The extent to which different manufacturing sources and long-range transport pathways contribute ... more The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.
Traffic vehicles are a main source of polycyclic aromatic hydrocarbon (PAH) emission in urban are... more Traffic vehicles are a main source of polycyclic aromatic hydrocarbon (PAH) emission in urban area. It is vital to understand PAH gas-particle partitioning in real traffic environment and assess PAH vehicular emission factors in developing China. Concentrations of particulate matter, carbonaceous products, gaseous and particulate PAHs were measured during 2011-2012 in a road tunnel of Shanghai, China. Time variation of them reflected basic traffic operation of the tunnel. PAHs approached equilibrium between gas and particle phases and the partitioning was predicted better by a dual sorption model combining absorption into organic matter and adsorption onto black carbon. The influence of black carbon adsorption on the partitioning behavior of PAHs was important. The difference in isomer ratios of gaseous and particulate PAHs was attributed to PAH contributions from different traffic-related PAHs sources. Real-world vehicle emission factors of gaseous and particulate PAHs were quantif...
A field calibration study of low density polyethylene (LDPE) for measuring atmospheric concentrat... more A field calibration study of low density polyethylene (LDPE) for measuring atmospheric concentrations of persistent organic pollutants (POPs) was performed in East Providence (RI), USA. LDPE samplers were collected after 3, 7, 10, 14, 17 and 21 days of exposure along with samples from a co-deployed high volume sampler. Uptake kinetics of POPs by LDPEs were confirmed both by using an uptake study over time and the inclusion of performance reference compounds (PRCs). Results indicated that only POPs with log sampler-air partitioning coefficient (KPE-A) ≤ 7.6 were approaching equilibrium by the end of the deployment period, whereas all the other POPs were still in the linear uptake rate. Sampling rates (1.0-80 m(3) per day) were higher for some POPs when compared to literature values possibly due to the open sampler housing design used. Derived KPE-As for the detected POPs in field calibration study were correlated against the compounds' octanol-air partitioning coefficients (log KOA): [log KPE-A = 0.88 ± 0.02 × log KOA + 0.40 ± 0.21 (R(2) = 0.96; n = 59; SE = 0.23)], and their subcooled liquid vapour pressures (log PL/Pa): [log KPE-A = -0.82 ± 0.02 × log PL + 6.22 ± 0.05 (R(2) = 0.96; n = 59; SE = 0.22)] to predict values for all POPs. PL was generally found to be a better predictor of KPE-A for all POPs.
This paper is a comprehensive, critical review of the levels, behaviour and processes affecting p... more This paper is a comprehensive, critical review of the levels, behaviour and processes affecting polychlorinated Ž . dibenzo-p-dioxins and -furans PCDDrFs in air and deposition. Aspects of sampling, analysis and quality assurancercontrol are discussed initially, before a review of the PCDDrF concentrations in ambient air is presented. The Ž . 3 Ž 3 . general trend in ⌺P CDDrF and ⌺TEQ is: remote sites -0.5 pgrm ⌺TEQ -10 fgrm ; rural sites ; 0.5᎐4
1] Accurate knowledge of Henry's law constants (K aw ) is very important for fate and transport s... more 1] Accurate knowledge of Henry's law constants (K aw ) is very important for fate and transport studies of organic chemicals. Here field-derived K aw 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 K aw values were derived from air and seawater samples simultaneously collected at these locations, and their relationship with temperature was determined. The average field-derived K aw 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 K aw values for PCB 149 and PCB 153 were up to 10 times higher than literature values. The comparison of field-and laboratory-derived K aw shows that their temperature dependence is not significantly different (95% confidence) from those reported in the literature.
Freely dissolved and gas phase polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibe... more Freely dissolved and gas phase polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were measured in the water column and atmosphere at five locations within Newark Bay (New Jersey, USA) from May 2008 to August 2009 with polyethylene (PE) passive samplers. Mono- to octa-CDDs and mono- to hepta-CDFs were detected in bottom and surface waters at ≤ 20 pg/L with no clear gradient between sampling locations, suggesting freely dissolved PCDD/Fs are well mixed in Newark Bay. The most concentrated, freely dissolved gas phase congener was 2,7/2,8-dichlorodibenzo-p-dioxin (2,7/2,8-DiCDD), likely originating from photochemical conversion of triclosan in Newark Bay. Air-surface water gradients strongly favored net volatilization of PCDD/PCDFs from Newark Bay. Water-to-air fluxes of 2,7/2,8-DiCDD and 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), the most concentrated and the most toxic PCDD/PCDFs, respectively, were approximately 60 ng/m(2) per month and 14 to 51 pg/m(2) per month. Significant decreases in freely dissolved 2,3,7,8-TCDD concentrations with increasing freshwater near the Passaic River and conservative behavior during the summer of 2009 suggested Passaic sediments as a likely source of 2,3,7,8-TCDD to Newark Bay. Mass balance calculations implied that almost 50% of freely dissolved 2,3,7,8-TCDD delivered to Newark Bay from the Hackensack and Passaic Rivers was lost to volatilization in the summer of 2009.
