Bedford Harbor Sediment Research Articles

Hydroxylated Polychlorinated Biphenyls Are Emerging Legacy Pollutants in Contaminated Sediments.

We measured the concentrations of 837 hydroxylated polychlorinated biphenyls (OH-PCBs, in 275 chromatographic peaks) and 209 polychlorinated biphenyls (PCBs, in 174 chromatographic peaks) in sediments from New Bedford Harbor in Massachusetts, Altavista wastewater lagoon in Virginia, and the Indiana Harbor and Ship Canal in Indiana, USA and in the original commercial PCB mixtures Aroclors 1016, 1242, 1248, and 1254. We used the correlation between homologues and the peak responses to quantify the full suite of OH-PCBs including those without authentic standards available. We found that OH-PCB levels are approximately 0.4% of the PCB levels in sediments and less than 0.0025% in Aroclors. The OH-PCB congener distributions of sediments are different from those of Aroclors and are different according to sites. We also identified a previously unknown compound, 4-OH-PCB52, which together with 4′-OH-PCB18 made up almost 30% of the OH-PCBs in New Bedford Harbor sediments but less than 1.2% in the Aroclors and 3.3% in any other sediments. This indicates site-specific environmental transformations of PCBs to OH-PCBs. We conclude that the majority of OH-PCBs in these sediments are generated in the environment. Our findings suggest that these toxic breakdown products of PCBs are prevalent in PCB-contaminated sediments and present an emerging concern for humans and ecosystems.

Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment.

The Gold Standard for determining freely dissolved concentrations (Cfree) of hydrophobic organic compounds in sediment interstitial water would be in situ deployment combined with equilibrium sampling, which is generally difficult to achieve. In the present study, ex situ equilibrium sampling with multiple thicknesses of silicone and in situ pre-equilibrium sampling with low density polyethylene (LDPE) loaded with performance reference compounds were applied independently to measure polychlorinated biphenyls (PCBs) in mesocosms with (1) New Bedford Harbor sediment (MA, U.S.A.), (2) sediment and biota, and (3) activated carbon amended sediment and biota. The aim was to cross validate the two different sampling approaches. Around 100 PCB congeners were quantified in the two sampling polymers, and the results confirmed the good precision of both methods and were in overall good agreement with recently published LDPE to silicone partition ratios. Further, the methods yielded Cfree in good agreement for all three experiments. The average ratio between Cfree determined by the two methods was factor 1.4 ± 0.3 (range: 0.6-2.0), and the results thus cross-validated the two sampling approaches. For future investigations, specific aims and requirements in terms of application, data treatment, and data quality requirements should dictate the selection of the most appropriate partitioning-based sampling approach.

Environmental biodegradability of [¹⁴C] single-walled carbon nanotubes by Trametes versicolor and natural microbial cultures found in New Bedford Harbor sediment and aerated wastewater treatment plant sludge.

Little is known about environmental biodegradability or biotransformations of single-walled carbon nanotubes (SWNT). Because of their strong association with aquatic organic matter, detailed knowledge of the ultimate fate and persistence of SWNT requires investigation of possible biotransformations (i.e., biodegradation) in environmental media. In the present study, [(14)C]SWNT were utilized to track biodegradation over 6 mo by pure liquid culture of the fungus Trametes versicolor and mixed bacterial isolates from field-collected sediment or aerated wastewater treatment plant sludge. The mixed cultures were chosen as more environmentally relevant media where SWNT will likely be deposited under both aerobic and anaerobic conditions. Activity of [(14)C] was assessed in solid, aqueous, and (14)CO2 gaseous phases to determine amounts of intact SWNT, partially soluble SWNT degradation products, and mineralized SWNT, respectively, during the 6 mo of the experiment. Mass balances based on radiocarbon activity were approximately 100% over 6 mo, and no significant degradation of SWNT was observed. Approximately 99% of the [(14)C] activity remained in the solid phase, 0.8% in the aqueous phase, and less than 0.1% was mineralized to (14)CO2, regardless of culture type. These results suggest that SWNT are not readily biodegraded by pure fungal cultures or environmental microbial communities, and are likely persistent in environmental media.

