Transport Of Polychlorinated Biphenyls Research Articles

Uptake and translocation of lesser-chlorinated polychlorinated biphenyls (PCBs) in whole hybrid poplar plants after hydroponic exposure

Mono-, di-, tri-, and tetra-chlorinated polychlorinated biphenyls (PCBs) are congeners with greater volatility which remain in air, soils and sediments requiring treatment. In this study, the fate of these PCBs was investigated within whole poplar plants ( Populus deltoides x nigra, DN34) with application for a treatment system such as a confined disposal facility for dredged material. Whole hybrid poplars were exposed hydroponically to a mixture of five congeners, common in the environment, having one to four chlorine atoms per molecule. Results indicated that PCB 3, 15, 28, 52, and 77 were initially sorbed to the root systems. The root concentration factor (RCF) of PCBs during the exposure was calculated and correlated with K ow. PCB congeners were taken up by the roots of hybrid poplar, and the translocation of PCBs to stems was inversely related to congener hydrophobicity (log K ow). PCB 3 and 15 were translocated to the upper stem at small but significant rates. PCB 28 was translocated to the wood of the main stem but no farther; translocation from the roots was not detected for PCB 52 and 77. The distribution of PCBs within poplars was determined, and mass balances were completed to within 15% for each chemical except for PCB 3, the most volatile congener. This is the first report on the transport of PCBs through whole plants designed for use in treatment at disposal facilities.

Simulation of polychlorinated biphenyls transport in the vadose zone

Polychlorinated biphenyls (PCBs) are the main constituents of clophen (the liquid of the electric transformers and capacitors) and have been characterized as potential human carcinogens. PCBs can be a hazardous contaminant of soil and groundwater. We used the mathematical model variably saturated 2D flow and transport (VS2DT model) to simulate the transport of PCBs from the soil surface to groundwater for a time period of 30 years. We also used a mathematical model to simulate the colloid-facilitated PCB transport, under saturated flow conditions. The results showed that PCBs dissolved in water cannot be transported to large depths in unsaturated soils, because of their strong sorption onto soil and low solubility in water. For soils with very low or no organic matter content, PCB transport is much faster and the probability of groundwater contamination is much higher. PCBs can partition to colloids originating from dissolved organic matter in groundwater. Colloid-facilitated PCB transport is faster compared to PCB transport in aqueous solution with no colloids present.

Measurement and modeling of urban atmospheric PCB concentrations on a small (8 km) spatial scale

Atmospheric transport and deposition of polychlorinated biphenyls (PCBs) is an important problem for ecosystems around the world. Data from several monitoring networks demonstrate that atmospheric PCB concentrations are dramatically elevated in urban areas compared to rural or background regions, such that these urban emissions of PCBs support the regional and global transport and deposition of PCBs to more remote areas. Identifying and controlling the sources of urban atmospheric PCBs is thus essential in minimizing the regional and global transport and deposition of these compounds. From December 1999 to November 2000, gas-phase PCB concentrations were measured at two monitoring locations, ∼8 km apart, within the New York City metropolitan area, at Jersey City and Bayonne, NJ. Concentrations, congener patterns, and temporal patterns of PCBs differ dramatically at the two sites, suggesting that a significant source of atmospheric PCBs exists within 8 km of the Bayonne site, resulting in spikes in gas-phase PCB concentration at Bayonne that are not observed at Jersey City. The Regional Atmospheric Model System (RAMS) coupled with the Hybrid Particle and Concentration Transport model (HYPACT) was used to estimate that the PCB source near Bayonne emits a flux of ΣPCBs on the order of 100 g d −1. Extrapolation of this source magnitude to the area of New York City suggests that this urban area emits at least 300 kg yr −1 ΣPCBs to the regional atmosphere, similar in magnitude to the flow of ΣPCB out of the Upper Hudson River into the New York/New Jersey Harbor.

