Polycyclic aromatic hydrocarbons in atmospheric particulate depositions and urban soils of Moscow,Russia

Purpose

The study was conducted to quantify the polycyclic aromatic hydrocarbons (PAHs) accumulation in urban soils from different functional areas via atmospheric inputs with particulate matter.

Materials and methods

PAH concentration and pattern were measured in the particulate matter of snow depositions, in the upper layers of artificial soils from densely built-up areas and in the undisturbed natural soils (Umbric Retisols) from green park area. Samples were collected in 2011–2013 at 58 sites with different traffic activities located at the territory of the Eastern Administrative Okrug of Moscow. The soil samples and filters with particulate matter were extracted by pressurized liquid extraction using Dionex ASE200. Clean-up analyses were performed on SPE cartridges filled with silica gel. Concentrations of PAHs were determined by high-performance liquid chromatography using an Agilent 1100 System equipped with fluorescent detector.

Results and discussion

Mean values of PAH input with snow particles were 45–57 μg/m² for recreational and residential zones, and 140–264 μg/m² for traffic zones. The samples of depositions from different functional areas showed a similar PAH pattern and consisted primarily of 3–4-ring PAHs. Total PAH concentrations in upper layers of artificial soils showed similar mean values of 1.43–2.21 μg/g for all functional zones. The PAH content in soils from the park area was twofold lower than that from the built-up area (0.34–0.63 μg/g), despite equal levels of atmosphere contamination on these territories. The upper layers of natural soils from recreational and traffic zones showed slight differences in PAH content, though PAH input with snow was fivefold higher in the traffic zone. Compared with airborne depositions, soils contained significant amounts of 5–6-ring PAHs.

Conclusions

A high level of soil PAH contamination in urban areas of Moscow, several orders of magnitude higher than the current PAH input to them from the atmosphere, indicates a lack of direct connection of the PAH pool in soils with this source. The high PAH content in the upper layer of constructed soils can be the result of repeated use of materials subjected to a constant technogenic impact for the production of artificial soils.

     

Annual and Growing Season Temperature Changes in the San Luis Valley, Colorado

Pine needles were selected as cost-effective and easy collectable matrices suitable for long-term monitoring of the lower troposphere pollution with polycyclic aromatic hydrocarbons (PAHs). Overall, 27 sampling sites around the island of Crete were selected, and upon availability, second- and third-year needles from two pine species (Pinus brutia Ten. and Pinus pinea L.) were collected. In general, the results for both pine species showed that sites belonging in the urban group yielded the highest contamination levels when compared to the rural and the remote ones and that third-year needles had higher PAH contamination than the second-year ones. Phenanthrene was the prevailing PAH, representing 39% and 46% of the total contamination for second- and third-year needles, respectively. Fluoranthene, pyrene, chrysene and fluorene followed, with individual concentrations between 6% and 12%. The dominance of three-ringed PAHs was evidenced for the vast majority of the sites. An urban, rural and remote fingerprint was determined over a more general uniform contamination pattern, and the diagnostic PAH ratios pointed towards mixed petrogenic and pyrogenic sources. Overall, the present findings showed that the presence of PAHs is not negligible throughout the Cretan atmosphere and can be even considered quite high in some areas, especially when comparing the results to the ones found for more densely populated or industry-related areas.     

Air pollution patterns in two cities of Colombia,S. A. According to trace substances content of an epiphyte (Tillandsia recurvata L.)

