), not river discharge, with an additional high variability in summer suggesting a link with biological activity. P and Cd show no significant seasonal variation and are at a low level at both inshore and midreef locations. However, leaching experiments suggest that part of the coral P is not lattice bound.

    Original languageEnglish
    Pages (from-to)231-246
    Number of pages16
    JournalGeochimica et Cosmochimica Acta
    Volume67
    Issue number2
    DOIs
    Publication statusPublished - 15 Jan 2003

    Fingerprint

    Dive into the research topics of 'Source of trace element variability in Great Barrier Reef corals affected by the Burdekin flood plumes'. Together they form a unique fingerprint.

    Cite this