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Biomedical subjects

Debra Reinhart

Publications and source records attributed to Debra Reinhart.

5 recordsLinked to original sources
PubMed2006

Changes in landfill gas quality as a result of controlled air injection.

Air addition has been proposed as a technique for rapid stabilization of municipal solid waste (MSW) in landfills. The objective of this study was to observe the change in concentration of trace constituents of landfill gas in response to air addition. Air injection tests were conducted at a MSW landfill in Florida, and the concentrations of several gaseous constituents at adjacent wells within the waste were measured. The concentrations of methane, carbon dioxide, and oxygen, as well as several trace constituents, were measured both prior to and during air addition. The trace components investigated included a suite of volatile organic compounds (VOCs), nitrous oxide (N20), carbon monoxide (CO), and hydrogen sulfide (H2S). A significant increase in CO was observed in 9 of 14 monitoring points; overall, CO concentrations were found to increase as the ratio of CH4 to CO2 decreased. A significant decrease in H2S was observed at 6 of 14 monitoring points. Air injection did not have a noticeable affect on VOC or N2O concentrations compared to initial levels.

Air Movements↗
PubMed2005

Airborne emissions of mercury from municipal solid waste. I: new measurements from six operating landfills in Florida.

Mercury-bearing material enters municipal landfills from a wide array of sources, including fluorescent lights, batteries, electrical switches, thermometers, and general waste; however, the fate of mercury (Hg) in landfills has not been widely studied. Using automated flux chambers and downwind atmospheric sampling, we quantified the primary pathways of Hg vapor releases to the atmosphere at six municipal landfill operations in Florida. These pathways included landfill gas (LFG) releases from active vent systems, passive emissions from landfill surface covers, and emissions from daily activities at each working face (WF). We spiked the WF at two sites with known Hg sources; these were readily detected downwind, and were used to test our emission modeling approaches. Gaseous elemental mercury (Hg(O)) was released to the atmosphere at readily detectable rates from all sources measured; rates ranged from approximately 1-10 ng m(-2) hr(-1) over aged landfill cover, from approximately 8-20 mg/hr from LFG flares (LFG included Hg(O) at microg/m3 concentrations), and from approximately 200-400 mg/hr at the WF. These fluxes exceed our earlier published estimates. Attempts to identify specific Hg sources in excavated and sorted waste indicated few readily identifiable sources; because of effective mixing and diffusion of Hg(O), the entire waste mass acts as a source. We estimate that atmospheric Hg releases from municipal landfill operations in the state of Florida are on the order of 10-50 kg/yr, substantially larger than our original estimates, but still a small fraction of current overall anthropogenic losses.

Air Pollutants↗
PubMed2005

Airborne emissions of mercury from municipal solid waste. II: potential losses of airborne mercury before landfill.

Waste distribution and compaction at the working face of municipal waste landfills releases mercury vapor (Hg(o)) to the atmosphere, as does the flaring of landfill gas. Waste storage and processing before its addition to the landfill also has the potential to release Hg(o) to the air if it is initially present or formed by chemical reduction of Hg(II) to Hg(o) within collected waste. We measured the release of Hg vapor to the atmosphere during dumpster and transfer station activities and waste storage before landfilling at a municipal landfill operation in central Florida. We also quantified the potential contribution of specific Hg-bearing wastes, including mercury (Hg) thermometers and fluorescent bulbs, and searched for primary Hg sources in sorted wastes at three different landfills. Surprisingly large fluxes were estimated for Hg losses at transfer facilities (approximately 100 mg/hr) and from dumpsters in the field (approximately 30 mg/hr for 1000 dumpsters), suggesting that Hg emissions occurring before landfilling may constitute a significant fraction of the total emission from the disposal/landfill cycle and a need for more measurements on these sources. Reducing conditions of landfill burial were obviously not needed to generate strong Hg(o) signals, indicating that much of the Hg was already present in a metallic (Hg(o)) form. Attempts to identify specific Hg sources in excavated and sorted waste indicated few readily identifiable sources; because of effective mixing and diffusion of Hg(o), the entire waste mass acts as a source. Broken fluorescent bulbs and thermometers in dumpsters emitted Hg(o) at 10 to >100 microg/hr and continued to act as near constant sources for several days.

Air Pollutants↗