Title:
Introduction
Text: Navy and Marine Corps facilities are often located along urban waterways adjacent to industrial facilities with long operational histories. Sediments in these waterways may contain commingled contaminants from both Navy and non-Navy point sources and non-point sources such as urban runoff. Failure to distinguish between Navy releases, background conditions, and other non-Navy responsible parties may lead to costly or unnecessary remediation and delay property transfer and re-use.
Advanced Chemical Fingerprinting (ACF) can be a powerful tool for Navy Remedial Project Managers (RPMs) to quantify the nature, extent, and source of contamination at their sites. While ACF is applicable in all media, it is particularly useful for sediments in which contaminant sources are often difficult to differentiate.
While chemical fingerprinting is applicable to a wide variety contaminants of concern (COCs), this Web Tool provides an introduction to ACF methods focusing on polycyclic aromatic hydrocarbons (PAHs) which are common contaminants in urbanized watersheds.
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Title:
Background (1 of 2)
Text: Contaminants, such as metals and organic compounds, enter shallow coastal waters from many point sources including ships, shoreside facilities, municipal outfalls, spills, and non-point source runoff. Sediments typically are considered a primary sink for these contaminants. In addition to surface sources, contaminated groundwater may migrate upward through the sediment layer and discharge to the water column.
Determining the source of contamination is a necessary component of the site assessment process because both natural processes and anthropogenic activities (Navy and non-Navy) may result in elevated concentrations of hazardous substances at a given site.
It is Navy policy that source identification is critical in determining the Navy's cleanup responsibility and the potential for site recontamination at sediment sites.
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Title:
Definition: Point Source
Text: A point source is a location, property, or incident that has introduced contaminants to the environment.
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Title:
Definition: Advanced Chemical Fingerprinting
Text: Advanced chemical fingerprinting involves the chemical analysis of contaminants and associated chemicals to provide source-specific information. It is one component of an environmental forensics investigation which is typically undertaken to identify a source and allocate liability for contamination.
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Definition: Sediments
Text: Particulate matter that deposits to the bottom of a water body including, but not limited to lakes, seas, ponds, rivers, streams, harbors, and storm drain systems.
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Title:
Background (2 of 2)
Text: ACF uses modified EPA Laboratory Methods, which have lower method detection limits (MDLs) and test for a larger number of priority pollutants.
The "fingerprint" of these priority pollutants can help to identify the contaminant source. ACF may be used alone or with Rapid Sediment Characterization (RSC) if the extent of sediment contamination is unknown. Click here to view the Guide For Using Rapid Sediment Characterization Methods in Ecological Risk Assessments.
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Definition: Method Detection Limit (MDL)
Text: The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero and is determined from analysis of a sample in a given matrix containing the analyte.
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Title:
Definition: Priority Pollutants
Text: Priority pollutants are defined as 126 specific contaminants including heavy metals and organic compounds. The priority pollutants are a subset of "toxic pollutants" as defined in the Clean Water Act (USA).
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Definition: Rapid Sediment Characterization (RSC)
Text: RSC is an integrated screening methodology used to map contaminant distributions or related biological effects in a timely and cost-effective manner. Examples of RSC tools include x-ray fluorescence spectrometry (XRF) for metals, ultraviolet fluorescence spectrometry (UVF) and immunoassay for PAHs, and immunoassay for PCBs and pesticides.
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Title:
Contaminant Source Study (1 of 2)
Text: An ACF project may be conducted independently or as part of a contaminant source study (CSS).
A CSS helps to identify the presence and extent of other sources if contaminant concentrations cannot be reasonably attributed to Navy operations. The guidelines for designing and conducting a CSS are documented in the User's Guide for Determining Sources of Contaminants in Sediments. Click on the graphic to view this document.
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Title:
Contaminant Source Study
Text: Contaminant source studies have particular application in industrial and urban waterways where multiple potentially responsible parties (PRPs) operate (or had previously operated) in the area. The CSS may be conducted to:
Clearly define the background conditions of sediments as well as previous or ongoing sources of contamination beyond the control of the Navy. Examples include urban runoff/fallout, discharges from neighboring properties, and water vessel traffic.
