Angela A. Peverly

Octopods versus Concave Nanocrystals: Control of Morphology by Manipulating the Kinetics of Seeded Growth via Co-Reduction

Au/Pd octopods and concave core@shell Au@Pd nanocrystals have been prepared by coupling for the first time a seed-mediated synthetic method with co-reduction. The integration of these two methods is central to the formation of these binary Au/Pd nanocrystals wherein the kinetics of seeded growth are manipulated via the co-reduction technique to control the final morphology of the nanocrystals. Significantly, the synthesis of these structures under similar reaction conditions illustrates that they are structurally related kinetic products. Detailed characterization by STEM-EDX analysis highlights the unique structural features of these nanocrystals and indicates that Pd localizes on the higher-energy features of the nanocrystals. Optical and electrocatalytic characterization also demonstrates their promise as a new class of multifunctional nanostructures.

Chicago's Sanitary and Ship Canal sediment: Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, brominated flame retardants, and organophosphate esters.

The Chicago Sanitary and Ship Canal (CSSC) links the Great Lakes to the Mississippi River starting in downtown Chicago. In addition to storm water, the CSSC receives water from Chicagos wastewater treatment plants (WWTP). Such effluents are known to be sources of organic pollutants to water and sediment. Therefore in 2013, we collected 10 sediment samples from the CSSC and measured the concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), brominated flame retardants, and organophosphate esters (OPEs). Geometric mean concentrations of the summed concentrations of 16 PAHs ranged from 11,000 to 420,000 ng/g dw, with the highest concentrations located at each end of the canal. Total PCB concentrations had a geometric mean of 1,400 ± 500 ng/g dw. Brominated flame retardants were separated into two groups: polybrominated diphenyl ethers (PBDEs) and non-PBDEs. Concentrations of PBDEs and those of the non-PBDE flame retardants had a geometric average of 83 ± 19 and 7.0 ± 5.8 ng/g dw, respectively. The summed concentrations of 8 OPEs ranged from 470 to 2,800 ng/g dw, with the highest concentration detected at a site located downstream of the Stickney water reclamation plant. Using ANOVA results, some hypotheses on sources to the CSSC could be formulated: downtown Chicago is probably a source of PAHs, the Cal-Sag Channel may be a source of PCBs, and neither the WWTP nor the Cal-Sag Channel seem to be significant sources of brominated flame retardants or OPEs.

Locating POPs Sources with Tree Bark.

Locating sources of persistent organic pollutants (POPs) to the atmosphere can sometimes be difficult. We suggest that tree bark makes an excellent passive atmospheric sampler and that spatial analysis of tree bark POPs concentrations can often pinpoint their sources. This is an effective strategy because tree bark is lipophilic and readily adsorbs and collects POPs from the atmosphere. As such, tree bark is an ideal sampler to find POPs sources globally, regionally, or locally. This article summarizes some work on this subject with an emphasis on kriged maps and a simple power-law model, both of which have been used to locate sources. Three of the four examples led directly to the pollutants manufacturing plant.

Air is still contaminated 40 years after the Michigan Chemical plant disaster in St. Louis, Michigan.

The Michigan Chemical (also known as Velsicol Chemical) plant located in St. Louis, Michigan operated from 1936-1978. During this time, the plant manufactured polybrominated biphenyls (PBBs), hexabromobenzene (HBB), 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT), and tris(2,3-dibromopropyl) phosphate (TDBPP), among other products. Due to widespread PBB contamination of Michigan, the plant eventually became a Superfund site, and despite years of cleanup activities, many of the compounds can still be found in the local ecosystem. To investigate the current atmospheric levels and to determine their spatial distributions, we collected tree bark samples from around Michigan and measured the concentrations of these pollutants. For comparison, other organic pollutants, such as polybrominated diphenyl ethers (PBDEs) and organophosphate esters (OPEs), which were not manufactured at the Michigan Chemical plant, were also measured in the same tree bark samples. Our results show levels of PBBs, DDT, and HBB in tree bark collected within 10 km of the Velsicol Superfund site (43, 477, and 108 ng/g lipid wgt., respectively) are 1-2 orders of magnitude higher than at sites located more than 10 km from the site (0.36, 28, and 0.36 ng/g lipid wgt., respectively). Levels of PBDEs and OPEs did not depend on distance from St. Louis. This is the first study on the atmospheric distribution of these chemicals around the Superfund site.

Electrochemical determination of trihalomethanes in water by means of stripping analysis.

A protocol has been developed and evaluated for the determination of trihalomethanes (THMs) at the submicromolar concentration level in water. This method is based on a three-step stripping analysis that utilizes a single electrochemical cell and that entails (a) direct electrochemical reduction of a trihalomethane at a silver cathode to form halide ions in an aqueous sample containing tetraethylammonium benzoate, (b) capture of the released halide ions as a silver halide film on the surface of a silver gauze anode, and (c) cathodic reduction and quantitation of the silver halide film by means of differential pulse voltammetry. Using this procedure, we have determined THMs individually; bromoform and chloroform have been successfully quantitated in 30 min and with a detection limit of 3.0 μg L(-1) (12 nM) and 6.0 μg L(-1) (50 nM), respectively. In addition, we have employed our methodology to determine the total trihalomethane (TTHM) content in a prepared water sample at a level commensurate with the maximum allowable annual average of 80 μg L(-1) mandated by the United States Environmental Protection Agency. We have compared our TTHM results to those obtained by an independent testing laboratory.

Comment on "Halogenated indigo dyes: A likely source of 1,3,6,8-tetrabromocarbazole and some other halogenated carbazoles in the environment".

h 0 Parette et al. (2015) recently suggested that 1,3,6,8etrabromocarbazole could be a by-product formed in the anufacturing of the blue dye 5,5′,7,7′-tetrabromoindigo (see ig. 1) and that this could explain the presence of this tetraromocarbazole (and other related halogenated carbazoles) in nvironmental samples, including sediment from Lake Michigan Zhu and Hites, 2005; Guo et al., 2014). To test this hypothesis, we obtained a commercial sample of ,5′,7,7′-tetrabromoindigo (also called Ciba Blue 2B) from Sigmaldrich (cat. no CDS010542) and analysed it by election impact EI) and electron capture negative ionization (ECNI) gas chromatoraphic mass spectrometry. For ECNI, an Agilent 7890 series gas hromatograph (GC) coupled an Agilent 5975C mass spectromeer (MS) was used, with methane as the reagent gas. The mass pectrometer ion source and quadrupole temperatures were mainained at 200 and 140 °C, respectively. For EI, an Agilent 6890 eries GC coupled to an Agilent 5973 MS was utilized. The mass pectrometer ion source and electron energy were maintained at 30 °C and 70 eV, respectively. In both EI and ECNI experiments, he chromatographic resolution was achieved with an Rtx-1614 15 m × 250 μm i. d., 0.1 μm film thickness) fused silica capilary GC column (Restek Corporation, Bellefonte, CA). The carrier gas as helium (99.999%; Liquid Carbonic, Chicago) regulated at a contant flow of 1.5 mL/min. The GC oven temperature was programed s follows: 60 °C for 4 min, then 10 °C/min to 320 °C, holding for 0 min.