Atmospheric concentrations,gaseous–particulate distribution,and carcinogenic potential of polycyclic aromatic hydrocarbons in Assiut,Egypt

The concentrations of 15 priority PAHs were determined in the atmospheric gaseous and particulate phases from nine sites across Assiut City, Egypt. While naphthalene, acenaphthene, and fluorene were the most abundant in the gaseous phase with average concentrations of 377, 184, and 181 ng/m³, benzo[b]fluoranthene, chrysene, and benzo[g,h,i]perylene showed the highest levels in the particulate phase with average concentrations of 76, 6, and 52 ng/m³. The average total atmospheric concentration of target PAHs (1,590 ng/m³) indicates that Assiut is one of the highest PAH-contaminated areas in the world. Statistical analysis revealed a significant difference between the levels of PAHs in the atmosphere of urban and suburban sites (P?=?0.029 and 0.043 for gaseous and particulate phases, respectively). Investigation of diagnostic PAH concentration ratios revealed vehicular combustion and traffic exhaust emissions as the major sources of PAHs with a higher contribution of gasoline rather than diesel vehicles in the sampled areas. Benzo[a]pyrene has the highest contribution (average?=?32, 4 % for gaseous and particulate phases) to the total carcinogenic activity (TCA) of atmospheric PAHs. While particulate phase PAHs have higher contribution to the TCA, gaseous phase PAHs present at higher concentrations in the atmosphere are more capable of undergoing atmospheric reactions to form more toxic derivatives.     

Elemental and isotopic determination of lead (Pb) in particulate matter in the Brazilian city of Goiânia (GO) using ICP-MS technique

Environmental Science and Pollution Research - The toxic metal lead (Pb) can be harmful to human health in various manners, but is also considered as a distinguished tracer of environmental...     

Determination of aliphatic and polycyclic aromatic hydrocarbons in atmospheric particulate samples of a coruña city (Spain)

The hydrocarbon composition of atmospheric particulate matter from A Coruña city (Northwest Spain) has been studied. TSP (total suspended particulate) and PM₁₀ (particulate matter with aerodynamic diameter <10 µm) samples were taken over 7 and 4 months at two stations located in residential and industrial sectors of A Coruña city, respectively. The levels of hydrocarbons found in atmospheric particulate samples of A Coruña city are higher than the ones found in other cities over the world. Ratios between the analysed compounds and their sources were established. Both anthropogenic and biogenic origins were found.     

N-alkane studies in the troposphere—II: Gas and particulate concentrations in Indian Ocean air

Westerly winds arriving at the Australian Clean Air Baseline Station Cape Grim at the North Western tip of Tasmania have exceedingly long trajectories over the Indian Ocean. In these air masses we found the n-alkanes C₉-C₂₈ to be always present in the gas phase and also in the aerosols. In aerosols we also measured total organic matter and its general composition. All these concentrations agree fairly well with our earlier data in marine air over the North Atlantic Ocean. Calculations of the life time of the gas phase n-alkanes due to reaction with OH radicals lead to the conclusion that these n-alkanes must be of oceanic origin in Indian Ocean air and — to a large extent — also in the North Atlantic air. The same conclusion is reached for the organic component in aerosols. Water Analyses show that the n-alkanes C₉-C₂₈ seem to be normal constituents of the oceans.     

n-Alkane studies in the troposphere—I. Gas and particulate concentrations in north Atlantic air

Simultaneous measurements of gas phase and paniculate concentrations of C₉–C₂₈n-alkanes in clean air at the west coast of Ireland are reported. All n-alkanes were regularly present with gas phase concentrations between about 10 and 20 × 10⁻⁹ g m⁻³ STP, showing no systematic decrease above C₁₃. Continental air showed higher concentrations. The fraction of alkanes attached to aerosol particles increases from less than 1% at low C-numbers to several per cent at high C-numbers. The carbon preference index is generally close to 1.0; seawater samples from that area exhibit similar distributions of n-alkanes as the gas phase.     

Mathematical model for transport,interconversion, and removal of gaseous and particulate air pollutants—application to the urban plume

A steady state, three-dimensional solution of the atmospheric diffusion equation including settling, deposition, and first-order removal is presented. The solution is applied to the prediction of airborne concentrations of gaseous and particulate pollutants in the case in which gases are converted to secondary particulate matter. The conversion of sulfur dioxide, nitrogen oxides, and hydrocarbons to particulate sulfate, nitrate, and organics in the Los Angeles atmosphere and urban plume is analysed.     