Predicting bioavailability of PAHs and PCBs with porewater concentrations measured by solid‐phase microextraction fibers

Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) was measured in the deposit-feeding oligochaete Ilyodrilus templetoni exposed for 28 d to Anacostia River sediment (Washington, DC, USA) and to an initially uncontaminated sediment from Brown Lake (Vicksburg, MS, USA) sequentially diluted with 3 to 25% contaminated New Bedford Harbor sediment (New Bedford, MA, USA). The Anacostia River sediment studies represented exposure to a historically contaminated sediment with limited availability, whereas exposure to the other sediment included both the historically contaminated New Bedford Harbor sediment and fresh redistribution of contaminants into the Brown Lake sediments. Organism tissue concentrations did not correlate with bulk sediment concentrations in the Anacostia River sediment but did correlate with the sequentially diluted sediment. Porewater concentrations measured via disposable solid-phase microextraction fiber (SPME) with polydimethylsiloxane (PDMS), however, correlated well with organism uptake in all sediments. Bioaccumulation was predicted well by a linear relationship with the product of porewater concentration and compound octanol-water partition coefficient (Anacostia, slope = 1.08, r² = 0.76; sequentially diluted sediments, slope = 1.24, r² = 0.76). The data demonstrate that the octanol-water partition coefficient is a good indicator of the lipid-water partition coefficient and that porewater concentrations provide a more reliable indicator of bioaccumulation in the organism than sediment concentrations, even when the route of uptake is expected to be via sediment ingestion.

Use of Ecotoxicological Tools to Evaluate the Health of New Bedford Harbor Sediments: A Microbial Biomarker Approach

We have been investigating microbial communities in sediments from New Bedford Harbor (NBH), Massachusetts, USA, for a number of years. NBH is a U.S. Environmental Protection Agency–designated Superfund site heavily contaminated with polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and heavy metals. Microorganisms are thought to contribute to the fate and distribution of contaminants in NBH through a variety of mechanisms, including direct transformations and formation of soluble and insoluble species. Our more recent research has focused on changes in microbial community structure and function in response to exposure to toxic contaminants, with the ultimate goal of using microbes as ecotoxicological tools. Microbial diversity, as measured by restriction fragment-length polymorphism analysis, changes along pollution gradients, with an apparent increase in diversity at the most contaminated sites, concomitant with an increase in genetic relatedness. Current work on microbial communities examines the presence of arsenic-resistance genes in NBH isolates. In collaboration with the Plymouth Environmental Research Center, Plymouth University, United Kingdom, we have also used more conventional ecotoxicological approaches to examine the health of the NBH biota.

Environmental stress and recovery: the geochemical record of human disturbance in New Bedford Harbor and Apponagansett Bay, Massachusetts (USA)

Sediments record the history of contamination to estuaries. Analysis of the concentrations of toxic organic compounds, contaminant and crustal metals, organic carbon content and isotopic composition in sediment cores from two estuarine systems in Buzzards Bay allowed reconstruction of human impacts over 350 years. Vertical distributions of the contaminants correlate with changes in the nature of watershed/estuarine activities. All contaminants were highly enriched (tens to hundreds times background) in modern New Bedford Harbor sediments. Enrichment began around the turn of the 20th century for all but PCBs, which were first synthesized in the 1930s. An increase in organic carbon content and a shift of carbon isotopes toward a more terrestrial signature illustrates increasing anthropogenic impact in New Bedford as population grew along with the industrial base. Institution of environmental protection measures in the late 20th century was reflected in decreased, although still substantially elevated, concentrations of contaminants. A lack of industrial development in Apponagansett Bay resulted in much lower concentrations of the same indicators, although specific contaminants related to the early whaling industry increased significantly above background as early as the late 18th century. The similarity of indicators in older portions of cores from NBH and unimpacted Apponagansett Bay demonstrates that cores can be used to establish reference conditions as successfully as using separate sites judged a priori to represent the reference state. The historical reconstruction approach provides the basis for establishing relationships between environmental stressors and factors that drive the stressors, as well as a framework for the assessment of ecological response(s) to environmental stressors over a range of time and/or exposure scales.