The air pollution of two major Colombian cities (Medellin and Cali) has been examined by means of 66 samples of the epiphyte Tillandsia recurvata L., which acts as a biofilter. After performing heavy metals (Zn, Pb, Cd, Cu, Ni, Cr), pesticides (BHCs, HCB, dieldrine, endrine, DDTs), PCBs, and polycyclic aromatic hydrocarbons (PAH: FA, BaP, IcdP, BghiP) analyses, the results proved the utility of this inconspicuous plant to determine the airborne contamination of both inorganic and organic trace substances. Using principal component analysis, 10 classes of independent pollution sources could be discriminated for both regions: (1) Zn and the PAH, (2) BHCs, endrine and DDTs, (3) Ni and Cr, and (4) to (10) the other contaminants, which resulted to be more or less independent from each other. By means of cluster analysis, 6 to 8 pollutional groups were clustered for heavy metals, pesticides, and PAH separately. The topographic and industrial features of the Cali and Medellin areas are discussed in relation to the regional means of heavy metals, pesticides, and PAH content. While Cali is distinctive of high levels of Pb, Cu, BaP, and pesticides, Medellin is more severely polluted by Zn, Cd, Ni, Cr, FA, and IcdP. In comparison to the southern U.S. and Central Europe, both conglomeration areas appear to be heavily polluted by Zn, Cu, Ni, Cr, and DDTs.     

Creosote Contamination in Sediments of the Grey Owl Marina in Prince Albert National Park, Saskatchewan, Canada

The rate at which creosote-treated pilings release polycyclic aromatic hydrocarbons (PAHs) into the environment should diminish with structure age and weathering, and so, it may be assumed that PAH concentrations in the vicinity of old structures (>30 years) may approach background levels. However, this may not be true in cold environments where PAH release and degradation rates are slow and where pilings continue to experience significant physical damage. Moreover, PAHs will remain high in the vicinity of pilings if current and wave action is insufficient to disperse and dilute PAHs over a wider area and/or where PAHs do not become diluted and buried by uncontaminated sediments. This is demonstrated in our investigation of the sediments of the Grey Owl Marina, located in Prince Albert National Park, in central Saskatchewan, Canada. The marina, constructed in the early 1960s, consists of six piers and is protected from strong wave action by a breakwater. PAH concentrations were high in sediments collected under the piers and inside the boat slips, exceeding probable effect levels for several compounds. Various lines of physical and chemical evidence pointed to creosote as being the primary PAH source with a mixture of relatively undegraded and weathered PAHs being present. PAH concentrations decreased rapidly 2 m and further away from the pilings as a result of dilution with increasing dispersal over a broadening area. There was evidence of benthic community impairment, with total abundances negatively correlated with PAH concentrations. According to the Methods for Ranking Contaminated Aquatic Sites on Canadian Federal Properties, areas with the highest hazard scores were under the piers and inside the boat slips, while areas with the lowest hazard scores were >10 m from the pilings. Therefore, remedial actions based on piling and contaminated sediment removal may need to be conducted over only a small area, i.e., within 2 m of the pilings.     

Input and behavior of polycyclic aromatic hydrocarbons in arable,fallow, and forest soils of the taiga zone (Tver oblast)

Contents of 11 most prevalent polycyclic aromatic hydrocarbons (PAHs) in snow and soils of arable, fallow, and forest areas significantly remote from impact technogenic sources of polyarenes have been examined in the Torzhok district of Tver oblast. From the analysis of snow samples, the volumes and composition of PAHs coming from the atmosphere onto the areas of different land use have been determined. Light hydrocarbons prevail in PAHs. They make up 65–70% of total PAHs; their share in soils reaches almost 95%. An increase in the content of PAHs is revealed in fallow soils compared to arable and afforested areas. A direct relationship is revealed between the lateral distribution of total PAHs and the content of organic carbon. The distribution of total PAHs is surface-accumulative in forest soils, mainly uniform in arable soils, and deepaccumulative in fallow soils. PAH groups characterized by similar radial distributions and ratios between their reserves in snow and soils are distinguished: (1) fluorene and phenanthrene, (2) biphenyl and naphthalene, (3) benzo(a)anthracene, chrysene, perylene, and benzo[a]pyrene, and (4) anthracene and benzo[ghi]pyrene.     