Refute or substantiate the conceptual site model (CSM)
Evaluate the effectiveness of source control measures and potential for future recontamination
Provide supplemental data for Human Health and Ecological Risk Assessments
Assess remedial alternatives
Recognize previously unknown sources of contamination
Establish detailed baseline data for long-term monitoring by natural recovery
Determine options for liability reduction or cost recovery through identification of other non-Navy sources, if warranted.
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Title:
Contaminant Source Study (2 of 2)
Text: There are seven recommended steps for a CSS. ACF is the key step in the process because it can identify contaminant sources and establish background criteria. View the flowchart for more information on the CSS process.
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Title:
Why ACF? (1 of 3)
Text: ACF provides chemists with detailed information to identify chemicals present in sediment, their concentrations, and any effects of weathering. The correct application of ACF methods requires a highly experienced chemist to acquire and interpret data. However, recognizing the need for ACF and designing a successful study approach requires an experienced and knowledgeable RPM.
Contaminant "fingerprinting" has many applications within the Remedial Investigation/Feasibility Study (RI/FS) process. Since source identification is important in determining the Navy's cleanup responsibility, fingerprinting techniques applied early in the RI can be effectively used for source identification and for verification of background locations and concentrations.
Fingerprinting methods are also applicable in later stages of the FS to evaluate potential (and baseline) for natural attenuation in remedy selection and/or appropriate cleanup goals.
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Title:
Standard vs. ACF Methods for PAHs (2 of 3)
Text: PAHs are ubiquitous and persistent "background" contaminants in urbanized waterways. Standard laboratory analytical methods may in some cases be sufficient (FID or chromatograms) to gather valuable information or often times, ACF may be necessary to defensibly tease apart the proportional contributions of "background" PAH from various PAH point-sources. Detection of PAHs is greatly increased when using ACF methods.
Standard methods analyze up to 16 target PAHs. The ACF approach is a modified 8270C method that analyzes up to 43 target PAHs. This additional information helps to differentiate between sources of PAH contamination when standard methods do not provide sufficient information.
An example is shown here of a histogram for Fuel Oil #6 with 4 target PAHs detected by Standard Method 8270C and 41 target PAHs detected by ACF-Modified Method 8270C.
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Title:
Definition: PAHs
Text: Polycyclic aromatic hydrocarbons (PAHs) are a class of chemicals containing carbon and hydrogen in two or more condensed benzenoid-rings. Also called polynuclear aromatics (PNAs) or polycyclic aromatic compounds (PACs).
The 16 target PAHs are Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Anthracene, Phenanthrene, Fluoranthene, Pyrene, Benzo(a)anthracene, Chrysene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Indeno(1,2,3-c,d)pyrene, Dibenz(a,h)anthracene and Benzo(g,h,i)perylene.
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Title:
Limitations of Standard Methods (3 of 3)
Text: Certain ACF methods may also provide lower MDLs, affecting the appearance of the visible fingerprint. The higher MDLs in standard methods detect chemicals above a certain concentration. This hinders the ability to find the source of contamination because the chemicals in lower concentrations can provide added information on the source of the higher concentration chemicals. When matrix interference is not encountered, the full fingerprint is seen when using the ACF methods with lower MDLs.
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Title:
Definition: Matrix Interference
Text: Matrix interference is encountered when sample characteristics that interfere with the test method such that reliable data cannot be generated. Examples may include samples with high alkalinity or acidity, and high concentrations of chemicals that that react with target analytes. Even though this compound may not be of interest to the client, the sample often requires dilution in order to prevent contamination of instrumentation.
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Title:
ACF Advantages and Limitations
Text: The following are major advantages and limitations associated with ACF:
Advantages:
Focuses Navy funds on cleaning up Navy responsibilities
Allows methods to be tailored to meet project objectives and site-specific COPCs
Provides lower method detection limits than standard methods Provides sufficient analytical data to identify sources, mixtures, and background concentrations
Allows assessment of the potential for future recontamination by non-Navy sources such as urban background Helps to establish remedial goals or baseline for monitoring natural recovery.
Limitations: Increases site characterization cost compared to standard methods (Non-routine)
Requires expenditure for site assessment to (potentially) save on cleanup costs
Requires experienced chemist to acquire and interpret data
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Title:
Methods for Contaminants of Potential Concern
Text: This slide summarizes analytical methods typically used for chemical fingerprinting applications. Click on a contaminant of potential concern (COPC) on the left to view its commonly associated ACF method.