16S rRNA Restriction Fragment Length Polymorphism Analysis of Bacterial Diversity as a Biomarker of Ecological Health in Polluted Sediments from New Bedford Harbor, Massachusetts, USA

A polymerase chain reaction (PCR)-based method was developed to compare bacterial diversity among environmental sites with varying degrees of anthropogenic impact. New Bedford Harbor, MA, a US Environmental Protection Agency-designated Superfund hazardous waste site, was studied to assess changes in bacterial diversity resulting from long-term inputs of organic and inorganic pollutants. Total DNA was extracted from surficial sediments sampled from four sites along a transect of decreasing contamination (Upper and Lower Acushnet Estuary, New Bedford Harbor, and Buzzards Bay, respectively). Oligonnucleotide primers specific to conserved regions of the 16S rRNA gene were used to PCR-amplify sequences from DNA extracts. Restriction fragment length polymorphism (RFLP) analysis resulted in generation of a number of unique operational taxonomic units (OTUs). Cluster analysis of fragment pattern data using the computer program RESTSITE ® allowed for bacterial diversity estimations, which, in agreement with standard culture techniques, showed higher bacterial diversity in New Bedford Harbor sediments, relative to Buzzards Bay. By employing bacterial diversity as a sensitive indicator of environmental stress, the method has wide applicability to many environments for the assessment of anthropogenic impact on aquatic ecosystems.

Identification of acute toxicants in new bedford harbor sediments

AbstractNew Bedford Harbor (NBH) is a marine Superfund site contaminated with high concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and metals. Experiments were conducted to determine the causal toxic agent(s) in pore waters from New Bedford Harbor sediments to amphipods and mysid shrimp. Chemical manipulations to characterize toxicity revealed that pore‐water toxicity was organic in nature. Fractionation and subsequent mass spectral identification of peaks in the toxic fraction indicated that PCBs, PAHs, and unknown compounds were present. Comparisons of PAH LC50s and PAH concentrations in this fraction indicated that the toxicity was not due to PAHs because the PAH concentrations were much lower than the reported PAH LC50s. One unknown peak was positively identified as bis(2‐ethylhexyl) phthalate, and the other tentatively identified as pyrazole. Toxicity tests and comparison of toxicity in the blank and toxic fractions eliminated the two “unknowns” as toxic causal agents. We determined the range of PCB LC50s to fall between 10 and 110 ppb for Mysidopsis bahia and Ampelisca abdita. Concentrations of PCBs for the toxic fractions ranged from 12 to 27 ppb. This range falls within our observed PCB LC50s for M. bahia and A. abdita. Based upon these PCB concentrations, we concluded that PCBs were the acute toxic agents in NBH pore waters. Other compounds in the toxic fractions, or compounds that coeluted and were undistinguished from PCBs had minor contributions to the measured toxicity.

IDENTIFICATION OF ACUTE TOXICANTS IN NEW BEDFORD HARBOR SEDIMENTS

New Bedford Harbor (NBH) is a marine Superfund site contaminated with high concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and metals. Experiments were conducted to determine the causal toxic agent(s) in pore waters from New Bedford Harbor sediments to amphipods and mysid shrimp. Chemical manipulations to characterize toxicity revealed that pore-water toxicity was organic in nature. Fractionation and subsequent mass spectral identification of peaks in the toxic fraction indicated that PCBs, PAHs, and unknown compounds were present. Comparisons of PAH LC50s and PAH concentrations in this fraction indicated that the toxicity was not due to PAHs because the PAH concentrations were much lower than the reported PAH LC50s. One unknown peak was positively identified as bis(2-ethylhexyl) phthalate, and the other tentatively identified as pyrazole. Toxicity tests and comparison of toxicity in the blank and toxic fractions eliminated the two “unknowns” as toxic causal agents. We determined the range of PCB LC50s to fall between 10 and 110 ppb for Mysidopsis bahia and Ampelisca abdita. Concentrations of PCBs for the toxic fractions ranged from 12 to 27 ppb. This range falls within our observed PCB LC50s for M. bahia and A. abdita. Based upon these PCB concentrations, we concluded that PCBs were the acute toxic agents in NBH pore waters. Other compounds in the toxic fractions, or compounds that coeluted and were undistinguished from PCBs had minor contributions to the measured toxicity.

