Field-derived Henry's law constants for polychlorinated biphenyls in oceanic waters

Accurate knowledge of Henry's law constants (Kaw) is very important for fate and transport studies of organic chemicals. Here field-derived Kaw values for polychlorinated biphenyl (PCB) congeners (PCBs 28, 49, 52, 118, 138, 149, and 153) were determined in the open Atlantic Ocean, at locations where air and seawater were assumed to be at equilibrium. Field-based Kaw values were derived from air and seawater samples simultaneously collected at these locations, and their relationship with temperature was determined. The average field-derived Kaw for PCBs 28, 49, 52, 118, and 138 was generally 2–3 times higher than laboratory-derived values reported in the literature. Possible causes of differences between the field and the laboratory data may be attributed to differences between pure water and seawater and the use of much higher persistent organic pollutant concentrations in laboratory studies compared to that of the remote ocean. Field-derived Kaw values for PCB 149 and PCB 153 were up to 10 times higher than literature values. The comparison of field- and laboratory-derived Kaw shows that their temperature dependence is not significantly different (95% confidence) from those reported in the literature.Department of the Environment, Food and Rural Affairs (DEFRA) and the Natural Environment Research Council (NERC) on persistent organic pollutants at Lancaster University and the Spanish Ministry of Science and innovation through the MIMOSA and ATOS projects.Peer reviewe

The TOMPs network:continuous data on the UK air quality for 20 years

The Toxic Organic Micro Pollutants (TOMPs) Network, which has operated since 1991, currently collects ambient air samples at six sites across England and Scotland, using high-volume active air samplers. Lancaster University has been operating this UK Department of Environment, Food and Rural Affairs (Defra) funded network from its inception, delivering long-term ambient air trend data for a range of Persistent Organic Pollutants (POPs) at both urban and rural locations. Data from the network provides Defra with valuable information on emission/source controls and on the effectiveness of international chemicals regulation. It is also used to demonstrate UK compliance with its obligations under the 2001 Stockholm Convention on Persistent Organic Pollutants and the 1998 UN/ECE Long-Range Atmospheric Transport Protocol. Moreover, long-term analysis of air pollutants at trace levels allows detailed studies on atmospheric fate and behaviour processes of persistent chemicals and is the inevitable basis of their successful modelling. The target chemicals of TOMPs have been polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and, since 2010, polybrominated diphenyl ethers (PBDEs). PCBs, PCDDs, PCDFs, and selected PBDEs are all listed under the Stockholm Convention. The continuous monitoring of these compounds has demonstrated the constant decline in their UK air concentrations over the last decades. The concentrations of all compounds are generally significantly higher at urban compared to semi-rural and rural sites, with estimated clearance rates between 2 and 9 years for PCBs at all sites, 2 to 4 years for PBDEs at urban and semi-rural sites, and 4 to 5 years for PCDDs and PCDFs at urban sites. All these data are in good agreement with emission estimates. Additionally, an archive is maintained, which can be used for analysing emerging chemicals, such as alternative flame retardants, pesticides, and further substances of interest as soon as they have been identified

Volatile per- and polyfluoroalkyl compounds in the remote atmosphere of the western Antarctic Peninsula: an indirect source of perfluoroalkyl acids to Antarctic waters

Volatile per– and polyfluoroalkyl compounds were measured in air in the vicinity of the Western Antarctic Peninsula during February 2009 (Austral summer). The 6:2, 8:2 and 10:2 fluorotelomer alcohols (FTOHs) were the most abundant compounds with 8:2 and 10:2 FTOH concentrations averaging 9.9 and 7.4 pgm –3 respectively, followed by the shorter chain (C4) compounds of methyl perfluorobutane sulfonamide (MeFBSA) and sulfonamidoethanol (MeFBSE) with average concentrations of 3 to 4 pgm–3. Methyl/ethyl fluorooctane sulfonamides and sulfonamidoethanols (FOSA/Es) were <1 pgm–3 in all air samples (n = 8). The concentrations of FTOHs and FOSAs were in good agreement with a previous study (2007) that measured these chemicals in the background atmosphere of the Southern Ocean, although the levels of the MeFBSA/E were found to be 10–fold higher and possibly indicative of the increased use of these chemicals. Air mass back trajectories revealed that air mass movement was from the Antarctic landmass or from the Southern Ocean, the latter in keeping with the prevailing direction of the Antarctic Circulation Current. Those samples corresponding to air passing over the Antarctic Peninsula did not show notable differences in chemical concentrations or profile indicating that the scientific bases located on or near the Peninsula did not appear to influence PFC levels in the regional atmosphere.Given the lack of air mass incursions from the north (i.e. from the South American continent) then the levels measured here are representative of background concentrations around Antarctica. However,the relatively high levels of MeFBSE were surprising given the reported reactivity of this chemical and short atmospheric residence time. It is likely that this compound, alongside MeFBSA, is providing a source of C2–C4 perfluoroalkyl acids(PFAs)to Antarctic surface waters. We recommend that long–term air monitoring be established in Antarctica for volatile PFCs and possibly accompanied by deposition monitoring for the PFAs