We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6... more We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6)-C(14) perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (∑PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). ∑PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L ∑PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, ∑PFAAs were <210 pg/L. PFOA/PFOS ratios were typically ≥1 in the northern hemisphere, ∼1 near the equator, and ≤1 in the southern hemisphere. In the Canadian Arctic, ∑PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically ≫1) decreased from Baffin Bay to the Amundsen Gulf, possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.
Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon ... more Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon (BC), and their δ 13 C isotope ratios. Sediments displayed high OC (20-25%) and increasing BC concentrations from ∼0.40% (in 1800 C.E.) to ∼0.60% dry weight (in 2000 C.E.). Petrographic analysis confirmed the presence of fire-derived carbonaceous particles/BC at ∼2% of total OC. Natural fires were the most likely cause of both elevated polycyclic aromatic hydrocarbon (PAH) concentrations and enhanced sorption in Oriole Lake sediments prior to 1850, consistent with their tree-ring-based fire history. In contrast to other PAHs, retene and perylene displayed decreasing concentrations during periods with natural fires, questioning their use as fire tracers. The occurrence of natural fires, however, did not result in elevated concentrations of black carbon or chars in the sediments. Only the 1912-2007 sediment layer contained anthropogenic particles, such as soot BC. In this layer, combining OC absorption with adsorption to soot BC (using a Freundlich coefficient n = 0.7) explained the observed sorption well. In the older layers, n needed to be 0.3 and 0.5 to explain the enhanced sorption to the sediments, indicating the importance of natural chars/inertinites in sorbing PAHs. For phenanthrene, values of n differed significantly between sorption to natural chars (0.1-0.4) and sorption to anthropogenic black carbon (>0.5), suggesting it could serve as an in situ probe of sorbents.
Passive polyethylene (PE) samplers were deployed at six locations within Narragansett Bay (RI, US... more Passive polyethylene (PE) samplers were deployed at six locations within Narragansett Bay (RI, USA) to determine sources and trends of freely dissolved and gas-phase polycyclic aromatic hydrocarbons (PAHs) from May to November 2006. Freely dissolved aqueous concentrations of PAHs were dominated by fluoranthene, pyrene, and phenanthrene, at concentrations ranging from tens to thousands of pg/L. These were also the dominant PAHs in the gas phase, at hundreds to thousands of pg/m3. All stations mostly followed the same temporal trends, with highest concentrations (up to 7300 pg/L for sum PAHs) during the second of 11 deployments, coinciding with a major rainstorm. Strong correlations of sum PAHs with river flows and wastewater treatment plant discharges highlighted the importance of rainfall in mobilizing PAHs from a combination of runoff and atmospheric washout. PAH concentrations declined through consecutive deployments III to V, which could be explained by an exponential decay due to flushing with cleaner ocean water during tides. The estimated residence time (tres) of the PAH pulse was 24 days, close to an earlier estimate of tres of 26 days for freshwater in the Bay. Air-water exchange gradients indicated net volatilization of most PAHs closest to Providence. Further south in the Bay, gradients had changed to mostly net uptake of the more volatile PAHs, but net volatilization for the less volatile PAHs. Based on characteristic PAH ratios, freely dissolved PAHs at most sites originated from the combustion of fossil fuels; only two sites were at times affected by fuel spill-derived PAHs.
