Atmospheric deposition of toxics onto Massachusetts Bay .1. Metals

Wet and dry atmospheric deposition of toxic metals was measured at biweekly intervals for one year, from 15 September 1992 to 16 September 1993 at two sites on Massachusetts Bay, Nahant, near Boston and Truro, near the tip of Cape God. Wet and dry deposition was measured using a conventional wet/dry collector, except that the dry bucket contained a layer of water in order to simulate the uptake of dry deposition onto a water surface. In addition, at Nahant, a dichotomous particle collector was used to measure metal concentrations on particles. Analytical methods were INAA and ICP-MS. Generally, dry deposition of metals was greater at Nahant than at Truro, and wet deposition was greater or equal at Truro than at Nahant. Averaging results from the two sites, the following deposition rates (wet + dry) were obtained for the Bay in mu g m(-2) yr(-1): Al 102000, As 132, Cd 405, Co 58, Cr 2700, Cu 3500, Fe 140,000, Mn 4420, Ni 7200, Pb 2700, Sb 160, Se 264, Zn 7800. Preliminary results are also given for mercury wet deposition, which was measured for 6 weekly periods in the fall of 1993. (C) 1997 Published by Elsevier Science Ltd.