Spatial distribution of atmospheric PAHs and PCNs along a north-south Atlantic transect

An extensive assessment on the distribution pattern of organic contaminants in the aerosols samples in the Middle East

Nowadays, in spite of a significant progress in indoor air quality (IAQ), an assessable and predictive understanding of atmospheric aerosol sources, chemical composition, transformation processes, and environmental effects are still rather incomplete and therefore signifies a key research challenge in the atmospheric science. Thus, the current comprehensive review is concerned with the dominant sources, organic compositions, and potential health impacts of the organic contaminants in the atmospheric particle matters (PMs) in the Middle East (ME). The ME contributes a major impact of organic contaminants on the atmosphere along with other Asian and African countries. In the Gulf Cooperation Council (GCC) countries, the communities are noted for being the center of the great majority of the world’s oil reserves and infrastructure for producing crude oil. The review starts with a historical outlook on the scientific queries regarding major source of organic contaminants to the atmospheric aerosols over the past centuries, followed by an explanation of the distribution, sources, transformation processes, and chemical and physical properties as they are formerly assumed. Natural product chemicals from biota, manufactured organic compounds including pesticides, chlorinated hydrocarbons, and lubricants, as well as organic compounds from the use and combustion of fossil fuels make up the aerosol contamination. Thus, in the recent years, IAQ may be seen as a significant health issue because of the increase in industrial activity. Fugitive emissions from industrial processes, as well as natural and anthropogenic emissions from other sources such as forest fires, volcanic eruptions, incomplete combustion of fossil fuels, wood, agricultural waste, or leaves, are typical sources of organic pollutants to the aerosol. In the spring and early summer in the GCC countries, aerosol concentration increases because of dust storms; however, in winter, there are fewer dust storms and higher precipitation rates, and aerosol concentrations are lower. Significances of future research and major suggestions are also outlined to narrow the gap between the present understanding of the contribution of both anthropogenic and biogenic aerosols to radiative forcing, resulting from the spatial nonuniformity, intermittency of sources, unresolved composition, and reactivity.

Atmospheric PAHs in rural, urban, industrial and beach locations in Buenos Aires Province, Argentina: sources and health risk assessment

The first atmospheric PAHs levels and associated inhalation cancer risk were assessed over southwest Buenos Aires region by deploying PUF disk PAS samplers. Eight sampling location included coastal zones, touristic beaches, and rural inland areas were considered. PUF disks were fortified with surrogate standards and extracted by automated Soxhlet prior to GC-MS analysis. Σ₁₆ PAHs ranged from 1.13 to 44.5 ng m^-3 (10.3 ± 9.8), while urban locations showed up to 10 times higher PAH levels than rural or beach locations. Direct sources of PAHs, such as intensive vehicle traffic, heating, and general combustion activities, were identified. PAHs with four to six rings (46.62%) were predominantly Flt, Pyr, BbF, and BkF, and carcinogenic risk was expressed by BaP (0.10 ± 0.07 ng m^-3) and BaPTEQs (0.26 ± 0.22 ng m^-3). Inhalation ECR (2.23E-5, WHO) presented the lowest risk at beach locations. Molecular ratios and PCA showed a strong dominance in pyrolytic sources, such as biomass and coal combustion, with a particular signature in fires at inland locations. Overall, this study demonstrated that PUF disk passive air sampling provided a sound and simple approach for tracking air PAHs, their sources and public health risks, bringing a cost-effective tool for pollution control measures, even at small and remote towns. This is particularly relevant in extensive countries with medium or low income, such as Argentina.

Polycyclic Aromatic Hydrocarbons in the Marine Atmosphere from the Western Pacific to the Southern Ocean: Spatial Variability, Gas/Particle Partitioning, and Source Apportionment

The spatial variability of polycyclic aromatic hydrocarbons (PAHs) in the marine atmosphere contributes to the understanding of the global sources, fate, and impact of this contaminant. Few studies conducted to measure PAHs in the oceanic atmosphere have covered a large scale, especially in the Southern Ocean. In this study, high-volume air samples were taken along a cross-section from China to Antarctica and analyzed for gaseous and particulate PAHs. The data revealed the spatial distribution, gas-particle partitioning, and source contributions of PAHs in the Pacific, Indian, and Southern Oceans. The median concentration (gaseous + particulate) of ∑₂₄PAHs was 3900 pg/m³ in the Pacific Ocean, 2000 pg/m³ in the Indian Ocean, and 1200 pg/m³ in the Southern Ocean. A clear latitudinal gradient was observed for airborne PAHs from the western Pacific to the Southern Ocean. Back trajectories (BTs) analysis showed that air masses predominantly originated from populated land had significantly higher concentrations of PAHs than those from the oceans or Antarctic continents/islands. The air mass origins and temperature have significant influences on the gas-particle partitioning of PAHs. Source analysis by positive matrix factorization (PMF) showed that the highest contribution to PAHs was from coal combustion emissions (52%), followed by engine combustion emissions (27%) and wood combustion emissions (21%). A higher contribution of PAHs from wood combustion was found in the eastern coastal region of Australia. In contrast, engine combustion emissions primarily influenced the sites in Southeast Asia.

The use of Pinus nigra as a biomonitor of pesticides and polycyclic aromatic hydrocarbons in Lebanon

Among the various species of vegetation, conifers play an important role as a biomonitor of air pollution. The current study presents the determination of pesticides and polycyclic aromatic hydrocarbons in 15 conifer samples collected in August 2018 (summer season) from different regions in north Lebanon (Tripoli, Koura, Bcharre, and Akkar). Pollutants were extracted based on QuEChERS-SPME followed by liquid and gas chromatography-tandem mass spectrometry. Results showed that the samples collected from Bcharre region had the lowest concentration in both pesticides and polycyclic aromatic hydrocarbons with a total concentration of 50 and 66 ng g^-1, while the samples collected from the regions widely known by their agriculture (Akkar, Tripoli, and Koura areas) were the most polluted with concentrations of 231 and 422 ng g^-1, 192 and 370 ng g^-1, and 127 and 98 ng g^-1 for pesticides and polycyclic aromatic hydrocarbons respectively. This study revealed that conifers are suggested to be efficient biomonitors of contamination levels in the air.