An integrated geochemical and hydrodynamic model for tidal coastal environments

In this paper, the design, calibration and application of an integrated geochemical–hydrodynamic model are described. The model comprises three parts: A hydrodynamic submodel that was adopted from a depth-averaged, semi-implicit hydrodynamic model, a geochemical submodel based on equilibrium partitioning of chemicals between aqueous and particulate phases, and a particle dynamic submodel that simulates resuspension, transport and settling of suspended particulate matter (SPM). The integrated model was implemented in San Diego Bay (SDB), a heavily urbanized, semi-closed mesotidal embayment. A series of model calibrations were carried out based on observations on salinity, polychlorinated biphenyls (PCBs) and SPM. Salinity calibrations indicated that only 15% of precipitation in the drainage area of SDB could reach the bay, presumably due to the dams on the tributary rivers. Steady-state calibrations of PCBs based on fixed concentrations at known ‘hot spots’ have reproduced observed PCB concentrations in both the dissolved and particulate phases. SPM calibrations showed that shipping-induced resuspension produce more SPM than natural processes. Based on the calibrated model, the annual transport of PCBs out of SDB was estimated to be 3.85 kg (3.5 kg and 0.35 kg in the dissolved and particulate phases, respectively), much higher than the previous estimates based on steady-state assumptions. It was also found out that only a small portion of the fine sediment exported from SDB was derived from riverine input. This model can be applied to the studies of the transport and fate of other chemical species. It can be transplanted to other coastal areas as well. The integrated model represents a novel framework in which geochemical processes in coastal environments can be investigated on a truly dynamic basis.

Microcosm Approach to Study Transport of Polychlorinated Biphenyls in Sediment

The transport of polychlorinated biphenyls (PCBs) in sediment is difficult to study in the laboratory due to their low solubility and strong tendency to sorb to sediment and experimental equipment. A small-scale laboratory microcosm was designed to study PCB transport in anaerobic surface sediment at microscale and to quantify transport rates. Results of verification testing showed that the experimental system enabled quantitative characterization of the diffusive transport of PCBs in sediment in a reasonable time frame (months). The fine-spatial-resolution results obtained were as expected with the less chlorinated, more mobile congeners transporting the fastest and the more heavily chlorinated compounds transporting more slowly. This laboratory microcosm system could be used to study the transport of many types of pollutants in sediment, but is particularly useful for hydrophobic organic compounds.

PCB Volatilization from Sediments

The loss of polychlorinated biphenyls (PCBs) from sediment by volatilization is currently under scrutiny by polluters, regulators, and researchers. In this research, a one-dimensional mathematical model for the volatilization of PCBs from sediment was developed. The model considers a system with three phases: A water-saturated PCB contaminated sediment, the overlying water, and air above the water. A simple microcosm consisting of sediment, water and air that allows for (pseudo)-one-dimensional transport of PCB from the sediment to the gas phase was utilized to perform PCB transport studies using two PCB congeners: 4,4′-dichlorobiphenyl (DCB) and 2, 2′,4,4′,5,5′-hexachlorobiphenyl (HCB). The experimental data on DCB were used to calibrate and validate the mathematical model. The calibrated model was then used to simulate the effect of sediment layer thickness, depth of the overlying water, and the level of contamination on the rate of DCB volatilization.

Environmental Monitoring Of Remedial Dredging At The New Bedford Harbor, Ma, Superfund Site

New Bedford Harbor (NBH), MA, is a Superfund site because of high polychlorinated biphenyl (PCB) concentrations in the sediment. From April 1994 to September 1995, a remedial dredging operation (termed the "Hot Spot") removed the most contaminated sediments (PCB concentrations greater than 4000 microg/g) from the upper harbor. During remediation, a monitoring program assessed the potential environmental impacts to NBH and adjacent Buzzards Bay. The monitoring program was developed with input from federal, state, and local authorities. Site-specific decision criteria were established to assess net PCB transport, water column toxicity, and PCB bioaccumulation in blue and ribbed mussels (Mytilus edulis and Geukensia demissa, respectively). The remediation was completed without exceeding PCB net transport or acute toxicity effects specified in the decision criteria. In addition, PCB bioaccumulation in mussels during this time period was not significantly greater than pre- or post-operational measurements. The results indicated that approximately 14000 cubic yards of highly PCB contaminated sediment were permanently removed with minimal environmental effects. The lessons learned during this operation, as well as previous pilot studies at the site, will be used to make full-scale remedial efforts in NBH more efficient and environmentally protective.

PCB Congeners and Dechlorination in Sediments of Sheboygan River, Wisconsin, Determined by Matrix Factorization

Nine sediment cores were collected from the Sheboygan River Inner Harbor, WI, and analyzed for polychlorinated biphenyl (PCB) congeners. Total PCBs ranged from approximately 0 to 161 mg/g. Positive matrix factorization (PMF) was applied to the PCB data setto determine source profiles. Two factors were determined to be significant. One factor resembled the original approximated PCB mixture of 50% Aroclor 1248 and 50% Aroclor 1254 and the other factor was a dechlorinated version of the mixture. An anaerobic dechlorination model was applied to the dechlorinated source profiles to quantify possible dechlorination pathways. It was found that dechlorination process H' provided the best fit for an individual process, and H' + M provides the best fit for combined processes. PMF source contributions, and plots of PCB concentration versus congener for individual samples, provide evidence of enhanced dechlorination at high concentrations (>40 ppm) and small amounts of dechlorination at low concentrations (<3 ppm). In addition, downward migration of lower chlorinated PCBs in core SR1a has occurred. Remediation dredging in the Upper Sheboygan River in 1989 and 1990 reintroduced PCBs to the water column and selective transport of PCB 18 is observed in core SR7.

