Ronald J. Scrudato

Iron-mediated reactions of polychlorinated biphenyls in electrochemical peroxidation process (ECP).

A study was conducted to explore some of the basic processes of polychlorinated biphenyl (PCB) destruction by a new technology termed electrochemical peroxidation process (ECP). ECP represents an enhancement of the classic Fenton reaction (H2O2 + Fe2+) in which iron is electrochemically generated by steel electrodes. Focus was on the extent of adsorption of a mixture of Aroclor 1248 on steel electrodes in comparison to iron filings. Commercially available zero-valent iron filings rapidly adsorbed PCBs from an aqueous solution of Aroclor 1248. Within 4 h, all the PCBs were adsorbed at 1%, 5%, and 10% Fe0 (w/v) concentrations. Little difference in adsorption was found between acidic (2.3) and unamended solutions (pH 5.5), even though significant differences in iron oxidation state and Fe2+ concentrations were measured in solution. PCB adsorption also occurs on steel electrodes regardless of the pH or electric current applied (AC or DC), suggesting the combination of oxidizing (free radical-mediated reactions) and reducing (dechlorination reactions) iron-mediated degradation pathways may be possible. Extraction of the iron powder after 48 h of contact time yielded the progressive recovery of biphenyl with increasing Fe mass(from 0.4% to 3.5%) and changes of the PCB congener-specific pattern as a consequence of dechlorination. A variety of daughter congeners similar to those accumulated during anaerobic microbial dechlorination of Aroclor 1248 in contaminated sediments indicate preferential removal of meta- and para-chlorines.

Volatilization of polychlorinated biphenyls from sediment during drying at ambient conditions

Air drying sediment from a Federal Superfund Site for 24 hours at ambient conditions (T=20°C; RH=25%) resulted in PCB volatilization losses of 14–23%, with 80–90% of the total loss occurring within the first eight hours. A sample dried for 24 hours lost 21.3% of PCBs via volatilization and an additional 7.5% during a second 24 hour drying period after rewetting. PCB loss was positively correlated with water loss (R2 > .99). Sediment samples (∼0.25 grams) suspended in 100 milliliters of double deionized water that was allowed to evaporate over a 7 day period lost 74–76% of their initial PCB concentration. Lower orthochlorinated congeners volatilized preferentially. These data indicate PCB loss through volatilization during drying at ambient conditions is more significant than previously recognized, particularly for sediments that have undergone extensive anaerobic microbial PCB dechlorination.

Photodecomposition of PCBs in aqueous systems using TiO2 as catalyst

Abstract The catalytic decomposition of PCBs promoted by sunlight in an aqueous solution, clay suspension and contaminated sediment is reported. The titanium dioxide catalyzed photolytic process destroyed almost 80% of the total PCBs in an aqueous solution and clay suspension after 4 h of radiation, and 50% of total PCBs were destroyed in sediment suspension within 6 h. It was observed that the lower chlorinated PCB congeners underwent the highest rate of decomposition in the aqueous systems. This preliminary study suggests that photocatalytic processes may be an efficient and low cost technique to remediate PCB-contaminated soils, sediments and waters.

Reductive dechlorination of PCB-contaminated sediments in an anaerobic bioreactor system

An anaerobic bioreactor system was operated in a batch recycle mode to establish the microbial biodegradation of Aroclor 1248-spiked sediment, utilizing sanitary landfill leachate as a novel carbon, nutrient, and/or microbial source. Experiments conducted on two bioreactors confirmed that significant dechlorination of Aroclor 1248-spiked sediments occurred. After 13 weeks of operation, the average total chlorine/biphenyl of the original Aroclor was reduced by 11% and 23%, with the majority of dechlorination occurring within 7 weeks. No dechlorination was observed in the sterilized control reactor. The overall significance is the first reported occurrence of anaerobic dechlorination of a PCB-contaminated sediment in a low-cost laboratory-scale bioreactor system. The environmental significance is the reduction in chlorine content of the original Aroclor, an important component in any environmental bioremediation program. Innovative approaches to laboratory-scale bioreactor monitoring and bioreactor design principles applicable to hazardous waste containment areas are also discussed.

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

Abstract 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)

Lake Ontario Sediment - Mirex Relationships

Abstract Sediment samples collected from within the eastern basin of Lake Ontario, the Oswego River and harbor indicate that mirex, a persistent, chlorinated hydrocarbon continues to accumulate in harbor and offshore lake sediments. A high statistical relationship exists between mirex and organic carbon concentrations in deep water lake sediments. Mirex-contaminated sediments are accumulating in the deeper waters (>100m) of the lake at rates ranging from about 2.2–7.0 mm/yr. Nearshore bottom sediments are subject to redistribution, providing a continuing source of mirex to lake organisms.

