Airborne Emissions of Mercury from Municipal Landfill Operations: A Short-Term Measurement Study in Florida

Abstract

Large quantities of mercury (Hg) have been placed in municipal landfills from a wide array of sources, including fluorescent lights, batteries, electrical switches, thermometers, and general waste. Despite its known volatility, persistence, and toxicity in the environment, the fate of this Hg has not been widely studied. Using automated flux chambers and atmospheric sampling, we quantified the primary pathways of Hg vapor releases to the atmosphere at two municipal landfill operations in south Florida for eight days in April 1997. These pathways included landfill gas (LFG) releases from passive and active vent systems, passive emissions from landfill surface covers of different ages (including CH 4 "hot spots"), and emissions from daily activities at a working face (WF). Hg vapor was released to the atmosphere at readily detectable rates from all sources measured. Emission rates ranged from ~1 to 20 ng m -2 hr -1 over aged surface covers (generally comparable to background soils), from ~6 to 2400 ng/hr from LFG vents and flares, and from ~5 to 60 mg/hr at the WF. In general the fluxes increased from older to newer landfills, from fresh to aged cover, and from passive to active venting systems. Limited data suggest that methyl-and other organo-mercury compounds may also be emitted from these sites, suggesting an important area for future research. We estimate that atmospheric Hg releases from municipal landfill operations in the state of Florida are on the order of 10 kg/yr, or <1% of the estimated total anthropogenic Hg releases to air in this region.

Airborne Emissions of Mercury from Municipal Solid Waste. I: New Measurements from Six Operating Landfills in Florida

“…The estimated annual Hg emissions to air from these landfills are significantly higher than those we estimated for smaller landfill operations in south Florida (0.1 kg/yr). 2 The previously unrecognized but clearly important role of the WF is difficult to quantify directly. Because our modeling approach relies on various assumptions and limited downwind measurements near each diffuse source, it would be reassuring to repeat our studies under more controlled conditions.…”

“…Table 1 presents selected characteristics of these sites including the Martin County (MC) site previously studied in 1997 2 and again in 2002 (LFG only in 2002). In November 1998 we sampled the Brevard County Central Disposal Facility near Orlando, FL.…”

“…For example, total gaseous Hg (TGM) concentrations in LFG at Brevard County averaged ϳ7 times that measured at Orange County (see LFG discussion below) and were substantially higher than concentrations we have measured at several other Florida landfills. 2 There simply must be more Hg-bearing material delivered to the Brevard landfill. The estimated annual Hg emissions to air from these landfills are significantly higher than those we estimated for smaller landfill operations in south Florida (0.1 kg/yr).…”

“…2 These pathways included landfill gas (LFG) releases from passive and active vent systems, passive emissions from landfill surface covers of different ages, and emissions from daily activities at the working face (WF). Emission rates ranged from ϳ1 to 20 ng m Ϫ2 hr Ϫ1 over aged surface covers (generally comparable to background soils), from ϳ6 to 2400 ng/hr from LFG vents and flares, and from ϳ5 to 60 mg/hr at the WF.…”

“…In cooperation with the Florida DEP we quantified the primary sources of atmospheric Hg releases at two municipal landfills in south Florida in April 1997. 2 These pathways included landfill gas (LFG) releases from passive …”