Microcosm Experiments to Assess the Effects of Temperature and Microbial Activity on Polychlorinated Biphenyl Transport in Anaerobic Sediment

Increased polychlorinated biphenyl (PCB) loadings from sediment to the water column under low-flow conditions during late spring and summer months have been observed in the Grasse River (Massena, NY) and other PCB-contaminated rivers in the United States. Temperature appears to be an important factor affecting this phenomenon, as increased sediment temperature leads to increased microbial and bioturbator activity as well as increased rates of diffusion and desorption. Laboratory-scale sediment microcosms were developed and used to study with fine-scale resolution the effects of temperature and microbial activity on PCB transport in river sediment. Over the time course of these experiments, with the extraction procedures used, irreversible sorption of each congener to sediment was observed and increased with aging of the sediment. Temperature-dependent transport was observed for PCB congeners 2,4,5-trichlorobiphenyl (BZ29), 2,5-dichlorobiphenyl (BZ9), and 2-chlorobiphenyl (BZ1) in Grasse River sediment and a synthetic sediment system. The fastesttransport of the congeners occurred in biologically active Grasse River sediment followed by biologically inactive (autoclaved) Grasse River sediment, and synthetic sediment. The increased transport in biologically active sediment demonstrated the importance of microbial activity, in particular gas bubble generation, in PCB transport in near-surface sediments.

Mass budget and dynamics of polychlorinated biphenyls in the eastern Mediterranean Sea

Polychlorinated biphenyls (PCBs) were measured in dry deposition and sediment trap samples from the eastern Mediterranean and the results of the present and previous studies were synthesized in order to construct a mass balance budget describing the status and dynamics of PCBs in this region. According to our calculations, the burden of total PCBs in the euphotic zone of the eastern Mediterranean should approach 84,000 kg, while the corresponding pool in the overlying atmosphere should be about 162 kg. The atmospheric input of PCBs in the respective water basin through dry and wet deposition should be 300 and 1300 kg yr−1, respectively. On the contrary, air‐sea exchange should cause a net volatilization of PCBs from seawater to the atmosphere by 3150 kg yr−1. Moreover, PCBs are removed from the water column with a settling flux of 350 kg yr−1 and under steady state conditions, an additional input of these pollutants should be required to counterbalance the outflows from the water basin. The discharge of urban and industrial sewage, riverine input and transport of more polluted surface waters from western to eastern Mediterranean may account for most of this inflow. In the atmospheric compartment, the removal flux of PCBs due to their destruction by hydroxyl radicals (6650 kg yr−1) was approximately 4 times higher than their deposition flux (wet plus dry). On the basis of these data, 5100 kg of PCBs should enter into the atmosphere of eastern Mediterranean annually in order to achieve steady state conditions. This influx may result from long or short range transport of atmospheric PCBs emitted from contaminated terrestrial surfaces.

Polychlorinated biphenyls in serum of the Siberian Yupik people from St. Lawrence Island, Alaska

Objectives. To determine serum levels of polychlorinated biphenyls (PCBs) in Siberian Yupik adults from St. Lawrence Island, Alaska, and to determine the relative contribution of atmospheric transport of PCBs and local contamination to body burdens.Study Design. Siberian Yupiks of various ages were recruited from three populations: residents of the village of Gambell, residents of the village of Savoonga who did not have family hunting camps near the Northeast Cape (NEC), a Formerly Used Defense Site (FUDS) known to be contaminated with PCBs, and residents of Savoonga whose families had a hunting camp at the NEC.Methods. Levels of PCBs were measured in serum samples from 130 people, ages 19–76. These Alaska Natives follow a traditional diet high in marine mammals and fish, which bioconcentrate organochlorine compounds that migrate to the Arctic via global air transport and ocean currents.Results. The lipid-adjusted serum PCB levels of those members of families with hunting camps at the NEC had a mean lipid-adjusted PCB concentration of 1,143 ppb, whereas other residents of Savoonga had values of 847 ppb and residents of Gambell had values of 785 ppb.Conclusions. Our observations suggest that atmospheric transport of PCBs contributes to levels in the Yupik people, but that the abandoned military site at the NEC may also contribute to the human body burden in those individuals who have either spent substantial time or consumed food from there. (Int J Circumpolar Health 2005; 64(4):322–335)

