Gas-particle concentration and distribution of n-alkanes and polycyclic aromatic hydrocarbons in the atmosphere of Prato (Italy)

Air samples were collected in an urban and industrialised area of Prato (Italy) during 2002, as part of a study to identify and measure aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs). Total concentrations of aliphatic hydrocarbons ranged between 170 and 282ngm(-3) in the gas phase and from 48.9 to 276ngm(-3) in the particulate phase. The average total PAH concentrations (gas+particulate) were 59.4+/-26.5ngm(-3), and both gas and particulate phase PAH concentrations decreased with increasing temperature. Source identification using diagnostic ratios and principal component analysis identified automobile traffic, in particular, the strong influence of diesel fuel burning, as the major PAH source. Gas-particle partition coefficients (K(p)'s) of n-alkane and PAHs were well correlated with the sub-cooled liquid vapour pressure (P(L)(0)) and indicate stronger sorption of PAHs to aerosol particles compared with n-alkanes.     

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.     

The characterisation of polycyclic aromatic hydrocarbons emissions from burning of different firewood species in Australia

Four kinds of woods used for residential heating in Australia were selected and burned under two burning conditions in a domestic wood heater installed in a laboratory. The selected wood species included pine (Pinus radiata), red gum (Eucalvptus camaldulensis), sugar gum (Eucalyptus cladocalyx) and yellow box (Eucalyptus melliodora). The two different burning conditions represented fast burning and slow burning, with the air inlet of the combustion chamber respectively 'full open' and 'half open'. By sampling and analysing particulate and gaseous emissions from the burning of each load of wood under defined experimental conditions, PAHs emissions and their profiles in the particulate and gaseous phases were obtained. 16 species out of the 18 selected PAHs were detected. Of these, seven species were detected in the gaseous phase and most were lower molecular weight compounds.Similarly, more than 10 species of PAHs were detected in the particulate phase and these were mostly heavier molecular weight compounds. Under both burning conditions, emission levels for total PAHs and total genotoxic PAHs were the highest for pine and lowest for sugar gum, with red gum being the second highest, followed by yellow box. Using the specific sampling method, gaseous PAHs accounted for above 90% mass fraction of total PAHs in comparison to particulate PAHs (10%). The majority of the genotoxic PAHs were present in the particulate phase. PAHs emission levels in slow burning conditions were generally higher than those in fast burning conditions.     

Characteristic study of polycyclic aromatic hydrocarbons for fine and coarse particulates at Pastureland near Industrial Park sampling site of central Taiwan

The concentrations of ambient air polycyclic aromatic hydrocarbons were measured in a farm area (Tunghai University Pastureland) between August 2001 and April 2002 in central Taiwan, Taichung. Particle-bound polycyclic aromatic hydrocarbons (PAHs) were collected on quartz filters, the collected sample was extracted with a dichloromethane (DCM)/n-hexane mixture (50/50, v/v) for 24 h, and then the extracts were subjected to gas chromatography-mass spectrometric analysis. The PM2.5 (fine particulate) and PM2.5-10 (coarse particulate) total PAHs concentrations at the Tunghai University Pastureland sampling site were found to be 180.62 ngm(-3) and 164.98 ngm(-3), respectively. In general, the concentrations of polycyclic aromatic hydrocarbons were higher in spring and winter than those of summer and autumn for either PM2.5 or PM2.5-10 in Pastureland in central Taiwan. Moreover, coarse particulates are the dominant species during the dust storm season (March and April) in central Taiwan.     

Exchange pattern of gaseous elemental mercury in an active urban landfill facility

The environmental behavior of gaseous elemental mercury (Hg) in the ambient air was investigated from the center of a municipal landfill site (area approximately 0.6km(2)) located in Dae Gu, Korea in the winter of 2004. In order to provide insight on the Hg exchange processes in strong source areas, we continuously analyzed Hg concentration gradients developed across two heights between 1m and 5m over soil surfaces at hourly intervals. The results displayed Hg concentrations in the lower and upper levels in the range of 1.46-13.1ngm(-3) (3.33+/-1.29ngm(-3): N=139) and 1.20-13.7ngm(-3) (3.27+/-1.23ngm(-3): N=139), respectively. The results of our analysis, when divided separately into emission and dry deposition, showed that emission of Hg was fairly dominant in frequency (up to 58%) over dry deposition. By multiplying our Hg gradient data with the K-values predicted indirectly from the results of previous studies, the emission and deposition fluxes of Hg were estimated as 39.0+/-43.3ngm(-2)h(-1) (N=80) and -60.0+/-80.2ngm(-2)h(-1) (N=59), respectively. Although the magnitudes of exchange were moderately lower than previously investigated anthropogenic sources, the overall results of this study suggest that an active landfill site can act as an important source of Hg in an urban environment along with other man-made activities.     