Deposition of polycyclic aromatic hydrocarbons (PAH) in the surroundings of primary aluminium industry

Polycyclic aromatic hydrocarbons (PAH) have been detemined in dust fallout at 4 sites in the neighborhood of primary Al plants over periods of 12 to 14 mo. The amounts of PAH deposited in these areas were large compared to other reported data. Variations were observed and the amounts were correlated with the frequencies of the wind direction from the factories to the sampling stations. Inversion episodes also seemed to cause an increase of the PAH depositions. Different PAH compositions were observed in samples exposed to pollutants from the al plants and in samples collected in an area where an anode plant was the main source.     

Gehalte an Polycyclischen Aromatischen Kohlenwasserstoffen (PAK) und deren Verteilungsmuster in unterschiedlich belasteten Böden

Contents of polycyclic aromatic hydrocarbons (PAH) and their distribution pattern in soils with different contamination levels In order to study the PAH-contamination of soils in North Rhine Westfalia, soil samples were taken at different sites and analysed for six PAH. The sites were selected with regard to different forms of land use such as arable land and pastures in rural areas and gardens in urban areas and with regard to varying immission situations. The results are valued according to reference (RW) and test values (PW) of the Netherlands Guidelines for soil restoration. The reference values of these guidelines characterizing normal contents are regularly and in part distinctly exceeded for fluoranthene and benzo(a)pyrene at some sites (coking plant, alluvial meadow soils, allotment gardens, close to a highway). The check values which imply more exact investigations are only exceeded at the most contaminated site, a coking plant. The PAH patterns at the different sites investigated depend on the number and kind of PAH sources. PAH typical for motor vehicle emission (benzo(b)fluoranthene, benzo(g,h,i)perylene) are dominating in soils close to a highway, whereas at the cokery site fluoranthene can be found in higher concentrations than the other PAH. In alluvial river soils and in soils of allotment gardens the pattern is more uniform because of diffuse sources with decreasing contents in the order fluoranthene > benzo(a)anthracene > benzo(b) fluoranthene > benzo(g,h,i)perylene > benzo(a)pyrene > benzo(k)fluoranthene. As a guide substance for a first risk assessment benzo(a)pyrene is suitable, since its content shows a strong correlation to the sum of five other PAH. In order to characterize the background contamination of soils with PAH new reference values are proposed.     

Human health risk due to consumption of vegetables contaminated with carcinogenic polycyclic aromatic hydrocarbons

Purpose  

Polycyclic aromatic hydrocarbons (PAH) are persistent, toxic, and carcinogenic contaminants present in soil ecosystem globally. These pollutants are gradually accumulating in wastewater-irrigated soils and lead to the contamination of vegetables. Food chain contamination with PAH is considered as one of the major pathways for human exposure. This study was aimed to investigate the concentrations of PAH in soils and vegetables collected from wastewater-irrigated fields from metropolitan areas of Beijing, China. Origin of PAH, daily intake, and health risks of PAH through consumption of contaminated vegetables were studied.     

Long-Range Atmospheric Transport and Local Pollution Sources on PAH Concentrations in a South European Urban Area. Fulfilling of the European Directive

A 12 months study on urban atmospheric concentrations of polycyclic aromatic hydrocarbons (PAH) contained in the particulate matter with an aerodynamic diameter less than or equal to 10 microns (PM10) was carried out in Zaragoza (Spain) from July 12th, 2001 to July 26th, 2002 by using a high-volume air sampler able to collect the PAH supported on a Teflon-coated fibre glass filter. Samples were analysed by using Gas Chromatography Mass Spectrometry (GC-MS/MS). PAH of high molecular weight, indeno[1,2,3-cd]pyrene (IcdP), benzo[g,h,i]perylene (BghiP) and coronene (Co) were the most abundant compounds. The concentrations of benz[a]pyrene equivalent carcinogenic power (BaP-eq) showed a mean value of 0.7 ng/m³ with 22.5% of the samples exceeding the 1.0 ng/m³ guide value established by the European Directive. These episodes were mainly produced during cold season. Regarding meteorological variables, a positive effect of the prevalent wind “cierzo” (NW direction) over the Zaragoza city was confirmed from the environmental point of view. The NE, E and S directions, corresponding to highway and industrial areas were the directions showing the high PAH atmospheric concentrations. Despite the proximity of a high-level traffic highway, stationary sources related to industry were the dominant source of PAH in the sampled area. Vehicular emissions and natural gas home heating also contributed to PAH concentrations. The predominance of local pollution sources versus long-range transport on PAH concentrations was shown. However, the contribution of long-range transport of anthropogenic origin from other European areas was reflected for specific dates on PAH concentrations and PM10 levels.     

