This work describes the assessment of a selection of fullerenes including C60 and C70 fullerene, N-methylfulleropyrrolidine, C60 pyrrolidine tris-acid ethyl ester, 6,6-Phenyl-C61 butyric acid butyl ...ester and 6,6-Thienyl C61 butyric acid methyl ester, in airborne particulate from the Mediterranean Sea collected during two sampling campaigns from Barcelona to Istanbul and Alexandria, respectively. The analysis of the samples was carried out using a new method based on liquid chromatography coupled to mass spectrometry (LC-MS) presenting sensitivities between 5.4 and 20.9 pg/m3. A total number of 43 samples covering the different basins of Mediterranean Sea were analyzed. Fullerenes were detected in all analyzed samples and quantifiable concentrations were found in 28 of the analyzed samples. The median of C60 and C70 fullerenes aerosol phase concentrations were 0.06 ng/m3 and 0.48 ng/m3 respectively for the Mediterranean Sea atmosphere. C70 fullerene was the most frequently detected compound and also it was found in the higher concentrations for most samples, reaching 233.8 ng/m3. The modeled back-trajectories disclose that those samples with higher concentrations of fullerenes were related to air masses which had been circulating over regions with an intense industrial activity, but the variability of the C70/C60 ratio suggests multiple different sources. These results are related to the incidental emissions from urban and industrial development, underpinning the need of studying the possible risks associated to carbon nanoparticles in the environment and the need of evaluating the possible consequences of their ubiquitous occurrence.
Hydrocarbons were analyzed in sediments from the Congo River deep-sea fan, from the Congo River, and in sinking particles collected by sediment traps 40m above the sediment. Studied sites encompassed ...three lobes of decreasing age of formation along the canyon: sites A, F and C and a another lobe system, disconnected from the active channel since 4 ka, Site E. Terrestrial long-chain odd n-alkanes were dominant in all sediments of the lobe system. Unsaturated terpenoids sourced by higher plants, such as gammacerene, lupene, ursene and oleanene, were also detected. At site C, characterized by high accumulation rates (10–20cmyr−1), the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations 10–17μggOC−1) evidenced recent terrestrial and phytoplanktonic remains reworked in anaerobic conditions. In these sediments, organic carbon-normalized concentrations of terrestrial alkanes and terpenoids were several fold higher than in the lobe sediments with lower accumulation rates (sites A and F), arguing for a more rapid degradation of terrestrial hydrocarbons than bulk organic carbon in the first steps of pre-diagenesis. Ample variations in the contributions of biomarkers from higher plants, ferns, bacteria and angiosperms, indicate an heterogeneous contribution of the soil and vegetation detritus delivered to the Congo lobe sediments. Lower concentrations in terrestrial hydrocarbons at site E, 45km away from the active canyon, indicated that river particles are still admixed to the dominant marine organic matter. Diploptene and hop-7(21)-ene have a dual origin, from terrestrial and marine microorganisms. Scatter in their relationship to gammacerene argues for a contribution of marine microorganisms, in addition to soils-sourced microorganisms. The close distribution patterns of diploptene, hop-21-ene, hop-7(21)ene and neohop-13(18)-ene is in line with the hypothesis of sequential clay-catalyzed isomerisation of bacterial hopenes. Terrestrial biomarker accumulation fluxes at site C are one order of magnitude higher than vertical pelagic flux, demonstrating the magnitude of the inputs delivered through turbiditic transport in the submarine canyon. Crude oil contamination was evidenced at the disconnected site E (UCM, C21 to C26 tricyclic diterpanes, CPI) and, in smaller amounts, in some sediments from sites A and C. It may be related to marine crude oil extraction and transport. A short-chain mode of alkanes with an even predominance is evidenced in sediments of the lobe complex and likely sources, crude oil, microorganisms and ferns, are discussed.
Polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and surface seawater between 49° N and 25° S in the open Atlantic Ocean. Elevated concentrations of PAHs (Σ10 PAHs ≈ ...1.4–2.5 ng m−3 air, and 0.7–1 ng L−1 seawater) occurred in the Biscay Bay and off the northwest coast of Africa. The unexpectedly high concentrations off NW Africa were discussed assessing the possible contribution of the emerging oil industry along the African shore, the role of biomass burning and natural sources of PAHs. In the southern Atlantic, concentrations of PAHs were close to detection limits (Σ10 PAHs ≈ 0.02–0.5 ng m−3 air, and 0.06–0.5 ng L−1 seawater) and showed decreasing trends with increasing latitudes. Correlations of PAHs’ partial pressures versus inverse temperature were not significant, in contrast to results for polychlorinated biphenyls from the same transect. This could have been due to the importance of ongoing primary sources and the shorter atmospheric life-times of PAHs. Air–water fugacity ratios (f a/f w) were calculated for selected compounds. They were close to 1 for fluoranthene and pyrene in remote open ocean areas suggesting air–water partitioning near equilibrium. Ratios for anthracene and phenanthrene were <0.3 in the remote tropical Atlantic, suggesting net volatilization.
