Use and validation of novel snow samplers for hydrophobic, semi-volatile organic compounds (SVOCs)

Two novel gas-tight snow samplers (snow-can and snow-tube) are presented and the performance of the snow-can in a field trial was assessed. The methodology for the sampling, extraction and analysis of persistent organic pollutants (POPs) are detailed. These samplers allow the various components of a snow sample to be analysed separately; these included the meltwater (MW), particulate matter (GFF) and vapour in the headspace (HS). Snow samples collected on the Punta Indren glacier in the Italian Alps revealed the occurrence of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OC). Replicate samples of the same snow type were undertaken as a test of sampling precision. Relative standard deviations (RSDs) for SigmaPCBs and SigmaPAHs were approximately 30% and approximately 35% respectively. The lowest precision was found for the particle-laden snow, notably for the heavier PCB homologues. For the chlorinated compounds, the pesticides lindane and endosulfan-I had the highest levels in snow, with mean concentrations of 402 and 103 pgl(-1) (snow meltwater) respectively. The vapour present in the headspace (HS) comprised a minor component of a collected sample for all compounds, but HS concentrations for three lighter PAHs gave good agreement with those calculated based on their dimensionless Henry's law constants. This suggests that volatilisation during melting of aged snow-can be reasonably predicted with knowledge of the temperature-dependent Henry's law constant.     

PCBs and PAHs in U.K. urban air

As part of a long term air monitoring programme the ambient air in four UK urban areas was sampled throughout 1991. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were sampled from the air in London, Cardiff, Manchester and Stevenage. Both vapour and particulate phases were collected at each site, and total concentrations are reported for 26 alternate weeks of the year.

Total PAH concentrations (sum of 15 compounds) varied between 11 and 735 ng/m³ for the four sites. For each site PAH levels were dominated by the lower molecular weight compounds of phenanthrene, fluorene and pyrene, which made up more than 75% of the ΣPAH. The contribution of individual compounds to the total was broadly similar at each site in both the winter and summer. Concentrations of the higher molecular weight compounds were greater by a factor of 2.5 in the winter months.

Eight PCB congeners (28, 52, 77, 101, 118, 138, 153 and 180) were measured at each site. London gave the highest recorded value of 3.85 ng ΣPCB/m³. Values at the four sites ranged between 0.19–3.85 ng/m³, this range being similar to levels reported in other European and American cities. Congeners 28 and 52 dominated the air mixture, comprising > 80% of the measured total. PCB concentrations in the summer were, on average, double those for the winter.     

Transitioning towards cleaner cooking fuels: an analysis of consumer preferences in Ghana’s cookstoves market

Environmental Science and Pollution Research - Globally, attention has been paid to policies that promote the manufacturing, distribution, and usage of ‘cleaner stoves’ to minimise the...     

Seasonal and long-term trends in atmospheric PAH concentrations: evidence and implications

Atmospheric monitoring data for selected polynuclear aromatic hydrocarbons (PAHs) were compiled from remote, rural and urban locations in the UK, Sweden, Finland and Arctic Canada. The objective was to examine the seasonal and temporal trends, to shed light on the factors which exert a dominant influence over ambient PAH levels. Urban centres in the UK have concentrations 1-2 orders of magnitude higher than in rural Europe and up to 3 orders of magnitude higher than Arctic Canada. Interpretation of the data suggests that proximity to primary sources 'drives' PAH air concentrations. Seasonality, with winter (W) > summer (S), was apparent for most compounds at most sites; high molecular weight compounds (e.g. benzo[a]pyrene) showed this most clearly and consistently. Some low molecular weight compounds (e.g. phenanthrene) sometimes displayed S>W seasonality at some rural locations. Strong W>S seasonality is linked to seasonally-dependent sources which are greater in winter. This implicates inefficient combustion processes, notably the diffusive domestic burning of wood and coal. However, sometimes seasonality can also be strongly influenced by broad changes in meteorology and air mass origin (e.g. in the Canadian Arctic). The datasets examined here suggest a downward trend for many PAHs at some sites, but this is not apparent for all sites and compounds. The inherent noise in ambient air monitoring data makes it difficult to derive unambiguous evidence of underlying declines, to confirm the effectiveness of international source reduction measures.     