Aging of combustion particles in the atmosphere — Results from a field study in Zürich

At different locations in Zürich (urban and suburban area) ambient aerosol has been measured by a variety of methods. Total mass concentration, black carbon mass concentration, size distribution, Fuchs surface and photoelectric charging of particles (as a measure for the PAH concentration) have been determined. As a reference for “fresh” aerosol, measurements have also been carried out in a car parking garage. By comparing the data obtained at different locations and different times of the day aging processes can be investigated. All measured signals show significant peaks during the rush-hours, indicating that the majority of the particles arise from automotive traffic. Aging is expressed by decreasing number concentrations, increasing diameter (coagulation) and decreasing black carbon and PAH content of the particles. The decrease in PAH and black carbon fraction may be due to mixing of the aerosol with non-combustion particles or by condensation of material from the gas phase on the particle; the decrease in PAH concentration may also be due to degradation of the PAHs.     

Isolation and Determination of Polycyclic Aromatic Hydrocarbons in Surface Runoff and Sediments

The distribution of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated in surface runoff and sediments of Lagos, Osogbo and Ile-Ife Western areas of Nigeria. Method for the analysis of PAHs was based on Liquid-Liquid extraction of the runoff and a soxhlet extraction of the sediments followed by a clean up adsorption procedure. The PAHs were separated and quantified by Gas Chromatography-Mass spectrometry (GC-MS) technique. A blank experiment was done using triply distilled water and following the same procedure for the samples to establish blank levels. In both street runoff and sediments 13 PAHs were identified and quantified. At Osogbo and Ile-Ife areas, the mean levels of PAHs in surface runoff ranged between 0.10–15.81 mg L^-1 while in the Lagos area the levels were between 0.1–73.72 mg L^-1. Generally, the PAH levels in surface runoff of Lagos constitute 53.03 mg L^-1 average ∑ PAH detected in the study area compared to 31.96 mg L^-1 average ∑ PAH contribution made by samples from Osogbo and Ile-Ife. The levels of PAHs in sediments are relatively higher compared to those of the street runoff in the study area. PAHs in sediment of Lagos contribute an average of 228.57 mg kg^-1 ∑ PAH to the total sediment PAH burden compared to Osogbo and Ile-Ife areas that contribute only 91.13 mg kg^-1 average ∑ PAH to the total PAH burden of the study area. The relatively higher average ∑ PAHs reported for Lagos area compared with those of Osogbo and Ile-Ife, is consistent with higher industrial activities and traffic density of the former (1000–10000 vehicles/hr) than the later (450–1500 vehicles/hr).     

中国南亚热带农业土壤中的多环芳烃

The contributions of persistent organic pollutants （POPs） from the subtropical regions of China to pollution of the global environment have been paid great attention; however, little is known about the state of POPs in agricultural ecosystems within these regions of China. This study primarily revealed the state of the contamination and distribution of polycyclic aromatic hydrocarbons （PAH） in agricultural soils in the subtropical regions. 115 surface soils （0-20 cm） were sampled in the breadbaskets of these regions. The concentrations and types of PAH were determined using gas chromatography linked to mass spectrometry （GC-MS）. The total PAH concentrations ranged from 22.1 to 1 256.9 ng g^-1 with a mean of 318.2 ± 148.2 ng g^-1. In general terms, the current PAH concentrations were lower than most PAH levels reported in a number of investigations from different countries and regions. PAH isomer ratios indicated that pyrolytic origins, such as fossil fuel combustion related to vehicle tail gas and industrial emissions, were the dominant sources of PAH in the southern subtropical areas of China. Although PAH concentrations decreased with decreasing pollution, population, and traffic density, to a great extent PAH compositions were similar throughout subtropical soils, with naphthalene, phenanthrene, fluoranthene, and benzo（b）fluoranthene being dominant.     