Influence of Harbor Contamination on the Level and Composition of Polychlorinated Biphenyls in Produce in Greater New Bedford, Massachusetts

Samples of produce (tomatoes, potatoes, carrots, and lettuce) from the area surrounding the New Bedford Harbor Superfund site were analyzed for the concentration and distribution of 47 polychlorinated biphenyl (PCB) congeners. Samples of produce from out of state also were analyzed for comparison purposes. New Bedford Harbor sediments are highly contaminated with PCBs, which may partition into the seawater and ultimately into air. During low tide, direct volatilization of PCBs is likely since the sediment is in contact with air. Also, sediment dredging, from the spring of 1994 until the fall of 1995, daily exposed fresh layers of contaminated sediment. Overall levels of PCBs in produce are within the range observed at local and out-of-state background sites, with the exception of greatly elevated levels in tomatoes grown during harbor dredging. Spatial and temporal differences in PCB concentrations and congener profiles indicate the effect of the harbor and other sources of environmental contamination. Our results are consistent with the view that atmospheric transport and gas-phase transfer play a pivotal role in influencing the concentration of PCBs in plant tissue. This work is an initial step toward gauging the significance of the consumption of local produce as a pathway of human exposure to PCBs in New Bedford before and during harbor dredging.

An examination of dechlorination processes and pathways in New Bedford Harbor sediments

Estuarine sediments from upper New Bedford Harbor, Massachusetts, which were heavily contaminated with polychlorinated biphenyls (PCBs), showed considerable compositional alterations of PCB residues relative to mixtures of Aroclor 1242 and 1254 standards, and PCB distributions present in sediments from lower New Bedford Harbor and Black Rock Harbor, Connecticut. The compositional alterations, which presumably resulted from reductive dechlorinations by bacteria, became more extensive with increasing PCB concentration and decreasing distance from the suspected PCB source, an electrical capacitor manufacturing plant. Three pathways which removed chlorine substituents from specific locations on PCB molecules were responsible for most of the observed dechlorinations. Considerable differences were found in the extent of dechlorination within sediment cores and between sampling sites in upper New Harbor. The most extensively altered PCB distribution was found in the 15–17·5 cm deep section of a core from nearest to the plant's outfall. In most cores, less altered PCB residues were found in the 0–2·5 and 5–7·5 cm core sections than in the 15–17·5 cm section. Large variations in estimates of dechlorination rates were found, depending on the sample and the congener. The dechlorination processes found may decrease the potential toxicity and bioaccumulation potential of the PCB residues in these sediments.

Nonconstant polychlorinated biphenyl partitioning in New Bedford Harbor sediment during sequential batch leaching

Leaching of PCB-contaminated sediment from the New Bedford Harbor Superfund Site, New Bedford, MA, was conducted to assess the long-term mobilization of PCB. Sequential batch extraction of the sediment with distilled-deionized water resulted in a progressive increase in concentrations of PCB, dissolved organic carbon, and numbers of microorganisms in the extract. Sequential extraction with saline water produced extractant PCB concentrations that were relatively constant and significantly lower than those obtained with distilled-deionized water. The PCB mobilization pattern in distilled-deionized water extractant demonstrated dependence of PCB partitioning on ionic strength (as measured by conductivity). The dependency on ionic strength was related to release of sediment organic carbon as ionic strength decreased during sequential batch extraction. The data show that organic colloids and microparticulates mobilized by changes in ionic strength significantly facilitate the release of PCBs.