Study of metal concentrations in the environment near diesel transport routes

In recent years, a river-dredging project has been executed in Nantou, Taiwan. A large number of diesel vehicles carrying gravel and sand shuttle back and forth on the main traffic roads (Tai-16 and Tai-21). The purpose of this study is to figure out the levels of metals contributed by those vehicles to the surrounding environment. Eight stations along the roadside of diesel transport routes were selected as exposure sites, while a small village located about 9 km away from the diesel transport routes was selected as the control site. The mass concentrations of coarse and fine particulate matter indicated that contributions from traffic fleets resulted in a higher percentage of coarse particulate matter in the ambient air at exposure sites in comparison with that at control site. Significantly higher values of EC (elemental carbon) concentrations and ratios of EC/OC (organic carbon) at exposure sites indicate that diesel vehicles at exposure sites contributed a greater amount of pollutants than gasoline vehicles. Exposure site concentrations for all metals measured (Fe, Al, Mn, Pb, Zn, Cu, Ni, Mo and As) for fine and coarse particulate matter were all higher than those at the control site. Recorded levels of metal contents in road dust and riverside soil near Tai-16 and Tai-21 showed that while the traffic fleet did not increase the metal contents of crustal elements in the road dust, it did significantly increase the metal contents of traffic-related elements. Enrichment factors (EFs) were calculated with respect to road dust (EF_road) and with respect to the samples of riverside soil (EF_river). Among these metals, Mo was the most highly-enriched metal. The extremely high EF_river value (4300) of Mo indicates that these stations were highly polluted by diesel emission. Whereas the significantly high EF_road value (810) of Mo implies that a considerable of Mo was emitted from tailpipe of diesel vehicles.     

Chromosomal damage in peripheral blood lymphocytes of traffic policemen and taxi drivers exposed to urban air pollution

Urban air contains a diversity of chemical compounds, some of which are genotoxins. An increased risk of cancer has also been reported in occupations with heavy exposure to traffic-related pollution. The aim of this study was to assess the cytogenetic effects of urban air pollution by analyzing the chromosomal aberration (CA) frequencies in lymphocytes and to estimate the polycyclic aromatic hydrocarbons (PAHs) exposure by measuring urinary 1-hydroxypyrene (1-OHP) levels. A total of 15 traffic policemen and 17 taxi drivers working in the city of Ankara were the exposed groups and 23 healthy men working in the office departments were the control group. The overall mean +/- S.D. values of 1-OHP excretions of traffic policemen, taxi drivers and control subjects were 0.59 +/- 0.40 micromol/mol creatinine, 0.32 +/- 0.25 micromol/mol creatinine and 0.57 +/- 0.36 micromol/mol creatinine, respectively. Urinary 1-OHP levels of non-smoking policemen were significantly greater than those of nonsmoking control subjects (p < 0.05). The overall mean +/- S.D. values for CA frequencies (%) from policemen, taxi drivers and control group were 1.29 +/- 1.59, 1.81 +/- 1.79, and 0.26 +/- 0.73, respectively. There was a significantly greater frequency of CAs in exposed groups relative to the matched control population (p < 0.05; p < 0.01). Age, sex and smoking habits have not influenced the cytogenetic end-point in this study. Our results demonstrate that occupational exposure to urban air pollutants leads to a significant induction of cytogenetic damage in peripheral lymphocytes of traffic policemen and taxi drivers.     