A one-year record of particle-bound polycyclic aromatic hydrocarbons at an urban background site in Lisbon Metropolitan Area, Portugal

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic chemicals that are widely distributed in the atmosphere and well known for their adverse health effects. This study aims to describe, for the first time, the levels, sources and associated health risks of particulate PAHs in an urban background atmosphere of Lisbon, the capital and largest city in Portugal. PM₁₀ aerosol samples were collected from early January to the end of December 2012 with a high-volume sampler and were later analyzed for 10 PAHs by high-performance liquid chromatography. The annual average of the sum of the concentrations of PAHs (ΣPAHs) was 1.64 ± 1.85 ng/m³. The dominant PAHs were pyrene, chrysene, benzo[b]fluoranthene, fluoranthene and benzo[g,h,i]perylene. Together these species accounted for approximately 70% of the ΣPAHs. A marked seasonal variation was observed for the investigated PAHs, with the highest values in winter and the lowest in spring and summer, reflecting the variation of emissions and meteorological conditions over time. The average concentration of benzo[a]pyrene was found to be 0.107 ± 0.152 ng/m³, not exceeding the target value of 1 ng/m³ established by European air quality legislation. Diagnostic ratios and principal component analysis were employed for the source apportionment of PAHs. Both tools indicated that vehicle exhaust was the main contributor to the atmospheric levels of PAHs in the study area.

Fate and deposition of polycyclic aromatic hydrocarbons in the Bransfield Strait, Antarctica

Fifteen polycyclic aromatic hydrocarbons (PAHs) were detected in seawater and atmosphere of Bransfield Strait. The concentration of ∑₁₅[PAH] in the atmosphere ranged from 3.75 to 8.53 ng m^-3, and three-ring PAHs were the most abundant compounds. Dissolved ∑₁₅[PAH] in seawater ranged from 5.42 to 34.37 ng L^-1, and the level of PAHs was markedly different on each side of the strait. The air-sea gas exchange process and molecular diagnostic ratios were calculated, results showed that the environmental behavior of PAHs was net deposition along this cruise. Given the changes in global transport routes of pollutants under global warming, the role of long-range transport (LRT) may be enhanced. Taking the Antarctic as a sink of PAHs due to the LRT and net deposition, PAHs will continue to load into the seawater of this area via atmospheric deposition, which contributes to improving our understanding of the environmental behavior of PAHs.

Atmospheric monitoring of organochlorine pesticides across some West African countries

Most African countries have ratified the Stockholm Convention on persistent organic pollutants (POPs) and are expected to reduce emissions of POPs such as organochlorine pesticides (OCPs) to the atmosphere. Emerging evidence, however, suggests that there are contemporary sources of OCPs in African countries despite the global ban on these products. This study investigated the atmospheric contamination from OCPs in four West African countries-Togo, Benin, Nigeria, and Cameroon-to ascertain the emission levels of OCPs and the characteristic signatures of contamination. Polyurethane foam (PUF) disk passive air samplers (PAS) were deployed in each country for ca. 55 days in 2012 and analyzed for 25 OCPs. Hexachlorocyclohexanes (HCHs) and DDTs constituted the highest burden of atmospheric OCPs in the target countries, at average concentrations of 441 pg m^-3 (range 23-2718) and 403 pg m^-3 (range 91-1880), respectively. Mirex had the lowest concentration, ranged between 0.1 and 3.3 pg m^-3. The concentration of OCPs in rainy season was higher than in dry season in Cameroon, and presupposed inputs from agriculture during the rainy season. The concentrations of ∑25 OCPs in each country were in the following order: Cameroon > Nigeria > Benin > Togo. There was significant evidence, based on chemical signatures of the contamination that DDT, aldrin, chlordane, and endosulfan were recently applied at certain sites in the respective countries.

Latitudinal distribution of OCPs in the open ocean atmosphere between the Argentinian coast and Antarctic Peninsula

Long-range atmospheric transport is one of the most important ways in which persistent organic pollutants can be transported from their source to remote and pristine regions. Here, we report the results of the first Argentinian measurements of organochlorine pesticides in the Antarctic region. During a 9665-km track onboard OV ARA Puerto Deseado, within the framework of Argentinian Antarctic Expeditions, air samples were taken using high-volume samplers and analyzed using GC-μECD. HCB, HCHs, and endosulfans were the major organic pollutants found, and a north-south gradient in their concentrations was evident by comparing data from the Argentinian offshore zone to the South Scotia Sea.

Low concentrations of persistent organic pollutants (POPs) in air at Cape Verde

Ambient air is a core medium for monitoring of persistent organic pollutants (POPs) under the Stockholm Convention and is used in studies of global transports of POPs and their atmospheric sources and source regions. Still, data based on active air sampling remain scarce in many regions. The primary objectives of this study were to (i) monitor concentrations of selected POPs in air outside West Africa, and (ii) to evaluate potential atmospheric processes and source regions affecting measured concentrations. For this purpose, an active high-volume air sampler was installed on the Cape Verde Atmospheric Observatory at Cape Verde outside the coast of West Africa. Sampling commenced in May 2012 and 43 samples (24h sampling) were collected until June 2013. The samples were analyzed for selected polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB) and chlordanes. The concentrations of these POPs at Cape Verde were generally low and comparable to remote sites in the Arctic for several compounds. Seasonal trends varied between compounds and concentrations exhibited strong temperature dependence for chlordanes. Our results indicate net volatilization from the Atlantic Ocean north of Cape Verde as sources of these POPs. Air mass back trajectories demonstrated that air masses measured at Cape Verde were generally transported from the Atlantic Ocean or the North African continent. Overall, the low concentrations in air at Cape Verde were likely explained by absence of major emissions in areas from which the air masses originated combined with depletion during long-range atmospheric transport due to enhanced degradation under tropical conditions (high temperatures and concentrations of hydroxyl radicals).

