Extraction and Characterization of Surfactants from Atmospheric Aerosols

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in ...

Institut des Sciences Analytiques, UMR 5280

This work explores the heterogeneous reaction between HUmic-LIke Substances (so-called HULIS) and ozone. Genuine atmospheric HULIS were extracted from aerosol samples collected in Chamonix (France) in winter and used in coated flow tube experiments to evaluate heterogeneous uptake of O₃ on such mixtures. The uptake coefficient (γ) was investigated as a function of pH (from 2.5 to 10), O₃ concentration (from 8 to 33 × 10¹¹ molecules cm⁻³), relative humidity (20 to 65%) and photon flux (from 0 to 1.66 × 10¹⁵ photons cm⁻² s⁻¹). Reactive uptake was found to increase in the irradiated experiment with pH, humidity and photon flux. The extract was characterized before and after exposure to O₃ and/or UV light in the attempt to elucidate the effect of the photochemical aging. Carbon content measurements, UV-vis spectroscopy and functional groups analysis revealed a decrease of the UV absorbance as well as of the carbon mass content, while the functionalization rate (COOH and C═O) and therefore the polarity increased during the simulated photochemical exposure.

Oxidation of atmospheric humic like substances by ozone: a kinetic and structural analysis approach.

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs) once extensively used in the plastics of a wide range of consumer products. The listing of certain congeners that are constituents of commercial PBDE mixtures (including c-octaBDE) in the Stockholm Convention and tightening regulation of many other BFRs in recent years have created the need for a rapid and effective method of identifying BFR-containing plastics. A three-tiered testing strategy comparing results from non-destructive testing (X-ray fluorescence (XRF)) (n=1714), a surface wipe test (n=137) and destructive chemical analysis (n=48) was undertaken to systematically identify BFRs in a wide range of consumer products. XRF rapidly identified bromine in 92% of products later confirmed to contain BFRs. Surface wipes of products identified tetrabromobisphenol A (TBBPA), c-octaBDE congeners and BDE-209 with relatively high accuracy (>75%) when confirmed by destructive chemical analysis. A relationship between the amounts of BFRs detected in surface wipes and subsequent destructive testing shows promise in predicting not only the types of BFRs present but also estimating the concentrations present. Information about the types of products that may contain persistent BFRs will assist regulators in implementing policies to further reduce the occurrence of these chemicals in consumer products.

Towards development of a rapid and effective non-destructive testing strategy to identify brominated flame retardants in the plastics of consumer products.

The activation of aerosol particles into cloud droplets in the Earth's atmosphere is both a key process for the climate budget and a main source of uncertainty. Its investigation is facing major experimental challenges, as no technique can measure the main driving parameters, the Raoult's term and surface tension, σ, for sub-micron atmospheric particles. In addition, the surfactant fraction of atmospheric aerosols could not be isolated until recently. Here we present the first dynamic investigation of the total surfactant fraction of atmospheric aerosols, evidencing adsorption barriers that limit their gradient (partitioning) in particles and should enhance their cloud-forming efficiency compared with current models. The results also show that the equilibration time of surfactants in sub-micron atmospheric particles should be beyond the detection of most on-line instruments. Such instrumental and theoretical shortcomings would be consistent with atmospheric and laboratory observations and could have limited the understanding of cloud activation until now.

The dynamic surface tension of atmospheric aerosol surfactants reveals new aspects of cloud activation.

Perfluorinated chemicals including PFOA and PFOS have been widely used in consumer products and have become ubiquitous pollutants widely distributed in the aqueous environment. Following a major flood event in 2011, water samples were collected along a spatial gradient of the Brisbane River system to provide an initial estimate of the release of PFASs from flooded urban areas. PFOA (mean concentrations 0.13-6.1 ng L(-1)) and PFOS (mean concentrations 0.18-15 ng L(-1)) were the most frequently detected and abundant PFASs. Mean total PFASs concentrations increased from 0.83 ng L(-1) at the upstream Wivenhoe Dam to 40 ng L(-1) at Oxley Creek, representing an urban catchment. Total masses of PFOA and PFOS delivered into Moreton Bay from January to March were estimated to be 5.6 kg and 12 kg respectively. From this study, urban floodwaters appear to be a previously overlooked source of PFASs into the surrounding environment.

Spatio-temporal assessment of perfluorinated compounds in the Brisbane River system, Australia: impact of a major flood event.

