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This is the first investigation of the bioavailability of PCBs associated with paint chips (PC) dispersed in sediment. Bioavailability of PCB-containing PC in sediment was measured using ex situ polyethylene passive samplers (PS) and compared to that of PCBs from field-collected sediments. PC were mixed in freshwater sediment from a relatively uncontaminated site with no known PCB contamination sources and from a contaminated site with non-paint PCB sources. PC

Graphic Abstract Polychlorinated biphenyls (PCBs) were added to certain marine vessel bottom paints as a plasticizer to improve the adhesion and durability of the paint. The most common PCB formulation used to amend such paints was Aroclor 1254. Fugitive Aroclor-containing paint chips generated from vessel maintenance and repair operations represent a potential source of PCB contamination to sediments. Limited published studies indicate that Aroclor-containing paint is largely inert and exhibits low PCB leaching into water; however, the rate and degree of leaching of PCBs from paint chips have not been directly studied. This laboratory-based study evaluated the rate and extent of leaching of PCBs from paint chips into freshwater. The results of this investigation demonstrate that the rate of PCB dissolution from paint chips decreased rapidly and exponentially over time. Based on this study, it is estimated that the rate of leaching of PCBs from paint chips would cease after approximately 3 years of exposure to water. When all leachable PCBs were exhausted, it is estimated that less than 1% of the mass of PCBs in the paint chips was amenable to dissolution. The results of this experiment suggest that Aroclor-containing paint chips found in sediments are likely short-term sources of dissolved-phase PCB to pore or surface waters and that the majority of the PCBs in paint chips remain in the paint matrix and unavailable for partitioning into water. Supplementary Information The online version contains supplementary material available at 10.1007/s00244-021-00868-6.

Site investigations require the collection and analysis of representative environmental samples to delineate impacts, risks, and remediation options. When environmental samples are collected, concentrations of semi-volatile polycyclic aromatic hydrocarbons (PAHs) begin to change due to several processes, such as evaporation, adsorption, precipitation, photo, and microbial degradation. Preservation techniques are used to minimize these changes between collection and analysis. The most common techniques are refrigeration, freezing, and acidification. In the mid 1970 s, regulatory agencies developed a holding time limit of 14 days for PAHs in soil/sediment samples stored at

On or about July 25, 2010, approximately 843,000 gal of condensate diluted bitumen (dilbit, a heavy oil) was released into the Kalamazoo River near Marshall, Michigan. As the discharged Line 6B oil migrated downstream the lighter diluent volatilized, formed visible oil droplets/flakes in the water column, became denser than water and/or became aggregated with sediment and migrated to the underlying bottom sediments. Accurate identification and determination of the amount of Line 6B oil present in the sediment was a primary requirement for remediation and allocation of liability. Based on a multi-tiered application of advanced hydrocarbon fingerprinting methodology, key chemical characteristics of the spilled oil were identified that allow for distinguishing heavy oil-related contamination from the complex river sediment background hydrocarbon contamination. It was determined that among the characteristics evaluated, concentration ratios of selected tri-aromatic steranes and triterpanes were most efficient parameters for identification and quantification of the spilled oil in the environment. This quantification approach was successfully applied and validated with field sample results and is consistent with the well-established environmental stability of these petroleum biomarkers and modern hydrocarbon fingerprinting methodology.

The Deepwater Horizon (DWH) oil spill was unique because unlike most oil spills, a substantial fraction of the released oil was deposited on deep-sea floor as both particulate oil close to the Macondo well and as oily floc further from the well. In late 2010/2011 and in 2014, benthic macrofauna, including large populations of the deep-sea red crab (Chaceon quinquedens), were collected from the deep seafloor to determine if there was forensic evidence for their exposure to the spilled Macondo oil. In this study, polycyclic aromatic hydrocarbons and biomarkers (triterpane and steranes) were measured in more than 1700 dissected red crab tissue samples, in order to assess the concentrations and distributions (chemical fingerprint) of any oil present within the tissues. Results show that red crabs clearly were exposed to Macondo oil from the DWH oil spill—and as such can be considered as sentinel organisms for oil exposure in deep benthic environments. Specific results included (1) among various tissue types studied, the red crab hepatopancreas provided the most sensitive and diagnostic chemical fingerprints by which to assess exposure of these animals, (2) the highest exposures of red crabs to Macondo oil in 2010/2011 occurred closest to the well although exposures up to 14 km southwest of the well were identified, (3) detection of Macondo oil residuals in red crabs was consistent with spatial distribution of spill-impacted deep-sea sediments, and (4) exposures were lower in 2014 but still recognized, particularly within the more recalcitrant biomarkers.

We describe a new and rapid quantitative approach to assess the extent of aerobic biodegradation of volatile and semivolatile hydrocarbons in crude oil, using Shushufindi oil from Ecuador as an example. Volatile hydrocarbon biodegradation was both rapid and complete-100% of the benzene, toluene, xylenes (BTEX) and 98% of the gasoline-range organics (GRO) were biodegraded in less than 2 days. Severe biodegradation of the semivolatile hydrocarbons occurred in the inoculated samples with 67% and 87% loss of the diesel-range hydrocarbons (DRO) in 3 and 20 weeks, respectively. One-hundred percent of the naphthalene, fluorene, and phenanthrene, and 46% of the chrysene in the oil were biodegraded within 3 weeks. Percent depletion estimates based on C(30) 17α,21β(H)-hopane (hopane) underestimated the diesel-range organics (DRO) and USEPA 16 priority pollutant PAH losses in the most severely biodegraded samples. The C(28) 20S-triaromatic steroid (TAS) was found to yield more accurate depletion estimates, and a new hopane stability ratio (HSR = hopane/(hopane + TAS)) was developed to monitor hopane degradation in field samples. Oil degradation within field soil samples impacted with Shushufindi crude oil was 83% and 98% for DRO and PAH, respectively. The gas chromatograms and percent depletion estimates indicated that similar levels of petroleum degradation occurred in both the field and laboratory samples, but hopane degradation was substantially less in the field samples. We conclude that cometabolism of hopane may be a factor during rapid biodegradation of petroleum in the laboratory and may not occur to a great extent during biodegradation in the field. We recommend that the hopane stability ratio be monitored in future field studies. If hopane degradation is observed, then the TAS percent depletion estimate should be computed to correct for any bias that may result in petroleum depletion estimates based on hopane.

On January 30, 2000, an accidental oil release occurred from a fracture in the OSSA II pipeline where it crosses over the Rio Desaguadero in Bolivia, South America. This paper addresses the composition of the spilled oil and the unique weathering processes that occurred after the spill. Samples of oil, oiled sediment, water, and vegetation were collected from the riverbank and surrounding areas for approximately one year after the initial release. The samples were analyzed by gas chromatography with a flame ionization detector and by gas chromatography coupled with mass spectrometry to characterize the weathered product. Laboratory studies were also performed to evaluate the maximum extent of evaporation of the pipeline oil, and the extent of water solubility. Based on these chemical analyses, several conclusions were reached: • There was a rapid and substantial loss of the benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH) oil fractions. • The BTEX and PAH losses were due primarily to evaporation. • The stranded residual oil consisted primarily of heavy, immobile hydrocarbons. • Photooxidation of PAHs, including benzo(a)pyrene, was observed. • A unique weathering mechanism was observed that selectively removed mid-range hydrocarbons (C20 through C39) from the bulk oil. • The overall environmental risk of the spilled oil has been reduced due to the extensive weathering of the oil.