The impact of organic pollutants on oceanic ecosystem functioning is largely unknown. Prochlorococcus, the most abundant known photosynthetic organism on Earth, has been suggested to be especially ...sensible to exposure to organic pollutants, but the sub-lethal effects of organic pollutants on its photosynthetic function at environmentally relevant concentrations and mixtures remain unexplored. Here we show the modulation of the expression of two photosynthetic genes, rbcL (RuBisCO large subunit) and psbA (PSII D1 protein), of oceanic populations of Prochlorococcus from the Atlantic, Indian and Pacific Oceans when exposed to mixtures of organic pollutants consisting of the non-polar fraction of a seawater extract. This mixture included most persistent organic pollutants, semivolatile aromatic-like compounds, and the unresolved complex mixture of hydrocarbons. Prochlorococcus populations in the controls showed the expected diel cycle variations in expression of photosynthetic genes. However, exposure to a complex mixture at concentrations only 2-fold above the environmental levels resulted in a decrease of expression of both genes, suggesting an effect on the photosynthetic function. While organic pollutant effects on marine phytoplankton have been already demonstrated at the cellular level, this is the first field study showing alterations at the molecular level of the photosynthetic function due to organic pollutants.
Air and seawater samples were collected on board the RV Polarstern during a cruise from Bremerhaven, Germany to Cape Town, South Africa from October–November 2005. Broad latitudinal trends were ...observed with the lowest Σ27PCB air concentration (∼10 pg m−3) in the South Atlantic and the highest (∼1000 pg m−3) off the west coast of Africa. ΣICESPCBs ranged from 3.7 to 220 pg m−3 in air samples and from 0.071 to 1.7 pg L−1 in the dissolved phase seawater samples. Comparison with other data from cruises in the Atlantic Ocean since 1990 indicate little change in air concentrations over the remote open ocean. The relationship of gas-phase partial pressure with temperature was examined using the Clausius-Clapeyron equation; significant temperature dependencies were found for all PCBs over the South Atlantic, indicative of close air–water coupling. There was no temperature dependence for atmospheric PCBs over the North Atlantic, where concentrations were controlled by advection of contaminated air masses. Due to large uncertainties in the Henry’s Law Constant (HLC), fugacity fractions and air–water exchange fluxes were estimated using different HLCs reported in the literature. These suggest that conditions are close to air–water equilibrium for most of the ocean, but net deposition is dominating over volatilization in parts of the transect. Generally, the tri- and tetrachlorinated homologues dominated the total flux (>70%). Total PCB fluxes (28, 52, 118, 138, and 153) ranged from −7 to 0.02 ng m−2 day –1.
Here we estimate the importance of vertical eddy diffusion in removing perfluorooctanoic acid (PFOA) from the surface Ocean and assess its importance as a global sink. Measured water column profiles ...of PFOA were reproduced by assuming that vertical eddy diffusion in a 3-layer ocean model is the sole cause for the transport of PFOA to depth. The global oceanic sink due to eddy diffusion for PFOA is high, with accumulated removal fluxes over the last 40 years of 660 t, with the Atlantic Ocean accounting for 70% of the global oceanic sink. The global oceans have removed 13% of all PFOA produced to a depth greater than 100 m via vertical eddy diffusion; an additional 4% has been removed via deep water formation. The top 100 m of the surface oceans store another 21% of all PFOA produced (∼1100 t).
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•Eddy diffusion has removed ∼660 t of PFOA from surface oceans over the last 40 years.•Atlantic Ocean accounts for 70% of the global oceanic sink of PFOA.•Vertical eddy diffusion has moved ∼13% of PFOA to oceans deeper than 100 m.•Around 4% of PFOA has been removed via deep water formation.•The top 100 m of global oceans contain ∼21% of historical PFOA production.
Vertical eddy diffusion is an important removal process for hydrophilic organic pollutants such as PFOA from the surface ocean.