While the literature has reported a widespread occurrence of perfluoroalkyl substances (PFASs) in marine biota, very limited studies have been dedicated to the southern hemisphere. Hepatic concentrations of nine PFAAs were analysed in 49 stranded stingrays from eastern Australia using liquid chromatograph coupled with tandem mass spectrometry and relationships with biological parameters (i.e. body size, age and sex) were investigated. Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were the predominant compounds quantified, with hepatic concentrations varying from 2 to 117 and from 0.2 to 19 ng·g(-1) w.w., respectively. A negative correlation between the concentration of PFASs in the livers of 32 blue-spotted stingrays and the body size/age was found. This relationship was independent of the animal's sex. We postulate that the dependence on body size is related to differing uptake kinetics of the chemicals, after the sting rays were exposed to an increased level of the contaminants in their environment. Such a pollution event could be related to a severe flood event that occurred at this location a few months before the samples' collection. Our results indicate that the influence of the body size/age should be taken into account when estimating bioaccumulation parameters from environmental measurements or exposure levels of biota to PFASs.

Size and age-concentration relationships for perfluoroalkyl substances in stingray livers from eastern Australia.

The present study investigates the occurrence and fate of 15 perfluoroalkyl substances (PFASs) and one fluorotelomer sulfonate from a firefighting training ground (FTG) that was contaminated by intensive use of aqueous film forming foams (AFFF). The contamination levels and their spatial and vertical distribution are assessed in the structure. At the surface of the pad, perfluorooctane sulphonate (PFOS) is the dominant PFASs measured, with concentration varying from 10 to 200 μg g(-1). PFASs were also detected in a concrete core at up to 12 cm depth, suggesting the vertical movement and higher transport potential of shorter chain compounds. The estimated mass load of linear PFOS in this specific pad was >300 g with a total of 1.7 kg for the sum of all PFASs analyzed. The kinetics of desorption of PFOS, PFOA and 6:2FTS from the concrete into an overlaying static water volume has been measured under field conditions at two constant temperatures. Fitting the desorption data and estimated rainfall/runoff to a kinetic model suggests that this and similar firefighting training pads will likely remain a source of PFASs for many decades (t0.5=25 years for PFOS).

Perfluoroalkyl substances in a firefighting training ground (FTG), distribution and potential future release.

Polychlorinated biphenyls (PCBs) are ubiquitous pollutants in the marine environment that are known to accumulate in apex predators such as sharks. Liver samples from dusky Carcharhinus obscurus, sandbar Carcharhinus plumbeus, and white Carcharodon carcharias sharks from south-eastern Australian waters were analysed for the seven indicator PCBs 28, 52, 101, 118, 138, 153 and 180. Median ∑PCBs were significantly higher in white than sandbar sharks (3.35 and 0.36 μg g(-1) lipid, respectively, p=0.05) but there were no significant differences between dusky sharks (1.31 μg g(-1) lipid) and the other two species. Congener concentrations were also significantly higher in white sharks. Significant differences in PCB concentrations between mature and immature dusky (3.78 and 0.76 μg g(-1) lipid, respectively) and sandbar (1.94 and 0.18 μg g(-1) lipid, respectively) sharks indicated that PCB concentrations in these species increased with age/growth. Higher-chlorinated congeners (hexa and heptachlorobiphenyls) dominated results, accounting for ~90% of ∑PCBs.

Bioaccumulation of PCBs in liver tissue of dusky Carcharhinus obscurus, sandbar C. plumbeus and white Carcharodon carcharias sharks from south-eastern Australian waters.

Recently, there has been an increasing trend towards multi-targeted analysis and non-target screening methods as a means to increase the number of monitored analytes. Previous studies have developed biomonitoring methods which specifically focus on only a small number of analytes with similar physico-chemical properties. In this paper, we present a simple and rapid multi-residue method for simultaneous extraction of polar and non-polar organic chemicals from biological matrices, containing up to 5% lipid content. Our method combines targeted multi-residue analysis using gas chromatography triple quadrupole mass spectrometry (GC-QqQ-MS/MS) and a multi-targeted analysis complemented with non-target screening using liquid chromatography coupled to a quadrupole time of flight mass spectrometry (LC-QTOF-MS/MS). The optimization of the chemical extraction procedure and the effectiveness of different clean-up methods were evaluated for two biological matrices: fish muscle (lipid content ∼2%) and breast milk (∼4%). To extract a wide range of chemicals, the partition/extraction procedure used for the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach was tested as the initial step for the extraction of 77 target compounds covering a broad compound domain. All the target analytes have different physico-chemical properties (log Kow ranges from -0.3 to 10) and cover a broad activity spectrum; from polar pesticides, pharmaceuticals, personal care products (PPCPs) to highly lipophilic chemicals such as polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochloride pesticides (OCPs). A number of options were explored for the clean-up of lipids, proteins and other impurities present in the matrix. Zirconium dioxide-based sorbents as dispersive solid-phase extraction (d-SPE) and protein-lipid removal filter cartridges (Captiva ND Lipids) provided the best results for GC-MS and LC-MS analysis respectively. The method was fully validated for samples of fish muscle and breast milk through the evaluation of recoveries, matrix effects, limit of quantification, linearity and precision (inter-day and intra-day). Mean recoveries (n=5) were between 70 and 120% with relative standard deviations (RSD) less than 20% in most of the cases. GC-MS/MS LOQs ranged from 0.08 to 3μg/kg and LC-QTOF-MS/MS LOQs ranged from 0.2 to 9μg/kg. The developed strategy was successfully applied for analysis of real samples; 22 target analytes were found in the breast milk samples and 10 in the fish samples. Non-target analysis allowed the detection and identification of an additional 14 contaminants and metabolites in the samples.

