Joan U. Clarke

Structure-activity relationships in PCBs: use of principal components analysis to predict inducers of mixed-function oxidase activity

Of the 209 PCB congeners, over 50 are known or suspected inducers of mixed-function oxidase activities in mammalian liver. These include inducers of cytochromes P-448 (MC-type inducers), P-450 (PB-type inducers), both P-448 and P-450 (mixed-type inducers), and one “novel” inducer. To elucidate structure-activity relationships with respect to these inducers, a statistical approach was taken using principal components analysis. Ten principal components (PCs) were extracted from variables coded for the positions of chlorines on the biphenyl. Three of these PCs, including an “ortho” component and a “para” component, were used to graph a three-dimensional space in which patterns of inducers can be clearly recognized. These patterns include five groups of congeners dominated, respectively, by weak PB-type inducers, MC-type inducers, mixed-type inducers, PB-type inducers, and suspected PB-type inducers. The remaining spatial configuration is a large, heterogeneous group composed of inactive congeners and a few “outlier” PB-type inducers. Re-evaluation of these outliers may indicate that inducer activity is less than previously thought. Conversely, congeners not currently known to be inducers, but falling within the spatial boundaries of the five inducer groups, may also turn out to be inducers. The congeners of the suspected PB-type inducer group are predicted to be weak PB-type inducers, and certain congeners having PC configurations similar to the one novel inducer may possibly also be novel inducers.

Monitored Natural Attenuation of Explosives

Explosives are subject to several attenuation processes that potentially reduce concentrations in groundwater over time. Some of these processes are well defined, while others are poorly understood. The objective of the project was to optimize data collection and processing procedures for evaluation and implementation of monitored natural attenuation of explosives. After conducting experiments to optimize data quality, a protocol was established for quarterly monitoring of thirty wells over a 2-year period at a former waste disposal site. Microbial biomarkers and stable isotopes of nitrogen and carbon were explored as additional approaches to tracking attenuation processes. The project included a cone penetrometry sampling event to characterize site lithology and to obtain sample material for biomarker studies. A three-dimensional groundwater model was applied to conceptualize and predict future behavior of the contaminant plume. The groundwater monitoring data demonstrated declining concentrations of explosives over the 2 years. Biomarker data showed the potential for microbial degradation and provided an estimate of the degradation rate. Measuring stable isotopic fractions of nitrogen in TNT was a promising method of monitoring TNT attenuation. Overall, results of the demonstration suggest that monitored natural attenuation is a viable option that should be among the options considered for remediation of explosives-contaminated sites.

Benthic Bioaccumulation and Bioavailability of Polychlorinated Dibenzo-p-Dioxins/Dibenzofurans from Surficial Lake Ontario Sediments

ABSTRACT The benthic bioavailability of surface sediment-associated polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) was quantified and assessed in Lake Ontario. Bottom sediments were collected from three areas along the Lake Ontario southern shoreline near Olcott, Rochester, and Oswego, New York. The sediment samples were subjected to 28-day, PCDD/F bioaccumulation experiments using the aquatic oligochaete Lumbriculus variegatus. Empirical data including only detectable PCDD/F tissue residues were used to quantify the benthic bioavailability of 11 PCDD/F congeners through the calculation of biota-sediment accumulation factors (BSAFs). BSAFs calculated for at least two lake areas were combined as Lake Ontario BSAFs for those specific congeners. Variability of the BSAFs was estimated by propagated error (PE) terms. Mean Lake Ontario BSAFs (±PE) ranged from 0.04±0.02 for octachlorodibenzofuran (OCDF) to 2.42±1.32 for 1,2,3,6,7,8-hexachlorodibenzofuran (HxCDF). Tetra-chlorodibenzo-p-dioxin (TCDD) and 1,2,3,4,7,8-HxCDF, shown to be among the highest toxic equivalencies (TEQs) in lake sediments, yielded BSAFs of 0.51±0.18 and 0.22±0.12, respectively. Statistical comparison of the TCDD BSAFs showed no significant differences among the lake areas. The benthic bioavailability of TCDD appeared lower than the results of other investigators. While hydrophobicity and degree of chlorination play some role, other factors, such as steric properties, and composition of organic carbon and matter, may have had a greater influence on the benthic bioavailability of PCDD/F congeners. Comparisons of these benthic BSAFs to fish BSAFs suggest that the bioaccumulation of PCDD/F congeners by fish is more related to water solubility and degree of chlorination than to sediment concentration.

Explosive Residues from Blow-in-Place Detonations of Artillery Munitions

Military live-fire training often generates unexploded ordnance (UXO) on training ranges. Explosive ordnance personnel typically render these UXO safe by blow-in-place (BIP) detonations using donor charges. These detonations potentially leave explosive residues on the soil surface where they may threaten ground water. The objective of this study was to determine the efficiency with which several donor charges consume energetic residues from heavy artillery rounds when used in BIP detonations. Residues from BIP of two types of mortars rounds and two types of artillery rounds with four donor charges were recovered from a large tarp after detonations. The binary donor charge produced limited residues for the mortar rounds, but was insufficient when used for larger rounds. TNT as a donor left significant quantities of TNT residue; therefore, it is a poor choice as a donor charge. C4 was the most effective for the larger rounds. Except for the binary charge, which left no detectable residue with the 60-mm mortar rounds, all donors left some residue, primarily RDX, in at least some replicates. Most of the mass was recovered within 15 meters of the detonation center. Results demonstrated that maximum detonation efficiency was achieved by the proper pairing of donor charge to round. Results also indicated that repeated BIP operations in the same location might lead to the building up of explosive contamination in surface soils.

