ATMOSPHERIC DEPOSITION AND RUNOFF OF MERCURY AND TRACE METAL IN AN URBAN WATERSHED

Abstract

Non-point and diffuse sources can be the most significant sources of pollutants in a watershed. Atmospheric deposition in its three forms (ambient, dry, and wet) has often been neglected and thus was not included in watershed approach for water resources management. Often regulatory frameworks for water resources protection have not taken into account atmospheric deposition because little or no data is available. The project undertaken is new and unique in its scope and approach to monitor and measure pollutants in atmospheric deposition and its impact on storm water quality within a river watershed. Specialized sampling equipment and ultra-clean analytical methodology were employed to quantify the concentrations or masses in ambient air, precipitation, and runoff for twelve trace metals. These metals include mercury (Hg), cadmium (Cd), antimony (Sb), aluminum (Al), arsenic (As), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn). Meteorological parameters including wind speed, wind direction, temperature, and relative humidity were also measured. This study represents the most complete set of atmospheric concentration and deposition data for trace metals and mercury in an urban watershed at this time. Additionally, this is the first time that mercury together with other trace elements in dry deposition and runoff has been measured in a study of this length. The results of this study provide both the critical information and valuable study approaches to monitor trace metal deposition in urban watersheds.