Emission and Dry Deposition Characteristics of Metal Elements from Engineering Construction Sites

In order to explore the emission characteristics of particulate and its particle-bound metal elements, eight construction sites in southern Taiwan were investigated during the period between Dec. 1996 and May 1997. Total suspended particulate (TSP) samples were collected with PS-1 samplers, and the dry deposition particles were sampled by dry deposition plates with smooth surfaces. The emission factors of particulate matter from construction sites were estimated using a dispersion model. Twenty elements, including Al, Ca, Fe, Mg, Na, Pb, Zn, Ni, V, Ba, Mn, Cr, Cu, Cd, Sr, Ag, Mo, Sb, As, and Ti, were analyzed in this study. The results indicated that dry deposition fluxes of TSP ranged between 762 and 3,760 mg/m super(2)-day with an average of 2,230 mg/m super(2)-day. The dry deposition velocities (V sub(d)) of TSP varied in a narrow range between 2.63 to 5.55 cm/s with an average of 4.31 cm/s and a standard deviation of 1.21 cm/s. The major elemental components of particulate matter in the ambient air at construction sites were found to be crustal elements including Al, Ca, Fe, Mg and Na. These compositions were similar to those of road dust. Dry deposition fluxes of crustal metals were much higher than those measured at urban and suburban sites.