Detailed mass size distributions of atmospheric aerosol species in the Negev desert, Israel, during ARACHNE-96

As part of the 1996 summer intensive of the Aerosol, RAdiation and CHemistr y Experiment (ARACHNE-96), the mass size distribution of various airborne p articulate elements was studied at a remote site in the Negev Desert, Israe l. Aerosol collections were made with 8-stage PINE International cascade im pactors (PCIs) and 12-stage small deposit area low pressure impactors (SDIs ) and the samples were analyzed by PINE for about 20 elements. The mineral elements (Al, Si, Ca, Ti, Fe) exhibited a unimodal size distribution which peaked at about 6 mu m. but the contribution of particles larger than 10 mu m was clearly more pronounced during the day than Juring night. Sulphur an d Br had a tendency to exhibit two modes in the submicrometer size range, w ith diameters at about 0.3 and 0.6 mu m, respectively. The elements V and N i, which are indicators of residual fuel bunting, showed essentially one fi ne mode (at 0.3 mu m) in addition to a coarse mode which represented the mi neral just contribution. Overall, good agreement was observed between the m ass size distributions from the PCI and SDI devices. The PCI was superior t o the SDI for studying the size distribution in the coarse size range, but the SDI was clearly superior for unravelling the various modes in the submi crometer size range. (C) 1999 Elsevier Science B.V. All rights reserved.