Polycyclic aromatic hydrocarbons in ocean sediments from the North Pacific to the Arctic Ocean

Eighteen polycyclic aromatic hydrocarbons (PAHs) were measured in surficial sediments along a marine transect from the North Pacific into the Arctic Ocean. The highest average Σ₁₈PAHs concentrations were observed along the continental slope of the Canada Basin in the Arctic (68.3 ± 8.5 ng g^-1 dw), followed by sediments in the Chukchi Sea shelf (49.7 ± 21.2 ng g^-1 dw) and Bering Sea (39.5 ± 11.3 ng g^-1 dw), while the Bering Strait (16.8 ± 7.1 ng g^-1 dw) and Central Arctic Ocean sediments (13.1 ± 9.6 ng g^-1 dw) had relatively lower average concentrations. The use of principal components analysis with multiple linear regression (PCA/MLR) indicated that on average oil related or petrogenic sources contributed ∼42% of the measured PAHs in the sediments and marked by higher concentrations of two methylnaphthalenes over the non-alkylated parent PAH, naphthalene. Wood and coal combustion contributed ∼32%, and high temperature pyrogenic sources contributing ∼26%. Petrogenic sources, such as oil seeps, allochthonous coal and coastally eroded material such as terrigenous sediments particularly affected the Chukchi Sea shelf and slope of the Canada Basin, while biomass and coal combustion sources appeared to have greater influence in the central Arctic Ocean, possibly due to the effects of episodic summertime forest fires.

Persistent organic pollutants (POPs) in the atmosphere of coastal areas of the Ross Sea, Antarctica: Indications for long-term downward trends

Passive air samplers were used to evaluate long-term trends and spatial distribution of trace organic compounds in Antarctica. Duplicate PUF disk samplers were deployed at six automatic weather stations in the coastal area of the Ross sea (East Antarctica), between December 2010 and January 2011, during the XXVI Italian Scientific Research Expedition. Among the investigated persistent organic compounds, Hexachlorobenzene was the most abundant, with air concentrations ranging from 0.8 to 50 pg m^-3. In general, the following decreasing concentration order was found for the air samples analyzed: HCB > PeCB > PCBs > DDTs > HCHs. While HCB concentrations were in the same range as those reported in the atmosphere of other Antarctic sampling areas and did not show a decline, HCHs and DDTs levels were lower or similar to those determined one or two decades ago. In general, the very low concentrations reflected the pristine state of the East Antarctica air. Backward trajectories indicated the prevalence of air masses coming from the Antarctic continent. Local contamination and volatilization from ice were suggested as potential sources for the presence of persistent organic pollutants in the atmosphere.

Time trends of persistent organic pollutants in spanish air

Passive air samplers consisting of polyurethane foam (PUF) disks were deployed in seven remote points and four urban locations to assess levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and some organochlorine pesticides including: 1,1'-(2,2,2-trichloroethane-1,1-diyl)bis(4-chlorobenzene) (DDT) and their metabolites (1,1-bis-(4-chlorophenyl)-2,2-dichloroethene (DDE) and 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene (DDD)), hexaclorobenzene (HCB) and hexachlorocyclohexanes (HCHs), in the Spanish ambient air. Results revealed HCB (49 pg m(-3); median) as the major pollutant, followed in decreasing order by HCHs (21 pg m(-3)), ∑DDT/E/Ds (20 pg m(-3)), PCBs (20 pg m(-3)), PBDEs (3.3 pg m(-3)) and PCDD/Fs (0.04 pg m(-3)), when urban and remote locations are evaluated together. Urban areas presented statistically significant (p < 0.05, Mann-Whitney U test) higher levels for all families studied, except for HCB, compared to remote locations revealing anthropogenic activities as potential sources for these chemicals. On the contrary, HCB concentrations seem to reflect background levels. Interestingly, results reveal a decreasing trend for PCBs, PBDEs and DDTs levels in remote areas, while this behaviour is only statistically significant in the case of the former chemicals in urban locations. The present study is framed in the Spanish air monitoring plan and represents the first complete analysis related to POP presence in Spanish air coming from inner sites.

Particulate PAHs and n-alkanes in the air over Southern and Eastern Mediterranean Sea

Particulate polycyclic aromatic hydrocarbons, n-alkanes and polar organic compounds were investigated in the marine atmosphere of Southern and Eastern Mediterranean Sea, in the frame of the scientific cruise of Urania ship between 27 July and 11 August 2013. The PM10 fraction of aerosol to which most organic substances are associated, were collected daily; contemporarily, gaseous regulated toxicants (ozone, nitrogen oxides and carbon oxide) and carbonyls were recorded. Samplings were carried out in front of Palermo and Messina, respectively the start and end harbors, and along the cruise, both in movement (transects, N = 14) and at stops (N = 11). Total PAHs ranged from 0.06 ng/m(3) up to 1.8 ng/m(3), with the maximums observed close to harbors. Unlike total concentrations that were in general comparable, the percent composition of PAHs was distinct for harbors, transects and stops, which allowed to draw insights about the pollution sources impact. Concentrations of n-alkanes (C18-C35) ranging from 6.7 to 43 ng/m(3) were quantified. The carbonyls evaluation revealed relatively high concentrations of formaldehyde (∼4-24 μg/m(3)) and acetone (∼5-35 μg/m(3)) near harbors, and of acrolein (up to 12 μg/m(3)) offshore, while benzaldehyde was quite independent of the site type (≈0.5 μg/m(3)). Nicotine and caffeine were detected, at different extents (0.0-2.2 ng/m(3) and 0.01-0.17 ng/m(3), respectively), in ca. 70% and 100% of samples. Alkyl phthalates ranged from 2.7 to 67 ng/m(3) and showed variable percentages in the samples. Finally, traces of N,N-diethyl-meta-toluene amide (up to 0.4 ng/m(3)) were found at all sites.

Polychlorinated naphthalenes in the air over the equatorial Indian Ocean: Occurrence, potential sources, and toxicity

Monitoring of marine polychlorinated naphthalenes (PCNs) is crucial, as they are considered persistent organic pollutants (POPs) by the Stockholm Convention. Data on PCNs in marine environment are scarce. In this study, 19 air samples were collected during a cruise in the equatorial Indian Ocean on board the Chinese research vessel Shiyan I from 4/2011 to 5/2011. PCN concentration of these air samples ranged from 0.033 to 2.56pgm(-3), with an average of 0.518pgm(-3), equal to or lower than the values reported for other oceans, seas, and lakes worldwide. Tri- and tetra-CNs were the main homologues in most samples. Reemission of Halowax mixtures and incineration processes were the major sources of atmospheric PCNs in the study area. The PCN-corresponding toxic equivalency values ranged from 0 to 0.190fgm(-3) (average: 0.038fgm(-3)), falling in the low end of global range.

