Dust concentration in San Jorge Gulf and adjacent shelf (Patagonia, Argentina)

Abstract

Patagonia is the major source of aeolian dust into the southern part of the Atlantic Ocean and Argentinean shelf. However, to the best of our knowledge there are no direct measurements in these regions. The objective of this study is to analyze, for the first time, the spatial distribution of dust concentration in San Jorge Gulf and adjacent shelf (43ºS-48ºS). Dust concentration was measured on 74 stations on an oceanographic survey conducted on board of the R/V Puerto Deseado between October 28th and November 8th of 2017. Measurements were conducted with a particle counter (PCE-PCO 1) and the concentration of particles in the air (particles per liter: p/l) was evaluated in six classes of particle sizes: 0.3 μm, 0.5 μm, 1.0 μm, 2.5 μm, 5.0 μm and 10 μm (size distribution around the mean of each is Gaussian and parameters are standardized in ISO 21501-4:2018). Additionally, data of relative humidity and air temperature were obtained. Particle concentrations varied inversely to particles sizes: the highest concentration was observed for smaller particles and the lowest concentration was observed for bigger particles (mean concentration for 0.3 μm: 18,500 p/l; 0.5 μm: 7030 p/l; 1.0 μm: 1750 p/l; 2.5 μm: 390 p/l; 5.0 μm: 80 p/l; 10 μm: 44 p/l). The highest concentration of particles was measured between 46ºS and 48ºS, while the lowest concentration was measured between 43ºS and 45ºS.