Bromobenzene Flame Retardants in the Great Lakes Atmosphere

Seven bromobenzene flame retardants were measured in vapor-phase samples collected at five sites, all near the shores of the North American Great Lakes during 2008–2009, inclusive. The target compounds were hexabromobenzene (HBB), pentabromobenzene (PBBz), pentabromotoluene (PBT), pentabromobenzylacrylate (PBBA), pentabromobenzyl bromide (PBBB), tetrabromo-<i>p</i>-xylene (pTBX), and pentabromoethyl benzene (PBEB). Detection frequencies were, on average, higher than 50% for all of the compounds, with the exception of PBBA, which was detected only in 22% of all the samples. Considering all the sampling sites together, HBB showed the highest average concentration (4.6 ± 1.0 pg/m³), followed by PBBB (3.3 ± 0.5 pg/m³) and PBEB (1.0 ± 0.1 pg/m³). The concentrations of these compounds were generally significantly correlated with one another, with the exception of PBBA, which was correlated only to PBBB. The atmospheric concentrations of PBT, pTBX, PBBB, and PBBA tracked local human population density, suggesting that these compounds are or were used in a variety of commercial products. Unexpectedly, the concentration of PBEB was highest at the remote site of Eagle Harbor in northern Michigan, whereas that of HBB was highest at Sturgeon Point, ∼25 km southwest of Buffalo, New York. The lack of dependence of these two compounds’ concentrations on human population suggests local point sources

Tribromophenoxy Flame Retardants in the Great Lakes Atmosphere

The 2,4,6-tribromophenoxy moiety is a common structural feature of several brominated flame retardants, and we have previously reported on the environmental concentrations of one such compound, 1,2-<i>bis</i>(2,4,6-tribromophenoxy) ethane (TBE). Here we report the atmospheric concentrations of TBE and three other tribromophenoxy compounds: allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), and 2,3-dibromopropyl 2,4,6-tribromophenyl ether (DPTE). The samples were collected at five sites near the shores of the Great Lakes during the period 2008–2009, inclusive. Of these four compounds, TBE and ATE are currently used as flame retardants, and DPTE was formerly used as a flame retardant until its production ceased in the mid-1980s. The total concentrations of ATE, BATE, and DPTE were ∼2 pg/m³ in the cities of Chicago and Cleveland and 0.1–0.4 pg/m³ at the rural and remote sites. The concentrations of TBE were ∼1 pg/m³ in these cities and 0.2–0.8 pg/m³ at the rural and remote sites. In both cases, this was a very significant urban effect. The concentrations of ATE, BATE, and DPTE did not change significantly over the two-year study, but the concentrations of TBE decreased by about a factor of 2 during this time. This temporal change was statistically significant but not strong compared to the urban effect

Has the Phase-Out of PBDEs Affected Their Atmospheric Levels? Trends of PBDEs and Their Replacements in the Great Lakes Atmosphere

Air and precipitation samples were collected every 12 days at five sites near the North American Great Lakes from 2005 to 2011 (inclusive) by the Integrated Atmospheric Deposition Network (IADN). The concentrations of polybrominated diphenyl ethers (PBDEs) and selected alternative brominated flame retardants [pentabromoethyl benzene (PBEB), hexabromobenzene (HBB), 1,2-<i>bis</i>(2,4,6-tribromophenoxy)­ethane (TBE or BTBPE), decabromodiphenylethane (DBDPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), and <i>bis</i>(2-ethylhexyl)-tetrabromo-phthalate (TBPH)] were measured in these samples. The concentrations of almost all of these flame retardants were related to the number of people within a 25 km radius of the sampling site, except for HBB, the concentrations of which were relatively high at Sturgeon Point, and PBEB, the concentrations of which were relatively high at Eagle Harbor. The temporal trends of all of these concentrations were variable. For example, BDE-47 vapor phase concentrations were increasing with doubling times of 5–10 years at Sturgeon Point, Sleeping Bear Dunes, and Eagle Harbor, but these concentrations were slowly decreasing in all phases at Chicago. The most consistent trend was for TBE, which showed concentrations that were unchanging or decreasing in all phases at all sites. TBPH concentrations in particles and HBB concentrations in precipitation were rapidly increasing at most sites with doubling times of ∼2 years. The concentrations of DBDPE and BDE-209 were strongly and positively correlated, and the concentrations of TBB and TBPH were also strongly and positively correlated. The concentrations of TBB plus TBPH (representing Firemaster 550) and BDE-47, 85, 99, 100, 153, plus 154 (representing the withdrawn penta-BDE commercial mixture) were also strongly and positively correlated. These positive relationships indicate that the replacement of the deca-BDE commercial product by DBDPE and the penta-BDE product by Firemaster 550 have not yet become evident in the Great Lakes’ atmospheric environment