Gas and particle size distributions of polychlorinated naphthalenes in the atmosphere of Beijing, China

Polychlorinated naphthalenes (PCNs) were listed as persistent organic pollutants in the Stockholm Convention in 2015. Despite numerous studies on PCNs, little is known about their occurrence in atmospheric particulate matter of different sizes. In this study, 49 PCN congeners were investigated for their concentrations and size-specific distributions in an urban atmosphere, and preliminary exposure assessments were conducted. Ambient air samples were collected using a high-volume cascade impactor for division into a gas fraction and four particle size fractions. Samples were collected from October 2013 to June 2014 at an urban site in Beijing, China. The concentration range for PCNs in the atmosphere (gas + particle fractions) was 6.77-25.90 pg/m(3) (average 16.28 pg/m(3)). The particle-bound concentration range was 0.17-2.78 pg/m(3) (average 1.73 pg/m(3)). Therefore, PCNs were mainly found in the gas phase. The concentrations of PCNs in a fraction increased as the particle size decreased (dae > 10 μm, 10 μm ≥ dae > 2.5 μm, 2.5 μm ≥ dae > 1.0 μm and dae ≤ 1.0 μm). Consequently, PCNs were ubiquitous in inhalable fine particles, and the ΣPCNs associated with PM1.0 and PM2.5 reached 68.4% and 84.3%, respectively. Tetra-CNs and penta-CNs (the lower chlorinated homologues) predominated in the atmosphere. The homologue profiles in different size particles were almost similar, but the particulate profiles were different from those in the gas phase. Among the individual PCNs identified, CN38/40, CN52/60 and CN75 were the dominant compounds in the atmosphere. CN66/67 and CN73 collectively accounted for most of the total dioxin-like TEQ concentrations of the PCNs. Exposure to toxic compounds, such as PCNs present in PM1.0 or PM2.5, may affect human health. This work presents the first data on size-specific distributions of PCNs in the atmosphere.

Differences in Ambient Polycyclic Aromatic Hydrocarbon Concentrations between Streets and Alleys in New York City: Open Space vs. Semi-Closed Space

Background: Outdoor ambient polycyclic aromatic hydrocarbon (PAH) concentrations are variable throughout an urban environment. However, little is known about how variation in semivolatile and nonvolatile PAHs related to the built environment (open space vs. semi-closed space) contributes to differences in concentrations. Methods: We simultaneously collected 14, two-week samples of PAHs from the outside of windows facing the front (adjacent to the street) open side of a New York City apartment building and the alley, semi-closed side of the same apartment unit between 2007 and 2012. We also analyzed samples of PAHs measured from 35 homes across Northern Manhattan and the Bronx, 17 from street facing windows with a median floor level of 4 (range 2–26) and 18 from alley-facing windows with a median floor level of 4 (range 1–15). Results: Levels of nonvolatile ambient PAHs were significantly higher when measured from a window adjacent to a street (an open space), compared to a window 30 feet away, adjacent to an alley (a semi-closed space) (street geometric mean (GM) 1.32 ng/m³, arithmetic mean ± standard deviation (AM ± SD) 1.61 ± 1.04 ng/m³; alley GM 1.10 ng/m³, AM ± SD 1.37 ± 0.94 ng/m³). In the neighborhood-wide comparison, nonvolatile PAHs were also significantly higher when measured adjacent to streets compared with adjacent to alley sides of apartment buildings (street GM 1.10 ng/m³, AM ± SD 1.46 ± 1.24 ng/m³; alley GM 0.61 ng/m³, AM ± SD 0.81 ± 0.80 ng/m³), but not semivolatile PAHs. Conclusions: Ambient PAHs, nonvolatile PAHs in particular, are significantly higher when measured from a window adjacent to a street compared to a window adjacent to an alley, despite both locations being relatively close to street traffic. This study highlights small-scale spatial variations in ambient PAH concentrations that may be related to the built environment (open space vs. semi-closed space) from which the samples are measured, as well as the relative distance from street traffic, that could impact accurate personal exposure assessments.

Field measurements of the atmospheric dry deposition fluxes and velocities of polycyclic aromatic hydrocarbons to the global oceans

The atmospheric dry deposition fluxes of 16 polycyclic aromatic hydrocarbons (PAHs) have been measured, for the first time, in the tropical and subtropical Atlantic, Pacific, and Indian Oceans. Depositional fluxes for fine (0.7-2.7 μm) and coarse (>2.7 μm) aerosol fractions were simultaneously determined with the suspended aerosol phase concentrations, allowing the determination of PAH deposition velocities (vD). PAH dry deposition fluxes (FDD) bound to coarse aerosols were higher than those of fine aerosols for 83% of the measurements. Average FDD for total (fine + coarse) Σ16PAHs (sum of 16 individual PAHs) ranged from 8.33 ng m(-2)d(-1) to 52.38 ng m(-2)d(-1). Mean FDD for coarse aerosol's individual PAHs ranged between 0.13 ng m(-2)d(-1) (Perylene) and 1.96 ng m(-2)d(-1) (Methyl Pyrene), and for the fine aerosol fraction these ranged between 0.06 ng m(-2)d(-1) (Dimethyl Pyrene) and 1.25 ng m(-2)d(-1) (Methyl Chrysene). The estimated deposition velocities went from the highest mean vD for Methyl Chrysene (0.17-13.30 cm s(-1)), followed by Dibenzo(ah)Anthracene (0.29-1.38 cm s(-1)), and other high MW PAHs to minimum values of vD for Dimethyl Pyrene (<0.04 cm s(-1)) and Pyrene (<0.06 cm s(-1)). Dry depositional processes depend on the concentration of PAHs in the suspended aerosol, but also on physicochemical properties and environmental variables (vapor pressure, wind speed, and on the affinity of aerosols for depositing to the sea surface). Empirical parametrizations are proposed to predict the dry depositional velocities of semivolatile organic compounds to the global oceans.

Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean

Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9-126 ng/m(3) (mean = 25 ± 34) at source and 0.05-0.71 ng/m(3) (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1-3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses.

