Quantitative Source Apportionment of Creosote-derived and Background PAHs in Urban Sediments from the Little Menomonee River, Wisconsin, using Positive Matrix Factorization
Scott A. Stout, NewFields, Rockland, MA
Thomas P. Graan, Weston Solutions, Inc., Vernon Hills, IL

Forensic Investigation of Indoor Hydrocarbon Vapors:  A Case Study
Eric L Butler, Gradient Corporation, Cambridge, MA
Carrie B. Tuit, Gradient Corporation, Cambridge, MA
Kim R. Reid, Gradient Corporation, Cambridge, MA
Eric J. Wannamaker, Gradient Corporation, Golden, CO 

Environmental Weathering of PCBs in Sediments - Case Studies
Tarek Saba, Exponent, Inc., Maynard, MA

Quantitative Source Apportionment of Creosote-derived and Background PAHs in Urban Sediments from the Little Menomonee River, Wisconsin, using Positive Matrix Factorization
Scott A. Stout, NewFields, 100 Ledgewood Place, Suite 302, Rockland, MA 02370, Tel: 781-681-5040, Fax: 781-681-5048, Email: sstout@newfields.com
Thomas P. Graan, Weston Solutions, Inc., 750 E. Bunker Court, Suite 500, Vernon Hills, IL  60061, Tel: 847-918-4142, Fax: 847-918-4055, Email: thomas.graan@westonsolutions.com

Sediments (350) collected from a ~1.5-mile stretch of the Little Menomonee River (LMR) in Milwaukee, Wisconsin were analyzed in an effort to determine the concentration and source(s) of carcinogenic PAHs (CPAHs).   All samples were analyzed for Priority Pollutant PAHs) and a subset (52) were also analyzed using advanced chemical fingerprinting (ACF) techniques including detailed characterization of the total petroleum hydrocarbons (TPH), alkylated-PAHs, and sulfur-containing aromatics.  The study area was located approximately 3.0 to 4.5-miles downstream from the Moss-America Superfund Site, a former wood-treating facility, and within a highly-urbanized portion of the LMR.   Remedial activities for creosote-derived CPAHs had been completed within the far less urbanized, upper 3-miles but, now within this highly urbanized portion of the LMR, the distinction between CPAHs derived from creosote versus “LMR background” was critical.

ACF in this and previous studies in the LMR had demonstrated the existence of both weathered creosote- and background-derived CPAHs – including many samples containing mixtures of these two sources.  Principal component analysis (PCA) and a CPAH-to-TPH mass balance approach had been unable to defensibly quantify the proportions of these two sources.  Positive matrix factorization (PMF), a factor analysis technique developed in the mid-1990’s, has received wide application for its ability to quantitatively apportion the sources of atmospheric pollutants –  but only recently has been applied to sediments. 

PMF conducted on ACF data for the 52 samples already well-characterized by ACF quantitatively corroborated the qualitative interpretations and showed that (1) between 25 to 100% of CPAH in the study area (avg. 73 ± 2%) were derived from LMR background sources (not creosote) and (2) background CPAHs consistently occurred in concentrations above 15 mg/kg (avg. 34 ± 33 mg/kg), i.e., above the remedial threshold specified in the Consent Decree.   PMF subsequently conducted on the Priority Pollutant HPAHs for all 350 sediments provided comparable results and showed background-derived CPAHs (1) increased in concentration with increasing distance downstream, (2) reached maximum concentrations in surface (< 6˝) sediments near major roads, and (3) decreased in concentration with increasing depth.   Creosote-derived CPAHs were (1) rarely present above 15 mg/kg in surface sediments and (2) present in isolated “hot spots”  in deeper sediments (6-24˝). 

This work exemplifies the utility of combining ACF and PMF in unraveling and quantifying the sources of pyrogenic PAHs in urban sediments.

Forensic Investigation of Indoor Hydrocarbon Vapors:  A case Study
Eric L. Butler, Gradient Corporation, 20 University Road, Cambridge, MA 02138, Tel:  617-395-5000, Fax:  617-395-5001, Email:  ebutler@gradientcorp.com
Carrie B. Tuit, Gradient Corporation, 20 University Road, Cambridge, MA 02138, Tel:  617-395-5000, Fax:  617-395-5001, Email:  ctuit@gradientcorp.com
Kim R. Reid, Gradient Corporation, 20 University Road, Cambridge, MA 02138, Tel:  617-395-5000, Fax:  617-395-5001, Email:  kreid@gradientcorp.com
Eric J. Wannamaker, Gradient Corporation, 659 Entrada Drive, Golden, CO 80401, Tel:  617-395-7439, Fax:  617-395-7882, Email:  ewannamaker@gradientcorp.com

A multi-faceted approach was used to evaluate whether current vapor intrusion events were related to an old, deep, subsurface body of NAPL or more recent, shallow releases of petroleum hydrocarbons.  The contemporary intrusion events were evidenced by reports of odors, allegedly correlated with rain, river levels, or water table elevation changes, and/or measurements of indoor petroleum hydrocarbon contamination.  Historically, vapor intrusion had caused fires and an explosion.  We collected and analyzed NAPL samples; compared the chemical composition of the measured subslab and indoor vapors to those associated with the NAPL (calculated using Raoult's Law); graphically evaluated the relationships between rain and water table elevation changes and odor events; evaluated the spatial relationship between the NAPL and the buildings with regard to clay layers and perched water tables; and evaluated the timing of rashes of vapor intrusion events with known releases.  Integrating the results of these analyses we were able to opine that the current vapor intrusion events were more likely associated with recent shallow releases and not the old, deep body of NAPL.   

Environmental Weathering of PCBs in Sediments – Case Studies 

Tarek Saba, Exponent, Inc., 1 Clock Tower Place, Suite 150, Maynard, MA 01754, Tel:  978-461-4605, Fax:  978-461-4699, Email:  tsaba@exponent.com

Identification of responsible parties in cases where sediments are impacted by PCBs is often a critical issue in liability and remedial cost recovery.   However, weathering of PCBs by water washing and/or dechlorination can alter the original source fingerprint and result in misidentification of PCB sources in contaminated sediments.  In a case where Aroclor 1242 was exclusively used in a manufacturing process and byproducts inadvertently discharged to a river, homologue and congener profiles were analyzed in the river sediment.  The results reported a systematic shift from typical Aroclor 1242 congener and homologue profiles to profiles similar to heavier Aroclors as the samples were collected further downstream from the plant.  This is likely due to the loss of the lighter PCB fraction by water washing.  In a different case, manufacturing processes involving exposing Aroclor 1242-containing compounds to chemical and physical treatments of temperature and pressure also resulted in altering the Aroclor 1242 profile to resemble heavier Aroclors.  This was reported in samples from historical materials disposed in a landfill.  Fingerprinting methods including homologue and congener profile comparisons and Principal Component Analysis (PCA) were  used to track these pattern alterations in sediments and landfill material.

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