Polycyclic aromatic hydrocarbon (PAH) dispersion and deposition to vegetation and soil following a large scale chemical fire

Polycyclic aromatic hydrocarbons (PAHs) were determined in soil and vegetation following a large scale chemical fire involving 10,000 ton of polypropylene. In comparison with sites outside the plume from the fire, PAH concentrations were elevated in grass shoots (by up to 70-fold) and in soil (by up to 370-fold). The pattern of PAH dispersion under the plume was dependent on the physical-chemical properties of individual PAHs. The lighter, least hydrophobic PAHs were dispersed into the environment at greater distances than heavier, more hydrophobic PAHs. At the most distant sampling point (4.5 km) under the plume, the low molecular weight PAHs were still considerably elevated in vegetation samples compared to control sites. Dispersion appeared to be regulated by the compounds partitioning between the vapour and particulate phase, with dry particulate deposition occurring closer to the fire source than gaseous deposition. For all PAHs, the fire resulted in greater contamination of soils compared to grasses, with the relative ratio of plant/soil contamination decreasing as hydrophobicity increased.     

Atmospheric polycyclic aromatic hydrocarbons (PAHs) in Asia: a review from 1999 to 2004

Polycyclic aromatic hydrocarbons (PAHs) are present in both gaseous and particulate phases. These compounds are considered to be atmospheric contaminants and are human carcinogens. Many studies have monitored atmospheric particulate and gaseous phases of PAH in Asia over the past 5 years. This work compares and discusses different sample collection, pretreatment and analytical methods. The main PAH sources are traffic exhausts (AcPy, FL, Flu, PA, Pyr, CHR, BeP) and industrial emissions (BaP, BaA, PER, BeP, COR, CYC). PAH concentrations are highest in areas of traffic, followed by the urban sites, and lowest in rural sites. Meteorological conditions, such as temperature, wind speed and humidity, strongly affect PAH concentrations at all sampling sites. This work elucidates the characteristics, sources and distribution, and the healthy impacts of atmospheric PAH species in Asia.     

Risk Assessment of 26 Polycyclic Aromatic Hydrocarbon (PAH) Compounds in Parkıng Garages

The aim of this study was to determine the level of 26 polycyclic aromatic hydrocarbons (PAHs) at parking garages and to provide the necessary annual information based on occupational inhalation exposure and non-occupational inhalation exposure, which carry risks for the environment. For this purpose, 22 samples were collected continuously from both gas and particulates phase PAHs from two parking garages at Konya City Center, Turkey. The exposure-based risk of these samples was evaluated using concentrations of the carcinogenic PAH compounds. None of the 26 PAHs measured had values exceeding the recommended exposure limits (RELs) standard values for inhalation rate recommended by the World Health Organization (WHO). Exposure levels of gas and particulate PAHs for the occupational group and the public (children and adults who spend time in shopping centers) were found to be 0.07–28.24 μgm^?3 and 0.05–5.753 μgm^?3, respectively, representing levels two to four times higher than those at the control site. Maximum daily inhalation of B[a]Py was estimated at 1.33 ngd^?1 for exposure of the public and as 274 ngd^?1 for the occupational group. It is believed that traffic makes a substantial contribution to the PAH profile, which had relatively high concentrations of naphthalene (Napth) and coronene (Coro). Highly carcinogenic dibenzo(a,l)pyrene (B[al]Pyre) was found in the ambient air at two parking garages. Napth and phenanthrene (Phen) were the main compounds found in nearly all the tested samples. In this study, benzo[e]pyrene (B[e]Py) was used as a reference for PAHs because its concentration is stable and does not change seasonally. Considering the importance of these compounds in relation to human health, the aim of this work was to characterize and quantify the more toxic PAHs in parking garages. Conducting PAH sampling and their chemical analysis is very costly and labor intensive. This study produced data that can be a powerful tool for environmental forensics.     

Occurrence of gaseous and particulate polycyclic aromatic hydrocarbons in the urban atmosphere: study of sources and ambient temperature effect on the gas/particle concentration and distribution