During the last decade the number of seawater dimethylsulfide (DMS) concentration measurements has increased substantially. The importance this gas, emitted from the ocean to the atmosphere, may have ...in the cloud microphysics and hence in the Earth albedo and radiation budget, makes it necessary to accurately reproduce the global distribution. Recently, the monthly global DMS climatology has been updated taking advantage of the threefold increased size and better resolved distribution of the observations available in the DMS database. Here, the emerging patterns found with the previous versions of the database and climatology are explored with the updated versions. The statistical relationships between the seasonalities of DMS concentrations and other variables are re-examined. The positive correlation previously found between surface seawater DMS and the daily-averaged climatological solar radiation dose in the upper mixed layer of the open ocean is confirmed with both the updated DMS database and climatology. Re-examination of the latitudinal match-mismatch between the seasonalities of DMS and phytoplankton, represented by the chlorophyll a concentration, reveals that they are highly positively correlated in latitudes higher than 40°, but anti-correlated in the 20°–40° latitudinal bands of both hemispheres. Overall, these global emerging patterns provide key information to further understanding the factors that control the emission of volatile sulfur from the ocean. The large uncertainties associated with the methodologies used in global computations, however, call for caution in using these emerging patterns as predictive tools, and prompt to the design of time series and process-oriented studies aimed at testing the validity of the observed relationships.
Phytoplankton and bacteria play an important role on the biogeochemical cycles of persistent organic pollutants (POPs). However, experimental data and quantitative knowledge of the kinetics of uptake ...and depuration of most POPs by bacteria and phytoplankton are scarce. In the present paper, a procedure to predict the sorption kinetics to bacteria and phytoplankton is developed. The prediction method is the combination of a mechanistic model for sorption and quantitative structure—activity relationships relating bioconcentration factors and membrane permeability to the chemical physical‐chemical properties. The model consists of two compartments where the first compartment is the cellular surface and the second compartment is the cell biomass or matrix. Equations for estimating uptake and depuration rate constants into the matrix and adsorption and desorption rate constants onto the surface are obtained. These expressions depend on the physical‐chemical properties of the chemical, the environmental temperature, the microorganism size, and species‐specific quality of organic matter. While microorganism shape has a secondary influence on uptake dynamics, microorganism size and chemical hydrophobicity arise as the key factors controlling the kinetics of POP incorporation into bacteria and plankton. Uptake, depuration, adsorption, and desorption rate constants are reported for POPs such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dioxins and furans (PCDD/Fs), and POPs of emerging concern, such as polybrominated diphenyl ethers (PBDEs). Finally, implications of uptake and depuration dynamics on the biogeochemical cycling of POPs are discussed.
Volatile per– and polyfluoroalkyl compounds were measured in air in the vicinity of the Western Antarctic Peninsula during February 2009 (Austral summer). The 6:2, 8:2 and 10:2 fluorotelomer alcohols ...(FTOHs) were the most abundant compounds with 8:2 and 10:2 FTOH concentrations averaging 9.9 and 7.4pg m−3 respectively, followed by the shorter chain (C4) compounds of methyl perfluorobutane sulfonamide (MeFBSA) and sulfonamidoethanol (MeFBSE) with average concentrations of ~3 to 4pg m−3. Methyl/ethyl fluorooctane sulfonamides and sulfonamidoethanols (FOSA/Es) were <1pg m−3 in all air samples (n=8). The concentrations of FTOHs and FOSAs were in good agreement with a previous study (2007) that measured these chemicals in the background atmosphere of the Southern Ocean, although the levels of the MeFBSA/E were found to be ~ 10–fold higher and possibly indicative of the increased use of these chemicals. Air mass back trajectories revealed that air mass movement was from the Antarctic landmass or from the Southern Ocean, the latter in keeping with the prevailing direction of the Antarctic Circulation Current. Those samples corresponding to air passing over the Antarctic Peninsula did not show notable differences in chemical concentrations or profile indicating that the scientific bases located on or near the Peninsula did not appear to influence PFC levels in the regional atmosphere. Given the lack of air mass incursions from the north (i.e. from the South American continent) then the levels measured here are representative of background concentrations around Antarctica. However, the relatively high levels of MeFBSE were surprising given the reported reactivity of this chemical and short atmospheric residence time. It is likely that this compound, alongside MeFBSA, is providing a source of C2–C4 perfluoroalkyl acids (PFAs) to Antarctic surface waters. We recommend that long–term air monitoring be established in Antarctica for volatile PFCs and possibly accompanied by deposition monitoring for the PFAs.
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