The importance of desert dust transported long distances: Ecosystem effects and human health

Background/Question/Methods

Desert dust, particles generally smaller than 50 micrometers that can be suspended in the air during wind erosion events and transported long distances, has gained increasing attention in atmospheric sciences for its impact on the planet’s radiation budget. Its importance in ecology is only now coming into view. The purpose of this presentation will be to synthesize current research on dust in terrestrial and marine ecosystems to show how dust that is transported long distance from its desert source, affects nutrient status of soils and surface waters, microbial ecology, growing season length, and human health.

Results/Conclusions

Both field and modeling experiments show that dust impacts downwind ecosystems. In marine environments, deposition of dust supports nitrogen fixation and growth of non-diazotrophic organisms, with significant impacts on carbon uptake in some ocean basins, leading to an indirect biogeochemical effect on the planet’s radiation balance. Changes to dust deposition to the ocean due to land use and climate change have the potential to impact the nutrient status of surface waters, particularly in the Southern Ocean. Dust also results in large-scale transport of microorganisms, highlighting the importance of atmospheric transport in microbial ecology. In terrestrial environments, the impact of dust transported long distances is varied. Many soils worldwide are depleted in rock-derived nutrients either as a result of parent material chemistry or weathering history. In these soils, dust deposition can contribute to the nutrient status and long-term productivity. Dust deposited on snowpack increases its albedo and leads to more rapid melting of snow.  This significantly impacts mountain hydrology and, by having the soil exposed for a longer period in the spring, also locally increases the length of the growing season. Finally, there is increasing effort to quantify the impact of dust on human health. In Europe and Asia, there is strong evidence for negative impacts of desert dust on pulmonary health.  In the southwestern United States, coccidioidomycosis (Valley Fever) is a dust-borne disease with considerable health and economic consequences.