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Woods Hole Oceanographic Institution

Sean Bryan

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Investigating the monsoon-driven dust input to the Red Sea in the past using Barium in corals

Collaborators:
Konrad Hughen, Marine Chemistry and Geochemistry, WHOI; Tom Farrar, Physical Oceanography, WHOI

Seasonal wind jets frequently develop through gaps in the coastal mountains that line the margins of the Red Sea (Jiang et al., 2009 Geophys. Res. Lett.).  The most prominent of these wind jets is an eastward blowing jet that is funneled through the Tokar Gap on the Sudanese coast.  This wind jet, which is related to the northward migration of the Inter-Tropical Convergence Zone (ITCZ) and nocturnal drainage airflow, develops almost daily from mid-June to mid-September.  The Tokar region of Sudan is an arid alluvial delta of the Baraka River, and is one of the primary dust sources in the Middle East.  Large dust plumes originating from the Tokar Gap can be observed over the Red Sea using satellite imagery.   These dust events can last several days and occur frequently during the summer season. We investigated past variability in the dust input to the Red Sea using Ba/Ca in corals.  We have drilled cores through massive Porites corals from the eastern margin of the Red Sea.  These corals grow ~1-1.5 cm/yr, and some of the cores contain continuous growth for the past 250-300 years.  Coral Ba/Ca has been previously used to examine sediment flux from rivers (e.g., McCulloch et al., 2003 Nature; Fleitmann et al., 2007 Geophys. Res. Lett.; Prouty et al., 2010 Mar. Poll. Bull.).  These studies were based on the observation that barium is released from river-borne suspended particles as they encounter increased salinities in estuaries (e.g. Coffey et al., 1997 Estuarine Coastal and Shelf Science).  We propose that wind-borne sediments will release barium to seawater just as river-borne sediments.  We test this hypothesis and examine how Red Sea coral Ba/Ca has changed over the past 250 years.


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