Ship-board air samples collected between The Netherlands and South Africa in January-February 200... more Ship-board air samples collected between The Netherlands and South Africa in January-February 2001 were analyzed for PCBs and selected organochlorine compounds. Broad latitudinal trends in compound concentrations were influenced by proximity to source areas, land, and air mass origin. Lowest concentrations were observed in the remote south Atlantic (1-32°S), where ∑ 7 PCB concentrations were ∼10 pg m -3 . Here, a diurnal cycle was noted for some PCB congeners, with the daytime concentrations higher than the nighttime concentrations, typically by a factor of 1.5-2.5. The data are consistent with a close coupling of air-open ocean concentrations, which has important implications for future rates of POP removal from the global "recyclable pool". The observations are discussed in the context of the potential controlling variables. Interactions between the phytoplankton and the dissolved phase are implicated in controlling the observations made here and a hypothesis to explain the cycling trends is presented. However, the precise mechanisms remain unclear; further studies are urgently required to elucidate them.
Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of ... more Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of persistent organic pollutants (POPs). A new methodology that combines aerosol remote sensing measurements with measured POP aerosol-phase concentrations is presented to derive dry particulate depositional fluxes of POPs to the oceans. These fluxes are compared with those due to diffusive airwater exchange. For all polychlorinated biphenyl (PCB) congeners and lower chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), air-water exchange dominates the dry deposition mechanism. However, this tendency reverses in some areas, such as in marine aerosol influenced areas and dust outflow regions, consistent with the important variability encountered for the depositional fluxes. Seasonal variability is mainly found in mid-high latitudes, due to the important influence of wind speed enhancing dry deposition fluxes and temperature as a driver of the gasparticle partitioning of POPs. The average dry aerosol deposition flux of ΣPCBs and ΣPCDD/Fs to the Atlantic Ocean is calculated to be in the order of 66 ng m -2 yr -1 and 9 ng m -2 yr -1 respectively. The total dry aerosol deposition of ∑PCBs and ∑PCDD/Fs to the Atlantic Ocean is estimated to be 2200 kg yr -1 and 500 kg yr -1 , respectively, while the net air-water exchange is higher, 22000 kg ∑PCBs yr -1 for PCBs and 1300 kg ∑PCDD/Fs yr -1 . Furthermore, it is suggested that marine aerosol plays an important role in scavenging atmospheric contaminants.
Air samples were taken concurrently for four sampling events in the winter of 1998 at three contr... more Air samples were taken concurrently for four sampling events in the winter of 1998 at three contrasting sites: an urban center and two rural sites. The rural sites were characterized by the extensive usage of coal and wood for space heating. Samples were analyzed for PCDD/Fs, PCBs, and PAHs. Recently measured octanol-air partition coefficients (K oa ) for PCDD/Fs enabled a comparison of the K oa -based versus the subcooled liquid vapor pressure (p L )based partition model for all three compound classes. Both K oa and p L were found to be excellent descriptors of the gas-particle partitioning of PCDD/Fs, PCBs, and PAHs. However, regressions for log K p -log p L gave higher regression coefficients than for log K p -log K oa . Both models showed roughly similar relative states of equilibrium for PCDD/Fs, PCBs, and PAHs. PCBs were closest to equilibrium at the urban site. It is argued that newly released particles at the rural sites caused nonequilibrium partitioning at those sites for PCBs. PAHs were released at all sites and were, in line with expectations, approaching equilibrium. The K oa -based and the p L -based model gave contradictory results for PCDD/Fs: according to the p L -model, PCDD/Fs were in equilibrium for event I but not for the other events, whereas the K oa -model showed the PCDD/ Fs not being in equilibrium for event I. A simple K oa -model, combining advective transport and locally released PCDD/ Fs and PAHs, can explain the observed nonequilibrium partitioning for the first sampling event.
Surface water and atmospheric samples were collected across the tropical Atlantic Ocean on a tran... more 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.
Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large ... more Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large section of the tropical Atlantic suggested net volatilization of PCBs to the atmosphere. Only for the higher chlorinated PCB 153 and hexachlorobenzene (HCB) were gradients near equilibrium detected. The use of passive samplers also enabled the detection of dichlorodiphenyltrichloroethane (DDT) and its transformation products across the tropical Atlantic, indicating net deposition. There were clear differences between the southern and northern hemisphere apparent in terms of atmospheric concentrations: Once the ship moved from the southern into the northern hemisphere air, concentrations of HCB and other organochlorine pesticides increased several-fold. For large swaths of the tropical Atlantic Ocean, neither PCB nor organochlorine pesticide dissolved concentrations varied much longitudinally, probably due to efficient mixing by ocean currents. In selected samples, dissolved concentrations reflected the influence of river plumes and major ocean currents far away from the continents. Dissolved concentrations of PCBs 28, 52, 101, 118, and HCB increased in the Amazon plume and the Gulf Stream. While the Amazon plume flushed only a few kg of PCBs and HCB, the Gulf Stream is potentially delivering tons of PCBs into the North Atlantic annually.
