Quantifying Uncontrolled Landfill Gas Emissions from Two Florida ...

An acidic neutralization tube was placed in front of the DMM sorbent to reduce the possibility of
analyte degradation.
The DMM content of the Carbotraps was determined by thermal-desorption, gas
chromatography, and cold vapor atomic fluorescence spectrometry (TD-GC-CVAFS). The
analytical system was calibrated by purging precise quantities of DMM in methanol (1 to 500
pg) from deionized water onto Carbotraps and then thermally desorbing (45 seconds at a 25 to
450 °C ramp) them directly into the isothermal GC (1 m 4 mm ID column of 15% OV-3 on
Chromasorb WAW-DMCS 80/100 mesh) held at 80 °C. The output of the GC was passed
through a pyrolytic cracking column held at 700 °C, converting the organomercury compounds
to elemental form. DMM was identified by retention time and quantified by peak height.
To collect the monomethyl mercury sample, a set of three impingers filled with 0.001 M HCl
was used. An empty fourth impinger was used to remove any impinger solution carryover to the
pump and meter system. A diaphragm air pump was used to pull sample through the train and
collect the sample. The volume of gas sampled was monitored and quantified using a volatile
organic sampling train (VOST) box. The sample flow rate was nominally 0.8 liters/minute for
37.5 minutes, which equates to a total volume of approximately 30 liters.
The analysis method uses distillation, ethylation, Carbotrap preconcentration, thermal
desorption, gas-chromatography separation, thermal conversion, and CVAFS detection.
2.4 Lumex Elemental Mercury Field Sampling
The Lumex mercury analyzer was used to sample elemental mercury concentration of the landfill
gas. The Lumex mercury analyzer was connected to a standard 500 ml 45/50 impinger using
28/15 connections to knock out excessive moisture. The impinger was cooled using a standard
Apex Instruments cold box with water and ice. Gas was forced through positive pressure through
the impinger to the Lumex analyzer using an atmospheric vent to eliminate over pressurization of
the Lumex sample cell.
2.5 Summa Canister Sampling
Summa canister samples were collected using an EPA Method 0040 VOST sample conditioning
train connected to a 6 liter Summa canister sample container. A sample pump was used to pull
the purge flow from the landfill gas header pipe through the VOC sampling system. Summa
canister samples were analyzed using EPA Method TO-15 and EPA Method 25-C.
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