Concentrations, fluxes, and residence time of PBDEs across the tropical Atlantic Ocean

Little is known about the fate of polybrominated diphenylethers (PBDEs) across the Oceans. Air and water were sampled using both active and passive polyethylene samplers on an east-west transect across the tropical Atlantic Ocean in 2009 and analyzed for PBDEs. Typical particle-bound concentrations of PBDEs in the surface water were low, at <1 pg L(-1). Truly dissolved concentrations from passive samplers were ∼0.5 pg L(-1) for BDE 47 and around 0.1 pg L(-1) for BDEs 28, 99, and 100 (results from active samples were compromised). In the atmosphere, particle-bound BDE 209 dominated overall concentrations (median 1.2 pg m(-3)), followed by BDE 99 (0.13 pg m(-3)). Gas-phase concentrations based on passive samplers were 1-8 pg m(-3) for BDE 47 and ≤ 4 pg m(-3) for BDE 99. Net air-water exchange gradients strongly favored gas-phase deposition of PBDEs into the water. Net gas-phase deposition fluxes ranged from tens of pg m(-2) day(-1) for BDEs 28 and 85 to around 1 ng m(-2) day(-1) for BDE 47, 99, and 209. Settling fluxes of particle-bound PBDEs in the atmosphere and surface water were around 50 pg m(-2) day(-1) for BDE 47 and <10 pg m(-2) day(-1) for the other congeners.

PAHs on a west-to-east transect across the tropical Atlantic Ocean

Surface water and atmospheric samples were collected across the tropical Atlantic Ocean on a transect of the R/V Endeavor in summer 2009 and analyzed for polycyclic aromatic hydrocarbons (PAHs). Across the entire tropical Atlantic Ocean, phenanthrene displayed on average highest dissolved concentrations (170 pg L(-1)), followed by pyrene (70 pg L(-1)) and fluoranthene (30 pg L(-1)). The Amazon plume was characterized by elevated dissolved concentrations of phenanthrene and benzo(g,h,i)fluoranthene. The warm eddy that we accidentally sampled at 66° W displayed highest concentrations of PAHs across the entire cruise, with phenanthrene, pyrene, and fluoranthrene all >1 ng L(-1). After having crossed the warm core, concentrations decreased back to previous levels. Samples taken in the Gulf Stream were below detection limit for all parent PAHs, implying very efficient removal processes. Dissolved dimethylphenanthrenes were frequently detected in the samples from the southern hemisphere, the Amazon plume, and in samples characteristic of the Gulf Stream and the U.S. East Coast. Atmospheric concentrations were dominated by gas-phase fluoranthene, pyrene, phenanthrene, and retene. Air-water gradients indicated that PAHs are mostly undergoing net deposition across the tropical Atlantic Ocean, with conditions closer to equilibrium off the U.S. East Coast and in Rhode Island Sound.

Factors affecting the occurrence and transport of atmospheric organochlorines in the China Sea and the northern Indian and South East Atlantic Oceans

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are reported in 97 air samples collected on board the RV Polarstern in November 2007 from the equator to Cape Town, South Africa and the MV Oceanic II (The Scholar Ship) in January-March 2008 from Shanghai, China to Cape Verde in the Central Atlantic Ocean. The atmospheric concentrations were higher close to the coast and lower in remote regions of the Indian and South Atlantic Ocean. Groups of samples were selected in the South China Sea, Indian Ocean and South Atlantic Ocean where the relative wind direction matched the trajectory of the ship, thus all the samples had the same input of sources upwind. In these three regions the concentrations of OCPs and PCBs declined during atmospheric transport following first order kinetics. These sets of measurements provided estimates of field derived residence times (FDRTs) for individual compounds. These values were compared with predicted atmospheric residence times (PARTs) computed using a model of long-range atmospheric transport potential of POPs. The FDRTs are 5-10 times longer for the more volatile PCB congeners and TC, CC, p,p'-DDT and p,p'-DDE than the respective PARTs, while they are similar to PARTs for the less volatile compounds. Possible causes of discrepancies between PARTs and FDRTs are discussed, and revolatilization from the ocean surface seems to be the main cause for the higher values of FDRTs of the more volatile compounds in comparison with the respective PARTs.

Factors affecting the level and pattern of polycyclic aromatic hydrocarbons (PAHs) at Gosan, Korea during a dust period

Polycyclic aromatic hydrocarbons (PAHs) in both gas and total suspended particles were measured at Gosan, Jeju Island in Korea, a remote background site, for 15 days (March 29-April 12, 2002). During the sampling period, a severe three-day Asian dust (AD) event originating from Mongolia and northern China was observed throughout the Korean Peninsula and Jeju Island. In addition, pollution (PO) and normal (NO) periods were also identified based on the levels of anthropogenic pollutants. Despite a large difference of PM(10) concentrations between the AD and PO periods, the levels of particulate PAHs in both periods were comparable (2.7±1.0 and 2.4±0.5 ng m(-3), respectively) since they were determined by the concentration of anthropogenic PM(2.5) transported from industrial areas of China. In the AD period, the level of gaseous PAHs, which were mostly from local sources, was the lowest due to strong winds; the gas/particle partitioning was close to equilibrium as the effect of long-range transport was manifested. The results of backward air trajectories, correlation analysis, and diagnostic ratios show that long-range transport of particulate PAHs produced by coal/biomass burning in China could strongly affect the levels and patterns of PAHs at Gosan, Korea.

Atmospheric concentrations of PCDD/Fs, dl-PCBs and some pesticides in northern Algeria using passive air sampling

Two monitoring campaigns were conducted in northern Algeria to assess the contamination level of pesticides and persistent organic pollutants (POPs) in ambient air. Six pesticides (α- and γ-hexachlorocyclohexane, fenitrothion, malathion, chlorpyrifos and λ-cyhalothrin) were monitored at two different sampling locations during the first campaign. The passive sampling was performed at a semi urban/industrial site but also in a rural area between July to September 2008. The pesticides levels, analyzed by GC/MS/MS, ranged from 16 pg m(-3) to 11 ng m(-3). The second campaign was carried out from May to November 2009. The polychlorodibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) concentrations were evaluated at an urban/industrial and at an industrial site. The PCDD/Fs and dl-PCBs, analyzed by HRGC/HRMS, ranged from 249 to 923 fg TEQ m(-3). In addition to passive sampling, active sampling using an isokinetic sampler was also performed at an industrial waste incinerator. The PCDD/Fs and dl-PCBs found was 268 pg TEQ m(-3). This paper presents the first measurements of PCDD/Fs, dl-PCBs and pesticides in rural, urban and industrial areas of northern Algeria.

