All these rich greens usually mean vegetation, but this is an arid, salty land almost totally inhospitable to plants. Instead, those are the markers of a brine rich in minerals, concentrated as the water evaporates.
Dabuxun Lake in China is a strangely eye-catching mine, where water evaporates to leave behind thick layers of mineral salts. While humans are exploiting it now as a natural resource, the lake may be the final remnant of an ancient salt lake lingering in the area for the last two million years.
Lake Qarhan in November 2013. Image credit: NASA/USGS
Dabuxun is part of Lake Qarhan, the largest salt lake in China. Qarhan is a 5855 square kilometre basin that only intermittently fills with water. The playa includes nine smaller lakes, where Dabuxun is the largest. Water dissolves nearby rocks, concentrating minerals in a solution. The brine then evaporates from the lakes, leaving behind mineral salts like sodium chloride (rock salt), potassium, bromine, halite, gypsum and magnesium chloride. Humans help this natural process along by building square evaporation ponds. The extracted minerals are used in industry. Sodium chloride is purified into table salt, while potassium is a key ingredient in fertiliser.
[ Landsat ]
Top image: On the shores of Dabuxun Lake in central China. Credit: NASA/Scott Kelly. Thank you to Ewan Mellor for identifying the location for us!