Nutritive contribution of Sahara dust to aquatic environment productivity: A laboratory experimental approach

摘要

Interest in studying the main features of Sahara dust has increased considerably throughout the last 2 decades. Most publications focused on its physical properities, atmospheric transportation and loads, trajectories, relatioship to precipitation, and mineral and chemical features (D'Almeida 1987, Levin et al. 1996, Swap et al. 1996, Guerzoni et al. 1999, Afeti & Resch 2000, Goudie & Middleton 2001). Recently, major interest was paid to study the role of Sahara dust in enhancing oceanic productivity (Gruber & Sarmiento 1997, Shinn et al. 2000, Kou-varakis et al. 2001, Markaki et al. 2003). Investigations were mainly based on theoretical calculations or on the hypothetical interpretation of the data obtained from the analysis of dust samples collected during dust storms, when high nutrients concentrations were detected. Most of the studies focused on the effect of Sahara dust on specific regions such as the Atlantic Ocean, the Mediterranean Sea and the Black Sea (Callot et al. 2000, Kubilay et al. 2000), but none studied the properities of Sahara dust blown from the Arabian penenisula and/or its effect on marine productivity. The Arabian penenisula is one of largest desert areas in the world, where sand dunes, arid conditions, and monsoon wind characterize its physical and geographical features. The United Arab Emirates (UAE), one of the Arabian Peninsula countries, has a long coastal area (up to 700 km) that extends along the Arabian Gulf and the Gulf of Oman. Sand dunes and mountains occupy the major part of its territory. Dust storms characterize the country's atmosphere during several months of the year due to both monsoon and trade winds that affect the country from the beginning of April until the end of July each year. Due to the lack of information regarding the composition of this dust and its effect on the marine life, this study aims to measure the relative nutritive contribution of the Sahara dust originating from the UAE sand dunes to marine productivity, based on a laboratory bioassay. The study was designed to evaluate atmospheric deposition, determine its mineral and chemical composition, and estimate its effect on a monoclonal algal culture.