Several of these method procedures are further described in EPA's on-line SW-846 manual Test Methods for Evaluating Solid Waste, Physical/Chemical Methods.
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Title:
ACF Methods for Metals
Text: In the case of metals, fewer ACF techniques are available than for SVOCs. Standard methods that use Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) such as EPA Method 6010B can typically provide low detection limits and suitable suites of metals to permit "fingerprinting" of their relative distributions. In some instances, this can help to reveal distinct sources. Therefore, standard EPA SW-846 methods for metals analyses are generally acceptable for source contamination studies in sediments.
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ACF Methods for Polychlorinated Biphenyls
Text: EPA Modified Method 8082A, Polychlorinated Biphenyls (PCBs) by Gas Chromatography, determines the concentrations of PCBs as Arochlors or as individual PCB congeners. It provides low level analysis of sediments and other matrices. The fingerprint patterns of congener data are also called end-member (EM) compositions.
Modified EPA Method 680, Determination of Pesticides and PCBs in Water and Oil/Sediment by Gas Chromatography/Mass Spectrometry, targets the full list of 209 PCB congeners as well as homologues (level of chlorination groups). Method 680 provides low level analysis of sediments and monitors weathering/dechlorination.
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Title:
ACF Methods for Pesticides
Text: ACF uses Modified EPA Method 8082 to determine pesticide contamination. There are 16 to 20 pesticides and degradation products for which this method analyzes.
Method 8081B, Organochlorine Pesticides by Gas Chromatography, may be modified for advanced pesticide fingerprinting. This method uses gas chromatography to determine the concentrations of various pesticides in solid and liquid matrices.
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Title:
ACF Methods for PAHs
Text: A modified EPA Method 8270, Semi-Volatile Organic Compounds by Gas Chromatography/Mass Spectrometry (GC/MS), is used to analyze for 43 PAHs along with additional heterocyclics and biomarkers.
A modified EPA Method 8015 is used to determine total extractable hydrocarbons (THCs).
These two methods are used together to provide correlations between THC and PAH contamination in order to identify potential sources and to distinguish from background conditions.
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Title:
PAH Structure (1 of 8)
Text: PAHs contain multiple ring structures comprised of carbon and hydrogen, which are aromatic in nature. Naphthalene is the simplest PAH because it is a nonalkylated or parent PAH (no carbon chains are attached to the compound). Alkylated PAHs contain carbon side chains called "alkyl groups" that provide significant fingerprint information.
Heterocyclics co-occur with PAHs and are similar in structure. These carbon rings contain a nitrogen, oxygen, or sulfur atom. Heterocyclics are often specific to certain sources, making source determination easier.
Biomarkers are compounds that result from the metabolism of contaminants and are another set of organic compounds used in ACF that are linked to specific PAH sources.
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Title:
PAH Source Categories (2 of 8)
Text: PAH sources fall under several categories:
Petrogenic
Pyrogenic
Biogenic
Background in urban sediments is site-specific and usually comprised of all PAH source categories. Petrogenic PAHs in background are often a result of petroleum dripping onto parking lots and roadways and then washing from the storm water outfalls into the waterway. However, background is mostly comprised of pyrogenic sources due to combustion of fossil fuels in urban areas. Levels of pyrogenic PAHs are usually seen in the upper sediment layers from the more recent urbanization of these areas.
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Title:
Definition: Petrogenic
Text: Petrogenic PAHs are generated from geochemical alteration of organic matter from petroleum spills, coal-fired plants and municipal sewage treatment facilities.
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Title:
Definition: Pyrogenic
Text: Pyrogenic PAHs form when organic matter is incompletely combusted at temperatures usually above 400 degrees Celsius over a short time interval. These are mostly coal tar or petroleum tar products generated from manufactured gas production. For example, creosote is a tar product used to preserve wood that often is found as a contaminant in sediments. Pyrogenic sources such as creosote contain a higher concentration of PAHs when compared to petrogenic sources.
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Title:
Definition: Biogenic
Text: Biogenic PAHs are nonanthropogenic PAHs. They are a result of oxidation of microbial or plant-derived compounds in older and deeper sediments. They are a minor contribution to near-surface sediment contamination.
