SMOKE CONCENTRATION AS AN INDICATOR OF POLYCYCLIC AROMATIC HYDROCARBONS LEVELS IN THE AIR

The relationship of polycyclic aromatichydrocarbons (PAH) and smoke concentrationwas analysed at four different locations in Zagreb during theheating season. At two sampling sitessmoke pollution came primarily from domestic heating while theother two sites were under a directinfluence of traffic. At locations away from trafficcorrelations between smoke and PAH concentrationswere stochastically significant at 0.01 level. Takingbenzo-a-pyrene (BaP) as a PAH representative itwas shown that for these two locations the smoke/BaPrelationship can be presented with a singleregression line which can serve for rough assessment of BaPlevels in the air. The BaP concentrationof 10 ng/m³ – proposed by the German FederalEnvironmental Agency as orientation < mark (Lahman et al., 1984) – might be expected to occurat smoke levels 60 g/m³,and above this level it is recommended to start measuringactual concentrations of PAH.     

Urban and rural transport of semivolatile organic compounds at regional scale: A multimedia model approach

Urban areas are generally regarded as major sources of some semivolatile organic compounds and other persistent organic pollutants(POPs) to the surrounding regions. Huge differences in contaminant emissions between urban and rural areas directly affect their fate in environmental media. Little is known about POPs behavior between urban and rural areas at a regional scale. A spatially resolved Berkeley-Trent-Urban-Rural Fate Model(BETR-UR) was designed by coupling land cover information to simulate the transport of POPs between urban and rural areas, and the Bohai Rim was used as a case study to estimate Polycyclic Aromatic Hydrocarbon(PAH) fate. The processes of contaminant fate including emission, inter-compartmental transfer, advection and degradation in urban and rural areas were simulated in the model. Simulated PAH concentrations in environmental media of urban and rural areas were very close to measured values. The model accuracy was highly improved, with the average absolute relative error for PAH concentrations reduced from 37% to 3% compared with unimproved model results. PAH concentrations in urban soil and air were considerably higher than those in rural areas. Sensitivity analysis showed temperature was the most influential parameter for Phen rather than for Bap, whose fate was more influenced by emission rate, compartment dimension, transport velocity and chemical persistence. Uncertainty analysis indicated modeled results in urban media had higher uncertainty than those in rural areas due to larger variations of emissions in urban areas. The differences in urban and rural areas provided us with valuable guidance on policy setting for urban–rural POP control.     

Oxidant denuder sampling for analysis of polycyclic aromatic hydrocarbons and their oxygenated derivates in ambient aerosol: evaluation of sampling artefact

The concentrations of some polycyclic aromatic hydrocarbons (PAH) and oxygenated PAH (O-PAH) can be changed by oxidation reactions during sampling. This can lead to an over- or underestimation of the corresponding adverse health effects. The aim of this study was the evaluation of these sampling artefacts. The potential of using an oxidant denuder was shown by parallel low-volume sampling with and without MnO₂ ozone denuder. Twenty-three PAH and 11 O-PAH in ambient air were analysed, both in the vapour and particulate phase. The denuder was proven to be highly efficient for stripping ozone from air while causing no significant particle losses. In general, the concentrations of 5- to 7-ring PAH, which are predominantly associated with particles, were underestimated in non-denuded samples. The highest losses due to reaction with ozone and other atmospheric oxidants were observed for benzo[a]pyrene and perylene. Concurrently, the concentrations of most of the mainly particle-associated 4- to 5-ring O-PAH were higher in the non-denuded samples. The denuder did not only remove ozone, moreover other gaseous species such as more volatile PAH and O-PAH were partially oxidized on the catalytic surface, too. Degradation of PAH and concurrent degradation/formation reactions of O-PAH occurred. The corresponding reactivities of selected PAH and O-PAH are discussed.     

