Saharan dust

Saharan dust (also yellow dust, yellow sand, yellow wind or Sahara dust storms) is an aeolian mineral dust from the Sahara desert, the largest hot desert in the world. The desert spans just over 9 million square kilometers, from the Atlantic Ocean to the Red Sea, from the Mediterranean sea to the Niger River valley and the Sudan region in the south. The Sahara is the largest source of aeolian dust in the world, with annual production rates of about 400-700 x 106 tons/year, which is almost half of all aeolian desert inputs to the ocean. Saharan dust is often produced by natural process such as wind storms and doesn't appear to be heavily impacted by human activities. In most cases marine bacteria and phytoplankton require small amounts of the micronutrient iron, which can be supplied by transport of Saharan dust. The dust delivered to the Atlantic Ocean and the Mediterranean Sea has a small percentage of dissolvable iron; however, since so much iron is supplied to the regions, even with a low soluble percentage, Saharan dust is a large source of iron to these regions. Factors that contribute to dust solubility are particle size, the mineral composition of the dust, the temperature of the water, and its pH. Organic molecules called ligands can also increase the solubility of iron and make it more accessible to organisms to use for primary production. Saharan dust has been found to travel to the Amazon basin, Scandinavia, Japan, and other regions. The dust supplied to the North Atlantic and the Mediterranean brings limiting nutrients that help to boost primary production. For the Amazon basin, which is limited in phosphorus in much of the soil in the basin, Saharan dust is a main source of phosphorus. This dust has also impacted ecosystems in the southeastern United States and the Caribbean by supplying limiting nutrients, and in some cases promoting soil development on land. Saharan dust has even been found on glaciers and studied to examine atmospheric circulation.