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Title:
Advanced PAH Methods (3 of 8)
Text: Several ACF methods can be used to determine PAH contamination and source.
One technique is to modify SW-846 Method 8270, Semi-Volatile Organic Compounds by Gas Chromatography/Mass Spectrometry (GC/MS). In this modified method, separation of target PAHs is optimized by operating a GC with a very slow oven temperature program. Interferences from other non-target compounds are minimized and detection limits are decreased by operating the mass spectrometer in selected ion monitoring (SIM) mode. These modifications to the standard methods reduce PAH detection limits from 660 μg/kg wet to 1 μg/kg dry. Modified Method 8270 detects alkylated PAHs and heterocyclics otherwise ignored by standard methods.
Another technique is to modify U.S. EPA Method 8015B. This method uses a GC along with flame ionization detection (GC/FID). The modification calls for a slower GC heating rate which provides more detail of concentration and character of total extractable hydrocarbons (THC) in the sediment. This data is then compared to total PAH concentrations to distinguish PAHs from the complex mixture of hydrocarbons present.
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Title:
Signature of Petrogenic PAHs (4 of 8)
Text: Petrogenic PAH signatures consist of lower molecular weight (2-3 ring) PAHs. They have a higher abundance of PAH’s containing alkyl groups than PAH’s without alkyl groups (parent PAH’s) and the distribution histograms typically display a Gaussian (bell-shaped) pattern.
Refining of crude oil is carried out under mild temperature and pressure conditions, thus the refined products only contain PAHs present in the parent crude oil. Crude oil and its petroleum products exhibit different PAH distributions that are useful in determining the individual petrogenic sources. In addition, petrogenic PAHs such as crude oil have a lower percent total PAH than pyrogenic PAHs such as creosote, making it possible to distinguish between them.
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Title:
Signature of Pyrogenic PAHs (5 of 8)
Text: Pyrogenic PAH source signatures consist of higher molecular weight (4,5,6 ring) PAHs. Most are unalkylated (parent) PAHs. There is a decrease in abundance of non-alkylated parent PAHs with an increase in degree of alkylated PAH’s. This is demonstrated in PAH C0 to C4. Pyrogenic PAHs are largely byproducts of coal and petroleum combustion. Creosote is an example that is used to preserve wood. Pyrogenic signatures display a much larger concentration of PAHs when compared to petrogenic materials.
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Title:
Signature of Typical Urban Background (6 of 8)
Text: The largest contribution to urban background contamination is PAHs in stormwater runoff. Sediment impacted by stormwater runoff often contains from 1,000 to 50,000 micrograms PAH per kilogram dry sediment. Background contamination consists mostly of pyrogenic (high molecular weight) PAHs that can be seen in the histogram. GC/FID chromatograms reveal an unresolved complex mixture (UCM) or hump that further distinguishes background from any point-source.
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Title:
Weathering of PAHs (7 of 8)
Text: Weathered PAH source signatures are distinguished by the depletion of lower molecular weight (2 ring) PAHs due to biodegradation, evaporation, and solubilization. There is also a reduction of nonalkylated PAHs. Weathered pyrogenic source signatures can often be confused with urban background. However, the proper use of GC/FID chromatograms can help to reduce confusion.
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Title:
PAH Data Analysis (8 of 8)
Text: A quantitative analysis of PAH fingerprints may be conducted using Principal Component Analysis (PCA). Weathering trends are typically indicated by the loss of lower molecular weight PAHs such as naphthalenes and acenaphthalene.
A PCA factor score plot (shown here) can be used to evaluate mixing trends between various sources. Samples clustered together within these plots are chemically similar and the samples in between indicate mixing of contaminants.
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Title:
Isotope Fingerprinting Tools
Text: Isotopic fingerprinting aids in establishing the source of contamination (including metals, PCBs, pesticides, and PAHs).
Stable isotopes of carbon, oxygen, hydrogen and sulfur are used in chemical fingerprinting. Carbon is the most widely used element for isotopic fingerprinting. The ratio of stable carbon isotopes carbon-13 and carbon-12 in any compound is a reflection of the original source because the ratios vary by source and do not change over time.
Radiogenic isotopes such as cesium-137, lead-210, and carbon-14 are used in sediment dating. Contaminated sites will usually have a long list of previous owners making source identification difficult.