Evaluation of sequentially-coupled POP fluxes estimated from simultaneous measurements in multiple compartments of an air–water–sediment system

Bulk atmospheric deposition fluxes, air–water exchange fluxes, particle settling fluxes out of the upper water column, sediment trap fluxes in deep waters, and sediment burial fluxes of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in the Koster Fjord, eastern Skagerak, on the Swedish west coast. The aim of the study was to compare the magnitude and direction of the compound fluxes in the system in order to diagnose key fate processes. The PCB and PAH fluxes via net atmospheric deposition, settling particles out of the surface and through deep waters, as well as into the accreting underlying sediments were shown to be remarkably similar, agreeing within a factor of a few for any given target compound. Fluxes of all PCB and PAH target compounds remained fairly constant with water column depth. Thus there was no evidence for net desorption from sinking particles. The net unidirectional and near balancing of vertical fluxes suggests a net transport of PCBs and PAHs from the atmosphere to the continental shelf sediments in the Koster Fjord, which is consistent with the hypothesis that the shelf sediments are important sinks for these compounds.

Redistribution of Polychlorinated Biphenyls from a Local Point Source: Terrestrial Soil, Freshwater Sediment, and Vascular Plants as Indicators of the Halo Effect

Polychlorinated biphenyl (PCB) concentrations and congener profiles in terrestrial soils, vascular plants, and freshwater lake sediments were compared with respect to their relative utilities for assessing the redistribution of PCBs from a local contaminant source into the surrounding arctic environment.Plants (n = 62), soils (n = 58), and surficial freshwater lake sediments (n = 16) were collected at varying distances up to 27 km from the source at Saglek, Labrador. Total PCB concentrations in these media exhibited similar negative log-linear relationships with increasing distance from the contaminant source. Analysis of congener compositions indicated that plants are more reflective of recent PCB exposure than either soils or sediments. Vascular plants reflect current ambient contaminant concentrations, whereas terrestrial soils and freshwater sediments represent much longer periods of contaminant deposition and are further influenced by such factors as their organic carbon content, particle size distribution, lake watershed size and productivity (in the case of sediments), and proximity to a drainage course (in the case of soils). Collectively, the data indicate that short-range transport of PCBs at Saglek has resulted in a halo of contamination that is up to 50 km in diameter.

Modeling of polychlorinated biphenyl removal from contaminated soil using steam.

Microwave-generated steam technology shows promise as an effective remediation alternative for removal of polychlorinated biphenyls (PCBs) from contaminated soils, based on our laboratory-scale experiments. The overall process can be described by a nonisothermal, unsteady, coupled heat and multicomponent PCB mass-transport model in a multiphase, variably saturated, porous soil medium. In this paper, a multicomponent PCB mass-transport model is presented that assumes evaporation is an important removal mechanism and that is based on first-order mass transfer between the interface of PCB films and the bulk steam. The model was calibrated using the experimental data, and the calibrated model was verified by computational mass-balance checks and comparisons with laboratory-scale column experimental results. From a qualitative point of view, the calibrated model successfully simulated the transport of PCBs in variably saturated soil media. The calculated increase/decrease factors of physicochemical properties of PCBs as a function of temperature in the soil, water, and free phases were consistent with the model hypothesis of an evaporation process. The effects of mass-transfer coefficients and initial PCB concentrations in the soils on PCB removal rates were investigated using the numerical code. It was determined that the PCB removal rates were sensitive to mass-transfer coefficients and initial PCB concentrations. Although the steam:soil mass ratios required to achieve a given percentage removal were lower for lower initial PCB soil concentrations, steam: soil mass ratios required to achieve a given unit mass removal were higherfor lower initial PCB soil concentrations.