Determination of pah in soil samples by high-performance thin-layer chromatography (HPTLC)

A thin-layer Chromatographic screening-method is presented for the determination of polycyclic aromatic hydrocarbons (PAH) in soil samples. This screening method is intended for a quick overview of the composition of a contaminant. The developed method of separation is well suited for the semi-quantitative determination of PAH in soil samples, and can be used to identify samples that require further analysis by means of GC or HPLC. The separation of 8 PAH groups with a maximum of 2 PAH (discernible by selective excitation of fluorescence) each is possible. The results of the analysis based on PAH group separation can be regarded as semi-quantitative. The extraction of PAH is effected by means of a solvent mixture consisting of n-hexane-acetone (1:1, v/v). The extraction is aided by ultrasonic treatment. The extract is purified by application to an activated silica gel column (solid-phase extraction). The qualitative analysis can be carried out either by visual observation or by fluorimetric scanning (TLC-Scanner). The characteristic fluorescent colours facilitate a reliable visual identification of PAH. The applicability of the method is shown and a comparison to other analytical methods is carried out. Some of the remarkable features of this method are its user-friendly handling, the low consumption of solvents and the applicability without the necessity for extra equipment.     

城市土壤多环芳烃的特征和来源解析研究进展

Polycyclic aromatic hydrocarbons (PAHs) are mainly produced by combustion processes and consist of a number of toxic compounds.They are always emitted as a mixture and have become a major type of pollutants in urban areas.The degree of soil contamination by PAHs is of special concern in areas immediately in proximity to cities with heavy traffic,factories,older buildings,and infrastructure.The accumulation of soil PAHs is also affected by non-anthropogenic factors,such as climate,vegetation,and soil property.This paper reviews three typical source identification techniques,including diagnostic ratios,positive matrix factorization,and principle conrponents analysis.The advantages or disadvantages of these techniques are analyzed.It is recommended that multiple identification techniques be used to determine the sources in order to minimize the weaknesses inherent in each method and thereby to strengthen the conclusions for PAH source identification.     

Spatial Distribution and Temporal Trends of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments from Lake Maryut, Alexandria, Egypt

Surface and core sediments from Lake Maryut, Egypt, one of the most polluted lakes in Egypt, were analyzed for polycyclic aromatic hydrocarbons (PAHs) using gas chromatography?Cmass spectrometry. This investigation represents the first extensive study of the distribution and sources of PAHs in sediments from Lake Maryut. The total PAHs concentrations (sum of 39 PAH compounds) in surface sediments varied greatly depending on the sampling location and ranged from 106 to 57,800 ng/g dry weight with a mean concentration of 6,950 ng/g. The most polluted areas are distributed in areas which are mainly influenced by municipal sewage and industrial effluent discharges, suggesting a direct influence of these sources on the pollutant distribution patterns. PAH concentrations were one to two orders of magnitude higher in comparison with those reported for riverine/estuaries systems around the world. Molecular indices, such as pyrogenic index (PI), methylphenanthrenes to phenanthrene ratio, HMW_PAH/LMW_PAH, A-PAHs/P-PAHs, FL/FL?+?PY, BaP/BaP?+?C, IP/IP?+?BgP, and Per/??(penta-aromatics) were calculated to evaluate different hydrocarbon origins and their relative importance. In general, sediments from the main basin and northwest basin of Lake Maryut showed the highest PAH concentrations with petrogenic signatures, indicating major sources of petrogenic PAHs in the city. On the other hand, lower levels of PAHs with a pyrogenic signature were widely recorded in areas that are distant from anthropogenic sources. At other locations, both petrogenic and pyrogenic inputs were significant. The concentrations of perylene relative to the penta-aromatic isomers are dominant especially in locations associated with terrestrial inputs and in the deepest core sediments, indicating diagenetic origin for the presence of perylene. Temporal trends of PAH concentrations in both cores sediments were influenced by input pathways and followed the economic development and the environmental policies of the Egyptian Government in the last 15 years. Finally, PAH levels in sediments were compared with Sediments Quality Guidelines (effects range median?Ceffects range low) for evaluation probable toxic effects on organism. Results suggest an ecotoxicological risk for benthic organisms mainly in the main basin area, where high concentrations of PAHs were found in sediments influenced by anthropogenic activities.     