Atmospheric polychlorinated naphthalenes in Ghana

A nationwide monitoring of atmospheric POPs (persistent organic pollutants) was conducted in Ghana between May and July 2010, applying polyurethane foam (PUF) disk passive air samplers (PAS). Reported here are preliminary findings on PCNs, an industrial organic contaminant currently under review for possible listing under the global chemical treaty. The present results constitute the first set of nationwide data on air PCNs from a West African country. Contrary to expectation, air PCNs levels were quite high in Ghana, at an average of 49 ± 5.4 pg/m(3). The coastal (southern) zone of Ghana appeared the most impacted, with crude open burning of waste, industrial emissions, and the harbor environment identified among possible emission factors. Tri- and tetra-CNs (the lowly chlorinated homologues) predominated in the atmosphere, altogether constituting approximately 90% of total PCN homologues composition. Increased volatilization under tropical conditions was presumed a key factor that contributed to this high atmospheric input of lowly chlorinated homologues. We further observed a significant level of fractionation of PCN homologues across the breadth of the country. The percentage composition of the lowly chlorinated homologues increased northwards, probably because of their transportation in the direction of prevailing winds. From congener profile analysis, PCN-45/36 is proposed as a possible source marker for emissions preempted by uncontrolled waste burning activities. Dioxin-like toxicity of air PCNs in Ghana was estimated to range 0.49-5.6 fg TEQ/m(3). This study brought to the fore the emerging problems of nonagricultural organohalogens that covertly might be confronting the environment in African nations like Ghana.

Chemical signatures of the Anthropocene in the Clyde estuary, UK: sediment-hosted Pb, (207/206)Pb, total petroleum hydrocarbon, polyaromatic hydrocarbon and polychlorinated biphenyl pollution records

The sediment concentrations of total petroleum hydrocarbons (TPHs), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), Pb and (207/206)Pb isotope ratios were measured in seven cores from the middle Clyde estuary (Scotland, UK) with an aim of tracking the late Anthropocene. Concentrations of TPHs ranged from 34 to 4386 mg kg(-1), total PAHs from 19 to 16,163 μg kg(-1) and total PCBs between less than 4.3 to 1217 μg kg(-1). Inventories, distributions and isomeric ratios of the organic pollutants were used to reconstruct pollutant histories. Pre-Industrial Revolution and modern non-polluted sediments were characterized by low TPH and PAH values as well as high relative abundance of biogenic-sourced phenanthrene and naphthalene. The increasing industrialization of the Clyde gave rise to elevated PAH concentrations and PAH isomeric ratios characteristic of both grass/wood/coal and petroleum and combustion (specifically petroleum combustion). Overall, PAHs had the longest history of any of the organic contaminants. Increasing TPH concentrations and a concomitant decline in PAHs mirrored the lessening of coal use and increasing reliance on petroleum fuels from about the 1950s. Thereafter, declining hydrocarbon pollution was followed by the onset (1950s), peak (1965-1977) and decline (post-1980s) in total PCB concentrations. Lead concentrations ranged from 6 to 631 mg kg(-1), while (207/206)Pb isotope ratios spanned 0.838-0.876, indicative of various proportions of 'background', British ore/coal and Broken Hill type petrol/industrial lead. A chronology was established using published Pb isotope data for aerosol-derived Pb and applied to the cores.

Evidence for major emissions of PCBs in the west African region

In previous studies unexpectedly high air concentrations of polychlorinated biphenyls (PCBs) were observed in ship-based measurements made ∼400 km off parts of the West African coast. To investigate further (i) samples were taken on board the RV Polarstern during a cruise from Germany to South Africa in October-November 2007; (ii) samples were obtained on Cape Verde Island during the same period to monitor airflows from Africa; and (iii) passive samplers were deployed in four West African countries to try to characterize potential sources on land. Results were as follows: on Cape Verde and on the ship air masses came predominantly (∼ 95%) from the African continent; the shipboard Σ29PCB concentrations off West Africa ranged from 10 to 360 pg m(-3) and from 6 to 99 pg m(-3) in Cape Verde; the highest land-based concentrations were observed in Ivory Coast and the Gambia (up to 300 pg m(-3)) and the lowest was observed in Ghana (9 pg m(-3)). Taken together, these and previous studies indicate there are more major emission(s) of PCBs and different source types in parts of West Africa than accounted for in current global atmospheric emissions estimates. Results from the FLEXPART model and PAH measurements show that emission inventories and biomass burning cannot fully explain the high PCB concentrations. Potential sources of the high PCB levels to the African regions are discussed, namely illegal dumping of PCB containing waste with release via volatilization and uncontrolled burning, and the storage and breakup of old ships.

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/m(3)) 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.

Integrated modelling of Polycyclic Aromatic Hydrocarbons in the marine environment: coupling of hydrodynamic, fate and transport, bioaccumulation and planktonic food-web models

Spatio-temporal variability of pollutants in the environment is a complex phenomenon that requires a combined approach for its analysis. Whereas data on measured levels of contaminants in various environmental compartments is essential, it is not always possible to monitor at the necessary frequency and with the adequate spatial sampling distribution to capture this variability. Therefore a modelling approach able to complement experimental data and close the gaps in the monitoring programs is useful for assessing the contaminant dynamics occurring at different time scales. In this work a 1D water column fate model has been developed and tested for Polycyclic Aromatic Hydrocarbons (PAHs). The model has been coupled with a simple ecological model that includes a bioaccumulation module. Afterwards, the model has been used to study the temporal variability of contaminant concentrations as well as the fluxes between compartments. The results evidence the complex coupling between spatio-temporal scales and its influence on environmental concentration levels.

PAHs in air and seawater along a North-South Atlantic transect: trends, processes and possible sources

Polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and surface seawater between 49 degrees N and 25 degrees S in the open Atlantic Ocean. Elevated concentrations of PAHs (sigma10 PAHs approximately 1.4-2.5 ng m(-3) air, and 0.7-1 ng L(-1) seawater) occurred in the Biscay Bay and off the northwest coast of Africa. The unexpectedly high concentrations off NW Africa were discussed assessing the possible contribution of the emerging oil industry along the African shore, the role of biomass burning and natural sources of PAHs. In the southern Atlantic, concentrations of PAHs were close to detection limits (sigma10 PAHs approximately 0.02-0.5 ng m(-3) air, and 0.06-0.5 ng L(-1) seawater) and showed decreasing trends with increasing latitudes. Correlations of PAHs' partial pressures versus inverse temperature were not significant in contrast to results for polychlorinated biphenyls from the same transect. This could have been due to the importance of ongoing primary sources and the shorter atmospheric life-times of PAHs. Air-water fugacity ratios (fa/fw) were calculated for selected compounds. They were close to 1 for fluoranthene and pyrene in remote open ocean areas suggesting air-water partitioning near equilibrium. Ratios for anthracene and phenanthrene were < 0.3 in the remote tropical Atlantic, suggesting net volatilization.