Organochlorine pesticides and polychlorinated biphenyls in air and soil across Azerbaijan

Concentrations of selected organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are reported in air and surface soil in an extensive spatial survey across Azerbaijan, a country bordering the Caspian Sea with a history of OCP production and extensive use. Polyurethane foam disc passive air samplers (PAS) were deployed during October-November 2008 with soil samples collected in July 2009. Levels of Σ(7)PCB in ambient air were generally low (mean of 0.046 ng m(-3), n?=?13) and comparable to concentrations reported in countries within Eastern Europe and similar to or lower than concentrations reported in urban air in the UK and other western countries. Surprisingly, PCB concentrations in rural/background soil fell below the method detection limits at most sites, although concentrations were 0.209 and 0.071 ng Σ(7)PCB g(-1) dry weight (dw) for two urban sites, again comparable to PCB levels measured at background sites in Europe. Levels of α-HCH, β-HCH, γ-HCH and p,p'-DDT/E were elevated in ambient air across Azerbaijan in comparison to PAS-derived concentrations reported elsewhere, with concentrations of α-HCH in air ranging from 0.085 to 2.699 ng m(-3) and p,p'-DDE, 0.037-2.290 ng m(-3). High concentrations of OCPs occurred at several of the urban sites and at sites in proximity to old pesticide storage facilities with concentrations in soil >0.1 μg g(-1) dw for p,p'-DDE and p,p'-DDT at several sites. The ratio of p,p'-DDT/p,p'-DDE was close to unity in the soil at these sites, but elsewhere, the ratio was <1, indicating a weathered DDT pattern, which was also reflected in the air at all sites. A fugacity approach revealed the strong likelihood of net soil-to-air transfer at the majority of sites for all OCPs. The calculated annual fluxes or loading to the atmosphere from a rural/agricultural area (representing land as vineyards and cotton cultivation) were estimated to be on the order of ≈10-100 kg year(-1) for the HCH isomers (including the β -isomer) and p,p'-DDE. The high levels of OCPs in soils, particularly in the vicinity of obsolete-pesticide storage facilities and at select urban sites are of concern and warrant regular monitoring activities and the development of containment or mitigation strategies.     

Photolytic degradation of methyl-parathion and fenitrothion in ice and water: Implications for cold environments

Here we investigate the photodegradation of structurally similar organophosphorus pesticides; methyl-parathion and fenitrothion in water (20 °C) and ice (−15 °C) under environmentally-relevant conditions with the aim of comparing these laboratory findings to limited field observations. Both compounds were found to be photolyzed more efficiently in ice than in aqueous solutions, with quantum yields of degradation being higher in ice than in water (fenitrothion > methyl-parathion). This rather surprising observation was attributed to the concentration effect caused by freezing the aqueous solutions. The major phototransformation products included the corresponding oxons (methyl-paraoxon and fenitroxon) and the nitrophenols (3-methyl-nitrophenol and nitrophenol) in both irradiated water and ice samples. The presence of oxons in ice following irradiation, demonstrates an additional formation mechanism of these toxicologically relevant compounds in cold environments, although further photodegradation of oxons in ice indicates that photochemistry of OPs might be an environmentally important sink in cold environments.     

Polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs) in urban air and deposition in the United Kingdom

Polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) have been monitored in air and deposition at four UK urban sites (London, Cardiff, Manchester and Stevenage) since the beginning of 1991; data from the first 2 years are presented here. Median Σ2,3,7,8-substituted PCDD/F concentrations in air were 3.2, 4.0, 3.5 and 2.6 pg/m³ respectively for London, Cardiff, Manchester and Stevenage. Median Σ2,3,7,8-substituted PCDD/F deposition fluxes were 1.5 ng/m²/day in London, 1.4 ng/m²/day in Cardiff and Manchester and 0.79 ng/m²/day in Stevenage. Seasonal variations in the PCDD/F concentrations were observed at all sites for both air and deposition, with concentrations/fluxes generally elevated during the winter.     

Photodegradation of hydroxyfluorenes in ice and water: A comparison of kinetics,effects of water constituents,and phototransformation by-products

The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry.Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs,2-hydroxyfluorene (2-OHFL) and 9-hydroxyfluorene (9-OHFL),which are newly recognized contaminants in the wider environment including colder regions.Interestingly,their photodegradation kinetics were clearly influenced by whether they reside in ice or water.Under the same simulated s...