Toxic equivalency factor approach for risk assessment of polycyclic aromatic hydrocarbons

The toxic equivalency factor (TEF) method has been developed to evaluate structurally related compounds, sharing a common mechanism of action. Because certain polycyclic aromatic hydrocarbons (PAHs) appear to fit this requirement and are ubiquitous environmental contaminants, these compounds are TEF candidates. Toxicity is often expressed relative to benzo[a]pyrene (BaP), the reference standard (e.g., TEF = EC50_BaP/EC50_PAH). BaP‐like toxicity or toxic equivalents (TEQs) can then be calculated: TEQ = S(PAH _i × TEF _i ), where PAH _i and TEF _i are the concentration and TEF, respectively, for individual PAH congeners. Representative TEFs for PAHs were compiled from studies measuring carcinogenic potency and surrogate biomarkers. This review examines the application of TEFs to PAHs with established criteria (i.e., demonstrated need, defined chemical grouping, broad toxicological database, endpoint consistency, additivity, common mechanism of action, consensus). Although all criteria are not satisfied (e.g., endpoint inconsistency, nonadditivity) and more rigorous validation studies are needed, the TEF method is useful when limitations are recognized. Refinements of the method might include incorporation of pharmacokinetic factors and segregation of TEFs derived from mammalian vs. nonmammalian systems to increase endopoint consistency. Probabilistic analysis may also prove useful to assess the range of TEF values reported both within and between human health and ecological risk assessments.     

The efficacy of an oxidation pond in mineralizing some industrial waste products with special reference to fluorene degradation: a case study

The efficacy of the oxidation pond on the outskirts of the 10th of Ramadan, the main industrial city, in Egypt was examined. Samples of wastewater collected from the inlet and the outlet were screened for some priority pollutants. Acenaphthene and fluorene were the most frequently detected polycyclic aromatic hydrocarbons, while dimethyl phthalate was the most frequently detected phthalate ester. The spectrum of pollutants, their concentrations and frequencies were similar in the inlet and the outlet, indicating an inferior mineralization capability of the pond. Several degradative bacterial strains were isolated from the pond and grown on M56 minimal media supplemented with different pollutants as the carbon source. The efficacy of pure and mixed cultures to break down fluorene, the most frequently detected pollutant was examined. Fluorene degradation was fast in the first 10 days, then followed by a slow phase. Mixed culture had a higher rate of fluorene degradation in comparison to pure cultures. High performance liquid chromatography analysis of fluorene degradation showed three degradative metabolites. But GC/MS analysis detected one compound, identified as acetamide. The present work has indicated the poor efficacy of the pond. Lack of primary treatment of industrial effluent at factory level, coupled with shock loads of toxicants that may damage the microorganisms and their degradative capabilities are presumably main factors behind such inferior performance. Moreover, the type of pollutants discharged into the pond tend to fluctuate and change depending on the rate from the factories discharge and work shifts. Such irregular feeding of persistent pollutants may have led to a wash out of specialized strains of bacteria capable to degrade such persistent pollutants.     

Source characterisation and mid-term spatial and temporal distribution of polycyclic aromatic hydrocarbons in molluscs along the Basque coast (northern Spain)

The variability of polycyclic aromatic hydrocarbons (PAH) measured in the soft tissues of Mediterranean mussels (Mytilus galloprovincialis) and Pacific oysters (Crassostrea gigas) are investigated. Samples were collected from estuarine waters within the Basque Country (Bay of Biscay), between 2003 and 2011. PAH bioaccumulation showed some seasonality and significant differences were observed between cold (autumn–winter) and warm (spring–summer) seasons. Sites located within the ports of Bilbao and Pasaia showed the highest PAH concentrations in molluscs, and the highest percentages of samples above the established Environmental Quality Standards and Environmental Assessment Criteria. Probably due to human activities carried out in the area, no clear trends were observed, between 2003 and 2011, for the autumn data. Since the Basque coast is an area with high population density and industrial activity, the congener profiles (which reveal the predominance of tetra-aromatics) and the diagnostic ratios identified urban/industrial combustion processes as the main PAH sources. However, natural and petrogenic sources cannot be disregarded.     