Chemistry of fog waters in California's Central Valley—Part 3: concentrations and speciation of organic and inorganic nitrogen

Although organic nitrogen (ON) has been found to be a ubiquitous and significant component in wet and dry deposition, almost nothing is known about its concentration or composition in fog waters. To address this gap, we have investigated the concentration and composition of ON in fog waters collected in Davis, in California's Central Valley. Significant quantities of dissolved organic nitrogen (DON) were found in these samples, with a median concentration of 303 μM N (range=120–1630 μM N). DON typically represented approximately 16% of the total dissolved nitrogen (inorganic+organic) in Davis fog waters. The median concentration of nitrogen in free amino acids and alkyl amines was 16 μM N (range=3.8–120 μM N), which accounted for 3.4% of the DON in Davis fogs. Thus, although the absolute concentrations of free amino compounds were significant, they were only a minor component of the DON pool. Combined amino nitrogen (e.g., proteins and peptides) was present at higher concentrations and accounted for 6.1–29% (median=16%) of DON. Overall, free and combined amino compounds typically accounted for a median value of 22% of DON in the fog waters.The high concentrations of DON found, and the fact that amino and other N-containing organic compounds can serve as nitrogen sources for microorganisms and plants, indicate that atmospheric ON compounds likely play an important role in nitrogen cycling in the Central Valley. In addition, due to the basicity of some N functional groups, ON compounds likely contribute to the previously observed acid buffering capacity of Central Valley fog waters. Finally, a comparison of fog waters with fine particles (PM_2.5) collected from the same site during the same period of time indicated that the median concentrations (mol N m⁻³-air) of total water-soluble ON, free amino nitrogen and total amino nitrogen were very similar in the fog water and PM_2.5. Given the high water solubility of many organic N compounds, this result suggests that ON might contribute to the hygroscopic properties of atmospheric particles.     

Analysis of aerosol particles and coarse particulate matter concentrations in Chillán, Chile, 2001-2003

Daily particle samples were collected in Chillán, Chile, at six urban locations from September 1, 2001, through September 30, 2003. Aerosol samples were collected using monitors equipped with a Sierra Andersen 246-b cyclone inlet on Teflon filters. Average concentrations of coarse particulate matter (PM10) for the 2001-2003 period ranged from 43.4 microg/m3 to 81.8 microg/m3 across the six sites. Annual PM10 concentration levels exceeded the European Union concentration limits. Mean PM10 levels during the cold season (April through September) were more than twice as high as those observed in the warm season (October through March). Average contributions to PM10 from organic matter, soil dust, nitrate (NO3-), elemental carbon, ammonium (NH4+), and sulfate (SO4(2-)) were 31%, 27%, 11%, 8%, 7%, and 5%, respectively. The chemical analyses indicated that carbonaceous substances were the most abundant components of PM10 in cold months, whereas crustal material was the most abundant component of PM10 during warm months. Higher concentration levels were observed in the downtown area suggesting a clear anthropogenic origin, whereas in the rural sites the source was mainly natural, such as resuspended soil dust associated with traffic on unpaved roads and agricultural activities.     

Analyses of ozone in urban and rural sites in Málaga (Spain)

Ozone concentrations were measured at two (urban and a rural) sites near the city of Málaga (Spain). The aim of this study was to determine the daily, monthly and seasonal variation patterns of ozone concentrations at both sites and to study the possible regional influences. The daily variations mostly have the usual features with the afternoon maximum and the night minimum being more pronounced in the urban area. The average monthly concentrations throughout the year start to increase in March reaching their maximum values in July for the urban site. However, in the rural area, the monthly variations are smaller reaching their maximum value in June. The hourly evolution of the ozone concentrations in both sampling sites is well defined in spring and summer and not so well defined in autumn and winter. Taking into account the four seasons, the rural concentrations are higher than the urban ones. Summer is the season when there are similar concentrations at both sampling sites. Average hourly summer afternoon ozone for the hours 12:00-20:00 LST exceeded the 110 microg m(-3) European Union guidelines for human health for 8 h ozone exposure at the urban and rural sites.     