Photodecomposition of PCBs absorbed on sediment and industrial waste: implications for photocatalytic treatment of contaminated solids

PCBs in contaminated sediment and soil have been photodegraded in slurry suspension with TiO2 and simulated solar illumination without pre-treatment or amendments. Degradation of 81% of the PCBs in St. Lawrence River sediment was achieved in a 24 h irradiation period. Replicate experiments using five times as much sediment and half the light intensity yielded similar results. The observed degradation rates of individual PCB congeners correspond with gas chromatograph retention time and chlorine number. Lesser and ortho chlorinated PCBs are preferentially photodecomposed. The solubility of individual congeners controls the observed rate of decomposition by regulation of the transfer of PCBs to the aqueous phase and thus effectively retards access to the catalyst (anatase). The rate and degree of photodegradation can be enhanced by the use of lower wavelength ultraviolet light which leads to hydroxylation of PCB congeners increasing solubility and accessibility to photocatalytic reactions. Photodecomposition of PCBs in a slurry composed of furnace ash, core sands, and aluminum-rich (>45% Al2O3) slag from an aluminum foundry was increased from 45 to 88% during a 24 h irradiation period by using low wattage UVC lamps instead of solar equivalent illumination.

PCB volatile loss and the moisture content of sediment during drying

Abstract PCB volatile loss shows a positive correlation with sediment moisture content during drying. Small amounts (0.25 g) of St. Lawrence River sediment were allowed to dry for periods of 24 hours under ambient conditions and lost up to 4μg of PCBs by volatilization. Submerged sediment lost the greatest amount of PCBs (26.9%), while dry sediment lost 0.3% of total PCB concentration. Four, entirely orthochlorinated congeners (2; 2 2 ; 2 6 ; 26 2 ), produced by anaeorbic degradation, account for 54–76% of the PCB total volatilized in each experiment with added moisture. With the complete evaporation of water or depletion of lower orthochlorinated congeners, the rate of volatile loss slows substantially. These results have numerous implications for the analysis, potential exposure pathways, and global fate and transport processes of persistent organic pollutants.

Photocatalytic degradation of simulated pesticide rinsates in water and water+soil matrices

Abstract Degradation of active biocide compounds in five commercially available pesticides ranged from 0–75% after a 24 hr irradiation period in the presence of anatase (TiO 2 ). Nearly identical results, with the exception of triadimefon, were obtained from simulated rinsates with and without admixed soil. This study provides a realistic assessment of the photocatalytic treatment of rinsates in a slurry reactor by utilizing a mixture of commercial products, high concentrations, admixed soil, and solar equivalent UVA lighting.

Community-based participatory research projects and policy engagement to protect environmental health on St Lawrence Island, Alaska

Objectives This article synthesizes discussion of collaborative research results, interventions and policy engagement for St Lawrence Island (SLI), Alaska, during the years 2000–2012. Methods As part of on-going community-based participatory research (CBPR) studies on SLI, 5 discrete exposure-assessment projects were conducted: (a) a biomonitoring study of human blood serum; (b–d) 3 investigations of levels of contaminants in environmental media at an abandoned military site at Northeast Cape – using sediment cores and plants, semi-permeable membrane devices and blackfish, respectively; and (e) a study of traditional foods. Results Blood serum in residents of SLI showed elevated levels of polychlorinated biphenyls (PCBs) with higher levels among those exposed to the military site at Northeast Cape, an important traditional subsistence-use area. Environmental studies at the military site demonstrated that the site is a continuing source of PCBs to a major watershed, and that clean-up operations at the military site generated PCB-contaminated dust on plants in the region. Important traditional foods eaten by the people of SLI showed elevated concentrations of PCBs, which are primarily derived from the long-range transport of persistent pollutants that are transported by atmospheric and marine currents from more southerly latitudes to the north. Interventions An important task for all CBPR projects is to conduct intervention strategies as needed in response to research results. Because of the findings of the CBPR projects on SLI, the CBPR team and the people of the Island are actively engaging in interventions to ensure cleanup of the formerly used military sites; reform chemicals policy on a national level; and eliminate persistent pollutants internationally. The goal is to make the Island and other northern/Arctic communities safe for themselves and future generations. Conclusions As part of the CBPR projects conducted from 2000 to 2012, a series of exposure assessments demonstrate that the leaders of SLI have reason to be concerned about the health of people due to the presence of carcinogenic chemicals as measured in biomonitoring and environmental samples and important traditional foods.