Patagonian Dust as a Source of Macronutrients in the Southwest Atlantic Ocean

Abstract

The role of Patagonian wind-borne dust as a source of macronutrients to the surface waters of the Southwest Atlantic Ocean was evaluated for the first time. During spring 2016, a series of experiments with dust was conducted to evaluate the dynamics of macronutrient dissolution in seawater. The results showed a differential contribution of macronutrients to seawater depending on the dust source and the amount added. Addition of a conservative amount of Patagonian dust to the sea­water contributed nitrate (NO3−) and silicic acid (Si(OH)4), but not phosphate (PO43–). Additional dust input to the system resulted in higher macronutrient concentrations. Particles collected from a nearby burned field did not contribute any macronutrients to the seawater. Thus, each dust event may affect biological productivity differently, depending on the source of the particles. Dissolution experiments suggest that macronutrients from dust are available immediately after particle deposition on the sea surface. The study includes field measurements of macronutrient concentrations before and after a dust storm at three nearshore marine stations. The data are consistent with macronutrient increase after the storms. Dust storms could become a very important source of nutrients to the ocean in future global warming scenarios.