Atmospheric Dispersion of Current-Use Pesticides: A Review of the Evidence from Monitoring Studies

Recently, evidence has accumulated that the extensive use of modern pesticides results in their presence in the atmosphere at many places throughout the world. In Europe over 80 current-use pesticides have been detected in rain and 30 in air. Similar observations have been made in North America. The compounds most often looked for and detected are the organochlorine insecticide lindane and triazine herbicides, especially atrazine. However, acetanilide and phenoxyacid herbicides, as well as organophosphorus insecticides have also frequently been found in rain and air. Concentrations in air normally range from a few pg/m³ to many ng/m³. Concentrations in rain generally range from a few ng/L to several µg/L. In fog even higher concentrations are observed. Deposition varies between a few mg/ha/y and more than 1 g/ha/y per compound. However, these estimates are usually based on the collection and analysis of (bulk) precipitation and do not include dry particle deposition and gas exchange. Nevertheless, model calculations, analysis of plant tissue, and first attempts to measure dry deposition in a more representative way, all indicate that total atmospheric deposition probably does not normally exceed a few g/ha/y. So far, little attention has been paid to the presence of transformation products of modern pesticides in the atmosphere, with the exception of those of triazine herbicides, which have been looked for and found frequently. Generally, current-use pesticides are only detected at elevated concentrations in air and rain during the application season. The less volatile and more persistent ones, such as lindane, but to some extent also triazines, are present in the atmosphere in low concentrations throughout the year. In agricultural areas, the presence of modern pesticides in the atmosphere can be explained by the crops grown and pesticides used on them. They are also found in the air and rain in areas where they are not used, sometimes even in remote places, just like their organochlorine predecessors. Concentrations and levels are generally much lower there. These data suggest that current-use pesticides can be transported through the atmosphere over distances of tens to hundreds, and sometimes even more than a thousand kilometres. The relative importance of these atmospheric inputs varies greatly. For mountainous areas and remote lakes and seas, the atmosphere may constitute the sole route of contamination by pesticides. In coastal waters, on the other hand, riverine inputs may prevail. To date, little is known about the ecological significance of these aerial inputs.     

Identifying sources of polycyclic aromatic hydrocarbons (PAHs) in soils: distinguishing point and non-point sources using an extended PAH spectrum and <Emphasis Type="Italic">n</Emphasis>-alkanes