The presence of polycyclic aromatic hydrocarbons (PAHs) in an urban region (Heraklion, Greece) and processes that govern their atmospheric fate were studied from November 2000 until February 2002. Sixteen samples were collected, by using an artifact-free sampling device, on a monthly basis and the concentration of PAHs in gas and particulate phase was determined. The most abundant members (gas + particles) were phenanthrene (20.0+/-7.0 ng m(-3)), fluoranthene (6.5+/-1.7 ng m(-3)), pyrene (6.6+/-2.4 ng m(-3)), and chrysene (3.1+/-1.5 ng m(-3)). Total concentration (gas+particulate) of PAH ranged from 44.3 to 129.2 ng m(-3), with a mean concentration of 79.3 ng m(-3). Total concentration of PAHs in gas phase ranged from 31.4 to 84.7 ng m(-3) with non-observable seasonal variation. Conversely, maximum PAH concentrations in the particulate phase occurred during winter months. Particulate concentration varied from 11.4 to 44.9 ng m(-3), with an average of 25.2 ng m(-3). PAH distribution between gas and particulate phase was in agreement with the sub-cooled vapor pressure. Shift in gas/particle distribution due to difference in ambient temperature elucidated to some extent the seasonal variation of the concentration of PAHs in particles.     

Seasonal variation of polycyclic aromatic hydrocarbons (PAHs) in Pearl River Delta region,China

A level IV fugacity model was applied to simulate the seasonal variation of polycyclic aromatic hydrocarbons (PAHs) in various bulk media in Pearl River Delta (PRD), China. The predictions were validated against monthly observed concentrations of gaseous and particulate phase PAHs in air and annual mean concentrations of all other bulk media. The uncertainty of the predictions was evaluated using Monte Carlo simulation. The influential parameters were identified using sensitivity analysis on both media concentrations and seasonal variations. The predicted concentrations and the patterns of seasonal variation generally agreed with the field observations. Concentrations of gaseous phase PAHs in air increased in the summer and decreased in the winter while concentrations of particulate phase PAHs in summer were lower than those in the winter. The relative variations of PAHs in the other bulk media were not as profound as those in air and the variation patterns were chemical compound dependent. Temperature and precipitation were the most important parameters leading to the seasonalities of PAH concentrations. Other key parameters included dry precipitation rate, advective water flow from upstream, and solid fractions in air and water.     

Effects of open burning of rice straw on concentrations of atmospheric polycyclic aromatic hydrocarbons in central Taiwan

The sizes and concentrations of 21 atmospheric polycyclic aromatic hydrocarbons (PAHs) were measured at Jhu-Shan (a rural site) and Sin-Gang (a town site) in central Taiwan in October and December 2005. Air samples were collected using semi-volatile sampling trains (PS-1 sampler) over 16 days for rice-straw burning and nonburning periods. These samples were then analyzed using a gas chromatograph with a flame-ionization detector (GC/FID). Particle-size distributions in the particulate phase show a bimode, peaking at 0.32-0.56 microm and 3.2-5.6 microm at the two sites during the nonburning period. During the burning period, peaks also appeared at 0.32-0.56 microm and 3.2-5.6 microm at Jhu-Shan, with the accumulation mode (particle size between 0.1 and 3.2 microm) accounting for approximately 74.1% of total particle mass. The peaks at 0.18-0.32 microm and 1.8-3.2 microm at Shin-Gang had an accumulation mode accounting for approximately 70.1% of total particle mass. The mass median diameter (MMD) of 3.99-4.35 microm in the particulate phase suggested that rice-straw burning generated increased numbers of coarse particles. The concentrations of total PAHs (sum of 21 gases + particles) at the Jhu-Shan site (Sin-Gang site) were 522.9 +/- 111.4 ng/ml (572.0 +/- 91.0 ng/ml) and 330.1 +/- 17.0 ng/ml (or 427.5 +/- 108.0 ng/ml) during burning and nonburning periods, respectively, accounting for a roughly 58% (or 34%) increase in the concentrations of total PAHs due to rice-straw burning. On average, low-weight PAHs (about 87.0%) represent the largest proportion of total PAHs, followed by medium-weight PAHs (7.1%), and high-weight PAHs (5.9%). Combustion-related PAHs during burning periods were 1.54-2.57 times higher than those during nonburning periods. The results of principal component analysis (PCA)/absolute principal component scores (APCS) suggest that the primary pollution sources at the two sites are similar and include vehicle exhaust, coal/wood combustion, incense burning, and incineration emissions. Open burning of rice straw was estimated to contribute approximately 5.0-33.5% to the total atmospheric PAHs at the two sites.     