High Levels of Organophosphate Flame Retardants in the Great Lakes Atmosphere

Levels of 12 organophosphate flame retardants (OPs) were measured in particle phase samples collected at five sites in the North American Great Lakes basin from March 2012 to December 2012 (inclusive). The target compounds were three chlorinated OPs [tris­(2-chloroethyl) phosphate (TCEP), tris­(1-chloro-2-propyl) phosphate (TCPP), and tris­(1,3-dichloro-2-propyl) phosphate (TDCPP)], three alkyl phosphates [tri-<i>n</i>-butyl phosphate (TnBP), tris­(butoxyethyl) phosphate (TBEP), and tris­(2-ethylhexyl) phosphate (TEHP)], and six aryl phosphates [triphenyl phosphate (TPP), tri-<i>o</i>-tolyl phosphate (TOTP), tri-<i>p</i>-tolyl phosphate (TPTP), tris­(3,5-dimethylphenyl) phosphate (TDMPP), tris­(2-isopropylphenyl) phosphate (TIPPP), and tris­(4-butylphenyl) phosphate (TBPP)]. Total OP (ΣOP) atmospheric concentrations ranged from 120 ± 18 to 2100 ± 400 pg/m³ at the five sites, with the higher ΣOP levels detected at Cleveland and Chicago. ΣOP concentrations at these urban sites were dominated by the chlorinated OPs (TCEP, TCPP, and TDCPP), with the sum of these three compounds comprising 51 ± 6 and 65 ± 12% of ΣOP concentrations at these two sites, respectively. Nonhalogenated OP compounds were major contributors to ΣOP concentrations at the remote sites, with the sum of all nine nonhalogenated OP concentrations comprising 70 ± 21 and 85 ± 13% of the ΣOP concentrations at Eagle Harbor and Sleeping Bear Dunes, respectively. On average, these ΣOP concentrations are about 2–3 orders of magnitude higher than the concentrations of brominated flame retardants in similar samples

High-Performance Microsupercapacitors Based on Bioinspired Graphene Microfibers

The miniaturization of portable electronic devices has fueled the development of microsupercapacitors that hold great potential to complement or even replace microbatteries and electrolytic capacitors. In spite of recent developments taking advantage of printing and lithography, it remains a great challenge to attain a high energy density without sacrificing the power density. Herein, a new protocol mimicking the spider’s spinning process is developed to create highly oriented microfibers from graphene-based composites via a purpose-designed microfluidic chip. The orientation provides the microfibers with an electrical conductivity of ∼3 × 10⁴ S m^–1, which leads to a high power density; the energy density is sustained by nanocarbons and high-purity metallic molybdenum disulfide. The microfibers are patterned in-plane to fabricate asymmetric microsupercapacitors for flexible and on-chip energy storage. The on-chip microsupercapacitor with a high pattern resolution of 100 μm delivers energy density up to the order of 10^–2 W h cm^–3 and retains an ultrahigh power density exceeding 100 W cm^–3 in an aqueous electrolyte. This work provides new design of flexible and on-chip asymmetric microsupercapacitors based on microfibers. The unique biomimetic microfluidic fabrication of graphene microfibers for energy storage may also stimulate thinking of the bionic design in many other fields

Variations of Flame Retardant, Polycyclic Aromatic Hydrocarbon, and Pesticide Concentrations in Chicago’s Atmosphere Measured using Passive Sampling

Atmospheric concentrations of flame retardants, polycyclic aromatic hydrocarbons, and pesticides were measured using passive air samplers equipped with polyurethane foam disks to find spatial information in and around Chicago, Illinois. Samplers were deployed around the greater Chicago area for intervals of 6 weeks from 2012 to 2013 (inclusive). Volumes were calculated using passive sampling theory and were based on meteorology and the compounds’ octanol–air partition coefficients. Geometric mean concentrations of total polybrominated diphenyl ethers ranged from 11 to 150 pg/m³, and tributyl phosphate, <i>tris</i>(2-chloroethyl)­phosphate, <i>tris</i>(1-chloro-2-propyl)­phosphate, and triphenyl phosphate concentrations were in the ranges of 54–290, 32–340, 130–580, and 170–580 pg/m³, respectively. The summed concentrations of 16 PAHs ranged from 8700 to 52 000 pg/m³ over the sampling area, and DDT, chlordane, and endosulfan concentrations were in the ranges of 2.7–9.9, 8.2–66, and 16–85 pg/m³, respectively. Sampling sites were split into two groups depending on their distances from the Illinois Institute of Technology campus in Chicago. With a few exceptions, the concentrations of most compound groups in the city’s center were the same or slightly higher than those measured >45 km away. The data also showed that the concentrations measured with a passive atmospheric sampling system are in good agreement with those measured with an active, high-volume, sampling system. Given that the sampling times are different (passive, 43 days; active, 1 day), and that both of these measured concentrations cover about 5 orders of magnitude, the agreement between these passive and active sampling methods is excellent