Polychlorinated biphenyls (PCBs) in sediments of the southern Baltic Sea — trends and fate

Polychlorinated biphenyls (PCBs) have been determined in recent [0–1(2), 1(2)–5 and 5–10 cm deep layers] sediments from different sites of the southern Baltic Sea, including the Szczecin Lagoon, collected from May 1996 to October 1999, i.e. before and after the great flood in Poland of July/August 1997. The PCB distribution has been correlated with location and hydrological conditions as well as with organic carbon, algal pigments and their derivatives in the sediments. The sum of PCB (seven congeners) was equal to ∼1–149 ng/g dry wt., on average this was rather low (up to 40 ng/g). There was a decreasing trend in PCBs concentrations in the bottom sediments of the southern Baltic in 1996 but considerable amounts were still accumulated there. The flood of 1997 caused a distinct increase of PCB concentration level in the sediments, which again showed a decreasing trend in the next few years. This illustrates that at present the main source of PCBs for the southern Baltic are not a direct consequence of human activity, but from floods and heavy rains washing these compounds from land to the sea. Algae and algal detritus play an important role in the transport and distribution of PCBs in the southern Baltic. High correlation of PCBs with chlorophyll a derivatives — products of zooplankton grazing — indicates that PCBs are ingested by zooplankton with phytoplankton and then exuded with fecal pellets. PCBs bound to algal detritus or to fecal pellets in the water column are transferred to sediments, there they may be trapped either in a bonded and unchanged form or resuspended, remobilized and/or dechlorinated, depending on their properties and environmental conditions.

Remediation of former military bases in the Canadian Arctic

This paper describes novel aspects of the remediation of three former military bases in the Canadian Arctic. At Iqaluit, the site has been totally cleaned up. All buildings were demolished, and soils contaminated with metals and polychlorinated biphenyls (PCBs) removed. Soils were excavated and most containerized and shipped south for disposal; soils containing 1–5 ppm PCBs were buried on site along with nonhazardous debris. PCB-contaminated concrete foundations were also investigated and removed. While most contamination was in the surface of the active layer, some migration of PCBs along the surface of the underlying bedrock at greater depth was found. At Sarcpa Lake, a dump leaching PCBs was excavated. Methodology was developed for this investigation and the difficulties of excavation in permafrost are described. The PCBs in the dump were from electrical equipment and/or PCB-containing paint used at this former Distant Early Warning (DEW) Line site. Investigation of the painted material at the site showed PCB levels as high as 7.4% in the paint. Wall swab results show that the repainting of the walls had effectively rendered the PCBs unavailable to solvent washing. At Resolution Island, the extent of contamination is much larger than the other two sites. Interceptor barriers were designed and installed in the leachate pathways carrying PCBs between the site and the ocean. At this site, the presence of petroleum products along the drainage pathway has led to increased transport of PCBs due to their higher solubility in these solvents as compared to water. Current progress at this unique remote site and the options for dealing with the contaminated soil are discussed.

PCBs in the Detroit River Water Column

Water samples (60 to 190 L) were taken from the Trenton Channel portion of the Detroit River during eight sampling events from March to October 1995, and in May 1996. Samples were filtered on-site or at the field-lab to retain the suspended particulates. Some of the samples were passed through XAD-2 columns to extract dissolved PCBs, depending on total sample volume and logistical considerations. Concentrations of polychlorinated biphenyls (PCBs) were measured in both the paniculate and dissolved fractions. Concentrations ranged from < 5 to 22 ng/L (average = 10 ng/L) in the paniculate, and from < 5 to 13 ng/L in the dissolved fractions. The average ratio of dissolved PCB concentration to particle-bound PCB concentration was 0.6; the calculated average total PCB concentration was 17 ng/L. Annual mass transport of PCBs through the Trenton Channel in 1995 was estimated to be 600 kg, with potential point sources along the west shore of the channel contributing less than 1.5% of the total mass of PCBs. A general seasonal trend was observed, with lowest PCB concentrations in March and greatest in July. Concentrations following a significant rainfall increased within the first 24 hr and decreased to approximate ambient levels after 96 hr. In general, PCB concentrations appear to be greater downstream than upstream, however, this trend was reversed for Day–1 of the rainfall events, perhaps due to greater particulate loading from upstream of the channel. Potential point-sources from industrial or municipal waste-water treatment outfalls showed PCB concentrations up to a factor of 4 greater than those from the transects in the channel. However, the annual loading of PCBs to the channel from these sources was small (< 2%) compared to the mass transported through the channel. Dissolved concentrations of PCBs determined byC18 Empore disks were 4.7-fold greater than those determined by XAD-2 (s.d. = 1.5, n = 4). Further investigations validating this finding are necessary. For this reason, comparisons among different studies must be done with caution.

