Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Freud, E; Krejci, R; Tunved, P; Leaitch, R; Nguyen, QT; Massling, A; Skov, H; Barrie, L
2017 | Atmos. Chem. Phys. | 17 (13) (8101-8128)
air pollution , atmospheric aerosol , black carbon , cluster-analysis , long-term observations , marine boundary layer , northeast greenland , ny-alesund , particle formation , polar sunrise
The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station - Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed. A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to similar to 40% from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites. The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulation-mode particles (N-acc) at all five sites - often above 150 cm(-3). There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes. The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of N-acc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be important on a regional scale and it is most active in summer. Cloud processing is an additional factor that enhances the N-acc annual cycle. There are some consistent differences between the sites that are beyond the year-to-year variability. They are the result of differences in the proximity to the aerosol source regions and to the Arctic Ocean sea-ice edge, as well as in the exposure to free-tropospheric air and in precipitation patterns - to mention a few. Hence, for most purposes, aerosol observations from a single Arctic site cannot represent the entire Arctic region. Therefore, the results presented here are a powerful observational benchmark for evaluation of detailed climate and air chemistry modelling studies of aerosols throughout the vast Arctic region.

Cats’ Internal Exposure to Selected Brominated Flame Retardants and Organochlorines Correlated to House Dust and Cat Food

Engdahl, JN; Bignert, A; Jones, B; Athanassiadis, I; Bergman, A; Weiss, JM
2017 | Environ. Sci. Technol. | 51 (5) (3012-3020)
Pet cats may be used as a biomarker for assessing exposures to organohalogen compounds (OHCs) adsorbed to household dust in home environments. This study explores two exposure routes of OHCs, ingestion of OHCs (i) via house dust and (ii) via cat food. House dust from 17 Swedish homes and serum from the participating families' pet cats were collected, and cat food was purchased matching the diet reported. Paired samples of cat serum, house dust, and cat food were analyzed for brominated flame retardants/natural products (polybrominated diphenyl ethers (PBDEs), decabromobiphenyl (BB-209), decabromodiphenyl ethane (DBDPE), 2,4,6-tribromophenol (2,4,6-TBP), OH-PBDEs) and organochlorines (polychlorinated biphenyls (PCBs), 1,1-bis(4,4'-dichlorodipheny1)-2,2,2-trichloroethane (4,4'-DDT), 1,1-bis(4,4'-dichlorodiphenyl)-2,2-dichloroethene (4,4'-DDE), hexachlorobenzene (HCB), pentachlorophenol (PCP)). Significant correlations were found between serum and dust samples from the living rooms for BDE-47 (p < 0.035), BDE-99 (p < 0.035), and BDE-153 (p < 0.039), from the adult's bedroom for BDE-99 < 0.019) and from all rooms for BDE-99 (p < 0.020) and BB-209 (p < 0.048). This is the first time a correlation between cat serum levels and household dust has been established, a finding that supports the hypothesis that dust is a significant exposure route for cats. Serum levels were also significantly correlated with concentrations found in cat food for 6-OH-BDE47 (p < 0.002), 2,4,6-TBP (p < 0.035), and BB-209 (p < 0.007). DBDPE was found in high concentrations in all dust (median 154 pmol/g) and food samples (median 0.7 pmol/ig lw) but was below detection in serum samples, suggesting low or no bioavailability for DBDPE in cats.

Athabasca Oil Sands Petcoke Extract Elicits Biochemical and Transcriptomic Effects in Avian Hepatocytes

Crump, D; Williams, KL; Chiu, S; Zhang, YF; Martin, JW
2017 | Environ. Sci. Technol. | 51 (10) (5783-5792)
2 , 3 , 7 , 8-tetrachlorodibenzo-p-dioxin , chicken embryonic hepatocytes , cultures , cytochrome-p4501a induction , egg extracts , flame retardants , in-vitro , messenger-rna expression , polycyclic aromatic hydrocarbons , sensitivity

