Microbes as Climate Engineers: Hurricane Formation and Saharan Dust Transport

Impact of Saharan Dust on the Amazon

The AI podcast discusses the significant role of Saharan dust in transporting micronutrients, which can act as fertilizers, to the Amazon rainforest. This transport happens primarily during boreal winter and spring, when northeasterly trade winds carry dust from the Sahara across the Atlantic to South America. The Bodélé Depression in Chad, known as the world's largest single source of atmospheric dust, is a significant contributor to this process.

Saharan dust provides the Amazon rainforest with essential nutrients like iron (Fe) and phosphorus (P), which are often limited in the region's soil.

Dust samples from the Bodélé Depression reveal that it exports up to 6.5 Tg of Fe and 0.12 Tg of P annually. A study utilising satellite data from CALIPSO estimated that an average of 28 Tg of dust is deposited into the Amazon Basin each year, potentially providing 0.022 Tg of phosphorus. This phosphorus input is comparable to the amount lost through hydrological processes, highlighting the role of Saharan dust in preventing long-term phosphorus depletion.

The amount of dust deposited in the Amazon exhibits interannual variations, influenced by factors like rainfall patterns in the Sahel region of Africa. Years with lower rainfall in the Sahel typically see increased dust transport to the Amazon.

However, there is still uncertainty about the exact amount of dust needed to sustain the Amazon's productivity.

Further research is needed to comprehensively understand the phosphorus cycle in the Amazon, including the contributions from various sources like dust, smoke, and biological particles, as well as the impact of hydrological loss.

References

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