The principles of effective post-spill environmental monitoring in marine environments and their application to preparedness assessment

Understanding the fate and effects of marine spills is essential if the scientific and response communities are to develop best practices. The effective deployment of environmental monitoring activity can be complex and requires planning and coordination but the levels of preparedness to deliver the necessary expertise, coordination and funding are often low. This paper identifies and describes the importance of 8 principles of effective post-spill monitoring programmes. These principles are then used in the assessment of monitoring preparedness through the generation of a monitoring preparedness assessment score (MPAS). This approach can be used by local, regional or national authorities to establish the level of preparedness for environmental monitoring and prioritise areas for improvement. It also has value to responders, policy makers, environmental scientists and planners as a tool to assess preparedness and capability for specific scenarios. The approach is demonstrated through the assessment of previous incidents and potential future scenarios

Coupling passive air sampling with emission estimates and chemical fate modeling for persistent organic pollutants : a feasibility study in Northern Europe.

Passive air samplers (polyurethane foam disks) were deployed at 23 background locations along a broadly west−east transect in 8 northern European countries and analyzed for PCBs, PBDEs, PAHs, and a range of organochlorine pesticides (HCB, DDTs, and DDEs). PCBs and PAHs were highest at the center of the transect (Denmark) and lowest in northern Norway. HCB was relatively uniformly distributed, reflecting its persistence and high degree of mixing in air. Higher DDE and DDT levels occurred in Eastern Europe and at several sites in Central Europe. PBDE levels were generally similar at all sites, but lower for some locations in Eastern Europe and Ireland. Emissions information for PCBs, HCB, and PBDEs was used as input for a multi-media chemical fate model, to generate predicted air concentrations and compare with these measured values. Different scenarios were highlighted by this exercise: (i) country and compound combinations where the national inventory gave predicted air concentrations in close agreement with those measured (e.g., PCBs in the UK); (ii) country and compound combinations where predicted concentrations were well below those measured, but where advection of emissions from elsewhere is likely to be important (e.g., PCBs in Norway); (iii) consistent underestimation of compound concentrations by the emissions modeling (i.e., HCB); and (iv) general overestimation of ambient concentrations (i.e., PBDEs). Air mass trajectory analysis showed the likely role of long-range atmospheric transport (LRAT) on national levels. In general, advection from the south and west of Europe appeared to contribute to ambient POPs levels for countries in the center and northeast of the transect. Guidelines are presented as to how countries that want to assess their POPs source inventories can do so with this relatively cheap initial screening approach

Assessing the importance of ab- and adsorption to the gas-particle partitioning of PCDD/Fs.

The gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was examined (i) by re-interpreting results from controlled field experiments and (ii) in diurnal samples taken in the New Jersey (NJ), New York (NY) City region. In the controlled field experiments, aerosol-laden filters were exposed to elevated concentrations of PCDD/Fs. Gas-particle partitioning coefficients, Kp's, were significantly correlated with octanol–air partitioning coefficients, Koa's. The regression of all individual datapoints resulted in the following best fit (r2=0.74, n=87): log Kp,meas=1.00(±0.13) log(10−12fomKoa/ρoct)−0.15(±0.48). We interpret this as showing that the ability of organic matter (OM) to absorb PCDD/Fs is generally well described by the octanol–air partitioning model (fomKoa). At the NJ land-based sites, samples were taken and analyzed for organic carbon (OC) and elemental carbon (EC), gaseous and particulate PCDD/Fs. Kp's were significantly correlated with the fomKoa approach. Adsorption to the filter and possibly to black carbon (BC), which was estimated based on EC measurements, could have contributed to the observed Kp values. Gas-particle predictions based on BC adsorption and OM absorption, with Kp=fomKoa/(1012ρoct)+fBCKBC–air/(1012ρBC) resulted in Kp predictions that were close to measured values. Adsorption to the filter might have been the major reason for elevated Kp's: The one NJ site with highest Kp's was most prone to the filter adsorption sampling artefact because of relatively low sampling volumes and concentrations of total suspended particulates. In addition, while adsorption to BC would result in better prediction of Kp values, no influence of fBC or fBC/fom ratios was seen, suggesting that it was of lesser importance in our sample set

Continuous Monitoring of PCDD/Fs in the UK Atmosphere : 1991-2008.