Petroleum coke or "petcoke" is a granular carbonaceous material produced during the upgrading of heavy crude oils, including bitumen. Petcoke dust was recently reported as an environmental contaminant in the Athabasca oil sands region, but the ecotoxicological hazards posed by this complex bitumen-derived material-including those to avian species-have not been characterized. In this study, solvent extracts (x) of delayed and fluid petcoke (xDP and xFP) were prepared and dissolved in dimethyl sulfoxide. A water accommodated fraction of delayed petcoke (waDP) was also prepared. Graded concentrations of xDP, xFP, and waDP were administered to chicken and double-crested cormorant hepatOcytes to determine effects on 7-ethoxyresorufin-O-deethylase (EROD) activity, porphyrin accumulation, and mRNA expression. Polycyclic aromatic compounds (PACs) were characterized, and xDP, xFP, and waDP had total PAC concentrations of 93 000, 270, and 5.3 ng/mL. The rank order of biochemical and transcriptomic responses was xDP > xFP > waDP (e.g., EROD EC50s, were lower for xDP compared to xFP and waDP). A total of 22, 18, and 4 genes were altered following exposure to the highest concentrations of xDP, xFP, and waDP, respectively, using a chicken PCR array comprising 27 AhR-related genes. To provide more exhaustive coverage of potential toxicity pathways being impacted, two avian ToxChip PCR-arrays chicken and double-crested cormorant-were utilized, and xDP altered the expression of more genes than xFP. Traditional PAC-related toxicity pathways and novel mechanisms of action were identified in two avian species following petcoke extract exposure. Extrapolation to real-world exposure scenarios must consider the bioavailability of the extracted PACs compared to those in exposed organisms.

Microbial utilization of mineral-associated nitrogen in soils

Turner S.; Meyer-Stüve S.; Schippers A.; Guggenberger G.; Schaarschmidt F.; Wild B.; Richter A.; Dohrmann R.; Mikutta R.
2017 | Soil Biol. Biochem. | 104 (185-196)

Diffusive dynamics during the high-to-low density transition in amorphous ice

Perakis, F; Amann-Winkel, K; Lehmkuhler, F; Sprung, M; Mariedahl, D; Sellberg, JA; Pathak, H; Spaeh, A; Cavalca, F; Schlesinger, D; Ricci, A; Jain, A; Massani, B; Aubree, F; Benmore, CJ; Loerting, T; Grubel, G; Pettersson, LGM; Nilsson, A
2017 | Proc. Natl. Acad. Sci. U.S.A. | 114 (31) (8193-8198)
1st-order transition , amorphous ice , behavior , glass transition , glass-liquid transition , liquid-liquid transition , phases , photon-correlation spectroscopy , pressure , reorientation , speckle , supercooled water , water , x-ray photon-correlation spectroscopy
Water exists in high- and low-density amorphous ice forms (HDA and LDA), which could correspond to the glassy states of high(HDL) and low-density liquid (LDL) in the metastable part of the phase diagram. However, the nature of both the glass transition and the high-to-low-density transition are debated and new experimental evidence is needed. Here we combine wide-angle X-ray scattering (WAXS) with X-ray photon-correlation spectroscopy (XPCS) in the small-angle X-ray scattering (SAXS) geometry to probe both the structural and dynamical properties during the high-to-low-density transition in amorphous ice at 1 bar. By analyzing the structure factor and the radial distribution function, the coexistence of two structurally distinct domains is observed at T = 125 K. XPCS probes the dynamics in momentum space, which in the SAXS geometry reflects structural relaxation on the nanometer length scale. The dynamics of HDA are characterized by a slow component with a large time constant, arising from viscoelastic relaxation and stress release from nanometer-sized heterogeneities. Above 110 K a faster, strongly temperature-dependent component appears, with momentum transfer dependence pointing toward nanoscale diffusion. This dynamical component slows down after transition into the low-density form at 130 K, but remains diffusive. The diffusive character of both the high- and low-density forms is discussed among different interpretations and the results are most consistent with the hypothesis of a liquid-liquid transition in the ultraviscous regime.

Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles

Ecke, F; Singh, NJ; Arnemo, JM; Bignert, A; Helander, B; Berglund, ÅMM; Borg, H; Bröjer, C; Holm, K; Lanzone, M; Miller, T; Nordström, Å; Räikkönen, J; Rodushkin, I; Ågren, E; Hörnfeldt, B
2017 | Environ. Sci. Technol. | 51 (10) (5729-5736)
ammunition , aquila-chrysaetos , bald eagles , birds , boreal sweden , ecology , field , swans

Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.

Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate

Rastak, N; Pajunoja, A; Navarro, JCA; Ma, J; Song, M; Partridge, DG; Kirkevag, A; Leong, Y; Hu, WW; Taylor, NF; Lambe, A; Cerully, K; Bougiatioti, A; Liu, P; Krejci, R; Petaja, T; Percival, C; Davidovits, P; Worsnop, DR; Ekman, AML; Nenes, A; Martin, S; Jimenez, JL; Collins, DR; Topping, DO; Bertram, AK; Zuend, A; Virtanen, A; Riipinen, I
2017 | Geophys Res Lett | 44 (10) (5167-5177)
atmospheric aerosols , boreal forest , condensation nuclei activity , droplet activation kinetics , earth system model , hygroscopic growth , liquid phase-separation , mass-spectrometer , regional dust samples , southeastern united-states
A large fraction of atmospheric organic aerosol (OA) originates from natural emissions that are oxidized in the atmosphere to form secondary organic aerosol (SOA). Isoprene (IP) and monoterpenes (MT) are the most important precursors of SOA originating from forests. The climate impacts from OA are currently estimated through parameterizations of water uptake that drastically simplify the complexity of OA. We combine laboratory experiments, thermodynamic modeling, field observations, and climate modeling to (1) explain the molecular mechanisms behind RH-dependent SOA water-uptake with solubility and phase separation; (2) show that laboratory data on IP- and MT-SOA hygroscopicity are representative of ambient data with corresponding OA source profiles; and (3) demonstrate the sensitivity of the modeled aerosol climate effect to assumed OA water affinity. We conclude that the commonly used single-parameter hygroscopicity framework can introduce significant error when quantifying the climate effects of organic aerosol. The results highlight the need for better constraints on the overall global OA mass loadings and its molecular composition, including currently underexplored anthropogenic and marine OA sources. Plain Language Summary The interaction of airborne particulate matter ("aerosols") with water is of critical importance for processes governing climate, precipitation, and public health. It also modulates the delivery and bioavailability of nutrients to terrestrial and oceanic ecosystems. We present a microphysical explanation to the humidity-dependent water uptake behavior of organic aerosol, which challenges the highly simplified theoretical descriptions used in, e.g., present climate models. With the comprehensive analysis of laboratory data using molecular models, we explain the microphysical behavior of the aerosol over the range of humidity observed in the atmosphere, in a way that has never been done before. We also demonstrate the presence of these phenomena in the ambient atmosphere from data collected in the field. We further show, using two state-of-the-art climate models, that misrepresenting the water affinity of atmospheric organic aerosol can lead to significant biases in the estimates of the anthropogenic influence on climate.

Spatial distribution and bioaccumulation of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in snails (Bellamya aeruginosa) and sediments from Taihu Lake area, China