Background, aim, and scope  Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. They are formed during pyrogenic and diagenetic processes and are components of petrogenic materials such as oils and coals. To identify PAH sources, several studies have employed forensic methods, which may be costly to execute. Although a large number of possible forensic methods are available (e.g., total ion chromatograms, PAH ratios, PAH alkyl homologue series, isoalkanes and isoprenoids, steranes and terpanes, stable isotope ratios, n-alkanes), one has to decide which method is the appropriate cost effective screening approach. In this study, three approaches were tested and compared by measuring (1) an extended PAH spectrum (i.e., 45 instead of the common 16 EPA-PAHs), (2) PAH ratios and (3) n-alkanes to determine if point sources are distinguishable from non-point sources, and if an individual source can be distinguished from a multiple source contaminated site in the study area. In addition, the study evaluated whether these methods are sufficient for source identification of selected samples, and if they constitute a sound strategy for source identification prior to the selection of more cost intensive methods. Materials and methods  Eighteen samples with previously characterized PAH point sources (previously characterized point sources in the Mosel and Saar region) were analyzed. Additionally, three river bank soils of Mosel and Saar rivers with known non-point PAH sources were investigated. The point sources were two gasworks, a tar impregnation facility, a creosoted timber, an acid tar, a tank farm, and a diesel contaminated site. Non-point sources were hard coal particles and atmospheric inputs in river bank soils. All samples were extracted with hexane and acetone, analyzed with a gas chromatograph coupled to a mass spectrometer for PAH distribution patterns and ratios. n-Alkanes were measured by a gas chromatograph equipped with a flame ionization detector. Results  Samples collected from point sources and non-point sources were analyzed by the use of three forensic methods, i.e., PAH patterns of an extended PAH spectrum, PAH ratios and n-alkanes. Identification by PAH patterns alone was insufficient for the non-point sources and some point sources, since the n-alkanes must be measured, as well. The use of PAH ratios with only 16 EPA-PAHs is less indicative in determining multiple sources because source assignments (or categories) change depending on the ratio used. Discussion  This study showed that by employing an extended PAH spectrum it is possible to fingerprint and distinguish sources. The use of alkylated PAHs is essential for identifying petrogenic sources. It is insufficient to rely exclusively on either the common 16 EPA-PAHs or the ratios to the parent PAHs when identifying non-point sources. Source identification using PAH ratios is only reliable if both parent and alkylated PAHs are measured. n-Alkane analyses provide more detailed information about petrogenic sources by verifying the presence of oils, diesel, gasoline, or coal in non-point sources. Conclusions  The three methods tested were deemed sufficient to distinguish between point and non-point PAH sources in the samples investigated. The use of an extended PAH spectrum provides the first step toward identifying possible sources. It simplifies the decision whether additional forensic methods should be necessary for more detailed source identification. Recommendations and perspectives  The determination of PAH alkyl homologue series, biomarkers, and isotopes is often advised (Kaplan et al., Environ Forensics 2:231–248, 2001; Oros and Simoneit, Fuel 79:515–536, 2000; Wang and Fingas, Mar Pollut Bull 47:423–452, 2003). The methods involved are complex and often expensive. We recommend a relatively uncomplicated and cost-effective method (i.e., extended PAH spectrum) before further and more expensive forensic investigations are to be conducted. Additional research with an extended sample set should be carried out to validate these findings for other sources and sites. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Processes and lands for sequestering carbon in the tropical forest landscape

Balancing the C budget in the tropics has been hindered by the assumption that those forests not undergoing deforestation are in C steady state with respect to their C pools and thus with the atmosphere. The long history of human activity in tropical forests suggests otherwise. In this paper we discuss the forest compartments into which C can be stored, what the likely rates of storage are and for how long, and over which areas of the tropical landscape these processes occur. Results of our analysis suggest that tropical forests have the potential to sequester up to 2.5 Pg C yr^?1 from the atmosphere if human pressure could be completely removed. Addition of agroecosystems and degraded lands could increase this estimate markedly.     

Organic geochemical parameters for estimation of petrogenic inputs in the coastal area of Kavala City,Greece