蜂窝煤燃烧烟气中多环芳烃的定量研究及粒径分布特征

通过对蜂窝煤燃烧排放的烟气中多环芳烃的定量分析,研究了17种多环芳烃在烟气颗粒相和气相中的分配以及在不同粒径颗粒物上的分布特征。结果表明：在室温下燃煤排放的多环芳烃总量以在气相中存在为主,但总体毒性则主要存在于颗粒相中;多环芳烃主要分布在亚微米级颗粒上,分子量越大的多环芳烃越趋于富集在细颗粒上,因而对健康的危害就越大。     

Polycyclic aromatic hydrocarbons in leaf cuticles and inner tissues of six species of trees in urban Beijing

Leaf samples of six tree species were collected along urban roadsides and a campus site in Beijing for measurement of polycyclic aromatic hydrocarbons (PAHs). PAHs in leaves were attributed to two fractions, leaf cuticles and inner leaf tissues, using sequential extraction. Total concentrations of 16 PAHs in the cuticles and the inner tissues were 69.3+/-64.6 microg g(-1) (d.w.) and 1.07+/-0.2 microg g(-1) (d.w.) at roadside and 57.5+/-52.6 microg g(-1) and 0.716+/-0.2 microg g(-1) on campus, respectively. The lipid-normalized inner tissue PAHs varied from 5.8 microg g(-1) to 15.0 microg g(-1). Similarities in PAH spectra between leaf cuticles and airborne particles and between the inner tissues and gaseous phase imply that airborne particulates and gaseous PAHs are likely the sources of PAHs for cuticles and the inner tissues, respectively. Difficulty in migration of heavier PAHs into inner tissues could be another reason.     

Estimation of PAHs dry deposition and BaP toxic equivalency factors (TEFs) study at Urban, Industry Park and rural sampling sites in central Taiwan, Taichung

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in gas phase and particle bound were measured simultaneously at industrial (INDUSTRY), urban (URBAN), and rural areas (RURAL) in Taichung, Taiwan. And the PAH concentrations, size distributions, estimated PAHs dry deposition fluxes and health risk study of PAHs in the ambient air of central Taiwan were discussed in this study. Total PAH concentrations at INDUSTRY, URBAN, and RURAL sampling sites were found to be 1650 +/- 1240, 1220 +/- 520, and 831 +/- 427 ng/m3, respectively. The results indicated that PAH concentrations were higher at INDUSTRY and URBAN sampling sites than the RURAL sampling sites because of the more industrial processes, traffic exhausts and human activities. The estimation dry deposition and size distribution of PAHs were also studied. The results indicated that the estimated dry deposition fluxes of total PAHs were 58.5, 48.8, and 38.6 microg/m2/day at INDUSTRY, URBAN, and RURAL, respectively. The BaP equivalency results indicated that the health risk of gas phase PAHs were higher than the particle phase at three sampling sites of central Taiwan. However, compared with the BaP equivalency results to other studies conducted in factory, this study indicated the health risk of PAHs was acceptable in the ambient air of central Taiwan.     

Uptake of PAHs by cabbage root and leaf in vegetable plots near a large coking manufacturer and associations with PAHs in cabbage core

Samples of ambient air (including gaseous and particulate phases), dust fall, surface soil, rhizosphere soil, core (edible part), outer leaf, and root of cabbage from eight vegetable plots near a large coking manufacturer were collected during the harvest period. Concentrations, compositions, and distributions of parent PAHs in different samples were determined. Our results indicated that most of the parent PAHs in air occurred in the gaseous phase, dominated by low molecular weight (LMW) species with two to three rings. Specific isomeric ratios and principal component analysis were employed to preliminarily identify the local sources of parent PAHs emitted. The main emission sources of parent PAHs could be apportioned as a mixture of coal combustion, coking production, and traffic tailing gas. PAH components with two to four rings were prevailing in dust fall, surface soil, and rhizosphere soil. Concentrations of PAHs in surface soil exhibited a significant positive correlation with topsoil TOC fractions. Compositional profiles in outer leaf and core of cabbage, dominated by LMW species, were similar to those in the local air. Overall, the order of parent PAH concentration in cabbage was outer leaf > root > core. Partial correlation analysis and multivariate linear stepwise regression revealed that PAH concentrations in cabbage core were closely associated with PAHs present both in root and in outer leaf, namely, affected by adsorption, then absorption, and translocation of PAHs from rhizosphere soil and ambient air, respectively.     