Yin, G; Zhou, YH; Strid, A; Zheng, ZY; Bignert, A; Ma, TW; Athanassiadis, I; Qiu, YL
2017 | Environ Sci Pollut Res | 24 (8) (7740-7751)
Taihu Lake area is one of the densest metropolitan areas in the world including diverse industrial activity. In the present study, the snail (Bellamya aeruginosa) and sediment were collected from the Taihu Lake area to investigate the contamination status, congener pattern, spatial distribution, and bioaccumulation effect of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The samples underwent liquid extraction, lipid removal by sulfuric acid, and acidic silica gel column, and subsequently analyzed by gas chromatography-electron capture detector (GC-ECD) and gas chromatography-mass spectrometry (GC-MS). Concentration of S22PCBs ranged between 90 and 680 ng g(-1) lipid weight in the snails and between 0.018 and 0.82 ng g(-1) dry weight in the sediments. Concentration of S24PBDEs varied from 25 to 200 ng g(-1) lipid weight in the snails and from 0.62 to 67 ng g(-1) dry weight in the sediments. The levels of PCBs and PBDEs observed were in the medium to low range compared with other studies in the world. CB-153 was the predominant PCB congener in both snails and sediments whereas BDE-209 showed a low bioavailability in the snails, even if it contributed up to 70% of S24PBDEs in the sediments. The spatial distribution showed that the highest concentration of PCBs and PBDEs were detected in samples from Zhushan Lake. East Taihu Lake and Dianshan Lake showed lower concentration of PCBs and PBDEs than the other sampling sites. Biota-sediment accumulation was found between snails and sediments of most of PCB and PBDE congeners except for the highly brominated BDEs (i.e., BDE-209). Therefore, sediment is suggested to be an appropriate matrix to monitor BDE-209 while aquatic species such as the snail could be good for monitoring of PCBs and lower brominated BDE congeners. No significant correlation (Spearman correlation test, two-tailed) of CB-153 (r = 0.54, p = 0.27) or BDE-47 (r = 0.60, p = 0.21) was found between snails and sediments.


Zetouni, NC; Siraki, AG; Weinfeld, M; Pereira, AD; Martin, JW
2017 | Environ. Toxicol. Chem. | 36 (5) (1397-1404)
assay , contaminants of emerging concern , genetic toxicology , genotoxicity , goldfish , mixture toxicology , naphthenic acids , oil sands , region , responses , sos chromotest , subchronic exposures , tailings , toxicity , yellow perch

Large volumes of oil sands process-affected water (OSPW) are produced by the oil sands surface mining industry during alkaline hot-water extraction of bitumen. It is well documented that the acid extractable organics (AEOs) in OSPW, a highly complex mixture of acidic and polar neutral substances, are acutely toxic; but few studies have examined the genotoxicity or mutagenicity of this mixture. In the present study, the in vitro SOS Chromotest and the Ames test (TA98 and TA100 strains) were used to evaluate genotoxicity and mutagenicity for whole OSPW AEOs in the presence and absence of biotransformation by rat S9 liver enzymes. Two subfractions were also examined in the same assays: neutral extractable fraction (F1-NE), and the subsequent acid extractable fraction (F2-AE). In the SOS assay, whole AEO was cytotoxic when concentrated 2 x (i.e., twice as concentrated as the environmental sample) and showed increasing genotoxic response above 6x. Co-exposure with S9 had a protective effect on the cell SOS-inducing factor and survival but did not eliminate genotoxicity above 6 x concentrations. Most of the cytotoxicity was attributable to F2-AE, but both F1-NE and F2-AE had similar genotoxic dose-responses above 6 x. In the Ames test without S9, whole AEO was mutagenic in both strains above 10x concentrations. Co-incubation with S9 had little effect on the TA100 strain but with TA98 resulted in bioactivation at midlevel doses (1.5-6.3x) and protection at higher doses (10-25x). The 2 subfractions were mutagenic in both strains but with different dose-responses. Further research in vivo or in more relevant cells is warranted to investigate the carcinogenic risks of OSPW. (C) 2016 SETAC

CCN production by new particle formation in the free troposphere

Rose, C; Sellegri, K; Moreno, I; Velarde, F; Ramonet, M; Weinhold, K; Krejci, R; Andrade, M; Wiedensohler, A; Ginot, P; Laj, P
2017 | Atmos. Chem. Phys. | 17 (2) (1529-1541)
atmospheric nucleation , boreal forest , boundary layer , cloud condensation nuclei , high-altitude site , northern finland , nucleation mode particles , size distributions , standard-deviation , wind direction
Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to similar to 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between 1 January and 31 December 2012, we found that 61% of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, and 1481 cm(-3) for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67% against 53% in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud-related radiative processes.

