Deposition of Aerosols onto Mass Bays |
In 1992 a study was initiated to investigate the chemistry of aerosols over eastern Massachusetts and the contribution of these aerosols to the total burden of various metals in Massachusetts Bays. Drs. Dan Golomb and David Ryan, UML, were the Principal Investigators. Two sampling sites were established, one at Nahant and the other at Truro. Conventional wet/dry samplers were used at both sites to measure wet and dry deposition. At each site, two parallel sampling systems were established, one using teflon buckets to collect samples for metal analysis and the other using stainless steel buckets to collect samples for organic analysis. In addition, a dichotomous particle collector was used to collect airborne particles for subsequent metal analyses. Sample collection was done in two week intervals for 12 months. Instrumental neutron activation analysis (INAA) and ICP-MS were used to determine particle chemistry. Publications resulting from the study and pictures of the sampling station at Truro are found below. |
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Atmospheric Deposition of Toxics onto Massachusetts Bay-I. Metals Golomb, D., Ryan, D., Eby, G. N., Underhill, J., and Zemba, S. 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 Cod. 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 mg 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. Data files as Excel spreadsheets |