Bio- and toxic elements in mushrooms from the city of Umeå and outskirts,Sweden

Edible mushrooms (Albatrellus ovinus, Boletus edulis, Clitocybe odora, Gomphidius glutinosus, Leccinum scabrum, Leccinum versipelle, Lycoperdon perlatum, Suillus bovinus, Suillus luteus, and Xerocomus subtomentosus) collected from unpolluted areas of the city of Umeå and its outskirts in the northern part of Sweden were examined for contents of toxic metallic elements (Cd, Pb, and Ag) and essential macro- and microelements (K, Na, Ca, Mg, Cu, Fe, Mn, and Zn) using a validated method and a final measurement by flame atomic absorption spectroscopy (F-AAS). The median values of the toxic metallic element concentrations (in mg kg^?1 dry biomass, db) ranged from: 0.12–3.9, 0.46–5.1, and 0.91–6.2 for Ag, Cd and Pb, respectively. For the essential metallic elements, the median values of concentrations ranged from: 24000–58000, 15–2000, 59–610, 520–1900, 2.0–97, 16–150, 15–120, and 4.3–26 mg kg^?1 db for K, Na, Ca, Mg, Cu, Zn, Fe, and Mn, respectively. The baseline concentrations of the metallic elements determined in mushrooms were mainly affected by the fungal species. The assessed probable maximal dietary intake of Cd (0.002 mg kg^?1 body mass) solely from a mushroom meal was only slightly below a revised value of the tolerable weekly intake for this element, while for Pb (0.003 mg kg^?1 body mass) it was tenfold below the provisionally tolerable weekly intake.     

Photocatalytic degradation of N-heterocyclic aromatics—effects of number and position of nitrogen atoms in the ring

This study demonstrates the influences of position, number of nitrogen (N) atoms and –C–N– or –N=N– linkage present in the six membered heterocyclic compounds such as pyridine, pyrazine, and pyridazine on their photocatalytic degradation by Au, Ag, and Fe⁺² deposited TiO₂ photocatalyst. The photodegradation rate of these heterocyclic compounds follow the order pyridine > pyrazine > pyridazine due to the different extent of hydroxylation and difference in position and number of N atoms in the aromatic moiety. The Au photodeposition significantly improved the TiO₂ photoactivity as compared to Ag and Fe⁺² loading. The presence of two N atoms in pyrazine and pyridazine as compared to one N atom in pyridine hamper the nucleophilc attack of OH radicals in comparison to easy hydroxylation of pyridine ring. There is 1 N atom, 4C–C, 1C–N and 1C=N bond in pyridine, 2 N atoms in the 1 and 4 positions, 2C–C, 2C–N bonds and 2C=N bonds in pyrazine, and pyridazine ring contains 2 N atoms in the 1 and 2 positions, 3C–C, 1N–N bond and 2C=N bonds. The bond strength/energy decreases gradually as: C=N– (615 KJ/mol)?>?–N=N– (418 KJ/mol)?>?–C–C– (347 KJ/mol)?>?–C–N– (305 KJ/mol)?>?–N–N– (163 KJ/mol). As pyridine has 1C–N, 1C=N, and no N–N bond, it photodegrades easily as compared to 1 N–N and 2C=N bonds of pyridazine of lowest photodecomposition rate. The improved photoactivity of Au–TiO₂ is explained on the basis of its favorable redox potential, work function, and electron-capturing capacity, etc.     

Hydrodynamic and geochemical constraints on pesticide concentrations in the groundwater of an agricultural catchment (Brévilles, France)

The monitoring of a spring and seven piezometers in the 3km(2) Brévilles agricultural catchment (France) over five and a half years revealed considerable spatial and temporal variability in the concentrations of atrazine and its metabolite deethylatrazine (both systematically quantified at the outlet spring): maximum 0.97 and 2.72microgL(-1), mean 0.19 and 0.59microgL(-1), respectively. Isoproturon, the pesticide applied in the greatest amount, was detected in only 10 of the 133 samples. These observations can only partly be explained by land use and intrinsic pesticide properties. Geochemical measurements and tritium dating showed the importance of the stratification of the sandy saturated zone and the buffer function of the unsaturated limestone. Principal component analysis on 39 monthly data series of atrazine, deethylatrazine, nitrate, chloride and piezometric levels revealed a temporal structuring of the data possibly reflecting the existence within the aquifer of two different reservoirs with time-variable contributions.     