Background, aims, and scope  Sediments and soils in coastal areas are frequently polluted by anthropogenic contaminants as the result of both riverine or terrestrial discharge and autochthonic marine emissions. In order to determine petrogenic contamination in the coastal industrial area of Kavala City in northern Greece, a combination of polycyclic aromatic hydrocarbon (PAH) and organic geochemical petroleum biomarker analyses has been performed on marine and freshwater sediments as well as soils. Materials and methods  Soils, freshwater, and marine sediments have been treated by standard extraction methods. The dried and desulphurized sample extracts have been fractionated by column chromatography, followed by addition of surrogate standards. Qualitative and quantitative data were obtained by gas chromatograph connected with a flame ionization and electron capture detector (GC-FID/ECD) and by GC linked to a mass spectrometer (GC/MS), whereas identification of compounds was based on EI⁺-mass spectra and gas chromatographic retention times. Quantitative data were obtained by integration of specific ion chromatograms. Results  The total PAH concentrations measured in the area varied highly, showing different levels from 18 up to 318,000 ng g⁻¹ dry weight (dw). Several PAH ratios, as well as the ratio of pristane (Pr) to phytane (Phyt), have been considered. Out of 39 samples, 22 revealed a specific distribution of hopane fingerprints indicating petrogenic input. Finally, in numerous samples, the ratio of 17α(H)-22,29,30-trisnorhopane (Tm) and 18α(H)-22,29,30-trisnorhopane (Ts) was calculated, as well as the ratio of 22S-17α(H),21β(H)-30 homohopane (αβC₃₁-hopane 22S) and 22R-17α(H),21β(H)-30 homohopane (αβC₃₁-hopane 22R). Discussion  Based on the specific PAH ratios, a group of samples was clearly characterized to be contaminated dominantly by combustion-derived emissions, whereas a second group of samples exhibited mixed influence from petrogenic and pyrogenic PAHs. On the other hand, the exhibition of specific hopane fingerprints in many samples indicates a direct petrogenic input. Finally, the values of the ratio of Tm/(Ts + Tm) and of αβC₃₁-hopanes 22S/(22S+22R)-isomer demonstrated an input of highly mature organic matter that has to be clearly attributed to petroleum-derived contamination, while the ratio of Pr/Phyt showed that most samples exhibited an input of organic matter. Conclusions  The coastal area of Kavala is strongly affected by anthropogenic contaminants. Petrogenic emissions were pointed out firstly by PAH analyses that separated dominantly pyrogenic contaminated sites from areas affected by both pyrogenic and petrogenic emissions. However, analyses of organic geochemical biomarkers revealed a much higher sensitivity in identifying petroleum-derived contaminations and were successfully used to differentiate several petrogenic contaminations in the marine and terrestrial samples. Recommendations and perspectives  Based on this study, it was recommended to use a complementary approach of source-specific substances to successfully characterize petrogenic emissions. Generally, a PAH-based source identification of petrogenic versus pyrogenic contaminations should be combined with petroleum biomarker analysis. PAH and biomarker ratios as well as individual biomarker fingerprints revealed a more comprehensive view on the quality and quantity of petrogenic emissions in sediments and soils.     

A model strategy for the simulation of chlorinated hydrocarbon distributions in the global environment

A model strategy that can be used for the study of global distributions of chlorinated hydrocarbons in the environment is presented. In this first approach the number of compartments and processes are kept on a minimum level by only considering the atmosphere, ocean and soil. Important processes are simulated or replaced by simple parameterizations, while processes believed to be less important are temporally omitted. The transport in the atmosphere is simulated by a simple two-dimensional zonally averaged model with a rather coarse resolution of 6 equally spaced latitude zones and 4 vertical layers. The soil is included in the model by dividing the continents into the same latitude zones as the atmosphere, and the land area in each zone into an uncultivated part and a cultivated part where pesticides may be incorporated. A model for tracer transport in the ocean which combines the features of the box and box-diffusion models has been modified for use in this study. Material is exchanged between the compartments by the processes believed to be most important in the real environment. The model is tested by simulating the life cycle of the α and γ isomers of hexachlorocyclohexane in the environment. The emissions of the two isomers are estimated from the total world consumption of HCH, and it is assumed that a fraction of 50% is lost to the atmosphere for long range transport during application or during the first days therefore. Comparison with observations indicates that in spite of the many assumptions and uncertain parameters the model is able to reproduce the atmospheric and oceanic concentration levels of εHCH. The HCH simulation indicates that the presented model strategy is usable when the aim is to increase the understanding of chlorinated hydrocarbons in the global environment. For the prediction of concentration levels in specific areas on the other hand, the present model strategy does not apply. The resolution of the model is too coarse and the simplifications are too extensive for such estimates to be valid.