Peter Adriaens

Bioavailability and Transformation of Highly Chlorinated Dibenzo-p-dioxins and Dibenzofurans in Anaerobic Soils and Sediments

The long-term fate of environmentally relevant concentrations (ppb) of penta- to heptachlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners was evaluated in both high and low organic carbon anaerobic sediments. The inocula were derived from historically contaminated environments and were amended with a mixture of aliphatic and aromatic acids to stimulate anaerobic microbial activity. The long-term (>2 years) removal patterns of sediment-sorbed PCDD/PCDF in both sediments could be explained by labile and resistant PCDD/PCDF desorption components, presumably due to intraparticle diffusion-controlled mass transfer limitations. Mass transfer limitations were based on incubation time-dependent decreased extraction efficiencies of PCDD/PCDF from autoclaved controls. Lesser chlorinated congeners were observed in both active and autoclaved sediments, accounting for up to 30% of the PCDD/F spiked. Whereas tetraCDD accumulated from hepta-, hexa-, and pentaCDD/F in active sediments, the extent of dechlorination in autoclaved sediments was limited to removal of one to two chlorines. These observations provide the first evidence for the contribution of biologically mediated reductive dechlorination of PCDD/PCDF to the overall fate of these contaminants in the environment and may lead the way to designing in situ transformation/biodegradation systems.

Reductive dechlorination of PCDD/F by anaerobic cultures and sediments

Abstract The fate of highly chlorinated (5 to 7 chlorines per molecule) dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners was studied in anaerobic microcosms, using polychlorinated biphenyl (PCB)-contaminated Hudson River sediments, and creosote-contaminated aquifer sediments. The PCDD/PCDF concentrations in active microcosms were shown to decrease at higher rates than in chemical and biological controls. The net loss of PCDD/F from active microcosms was up to 35% higher than in autoclaved controls after extended incubation periods. Lesser chlorinated PCDD/F, identified to be peri-dechlorinated, have been found as the accumulating products resulting from reductive dechlorination under anaerobic methanogenic conditions.

Scaling of economic benefits from Green Roof implementation in Washington, DC.

Green roof technology is recognized for mitigating stormwater runoff and energy consumption. Methods to overcome the cost gap between green roofs and conventional roofs were recently quantified by incorporating air quality benefits. This study investigates the impact of scaling on these benefits at the city-wide scale using Washington, DC as a test bed because of the proposed targets in the 20-20-20 vision (20 million ft(2) by 2020) articulated by Casey Trees, a nonprofit organization. Building-specific stormwater benefits were analyzed assuming two proposed policy scenarios for stormwater fees ranging from 35 to 50% reduction for green roof implementation. Heat flux calculations were used to estimate building-specific energy savings for commercial buildings. To assess benefits at the city scale, stormwater infrastructure savings were based on operational savings and size reduction due to reduced stormwater volume generation. Scaled energy infrastructure benefits were calculated using two size reductions methods for air conditioners. Avoided carbon dioxide, nitrogen oxide (NO(x)), and sulfur dioxide emissions were based on reductions in electricity and natural gas consumption. Lastly, experimental and fugacity-based estimates were used to quantify the NO(x) uptake by green roofs, which was translated to health benefits using U.S. Environmental Protection Agency models. The results of the net present value (NPV) analysis showed that stormwater infrastructure benefits totaled

Dechlorination of PCDD/F by organic and inorganic electron transfer molecules in reduced environments

1.04 million (M), while fee-based stormwater benefits were

Estimating population distributions when some data are below a limit of detection by using a reverse kaplan-meier estimator

0.22-0.32 M/y. Energy savings were

Flow cytometry for microbial sensing in environmental sustainability applications: current status and future prospects

0.87 M/y, while air conditioner resizing benefits were estimated at

The university of Michigan dioxin exposure study: Predictors of human serum dioxin concentrations in Midland and Saginaw, Michigan

0.02 to

An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect

0.04 M/y and avoided emissions benefits (based on current emission trading values) were

Geophysical Characterization, Redox Zonation, and Contaminant Distribution at a Groundwater/Surface Water Interface

0.09 M-0.41 M/y. Over the lifetime of the green roof (40 years), the NPV is about 30-40% less than that of conventional roofs (not including green roof maintenance costs). These considerable benefits, in concert with current and emerging policy frameworks, may facilitate future adoption of this technology.

The University of Michigan Dioxin Exposure Study: Population Survey Results and Serum Concentrations for Polychlorinated Dioxins, Furans, and Biphenyls

The dechlorination of octa- and pentachlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was investigated using organic and inorganic electron shuttles relevant to anaerobic sediments. OctaCDD was dechlorinated to hexaCDD in the presence of resorcinol, catechol, and 3,4-dichlorobenzoate, resulting in an increase of 2,3,7,8-substituted hepta- and hexaCDD. Vitamin B12 mediated the dechlorination of octaCDD to tetraCDD, octaCDF to hexaCDF, and 1,2,3,7,8-pentaCDD to at least two tetraCDD, including 2,3,7,8-TCDD. Zerovalent zinc stoichiometrically dechlorinated octaCDD to hexa- and pentaCDD under basic and neutral conditions, respectively. Thus, abiotically-mediated dechlorination reactions may contribute significantly to the fate of PCDD/F in reduced environments.