Bringing Together USEPA Methods 1631, 245.1, 245.7 and 7473 for Determination of Mercury in Solids and Liquids

David L. Pfeil, Teledyne Leeman Labs, 6 Wentworth Drive, Hudson, NH, 03051, Tel: 603-521-3234, Fax: 603-886-9141
Peter G. Brown, Teledyne Leeman Labs, 6 Wentworth Drive, Hudson, NH, 03051, Tel: 603-521-3324, Fax: 603-886-9141

Mercury determinations are required in a variety of sample matrices and across a very wide range of concentrations.  Sensitive techniques, such as purge and trap cold vapor atomic fluorescence spectroscopy, are available that can achieve detection limits at sub part-per-trillion levels but which cannot handle higher concentrations without massive dilutions.  On the other hand, there are less sensitive techniques, such as thermal decomposition mercury vapor generation that can handle diverse matrices with little to no sample pretreatment. 

Instrumentation designed for the differing techniques share much in terms of their detection systems but little in terms of sample introduction.  In all cases free gaseous mercury is the species that is ultimately quantified.  The processes to produce the mercury gas, however, diverge significantly.  Methods 1631, 245.1, & 245.7 employ chemical reactions with acids, oxidants, and reductants.  Method 7473 employs sample heating followed by vapor catalysis.  

We will discuss a thermal decomposition-based instrument to determine mercury in matrices such as solids, tissues, coal, and soils without sample pretreatment that can be equipped with a high sensitivity liquid introduction system including a comparison of performance characteristics for each.

Sampling and Chemical Analysis of Cranberries Potentially Affected by the Localized Discharge of Groundwater Containing Ethylene Dibromide

Ronald Citterman, CH2M HILL, 318D East Inner Road, Otis ANG Base, MA 02542-5028, Tel:  508-968-4670 x 5631, Fax:  508-968-4916, Email: Ron.Citterman@ch2m.com
Jon Davis, P.E., Air Force Center for Environmental Excellence, 322 East Inner Road, Otis ANG Base, MA 02542-5028, Tel:  508-968-4670 x 4952, Fax:  508-968-4476, Email: jon.davis@brooks.af.mil

Groundwater contaminated with ethylene dibromide (EDB), referred to as the Fuel Spill‑28 (FS-28) plume, is currently migrating beneath a series of commercial cranberry bogs within the Town of Falmouth, Massachusetts.  The FS-28 plume is detached from its source, which is inactive and located on the Massachusetts Military Reservation (MMR). Although most of the FS-28 plume is being captured by an extraction-treatment-discharge system operated by the Air Force Center for Environmental Excellence (AFCEE), EDB was detected at very low concentrations (0.012 micrograms per liter) in the summer of 2005 in ditches adjacent to the Augusta Bog for the first time in 6 years.  These ditches represent areas of groundwater discharge.  To determine if the discharge of groundwater containing EDB actually affected the cranberry fruit in the Augusta Bog, the Air Force Center for Environmental Excellence sampled and analyzed cranberries for EDB.  Samples were analyzed using gas chromatography mass spectrometry with Selected Ion Monitoring.  Advantages in using this method included low method detection limit (MDL) and the ability to target a specific compound.  A critical component was the performance of a MDL study for this non-traditional environmental medium (i.e., homogenized cranberry fruit).  The results of the study established a MDL sufficiently low to meet the project data quality objectives.  EDB was not detected above the MDL in any of the cranberry samples.

Improved PAH Field Screening Method & Fluorescence Fingerprinting Hydrocarbon Sites

Steve Greason, President, Sitelab Corporation, 4 Crane Neck Street, West Newbury, MA 01985, Tel: 978-363-2299, Fax: 978-363-2288, Email: sgreason@site-lab.com

Field screening soils and sediments for Polyaromatic Hydrocarbons (PAHs) has improved using on-site innovative technology, such as Sitelab’s new UVF-3100D model.  Sitelab’s portable ultraviolet fluorescence spectrometer, which has been widely used to test volatile and semi-volatile aromatic hydrocarbons for their gasoline and diesel range fractions, can now be used to help assess and clean up sites contaminated with Benzo[a]Pyrene and other carcinogenic PAHs of concern commonly found in coal tars, coal ash and weathered fuel oils typically encountered at manufactured gas plants, power plants or other petroleum sites. 

Sitelab has recently developed optical filters that are more sensitive and selective to the target PAH compounds reported by EPA Method 8270 performed by certified laboratories, a very time consuming and expensive analysis.   Samples are first extracted in methanol solvent using disposable test kits and then measured on the analyzer, which is calibrated to a standard containing 17 PAH compounds, the same compounds reported by the off-site GC/MS method.  The equipment is easy to operate and quality controlled.  From start to finish, results only take 5 to 10 minutes.  Correlation is very good, as illustrated in the case studies attached (see PDF file).

In addition, the new PAH optics have become an integral part of Sitelab’s fluorescence fingerprinting method for hydrocarbon identification.  The ratios, or proportions, of a sample’s VPH, EPH and Target PAH fractions vary depending on how old and what type of petroleum contamination is there.  The signatures exhibited provide environmental professionals forensic information in the field within minutes, allowing them to delineate contaminated sites more cost effectively.

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