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Title:
Definition: Stable isotopes
Text: Isotopes are atoms whose nuclei contain the same number of protons but different number of neutrons. They are stable because they do not decay appreciably over time.
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Title:
Definition: Radiogenic isotopes
Text: Radiogenic isotopes (or radionuclides) are unstable and undergo changes in mass number of atomic number over time. Decay processes that emit an electron or positron (beta decay) result in nuclides that have the same mass numbers. Other common decay mechanisms include gamma and alpha particle emission. All radiogenic decay mechanisms are associated with well-defined energies and half-lives, which may be used to characterize the parent radionuclide and daughter products.
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Title:
Norfolk Naval Shipyard: Elizabeth River Watershed
Text: A CSS was conducted by NAVFAC to determine the sources of PAH contamination in sediment along the Elizabeth River Watershed in Norfolk, Virginia.
The study area is a 2.6 mile stretch of the southern branch of the Elizabeth River. There is a long history of commercial, industrial, and Naval activities within the Elizabeth River Watershed.
The poor flushing characteristics of the tidal river leave sediments trapped within the river system. PAHs are the most prevalent chemical pollutants present in the trapped sediment.
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Title:
Multiple Sources of PAH Contamination
Text: There are several potential PAH sources within the Elizabeth River Watershed including:
1. Five Naval properties
Paradise Creek - storm water outfall
South Gate Annex
Scott Center Annex
St. Juliens Creek Annex
Norfolk Naval Shipyard
2. Ten petroleum storage terminals
3. At least four wood treatment facilities (Wood Preserver A is currently a Superfund Site)
4. Oceangoing freighters
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Title:
Paradise Creek - Storm Water Outfall
Text:
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Title:
Petroleum Terminal
Text:
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Title:
Wood Preserver
Text:
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Title:
Oceangoing Freighters
Text:
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Title:
RSC Screening Results
Text: RSC was used first to better define the most impacted areas within the watershed.
Approximately 200 sediment samples from the study area were analyzed using enzyme-linked immunosorbent assays (ELISAs) to rapidly measure total PAH concentrations. Click here for more information on the use of immunoassays.
RSC at the Elizabeth River site showed that the largest PAH contamination was found in the vicinity of two former wood treatment facilities (labeled A and E on the previous site map).
Outside of these two areas, the majority of sediments within the watershed were found to contain relatively low levels of total polycyclic aromatic hydrocarbons (TPAH) at 20 to 30 ppm.
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Title:
Immunoassay Description
Text: RSC for PAHs can be conducted using various immunoassay techniques. These techniques have been adapted from methods developed for use in soils. The method first requires dewatering of the sediment to below about 30% moisture by placing it on filter paper to remove excess water. The dewatered sediment is then extracted using solvent (e.g., methanol) and analysis of the extract is conducted. The extract is treated with specific antibodies that promote a color change depending upon PAH concentration. The sample is then measured against a PAH standard solution with a calibrated spectrophotometer.
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Title:
ACF Results
Text: Fifty samples were subsequently selected and analyzed via ACF using modified EPA SW-846 methods tailored for the “fingerprinting” of PAH and related hydrocarbons.
The ACF results further confirmed that the maximum TPAH concentrations were located in the vicinity of the former wood treatment facilities. TPAH concentrations were demonstrated to rapidly decrease away from these facilities.
The majority of sediments within the watershed contained less than 40 ppm TPAH using a modified method which analyzes for 43 target PAHs. ACF was used to demonstrate that these lower TPAH levels were typical of urban background contamination.
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Title:
Combined Results
Text: The TPAH screening concentrations from RSC correlated well with the ACF laboratory findings. This graph shows results from both methods (ACF versus RSC) and reveals that the concentrations are almost linear. This helps to demonstrate that RSC with PAH immunoassays can be a useful screening technique to guide the selection of ACF sample locations.
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Title:
Definition: Creosote(s)
Text: Creosote is a distilled or blended product most commonly used in wood preservation. The sediment samples dominated by creosote or creosote blends contained the highest concentrations of TPAH and also had the highest percentage of total extractable hydrocarbons (%THC) as PAH. For example, sediment samples most impacted by creosote contained 419 to 7,084 mg/kg of PAH and 24% to 75% THC as PAH.