Development of sample extraction and clean-up strategies for target and non-target analysis of environmental contaminants in biological matrices.

Recent analyses of atmospheric aerosols from different regions have demonstrated the ubiquitous presence of strong surfactants and evidenced surface tension values, σ, below 40 mN m(-1), suspected to enhance the cloud-forming potential of these aerosols. In this work, this approach was further improved and combined with absolute concentration measurements of aerosol surfactants by colorimetric titration. This analysis was applied to PM2.5 aerosols collected at the Baltic station of Askö, Sweden, from July to October 2010. Strong surfactants were found in all the sampled aerosols, with σ = (32-40) ± 1 mN m(-1) and concentrations of at least 27 ± 6 mM or 104 ± 21 pmol m(-3). The absolute surface tension curves and critical micelle concentrations (CMC) determined for these aerosol surfactants show that (1) surfactants are concentrated enough in atmospheric particles to strongly depress the surface tension until activation, and (2) the surface tension does not follow the Szyszkowski equation during activation but is nearly constant and minimal, which provides new insights on cloud droplet activation. In addition, both the CMCs determined and the correlation (R(2) ∼ 0.7) between aerosol surfactant concentrations and chlorophyll-a seawater concentrations suggest a marine and biological origin for these compounds.

Anionic, Cationic, and Nonionic Surfactants in Atmospheric Aerosols from the Baltic Coast at Askö, Sweden: Implications for Cloud Droplet Activation.

Flame retardants are associated to numerous adverse health effects, can accumulate in humans and have been used intensively worldwide. Recently, dust has been identified as a major human exposure route for flame retardants. The aim of this study was to develop a multi-residue method using a two-step SPE purification. It enabled us to effectively limit co-extracted matrix/interferets and therefore a simultaneous analysis of brominated and organophosphate flame retardants for indoor dust was achieved. The optimized method was validated according to standard protocol and achieved good accuracy and reproducibility (percent error ranged from -29% to 28%). Standard Reference Material (SRM) for dust was also analysed, and good agreement was found with reported brominated and organophosphate flame retardants (OPFRs) concentrations. The applicability of the validated method was demonstrated by the analysis of ten indoor dust samples from ten Australian homes. Overall 89% of the analytes were detected in these samples. The average concentrations of ∑OPFRs and ∑PBDEs in those samples were 41 and 3.6μg/g, respectively. Tris(2-butoxyethyl) phosphate and tris(2-chloroisopropyl) phosphate were the most abundant OPFRs, accounting for 57-92% ∑OPFRs, while decabromodiphenyl ether dominated the Polybrominated diphenyl ethers (PBDE) congeners contributing between 71-94% to the ∑PBDEs.

Christine Baduel

CNRS,
ENS de Lyon,
Université Claude Bernard Lyon 1,
CNRS, ENS de Lyon, Université Claude Bernard Lyon 1

Institut des Sciences Analytiques, UMR 5280

Extraction and Characterization of Surfactants from Atmospheric Aerosols

Christine Baduel

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}CNRS,ENS de Lyon,Université Claude Bernard Lyon 1,CNRS, ENS de Lyon, Université Claude Bernard Lyon 1

Institut des Sciences Analytiques, UMR 5280

Extraction and Characterization of Surfactants from Atmospheric Aerosols

CNRS,
ENS de Lyon,
Université Claude Bernard Lyon 1,
CNRS, ENS de Lyon, Université Claude Bernard Lyon 1