Chemical and toxicological characterizations of hydraulic fracturing flowback and produced water

He, YH; Flynn, SL; Folkerts, EJ; Zhang, YF; Ruan, DL; Alessi, DS; Martin, JW; Goss, GG
2017 | Water Res. | 114 (78-87)
acid , aquatic toxicity , aryl phosphate esters , drinking water , gas operations , hydraulic fracturing flowback and produced , marcellus , oil , oxidative stress , pah , polycyclic aromatic hydrocarbons , sands process water , synergistic effect , toxicity , trout oncorhynchus-mykiss , water (hf-fpw)

Hydraulic fracturing (HF) has emerged as a major method of unconventional oil and gas recovery. The toxicity of hydraulic fracturing flowback and produced water (HF-FPW) has not been previously reported and is complicated by the combined complexity of organic and inorganic constituents in HF fluids and deep formation water. In this study, we characterized the solids, salts, and organic signatures in an HF-FPW sample from the Duvernay Formation, Alberta, Canada. Untargeted HPLC-Orbitrap revealed numerous unknown dissolved polar organics. Among the most prominent peaks, a substituted tri-phenyl phosphate was identified which is likely an oxidation product of a common polymer antioxidant. Acute toxicity of zebrafish embryo was attributable to high salinity and organic contaminants in HF-FPW with LC50 values ranging from 0.6% to 3.9%, depending on the HF-FPW fractions and embryo developmental stages. Induction of ethoxyresorufin-O-deethylase (EROD) activity was detected, due in part to polycyclic aromatic hydrocarbons (PAHs), and suspended solids might have a synergistic effect on EROD induction. This study demonstrates that toxicological profiling of real HF-FPW sample presents great challenges for assessing the potential risks and impacts posed by HF-FPW spills. (C) 2017 Elsevier Ltd. All rights reserved.

Accumulation of Perfluoroalkylated Substances in Oceanic Plankton

Casal, P; Gonzalez-Gaya, B; Zhang, YF; Reardon, AJF; Martin, JW; Jimenez, B; Dachs, J
2017 | Environ. Sci. Technol. | 51 (5) (2766-2775)
atlantic-ocean , atmospheric transport , biogeochemical controls , environmental fate , fluorinated alternatives , food-web , perfluorinated compounds , perfluorooctanoic acid (pfoa) , persistent organic pollutants , polyfluoroalkyl substances

The bioaccumulation of perfluoroalkylated substances (PFASs) in plankton has previously been evaluated only in freshwater and regional seas, but not for the large oligotrophic global oceans. Plankton samples from the tropical and subtropical Pacific, Atlantic and Indian Oceans were collected during the Malaspina 2010 circumnavigation expedition, and analyzed for 14 ionizable PFASs, including perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS) and their respective linear and branched isomers. PFOA and PFOS concentrations in plankton ranged from 0.1 to 43 ng g(dw)(-1) and from 0.5 to 6.7 ng g(dw)(-1), respectively. The relative abundance of branched PFOA in the northern hemisphere was correlated with distance to North America, consistent with the historical production and coherent with previously reported patterns in seawater. The plankton samples showing the highest PFOS concentrations also presented the largest relative abundances of branched PFOS, suggesting a selective cycling/fractionation of branched PFOS in the surface ocean mediated by plankton. Bioaccumulation factors (BAFs) for plankton were calculated for six PFASs, including short chain PFASs. PFASs Log BAFs (wet weight) ranged from 2.6 +/- 0.8 for perfluorohexanesulfonic acid (PFHxS), to 4.4 +/- 0.6 for perfluoroheptanoic acid (PFHpA). The vertical transport of PFASs due to the settling of organic matter bound PFAS (biological pump) was estimated from an organic matter settling fluxes climatology and the PFAS concentrations in plankton. The global average sinking fluxes were 0.8 +/- 1.3 ng m(-2)d(-1) for PFOA, and 1.1 +/- 2.1 ng m(-2)d(-1) for PFOS. The residence times of PFAS in the surface ocean, assuming the biological pump as the unique sink, showed a wide range of variability, from few years to millennia, depending on the sampling site and individual compound. Further process-based studies are needed to constrain the oceanic sink of PFAS.

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