Occurrence of organochlorine pesticides (OCPs) and their enantiomeric signatures, and concentrations of polybrominated diphenyl ethers (PBDEs) in the Adélie penguin food web, Antarctica

Concentrations and enantiomeric signatures of organochlorine pesticides were determined in Antarctic krill, emerald rockcod and Adélie penguin from the Ross Sea, Antarctica. HCB and DDTs were prevalent contaminants in penguin eggs. The highest concentrations of SigmaHCHs (1.35 +/- 0.72 ng/g) were found in the rockcod muscle, where gamma-HCH (1.23 +/- 0.67 ng/g) was the principal isomer. The ratio gamma-HCH/alpha-HCH was evaluated. Enantioselective gas chromatography was used for the evaluation of enantiomeric fractions (EFs) for alpha-HCH and oxychlordane. An increase of 14% in the (+)alpha-HCH enantiomer was found from krill through penguin, suggesting the enantioselective biotransformation increased proportionately with trophic level. Polybrominated diphenyl ethers (PBDEs) were measured and their concentrations were 5.6 +/- 1.12, 5.81 +/- 2.32, 4.57 +/- 0.17 and 3.06 +/- 3.27 ng/g lipids in krill, rockcod muscle, rockcod homogenate and penguin eggs, respectively. The detection of BDE28, BDE47, BDE99 and BDE100 in Antarctic organisms confirmed their global transport and distribution; the detection of lower brominated congeners suggested a potential long-range transport.     

Comparison of black carbon (BC) aerosols in two urban areas – concentrations and size distributions

In this study, the BC aerosol measured at two very different urban sites is compared in terms of concentration, seasonal variation, and size distribution. During a 14 month study, one impactor sample was performed each month on a day with typical meteorological conditions. One (Vienna) or three (Uji) filter samples were obtained during the sampling time of the impactors. BC concentration in both the filter and impactor samples was analyzed with an optical technique (integrating sphere technique), where a calibration curve obtained from commercial carbon black is used to convert the optical signal to BC mass. Gravimetric mass concentration was measured at both sites. The gravimetric mass size distribution was measured only in Vienna. At both sites, the yearly average of the BC concentration on the sampling days was around 5 μg m⁻³. In Vienna, some seasonal trend with high concentrations during the cold season was observed, while in Uji, no pronounced seasonal trend was found. The BC size distribution in Uji was distinctly bimodal in the submicron size range. Log-normal distributions were fitted through the impactor data. The average BC mass median diameters (MMD) of the two submicron modes were 0.15 and 0.39 μm. Each mode contained about the same amount of BC mass. In Vienna only one submicron BC mode (average MMD 0.3 μm) was found because of the low size resolution of the impactor. An analysis of humidity effects on the MMDs of BC (both sites) and gravimetric mass (Vienna only) indicates that the Vienna aerosol is partly mixed internally with respect to BC, while the Uji aerosol seems to be externally mixed.     

Deposition of acidic components and heavy metals in the Federal Republic of Germany for the period 1979–1981

The paper discusses the results of the measurement of wet and dry deposition of sulfate, nitrate, chloride and heavy metal aerosols which were obtained from a network established in the Federal Republic of Germany during 1979 to 1981. The results characterize the deposition-pattern with respect to time and space.     

Sources,distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring

We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is responsible for sulfate concentrations in the Arctic. East Asian pollution influence is weak in winter but becomes important in spring through transport in the free troposphere. European influence is important at all altitudes but never dominant. West Asia (non-Arctic Russia and Kazakhstan) is the largest contributor to Arctic sulfate in surface air in winter, reflecting a southward extension of the Arctic front over that region. Ammonium in Arctic spring mostly originates from anthropogenic sources in East Asia and Europe, with added contribution from boreal fires, resulting in a more neutralized aerosol in the free troposphere than at the surface. The ARCTAS and ARCPAC data indicate a median aerosol neutralization fraction [NH₄⁺]/(2[SO₄^2?] + [NO₃^?]) of 0.5 mol mol^?1 below 2 km and 0.7 mol mol^?1 above. We find that East Asian and European aerosol transported to the Arctic is mostly neutralized, whereas West Asian and North American aerosol is highly acidic. Growth of sulfur emissions in West Asia may be responsible for the observed increase in aerosol acidity at Barrow over the past decade. As global sulfur emissions decline over the next decades, increasing aerosol neutralization in the Arctic is expected, potentially accelerating Arctic warming through indirect radiative forcing and feedbacks.     

Long-term impacts of reservoir operation on the spatiotemporal variation in nitrogen forms in the post-Three Gorges Dam period (2004–2016)

Environmental Science and Pollution Research - Nitrogen (N) is an essential nutrient limiting life, and its biochemical cycling and distribution in rivers have been markedly affected by river...