Air concentrations of PCDD/Fs, PCBs and PCNs using active and passive air samplers

The concentrations of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) were determined in air samples collected at four sampling sites located in two zones of Barcelona (Spain): near a municipal solid waste incinerator (MSWI) and a combined cycle power plant (3 sites), and at a background/control site. Samples were collected using high-volume active samplers. Moreover, 4 PUF passive samplers were deployed at the same sampling points during three months. For PCDD/Fs, total WHO-TEQ values were 27.3 and 10.9 fg WHO-TEQm(-3) at the urban/industrial and the background sites, respectively. The sum of 7 PCB congeners and the Sigma PCN levels were also higher at the industrial site than at the background site. In order to compare active and passive sampling, the accumulated amounts of PCDD/Fs, PCBs and PCNs in the four passive air samplers, as well as the total toxic equivalents in each sampling site were also determined. To assess the use of PUF passive samplers as a complementary tool for PCDD/F, PCB and PCN monitoring, sampling rates were calculated in accordance with the theory of passive air samplers. PUF disks allowed establishing differences among zones for the POP levels, showing that they can be a suitable method to determine POP concentrations in air in areas with various potential emission sources. Although both particle and gas phase were sorbed by the PUFs, data of gas phase congeners are more reproducible.

Global fate of POPs: current and future research directions

For legacy and emerging persistent organic pollutants (POPs), surprisingly little is still known in quantitative terms about their global sources and emissions. Atmospheric transport has been identified as the key global dispersal mechanism for most legacy POPs. In contrast, transport by ocean currents may prove to be the main transport route for many polar, emerging POPs. This is linked to the POPs' intrinsic physico-chemical properties, as exemplified by the different fate of hexachlorocyclohexanes in the Arctic. Similarly, our current understanding of POPs' global transport and fate remains sketchy. The importance of organic carbon and global temperature differences have been accepted as key drivers of POPs' global distribution. However, future research will need to understand the various biogeochemical and geophysical cycles under anthropogenic pressures to be able to understand and predict the global fate of POPs accurately.

Atmospheric occurrence and deposition of polycyclic aromatic hydrocarbons in the northeast tropical and subtropical Atlantic Ocean

Atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) over tropical oceans has not yet been studied even though tropical oceans account for 35% of the global oceans. Here we show the results from measurements of gas- and aerosol-phase PAHs and dry deposition samples in the NE tropical Atlantic Ocean atmosphere, a region between 26 degrees and 21 degrees N, off shore of the Saharan desert. The results show that PAHs concentrations are high at the coastal ocean (15-20 ng m(-3) for sum of 27 gas-phase individual PAHs) and decrease by a factor of 2-3 at open ocean (26 degrees W). The spatial variability observed is consistent with dilution, reaction, and deposition during transport. Atmospheric dry deposition velocities ranged between 0.1 and 0.3 cm s(-1) with higher deposition velocities for the more volatile PAHs. Outbreaks of Saharan Dust significantly increase the deposition rates of PAHs. The occurrence and deposition of PAHs in tropical regions is complex and results from the interplay of a number of processes, such as wind speed, aerosol loads, important sources from West Africa, processes controlling the diurnal variability, and sequestration driven by high primary productivity regions. The measured average atmospheric residence times of gas- and aerosol-phase PAHs are 3.7 and 3.5 days, respectively.

Polychlorinated naphthalenes in the Global Atmospheric Passive sampling (GAPS) study

Air concentrations of polychlorinated naphthalenes (PCNs) were measured as part of the Global Atmospheric Passive Sampling (GAPS) study to assess their spatial distribution on a worldwide basis for the first sampling period between December 2004 and March 2005. Results from more than 40 sites on seven continents show that PCNs are widespread, and highest levels are detected in urban/industrial locations consistent with other air sampling studies. The geometric mean air concentration of sigmaPCN is 1.6 pg/m3, ranging from below detection limit to 32 pg/m3. With technical PCN mixtures largely no longer produced, combustion inputs may be contributing increasingly to contemporary PCN air burden globally. Enrichment of combustion-related congeners, e.g., PCN-52/60, -50, -51,-54, and -66/67, is observed in the congeneric compositions of air at nearly all sites compared to relatively minor contribution of these congeners in technical PCN formulations. Further evidence of current combustion sources influencing global PCN levels is a higher relative abundance of combustion-related congeners quantified by sigmaPCNcombustion/sigmaPCN. The relative contribution by combustion sources and emissions from technical PCN mixtures is expected to vary among sites since it depends on the combustion sources and the technical mixture used in a particular country or region.

Influence of 17alpha-ethynylestradiol on CYP1A, GST and biliary FACs responses in male African sharptooth catfish (Clarias gariepinus) exposed to waterborne Benzo[a]Pyrene

