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Trace metals in the ocean act as both essential micro-nutrients and as toxins. There are relatively few multielement studies of dissolved trace metals in the ocean, and none from the Gulf of Aqaba, Red Sea. This semienclosed basin surrounded by desert is a natural laboratory for studying the impact of atmospheric dry deposition of trace metals on the ocean surface. We have combined measurement of dissolved metals in seawater with measurements of the flux of metals associated with dry deposition. The total dissolved trace metal concentrations in Gulf of Aqaba water are generally higher (Fe, Cu, Zn, Co, Mn, Pb) or similar (Ni, Al, Cd, Mo) to those measured in the open North Atlantic Ocean. The concentrations of elements that are highly enriched in aerosols relative to Al (e.g. Cd, Pb, Zn and Cu) are not necessarily proportionally enriched in surface seawater when compared to Al, indicative of the high reactivity of these elements in seawater. Iron concentrations in the Gulf of Aqaba are high relative to Al, despite the fact that the aerosols are not more enriched in Fe relative to Al. There may be additional sources of dissolved iron to the Gulf of Aqaba, not associated with Al. Alternatively, intense photochemically-driven redox cycling may act to enhance Fe dissolution from aerosols, or may otherwise increase the lifetime of Fe in the water column, relative to Al. Copper concentrations in the Gulf of Aqaba are close to the value found to be a threshold for Cu toxicity in this region. A surface maximum in Cd:P is found in the Gulf of Aqaba, in contrast to the more typical surface minimum in this ratio observed in other locations. The surface maximum appears to be driven by atypically low uptake of Cd relative to P. A low Cd:P uptake ratio for this region is consistent with known environmental determinants of low Cd:P uptake, such as high concentrations of dissolved Zn and Fe, and a predominance of small phytoplankton including cyanobacteria.

Item Type:	Refereed Article
Keywords:	Gulf of Aqaba, trace metals, aerosol
Research Division:	Earth Sciences
Research Group:	Oceanography
Research Field:	Chemical oceanography
Objective Division:	Environmental Management
Objective Group:	Marine systems and management
Objective Field:	Oceanic processes (excl. in the Antarctic and Southern Ocean)
UTAS Author:	Chase, Z (Professor Zanna Chase)
ID Code:	75117
Year Published:	2011
Web of Science® Times Cited:	35
Deposited By:	IMAS Research and Education Centre
Deposited On:	2012-01-11
Last Modified:	2017-10-31
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