African Dust and the Amazon JungleThis photo taken by NASA’s Suomi-NPP orbiting satellite show
African Dust and the Amazon JungleThis photo taken by NASA’s Suomi-NPP orbiting satellite shows a large plume of dust leaving the coast of Africa this week. This dust plume is being blown west out over the Atlantic, and will eventually reach the coast of North America.Plumes of dust like this one play an important role in the ecosystems of the western hemisphere. The Amazon rainforest is highly efficient at cycling nutrients – when some leaves fall to the jungle floor or some organism dies, the phosphorus and the nitrogen and other nutrients in that matter is rapidly taken back up by the surrounding plants. However, because the area receives so much rain, there is always a little bit of phosphorus that washes away and out to sea during the year.Some of this dust comes from an area of the nation of Chad called the Bodélé Depression. 6000 years ago the climate of the Sahara was wetter, and this depression was filled with the largest lake in Africa. Today, all that is left of that lake is lake Chad, which fills only about 10% of the former lake area. At the bottom of that ancient lake sits a deposit of diatomite – shells of organisms called diatoms that once lived in the lake. The shells of those diatoms are rich in phosphorus, and that phosphorus is blown across the entire ocean to the Americas, where some of it falls onto the rainforest.During the spring and summer months, phosphorus from this depression is the main supply of new phosphorus arriving to the Amazon jungle. During the fall, a different source appears - burning of biomass farther to the south in Africa also releases phosphorus, and that phosphorus similarly rains down on the Amazon basin.These two phosphorus sources balance out the amount being washed away each year by the rains, keeping the jungles productive year after year.-JBBImage credit:https://www.nasa.gov/feature/goddard/2020/nasa-observes-large-saharan-dust-plume-over-atlantic-ocean/Sources:https://doi.org/10.1002/2015GL063040https://www.pnas.org/content/116/33/16216https://www.sciencedirect.com/science/article/pii/S0009254114002964 -- source link
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