This study summarizes the key findings of a long-term (1991−2008) monitoring program to measure polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in urban and rural ambient air in the UK. Air concentrations are reported for 6 sites—3 urban (London, Manchester, and Middlesbrough) and 3 rural/semirural (Hazelrigg, High Muffles, and Stoke Ferry). Nearly 310 samples have been analyzed, each for a 3-month period. Annually averaged urban concentrations in the early 1990s were typically a few 100s fg (TEQ) m−3 and <50 fg m−3 in the mid-2000s. Applying first-order kinetics to the whole urban time series gave T1/2 (atmospheric half-lives) in London and Manchester of 3.2−5.9 and 4.1−5.9 years, respectively. Estimated national annual atmospheric emissions trends broadly correlated with the trends in urban ambient concentrations, suggesting that the inventory has captured the broad mixture of sources. However, rural air concentrations (in the low 10s fg m−3) show no discernible change since 1996, while recent urban concentrations are close to those in rural areas. Other UK trend data infer the declines in the 1990s followed previous declines in the 1980s from peak levels in the 1950−1970s, all before routine monitoring began. Winter concentrations are generally a factor of 2−3 higher than summer concentrations, implicating diffuse combustion sources (e.g., domestic space heating). These observations taken together suggest that most major readily controllable primary/point sources were reduced by the early/mid-1990s in the UK and that current ambient levels in both rural and urban areas may remain at broadly similar levels in the foreseeable future, unless there are major changes in energy requirements and generation options, fuel usage, and policy drivers

Atmospheric transport, cycling and dynamics of Polychlorinated Biphenyls (PCBs) from source regions to remote oceanic areas:occurrence, fate and impact of atmospheric pollutants on environmental and human health

Polychlorinated biphenyls (PCBs) are ubiquitous in the environment. Their persistence coupled with their potential toxicity has prompted international regulations and increased effort to understand their regional and global scale presence, and the processes that influence their fate and transport. PCBs can travel in the atmosphere away from source regions through long-range atmospheric transport and be deposited to water and terrestrial surfaces. This chapter focuses on the atmospheric concentrations of PCBs and factors controlling their spatial and temporal variability from source regions to oceanic remote areas. Air data show a strong latitudinal trend with the highest PCB concentrations in Europe and the lowest in the Arctic and in the tropical and subtropical southern hemisphere. High PCB levels were observed off the west coast of Africa and Asia, and possible factors controlling these high levels and their implications for the global cycling of PCBs are discussed. Furthermore, air-water interactions are disussed in remote areas of the open ocean. Of particular importance is the evidence for near steady-state air-water equilibrium or net volatilization in the tropical and subtropical regions, while advective inputs still dominate in the Northern hemisphere. Net deposition dominates over volatilization in the Arctic region. This chapter seeks o examine recent findings in the global transport of PCBs and to identify areas of uncertainty in the understanding of the factors controlling the residence time of PCBs in different areas of the globe

Temporal Trends and Controlling Factors for Polychlorinated Biphenyls in the UK Atmosphere (1991-2008)

Long-term air monitoring data sets are needed for persistent organic pollutants (POPs), to assess the effectiveness of source abatement measures and the factors controlling ambient levels. The Toxic Organic Micro-Pollutants (TOMPS) program in the United Kingdom started in 1991, generating a data set for polychlorinated biphenyls (PCBs). The history and volumes of production, usage, and subsequent restrictions on PCBs in the UK are well-characterized relative to many countries, providing a valuable case study on the effectiveness of controls and the factors influencing ambient levels and trends of these "model POPs". PCB air concentrations (congeners PCB 28, 52, 90/101, 118, 138, 153, and 180) from six rural and urban monitoring sites are presented. Most show a statistically significant decrease in PCBs levels over time, consistent with estimates of emissions, helping to validate emissions inventories. Times for a 50% decline in concentrations (sometimes called clearance rates) averaged 4.7 +/- 1.6 years for all congeners at all sites. The trends at different sites and for different congeners were not statistically different from each other. Concentration differences between sites are correlated with local population density (i.e., the degree of urbanization), which supports approaches to modeling of primary emissions on the national and regional scale. The data set indicates that ambient levels and underlying trends of PCBs continue to reflect the controlling influence of diffuse primary sources from the ongoing stock of PCBs in urban environments. Production and use restrictions came into force in the UK over 40 years ago; trends since monitoring began in the early 1990s should be seen as part of a continuing decline in ambient levels since that time