Contamination and source assessment of metals,polychlorinated biphenyls,and polycyclic aromatic hydrocarbons in urban soils from Addis Ababa,Ethiopia

Urban areas in developing countries are facing vast environmental problems as a result of rapid urbanization and industrialization. Of major concern is the contamination of soils which are increasingly becoming sinks for environmental pollutants. However, to date only little is known about the pollution in the megalopolises of developing countries. The aim of this study was to assess the contamination and potential sources of metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the urban environment of Addis Ababa, the capital of Ethiopia. The investigation revealed the presence of most of the analyzed pollutants in soil and sediment samples with total concentrations (dry wt) of PAHs ranging from 186 to 3150?µg?kg^?1, PCBs from 0.4 to 19?µg?kg^?1, Cu from 14 to 173?mg?kg^?1, Zn from 36 to 440?mg?kg^?1, Pb from 9 to 700?mg?kg^?1, and Ni from 16 to 72?mg?kg^?1. In addition, polyaromatic sulfur heterocycles, typical for oil and petrol residues, were detected in several soil samples. Source identification approaches revealed that Pb, Zn, and Cu are most likely derived from pyrolytic sources, with elevated values in samples related to waste combustion and traffic emissions. Ni is most probably of geogenic origin. For PCBs it is indicated that they are derived from a single source. However, correlations with technical PCB mixtures were inconsistent. PAHs originate from the combustion of biomass, vehicular exhausts, and petrogenic sources.     

Continuous monitoring of ambient polycyclic aromatic hydrocarbons near open‐air burning of metal scraps

Airborne concentrations of PAH in the vicinity of the source region with open‐air burning of metal scraps were measured between February, 1992 and November, 1993. The activity of open‐air burning decreased significantly since 1993 due to prohibition regulation. Both gaseous phase and particle‐bound PAH were measured at five sampling sites, which included one reference sampling site far away from the source region. Both values of gaseous and particle‐bound PAH concentrations, which were measured in the vicinity of source region, decreased clearly during the two years monitoring period. It shows that the uncontrolled open‐air burning of metal scraps was a significant emission source of airborne PAH in the study area. The profiles of various species of PAH were also compared. A large decrease in benzo(a)pyrene was observed in the source region.     

The Effect of Interaction Between White-rot Fungi and Indigenous Microorganisms on Degradation of Polycyclic Aromatic Hydrocarbons in Soil

White-rot fungi applied for soil bioremediation have to compete with indigenous soil microorganisms. The effect of competition on both indigenous soil microflora and white-rot fungi was evaluated with regard to degradation of polycyclic aromatic hydrocarbons (PAH) with different persistence in soil. Sterile and non-sterile soil was artificially contaminated with ¹⁴C-labeled PAH consisting of three (anthracene), four (pyrene, benz[a]anthracene) and five fused aromatic rings (benzo[a]pyrene, dibenz[a,h]anthracene). The two fungi tested,Dichomitus squalens and Pleurotus ostreatus, produced similar amounts of ligninolytic enzymes in soil, but PAH mineralization by P. ostreatus was significantly higher. Compared to the indigenous soil microflora, P.ostreatus mineralized 5-ring PAH to a larger extent, while the indigenous microflora was superior in mineralizing 3-ring and 4-ring PAH. In coculture the special capabilities of both soil microflora and P. ostreatus were partly restricted due to antagonistic interactions, but essentially preserved. Thus, soil inoculation with P. ostreatus significantly increased the mineralization of high-molecular-weight PAH, and at the same time reduced the mineralization of anthracene and pyrene. Regarding the mineralization of low-molecular-weight PAH, the stimulation of indigenous soil microorganisms by straw amendment was more efficient than application of white-rot fungi.     

Effect of heavy metals and PAH on soil assessed via dehydrogenase assay

Dehydrogenase enzyme activity (DHA) assay method using resazurin was accommodated for measuring of toxicity of compound contaminants on uncharacterized microbial communities present in any given soil. The method was used to compare the toxic effect of heavy metal and polycyclic aromatic hydrocarbon (PAH) contaminant mixture (Cr, Pb, Cu, Cd, Pyrene) on four typical Estonian soils covering a range of compositions. The method proved to be useable on all soils; the sensitivity of soil microbiology to toxic effect of contaminants was found to have a negative correlation with Ca and organic matter (OM) content and a positive correlation with amorphous phase content of soils.