Use of elemental tracers to source apportion mercury in South Florida precipitation

Source-receptor relationships for mercury(Hg) and other trace elements wet deposited in south Florida were investigated using daily event precipitatio n samples collected concurrently at 17 sites from August 6 to September 6, 1995. A multivariate receptor modeling approach found municipal waste incin eration and oil combustion sources to account for 71 +/- 8% of the Hg wet d eposited at five Florida Everglades sites. A similar analysis of a year-lon g record of event samples (June 22, 1995-June 21, 1996) collected at Davie, FL, found 73 +/- 6% of the Hg wet deposited to be accounted for by local a nthropogenic sources. Receptor modeling results closely agreed with stack m easurements made at local point sources during the study. An emissions reco nciliation found that local medical waste incineration sources, which emitt ed Hg primarily in the reactive form (Hg(ll)), could account for the Hg wet deposition left unexplained by the multivariate receptor model. The above findings suggest that emissions from local urban point sources have played the dominant role in the wet deposition of Hg to south Florida and the Ever glades. Additional speciated Hg emissions data are needed not only in south Florida but also nationally and globally to reduce uncertainties in modele d Hg loadings to aquatic ecosystems.