Compositional Analysis of Commercial Oligomeric Organophosphorus Flame Retardants Used as Alternatives for PBDEs: Concentrations and Potential Environmental Emissions of Oligomers and Impurities

Four commercial oligomeric organophosphorus flame retardants (o-PFRs) were characterized using a refractive index detector and atmospheric pressure photoionization (APPI)-quadrupole time-of-flight mass spectrometry (QTOF-MS) compatible with gel permeation chromatography (GPC). Commercial o-PFRs consisted of approximately 90% or more oligomers and several impurities. Triphenyl phosphate (TPHP), tris­(dimethylphenyl) phosphate (TDMPP), tris­(2-chloroisopropyl) phosphate (TCIPP), and some new impurities were identified as byproducts of some manufacturing process of commercial o-PFRs for the first time. The concentrations of TPHP, TDMPP, and TCIPP were more than 1 weight %, whereas those of new impurities might be approximately 1 weight % by comparison among their abundances acquired through GPC-APPI-QTOF-MS analysis. Based on their vapor pressure and water solubility estimations, the potential environmental emissions of low molecular weight impurities were expected to be higher than those of oligomers. The presence and environmental emissions of low molecular weight impurities might be regarded as risk factors along with commercial o-PFRs

<i>Symbiodinium</i> compositions of water column and naturally settled <i>Acropora</i> coral recruits.

<p>The water samples were collected during the coral mass spawning period in 2011 (gray bars), and the recruits were collected approximately 2 weeks after spawning (black bars). Left histograms show that the clade composition of the recruits did not reflect that of the water column (p<0.05). Clades A and D were detected in both the water and recruit samples, and these <i>Symbiodinium</i> clones were further sorted into ITS2 types. Type A1 was the dominant clade A type within the recruits (middle histogram). Right histogram showing clade D ITS2 type compositions; type D1 and D4 group sequences were predominant in both water and recruit samples. Type D3 relative sequences were only detected from water samples. In clade A and D, <i>Symbiodinium</i> type compositions were differ between recruits and environments (p<0.05).</p

<i>Symbiodinium</i> cell numbers observed in the attraction tests using PCR tubes with and without <i>Acropora tenuis</i> larvae.

(a)<p>The infected larvae/total observed larvae are shown in parentheses.</p

Infection rates and cell densities in laboratory infection tests with apo-symbiotic larvae and 10 <i>Symbiodinium</i> culture strains.

<p>Bars indicate infection rates (average ± SD of triplicates; left axis), and the lines indicate infected cell densities (average ± SE cells/larva; right axis) for each larval age. <i>Acropora tenuis</i> larvae were readily infected with AJIS2-C2 (type A1) and CCMP2556 (type D1-4). Infection rates and infected cell densities of AJIS2-C2 and CCMP2556 cells were significantly higher than that of other <i>Symbiodinium</i> culture strains (p<0.05).</p

Infection rates and infected <i>Symbiodinium</i> cell densities with different inoculated cell densities are shown.

<p>Inoculated <i>Symbiodinium</i> cell densities were low (7 cells/cup = 1 cell/larva = 140 cells/L), medium (70 cells/cup = 10 cells/larva = 1400 cells/L), and high (700 cells/cup = 100 cells/larva = 14,000 cells/L).</p>(a)<p>Infection rates are the average ± SD of triplicate experiments.</p>(b)<p>Infected-cell densities are the average ± SE in infected larvae.</p

Size-Controlled Preparation of Polyethylene Nanoplastic Particles by Nanoprecipitation and Insights into the Underlying Mechanisms

Plastic pollution is ubiquitous in the environment, and nanoplastics (<1 μm) are of growing concern as they pose more health risks than larger particles. However, because of a lack of appropriate model particles, studies examining the risks of polyolefin nanoplastics are very limited, despite the prevalence of these plastics in the environment. Although nanoprecipitation using organic solvents is a promising method for preparing model nanoplastic particles of polyolefins, there are currently no methods for controlling the particle size. Here, we examined how the concentration and volume of the feedstock polymer solution affect the size of polyethylene particles produced by nanoprecipitation. The mechanisms underlying the particle formation were investigated by using a simple population balance model. Increasing the concentration of the feedstock solution increased the growth rate and decreased the nucleation rate, and increasing the volume of the feedstock solution increased the growth rate, resulting in an increase in the mean particle diameter in both cases. These changes in particle diameter were linearly correlated with the suspension density of the dispersion up to a suspension density of 0.4 mg·mL–1. In addition, at these suspension densities, spherical particles were prepared without generating aggregates. Together, these results show that the diameter of polyethylene particles prepared by nanoprecipitation could be controlled according to the suspension density up to a suspension density of 0.4 mg·mL–1. This study provides a basis for the development of nanoprecipitation-based techniques for the precise, scale-independent production of model nanoplastic particles, which we hope will accelerate the risk assessment of nanoplastics

Relationship between coral skeletal weight and surface area.

<p>(A) <i>Acropora selago</i>. (B) <i>Acropora muricata.</i> Regression formulae are shown in each graph.</p

Composition of <i>Symbiodinium</i> cells of different morphology expelled from corals.

<p>Bars show the percentages of normal (white) and degraded (black) forms of <i>Symbiodinium</i>. Dotted lines show water temperature (average of 6 aquaria ± SD). (A) <i>Acropora selago</i>. (B) <i>Acropora muricata</i>. Error bars indicate the standard deviations based on triplicate experiments. Three temperature periods with water temperature (mean ± SD among the days) were shown below the graphs.</p

3D camera and 3D images of coral branches of <i>Acropora muricata</i>.

<p>(A) A 3D camera (VIVID 9i, KONICA MINOLTA) was used for measuring coral surface area. (B) A 3D image from the Polygon Editing Tool software used with polygon and dot data. (C) A 3D image from the rapidform 2006 software used with surface data. (D) A 3D image from the NX I-deas software used for surface area calculation.</p

<i>Symbiodinium</i> density <i>in hospite</i>.

<p>Bars show the numbers of normal (white) and degraded (black) forms of <i>Symbiodinium</i>. (A) <i>Acropora selago</i>. (B) <i>Acropora muricata</i>. Error bars indicate the standard deviations based on triplicate experiments. The samples were collected under non-thermal stress period (27.0±0.17°C (mean ± SD among the days); days 1, 3, and 5), and under moderate thermal stress period (30.2±0.06°C; days 9, 11, and 13).</p