Multicriteria decision analysis to assess options for managing contaminated sediments: Application to Southern Busan Harbor, South Korea

Many years of untreated effluent discharge from residential areas, a shipyard, a marina, and a large fish market resulted in substantial contamination of bottom sediment in Southern Busan Harbor, South Korea. Contaminants in these sediments include heavy metals and organic compounds. Newly introduced regulations for ocean disposal of dredged material in South Korea pose significant challenges, because the previous practice of offshore disposal of contaminated dredged material was no longer possible after August 2008. The South Korean government has mandated that such sediments be assessed in a way that identifies the most appropriate dredged material management alternative, addressing environmental, social, and cost objectives. An approach using multicriteria decision analysis (MCDA) in combination with comparative risk assessment was used as a systematic and transparent framework for prioritizing several dredged sediment management alternatives. We illustrate how MCDA can recognize the multiple goals of contaminated sediment management. Values used in weighting decision criteria were derived from surveys of stakeholders who were sediment management professionals, business owners, or government decision makers. The results of the analysis showed that land reclamation was the preferred alternative among cement-lock, sediment washing, 3 contained aquatic disposal alternatives (one in combination with a hopper dredge), geotextile tubes, solidification, and land reclamation after solidification treatment. Land reclamation was the preferred alternative, which performed well across all MCDA objectives, because of the availability of a near-shore confined disposal facility within a reasonable distance from the dredging area.

Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project

A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river.

A decision-analysis approach for contaminated dredged material management in South Korea.

To meet London Protocol requirements, South Korea is preparing to reduce the need for disposal of dredged material at sea. The new requirements controlling ocean disposal of dredged material pose significant challenges to the South Korean government, because the previous practice of offshore disposal of contaminated dredged material is no longer permitted. Hence, other alternatives for treating and disposing of contaminated dredged material are being evaluated and selected for implementation. A new management and decision approach is therefore needed for regulators and implementers to show what information and what decision-making processes were used to make the decision, to increase administrative transparency for such projects in the public domain. To address this need, an iterative approach was developed for dredged material management that includes the essential elements of process, people, and tools needed for successful environmental decision making. The approach has 6 steps: problem definition, developing objectives and criteria, identifying alternatives, performing the evaluation, comparing alternatives, and selecting the preferred alternative. The primary objective of the approach is to provide a systematic means of exploring contaminated dredged material management alternatives in South Korea using criteria that integrate risk with economic and stakeholder value information. The approach incorporates the desired decision-making attributes of transparency, comparative analysis, and inclusion of public input. Although it was developed for South Korea, the approach can be applied in any situation in which dredged material management alternatives are being considered to manage contaminated sediment risks.

Reservoir Characterization Based on Design and Operational Considerations

ABSTRACT Linkages between reservoir purpose, design, and operation have potentially important implications for water quality. Understanding these interactions provides an information base upon which to evaluate the water quality benefits associated with operational management alternatives. Since experiments involving changes to existing reservoir operation are difficult to implement, water quality models offer a reasonable experimental alternative. We compared selected physical, hydrologic, and operational characteristics of U. S. Army Corps of Engineers reservoirs and subsequently identified and characterized thirteen operational/morphometric groupings that may be useful in future modeling experiments.

Confined disposal facility characterization for beneficial reuse of dredged material: a case study to demonstrate a structured approach to sampling and data analysis

PurposeConfined disposal facilities (CDFs) are widely used for disposal of navigation dredged material, but many are running out of capacity. Removal of dredged material for beneficial use offers potential for sustainable operations, but requires characterization with a high degree of confidence. Few data are available to inform characterization efforts in these artificial depositional environments; thus, a CDF case study was used to demonstrate a structured approach to sampling and data analysis.Materials and methodsSelected data analysis procedures were applied to data collected from a CDF, with the objective of illustrating the utility of these procedures in (1) maximizing information obtained from limited data and (2) assessing the adequacy of the data in terms of estimating parameters of interest. In this case, the data were used to estimate the abundance of the desired fraction (sand), the contaminant levels in the sand and residual fractions, and the uncertainty of the parameters measured. From the outcome of this analysis, a stepwise approach to CDF characterization and data analysis was developed.Results and discussionThe available dataset proved sufficient to estimate the distribution of sand in the CDF, although estimate reliability was constrained by the small number of samples and the lack of samples along the western facility boundary. Soot, organic carbon, and oil and grease were statistically significant regressors for many contaminants of concern; however, data were too limited and variable to permit prediction of contaminant concentrations in unanalyzed samples on the basis of the sorptive phases. A contour surface of benzo(a)pyrene concentration was generated to illustrate the utility in identifying areas of the CDF that may be problematic with respect to meeting regulatory criteria or guidelines for beneficial use; such areas may require additional processing to remove more highly contaminated fractions.ConclusionsOf the graphical data analysis techniques evaluated, the most useful were: the aerial site view showing sample locations and per cent sand; the ternary diagram comparing sample characteristics; the contour map and the sand isopach map, representing aerial variation of sand thickness; and the depiction of contaminant concentrations as a contour surface. The predictive capability of the data was limited, but may have been aided with the addition of density fractionation and a larger dataset.