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Title:
Definition: Urban Background
Text: Urban runoff is a mixture of debris in water – dust, dirt, particulate matter, soot, solid wastes – that is transported to rivers or coastal waters and sediments via non-point (surface runoff) and point (end-of-pipe) sources.
The sediment samples associated with an urban background fingerprint showed the lowest concentrations of TPAH and the lowest %THC attributable to PAH. For example, sediments dominated by background runoff contained only 8 to 59 mg/kg of PAH and 1% to 5% of THC as PAH.
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Title:
Description: Mixture of Creosote and Urban Runoff
Text: Most mixed samples exhibited fingerprints with intermediate features in terms of PAH concentration and %THC as PAH. A general spatial trend was also observed showing trace, moderate, and then heavy PAH levels associated with creosote in proximity to the point source(s).
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Title:
Analysis of PAH Fingerprints (1 of 2)
Text: A qualitative assessment was used to interpret chromatographic "fingerprints" from the site based on common knowledge of the chemical constituents that make up gasoline, diesel, fuel oil, coal tar, and creosote.
The qualitative analysis of PAH chromatographic "fingerprints" showed no signatures for petroleum hydrocarbons that matched Navy sources.
Three major source types were found in the sediment as follows:
1. Creosote(s)
2. Urban Runoff Background
3. Mixtures of Creosote and Urban Runoff
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Title:
Analysis of PAH Fingerprints (2 of 2)
Text: A quantitative analysis of PAH fingerprints was conducted using PCA and revealed two trends in the PAH data that supported the qualitative assessments. Weathering trends are typically indicated by the loss of lower molecular weight PAHs such as naphthalenes and acenaphthalene. Sediments in this study contained moderately to severely weathered creosotes or creosote-tar mixtures. This is notable because there was no unweathered (fresh) or even mildly weathered creosote observed. This is consistent with the fact that the wood treatment operations have ceased in the area.
The PCA score factor plots also support the mixing trend between various sources. Samples clustered together within these plots are chemically similar and those samples in between indicate mixing of contaminants. PCA factor score plots for Elizabeth River revealed a mixture of PAHs related to creosote/creosote blends and urban background.
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Title:
Definition: PCA
Text: PCA is a powerful chemometric technique for visualizing intersample and intervariable relationships.
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Title:
Definition: PCA factor score plots
Text: PCA yields a distribution of samples (e.g., sediment samples) in n-dimensional space, where n is the number of variables (e.g., PAH analytes). The first PC is a line through this space upon which each sample point can be projected. The line's orientation is such that the variance of these projections is maximized. The second PC is another line defining the next highest variance. These lines define a plane. These planes are called factor score plots, which are one 'end product' of PCA.
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Title:
Spatial Results
Text: Spatial distribution of sample concentration gives a visual assessment of PAH contamination along the study area. The symbol size is proportional to percent THC as PAH at that location.
Background locations contain less than 5% of THC as PAH. Mixed sediments contain 5-20% THC as PAH. Anything greater than 20% THC as PAH is creosote-impacted sediment.
The spatial analysis shows that samples containing elevated percentages of PAH exist in close proximity to wood treatment facilities. This distribution reveals a strong influence of former creosote operations on the PAH contamination. This analysis helps to rule out nearby Navy facilities as potential sources of the contamination.
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Title:
Conclusions for ACF Case Study
Text: The results of this case study clearly indicate that the sources of PAH to the southern branch of the Elizabeth River are dominated by creosote-like sources that are related to historic wood treatment operations. In the remaining portions of the study area, sediments typically contain less than 30 mg/kg TPAH which is consistent with urban background levels. ACF methods were successfully used to demonstrate that there are no significant Navy-related point sources of PAH to sediments within the Elizabeth River watershed.
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Title:
Summary
Text: The purpose of this Web tool was to provide an introduction to ACF methods that can be used by Navy RPMs to prioritize cleanup efforts. ACF methods can help to distinguish between Navy and non-Navy sources by identifying contaminants reasonably derived from Navy or other sites and clearly defining background levels of contamination.
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Title:
Contact Information
Text: For more information about ACF Methods, please contact:
NFESC POC
(805) 982-1656
PRTH_NFESCT2@navy.mil
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