Elemental analyses of modern dust in southern Nevada and California

Abstract

Selected samples of modern dust collected in marble traps at sites in southern Nevada and California (Reheis and Kihl, 1995; Reheis, 1997) have been analyzed for elemental composition using instrumental neutron activation analysis (INAA) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). For information on these analytical techniques and their levels of precision and accuracy, refer to Baedecker and McKown (1987) for INAA, to Briggs (1996) for ICP-AES, and to Briggs and Meier (1999) for ICP-MS. This report presents the elemental compositions obtained using these techniques on dust samples collected from 1991 through 1997. The dust-trap sites were established at varying times; some have been maintained since 1984, others since 1991. For details on site location, dust-trap construction, and collection techniques, see Reheis and Kihl (1995) and Reheis (1997). Briefly, the trap consists of a coated angel-food cake pan painted black on the outside and mounted on a post about 2 m above the ground. Glass marbles rest on a circular piece of galvanized hardware cloth (now replaced by stainless-steel mesh), which is fitted into the pan so that it rests 3-4 cm below the rim. The 2-m height eliminates most saltating sand-sized particles. The marbles simulate the effect of a gravelly fan surface and prevent dust that has filtered or washed into the bottom of the pan from being blown back out. The dust traps are fitted with two metal straps looped in an inverted basket shape; the top surfaces of the straps are coated with a sticky material that effectively discourages birds from roosting.