FIELD EXPERIMENT USING THREE DIFFERENT PASIVE DUST COLLECTORS UNDER THREE DIFFERENT ENVIRONMENTAL CONDITIONS.

D. GAIERO; J. ARCE; H. MARELLI; P. SOSA; R. BECCHIO; C. FERRER; J.C. HORMAECHEA

Santa Rosa de la Pampa

Conferencia; ICAR VII, International Conference on Aeolian Research.; 2010

UNLP/INTA

We conducted a field experiment to assess the efficiency of three passives eolian dust samplers (pyramidal captor-PC, BSNE and MWAC, set up at 5 m height) under contrasting climatic condition across North Western Argentina (NWA, 24°S/65°W), the Pampas (MJ, 33°S/62°W) and Tierra del Fuego (RG, 54°S/68°W). The BSNE and MWAC are suitable for measure horizontal dust fluxes, though the PC is appropriate to measure vertical dust fluxes. According with results obtained from wind tunnel experiments, also our field experiment indicates that the MWAC is the most effective dust trap. Compared to MWAC, the mean BSNE efficiency was variable at the three locations: 40% at NWA, 60% at MJ and 75% at RG. Similarly, the mean PC efficiency was only 5% at NWA and MJ and, 1% at RG. Data indicate that fluxes measured with BSNE and MWAC are significantly dependent on the local relative humidity (RH) and wind speed (WS); i.e., high WS and low RH promote higher dust fluxes. In a few occasions and at MJ and RG, the efficiency of the BSNE was higher compared to the MWAC. The reasons of such changes are not clear as they have not apparent correlations with increase/decrease of WS or RH. At NWA, it is observed a clear drop in the efficiency of the BSNE during the dry period when the mean WS is about twice the one recorded during the rainy season and the mean RH decrease from 70% to 50%. At the three monitoring stations, the BSNE collected coarse dust particles indicating a lower capacity to retain fine particles compared to both PC and MWAC. The low efficiency of PC trap could indicate that deposition of atmospheric dust is significantly affected by vertical mixing. In unstable atmospheres like the one present in Patagonia, turbulence and vertical mixing are higher compare to the NWA and the Pampas atmosphere.