Dose dependent effects of Benzo[a]pyrene (BaP) on cytochrome P4501A (CYP1A), glutathione-S-transferase (GST) and fluorescent aromatic compounds (FACs) metabolites biomarker responses were studied in African sharptooth catfish (Clarias gariepinus) following 24 h of waterborne exposures. Based on biomass of C. gariepinus in different tanks, BaP concentrations of 1.60, 3.44, and 18.21 microg/L that corresponded to 0.5, 1.0, and 5.0 mg/kg body weight were used. Significant induction of EROD activities in gill filaments was observed at all doses and the accumulation of FACs metabolites in bile was significantly different between groups. Accumulation of FACs metabolites in bile strongly correlated (r (2) = 0.99) with BaP doses. Hepatic EROD activities were undetectable and no effect on GST activities was observed. The highest dose of BaP from the dose dependent study was further studied to assess the interactive and temporal responses of C. gariepinus on CYP1A, GST, and FACs metabolites biomarkers following exposure to either BaP alone, 17alpha-ethynylestradiol (EE(2)) alone or a combination of both compounds at concentrations of 54.17 microg/L for BaP, 51.38 microg/L for EE(2) and 54.44 microg/L for each of both compounds. Based on biomass in each tank, these concentrations corresponded to 5 mg/kg body weight. While a group of six fish was sacrificed on day 0 from the control tank only, other groups of six fish were sacrificed after 1, 3, and 6 days of exposure from the control and exposed groups. Maximum induction of gill filament and hepatic EROD activities was observed after 1 day of exposure. Both EROD activities in gill filaments and liver were significantly induced by exposure to BaP alone or co-administration with EE(2). Gill filament EROD induction was significantly inhibited (50%) by co-administration of BaP and EE(2) compared to administration of BaP alone. Levels of FACs in bile for BaP and BaP + EE(2) exposed groups were significantly different from the control at all doses and time points. A significant induction of GST activities was observed in fish exposed to BaP and BaP + EE(2) after 3 days. Exposure to EE(2) alone caused significant induction of this enzyme after day 6. This study reports for the first time the significant antagonistic influence of EE(2) on BaP in gills of fish following waterborne exposures. The results also indicate that chemical mixtures may affect biomarker responses differently from compounds administered alone and that the sensitivity of CYP1A to interactive chemicals is different in gills and liver.

Evaluation of the gill filament-based EROD assay in African sharptooth catfish (Clarias gariepinus) as a monitoring tool for waterborne PAH-type contaminants

The ability of African sharptooth catfish (Clarias gariepinus) in inducing cytochrome P-450 class 1A (CYP1A) and glutathione S-transferase (GST) biomarkers was determined in liver and gill filaments after 4 days of waterborne exposure to the polycyclic aromatic hydrocarbon, benzo[a]pyrene (B[a]P). Male (n=6) and female (n=6) fish were exposed to B[a]P added to the water (30 microg/l) corresponding to 5 mg/kg total body weight. Five female and six male fish, exposed to acetone alone added to the water served as controls. The 7-ethoxyresurufin-O-deethylase (EROD) activity was measured in hepatic microsomes and gill filaments. In addition, GST activity was determined in the hepatic cytosolic fraction and fluorescent aromatic compounds (FACs) in bile and biliverdin. Benzo[a]pyrene strongly induced EROD activities in gill filaments of both sex. Levels of FACs per ml of bile were 17-fold higher in exposed fish compared to the controls. Correlations between induction of EROD activities in gill filaments and liver and between induction of EROD activities in gill filaments and levels of biliary FACs metabolites were strong. GST activities in the hepatic cytosolic fraction were similar amongst the treated and control groups. This is the first report on studies determining EROD activities in gill filaments and hepatic tissue, FACs in bile and GST in hepatic tissues of C. gariepinus after waterborne exposure to B[a]P. The findings suggest that the gill filament-based EROD assay in C. gariepinus can be used to monitor the pollution of AhR agonists in aquatic ecosystems in eastern and southern African countries.

Polybrominated diphenyl ethers in airborne particulates collected during a research expedition from the Bohai Sea to the Arctic

In July to September 2003, particulates in the oceanic atmosphere from the Bohai Sea to the high Arctic (37 degrees N to 80 degrees N) were collected aboard a research expedition icebreaker, Xuelong (Snow Dragon), under the 2003 Chinese Arctic Research Expedition Program (CHINARE 2003). These samples were analyzed to elucidate the atmospheric distributions of polybrominated diphenyl ethers (PBDEs) in the North Pacific Ocean and adjacent Arctic region. The levels of 11 PBDE congeners (BDE-28, -47, -66, -100, -99, -85, -154, -153, -138, -183, and -209; the sum was defined as sigma11PBDE) in the oceanic atmosphere of Far East Asia (34-48 degrees N/122-148 degrees E) ranged from 2.25 to 198.9 pg/m3 with a mean of 58.3 pg/m3. BDE-47, -99, -100, and -209 were the dominant congeners in all the samples, suggesting that the widely used commercial penta- and deca-BDE products were the original sources. The PBDE levels exhibited a decreasing trend from the mid- to high-latitudinal regions of the North Pacific Ocean, probably resulting from dilution, deposition, and decomposition of PBDEs during long-range transport of air masses. On the other hand, no apparent geographical pattern of PBDE distribution was observed within the Arctic, attributable to unstable air circulation and strong air mixing. Correlations among the PBDE congeners suggested that air masses collected from the North Pacific Ocean were relatively fresh, whereas those from the Arctic were aged as a result of photodecompoisiton. The higher average level (17.3 pg/m3) of PBDE congeners in the Arctic than those in the adjacent North Pacific Ocean (12.8 pg/m3) or other remote areas reported in the literature was attributed to the impact of the North American continent and temperature effects, which was consistent with the hypotheses of global fractionation.

Long-term fate of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in an agricultural soil

Laboratory studies are useful for understanding the behavior of persistent organic pollutants (POPs) in soil, although such investigations do not always relate directly to field conditions. Outdoor lysimeter studies may be used to overcome this problem. This work aimed to investigate the behavior of two polycyclic aromatic hydrocarbons (PAHs) (fluoranthene and benzo[a]pyrene) and two polychlorinated biphenyls (PCBs; congeners 28 and 52) in soil, using lysimeters established in 1990 atthe Agrosphere Institute (Forschungszentrum Julich GmbH, Germany). The two PAHs were in one lysimeter, and the PCBs were in a second lysimeter. Afurther aim of the study was to determine soil half-lives for each of the contaminants. The overall decline in PAH concentrations was considerably greater than forthe PCBs over the 152 month study. The PCBs exhibited greater chemical extractability than the PAHs and were demonstrated to have migrated through the soil column to a greater extent than the PAHs. Loss of PCBs from surface soil was not considered to have been congener specific for the two PCB congeners in this study. The two PAHs varied in their extents of total loss and movement through the soil column. Soil half-lives were determined as 10.9 y for [12C]PCB 28, 11.2 yr for [12C]PCB 52, 2.7 yr for benzoqpyrene, and 32 d (phase 1) to 38 yr (phase 2) for fluoranthene. These are shown to disagree with some previous estimates of POP half-lives in soil, suggesting that previous studies underestimated persistence by 10-fold or more.