The flux of Saharan dust to Panama and its influence on soil geochemistry

The long-range transport of Saharan dust to South America, the Caribbean Basin, and even the southern United States has been demonstrated by both remotely sensed satellite data and direct measurements. In this work, we use Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data and deposition models developed by Yu et al. (2015) and African dust geochemical data (Muhs et al., 2010; Moreno et al., 2006) to calculate the elemental influx to the landscape in Panama. These deposition values are compared to our own soil geochemical data collected from soil pits and rock data from the Upper Rio Chagres watershed of central Panama. The CALIOP-based estimate of Saharan dust deposition to Panama is 50 kg ha-1 yr-1 and the flux of phosphorus is 35-122 g P ha-1 yr-1. Dust-derived Ca can add as much as ~4% to total topsoil Ca concentrations. Lower dust contributions were calculated for other key elements, such as K (~0.35%) and P (0.03%). Contributions of dust to soil depend on bedrock type, and vary seasonally, though spatial variation is likely to exist as well.

Keywords: Panama; African dust; Atmospheric deposition; Phosporous; Nutrient cycling