Characterizations of particle-bound trace metals and polycyclic aromatic hydrocarbons (PAHs) within Tibetan tents of south Tibetan Plateau, China

INTRODUCTION: Exposure to trace metals and polycyclic aromatic hydrocarbons (PAHs) adsorbed on particulates is of a serious health concern. Levels of some trace metals in total suspended particulate and 13 PAHs of fine particulate matter were measured from nomadic tents in the southern Tibetan Plateau in summer 2010. RESULTS AND DISCUSSION: The indoor air within the tents was seriously polluted, mainly due to yak dung combustion. Average trace metal concentrations were much higher (range of indoor/outdoor ratio 61-291) than those of the outdoor air. Additionally, enrichment factors of most trace metals of indoor air were similar to those of outdoor air, indicating outdoor air quality of the studied area was possibly influenced by pollutants emitted from local tents. Mean concentrations of total PAHs and BaP within tents was 5372.45 and 364.79 ng/m(3), hundred times higher than that of outdoor air of the Tibetan Plateau. Three- and four-ring PAHs were the predominant components. The diagnostic ratio of BaA/(BaA + Chr) was 0.33. Since Tibetan women typically spend longer time within the tents, they were exposed to PAHs (BaP exposure = 1.81 μg/m(3)) about two times of other family members. Among all the PAHs, Bap contributed the most (82.6%) of the total carcinogenicity. Similarly, the excess lifetime cancer risk for women and other family members were 2.75 × 10(-4) and 1.27 × 10(-4), respectively, indicating Tibetan herdsmen, especially women who are in charge of most house chores were at risk for adverse health effects.     

Polycyclic aromatic hydrocarbons in rainwater and surface waters of Lake Maggiore, a subalpine lake in Northern Italy

Fourteen polycyclic aromatic hydrocarbons (PAHs) were measured in surface waters and precipitation inputs to Lake Maggiore, a subalpine lake in Northern Italy, from July 2003 to January 2004. Particulate and dissolved phases in surface water and rain samples were determined. Analyses of PAHs were performed using XAD-2 resin to isolate the dissolved PAHs and subsequent extraction by accelerated solvent extraction (ASE). Both the dissolved and particulate phase PAH patterns in surface water and rainwater samples were dominated by the low molecular weight compounds (e.g., phenanthrene, fluoranthene and pyrene). More than 85% of PAHs in surface waters and 72% of PAHs in rainwater were associated to the dissolved phase. The SigmaPAH concentrations in surface waters (particulate and dissolved phases) were 0.584 +/- 0.033 ng l(-1), 2.9 +/- 0.312 ng l(-1) and in rainwater (particulate and dissolved phases) 27.5 +/- 2 ng l(-1), 75.4 +/- 9 ng l(-1), respectively. Temporal variability of PAH concentrations in rain and surface water samples were observed, with higher concentrations in November and December, coinciding with the largest precipitation amounts. The comparison of PAH signatures in rainwater and surface waters seems to indicate that wet deposition (2.5-41 microg m(-2) month(-1)) is the main source of PAH contamination into surface waters of Lake Maggiore.     

Levels of polycyclic aromatic hydrocarbons in Canadian mountain air and soil are controlled by proximity to roads

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in soil and XAD-based passive air samples taken from a total of 22 sites along three transects (Revelstoke, Yoho, and Observation, 6-8 sites for each transect) in the mountains of Western Canada in 2003-2004. Median concentrations in air (4-ring PAHs: 33 pg/m³) were very low and comparable to those in global background regions such as the Arctic. Low median soil concentrations (16 EPA PAHs: 16 ng/g dry weight) and compositional profiles dominated by naphthalene and phenanthrene are similar to those of tropical soils, indicative of remote regions influenced mostly by PAHs from traffic and small settlements. Comparing levels and composition of PAHs in soils between and along transects indeed suggests a clear relationship with proximity to local sources. Sampling sites that are closer to major traffic arteries and local settlements have higher soil concentrations and a higher relative abundance of heavier PAHs than truly remote sites at higher elevations. This remains the case when the variability in soil organic carbon content between sites is taken into account. Both air/soil concentration ratios and fugacity fractions suggest atmospheric net deposition of four-ring PAHs to soils.