A study of the spatial distribution of PCBs in the UK atmosphere using pine needles

Past and current polychlorinated biphenyl (PCB) inputs to the environment, mainly in industrialized countries, continue to determine a global re-distribution of these contaminants. In order to better understand PCB transport and distribution phenomena, a number of large-scale distribution studies have been recently published in the literature. In this paper a nationwide survey of 28 pine needle samples taken across the UK is presented. Mean PCB concentrations of a number of latitudinal bands (transects) revealed the presence of a decreasing concentration gradient from southern England to northern Scotland of a factor of ∼7. The pine needle data also provide evidence to suggest: 1) that there has been a decrease in the PCB concentration of the atmosphere in the southern UK; and 2) there is a relationship between regional mean needle PCB concentrations and population densities. Calculated air concentrations from the pine needle results were compared with measured literature data of a similar area to test the possibility of using bioconcentration factors (BCF) based on n-octanol: air partition coefficients (Koa) to predict air-leaf equilibrium of semivolatile organic compounds. A more detailed analysis, in accordance with some literature data, has revealed that uncertainties arise when leaf-air uptake of molecules with high Koa values (Log Koa > 8–9) is modelled.

Effect of fatty acids and the aqueous diffusion barrier on the uptake and transport of polychlorinated biphenyls in Caco-2 cells

Polychlorinated biphenyls (PCBs) dissolved in dietary fat are absorbed in the gastrointestinal tract by the enterocytes in combination with the fatty acids proceeding from the lipid hydrolysis in the gut lumen. The effect of fatty acid absorption on the uptake and transport of 14 PCBs in enterocytes was studied using monolayers of the human intestinal Caco-2 cell line as a model system. The diffusive resistance of the unstirred water layer and the facilitating role of mixed bile salt micelles on the PCB uptake were examined by varying the thickness of the unstirred water layer adjacent to the apical membrane. In additional experiments, the polarity of the PCB uptake and transport in Caco-2 cells was determined. The solubility of PCBs in the mixed bile salt-fatty acid micelles was 2.7 to 4.8-fold higher than the solubility in plain bile salt micelles. Both the uptake and transport of PCBs in Caco-2 cells were significantly higher (up to 10-fold) when the PCBs were presented mixed with fatty acids. Reducing the thickness of the unstirred water layer resulted in an increased uptake of PCBs. The PCB uptake in Caco-2 cells exceeded the uptake as expected from monomer diffusion only, indicating that bile salt micelles facilitate the PCB transport over the unstirred water layer. Concentrations of dichlorobiphenyls accumulating in the basolateral medium stayed unexpectedly low, suggesting that Caco-2 cells might possess the capability of metabolizing lower chlorinated biphenyls. Uptake of PCBs into the Caco-2 cells was not significantly different whether the PCBs were presented at the apical side or at the basolateral side. However, transport of PCBs over the cell monolayer was significantly higher when the PCBs were presented at the apical side as compared to the basolateral side, suggesting that the unidirectional transport of lipids and lipoproteins affected the PCB transport as well. Our studies indicate that monolayers of the Caco-2 cell line offer a useful model system for studying the intestinal uptake and transport processes of hydrophobic xenobiotics such as polychlorinated biphenyls.

Fate and transport of pcbs at the new bedford harbor superfund site

AbstractA unique, holistic modeling approach, combining theoretical, empirical, and deterministic elements, was developed to define the ambient background transport of polychlorinated biphenyl (PCB) from New Bedford Harbor, to provide a baseline for remediation assessment of this Superfund site. Both empirical and deterministic elements characterized sediment processes. The deterministic section employed experimental data to describe flocculation through fluid shear, differential settling, and Brownian motion mechanisms, yielding a sediment settling velocity. The empirical portion of the model used this settling velocity, along with suspended solids, and flow field data to characterize sediment action. The remaining PCB transport mechanisms (volatilization and sorption) are theoretically considered to give a complete contaminant transport assessment. The PCBs in New Bedford Harbor tend to volatilize at the rate of 5.9 g/d; or sorb, with sorption coefficients increasing with percent chlorination from 10−22 to 10−04 m3/g for Aroclors 1016 and 1260, respectively, rather than stay in solution. The deterministic model showed that fluid shear was the most significant flocculation mass removal mechanism contributing to the settling velocity calculation. From the empirical model, the dominant sediment action mechanisms, resuspension and deposition, were driven by the change in suspended solids concentration and tides. The cycling of PCB‐laden sediment, indicated by the PCB sorption tendency and the presence and dominance of resuspension, and subsequent transport from the site, can lead to PCB contamination of the water column, atmosphere, or downstream (marine) areas.