The environmental distribution and fate of microplastic in the marine environment represents a po... more The environmental distribution and fate of microplastic in the marine environment represents a potential cause of concern. One aspect is the influence that microplastic may have on enhancing the transport and bioavailability of persistent, bioaccumulative, and toxic substances (PBT). In this study we assess these potential risks using a thermodynamic approach, aiming to prioritize the physicochemical properties of chemicals that are most likely absorbed by microplastic and therefore ingested by biota. Using a multimedia modeling approach, we define a chemical space aimed at improving our understanding of how chemicals partition in the marine environment with varying volume ratios of air/water/organic carbon/polyethylene, where polyethylene represents a main group of microplastic. Results suggest that chemicals with log KOW > 5 have the potential to partition >1% to polyethylene. Food-web model results suggest that reductions in body burden concentrations for nonpolar organic chemicals are likely to occur for chemicals with log KOW between 5.5 and 6.5. Thus the relative importance of microplastic as a vector of PBT substances to biological organisms is likely of limited importance, relative to other exposure pathways. Nevertheless, a number of data-gaps are identified, largely associated with improving our understanding of the physical fate of microplastic in the environment.
The extent to which different manufacturing sources and long-range transport pathways contribute ... more The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.
Polyethylene (PE)-water equilibrium partitioning constants, K(PEw), were reviewed for trace hydro... more Polyethylene (PE)-water equilibrium partitioning constants, K(PEw), were reviewed for trace hydrophobic organic contaminants (HOCs). Relative standard deviations were <30% for phenanthrene, anthracene, fluoranthene, and pyrene implying excellent reproducibility of K(PEw) across laboratories and PE sources. Averaged K(PEw) values of various HOCs were best correlated with aqueous solubility, logC(w)(sat)(L): logK(PEw) = -0.99(±0.029)logC(w)(sat)(L) + 2.39(±0.096) (r(2) = 0.92, SE = 0.35, n = 100). For 80% of analytes, this equation predicted logK(PEw) within a factor of 2. A first-order estimation of K(PEw) can be obtained assuming constant solubility of the compounds in the PE, such that the variation in C(w)(sat)(L) determines the differences in K(PEw). For PE samplers, K(PEw) values do not change with the thickness of the PE sampler. The influence of temperature on K(PEw) seems dominated by solubility-changes of the compound in water, not in PE. The effect of salt is rather well understood, using a Schetschenow-style approach. The air-PE partitioning constant, K(PEa), can be approximated as the ratio of K(PEw)/K(aw) (the air-water partitioning constant). A critical review of diffusivities in PE, D(PE), suggests that best results are obtained when using the film-stacking method. A good correlation is then found between D(PE) and molar volume, V(m) (Ǻ(3)/mol): logD(PE) (m(2)/s) = 0.0145(±0.001)V(m) + 10.1(±0.20) (r(2) = 0.76, SE = 0.24, n = 74).
To be able to use polyethylene passive samplers (PE) in the field, the partitioning constants bet... more To be able to use polyethylene passive samplers (PE) in the field, the partitioning constants between PE and water (K PEw ) of the compounds examined must be known. The K PEw s of triclosan (TCS), methyl-triclosan (MTCS), n-nonylphenol (n-NP), nonylphenol-technical mix (NP-tech), n-octylphenol (n-OP), and t-octylphenol (t-OP) were measured as a function of pH, temperature, and salinity, and a salt effect was calculated for TCS, n-OP, and t-OP. Log K PEw s used for calculating dissolved concentrations were taken from 20°C studies taking salt into account: 3.42 (TCS), 4.53 (MTCS), 4.20 (n-NP), 3.69 (n-OP), and 2.87 (t-OP). The K PEw of hydroxyl-group containing compounds were strongly affected by pH, whereas MTCS with its methoxy-group was not. Measured K PEw s could not be estimated from octanol-water partitioning constants due to the semipolar makeup of the compounds investigated. Instead, a good correlation (K PEw = 0.679 Â K hdw þ 1.033, r 2 = 0.984, p = 0.001) was obtained with hexadecane-water partitioning constants (K hdw ) predicted from COSMOtherm. During deployments in Narragansett Bay (RI) in the fall of 2009, concentrations of MTCS and t-OP in surface and bottom waters ranged from 40-225 pg L -1 and 3.5-11 ng L -1 , respectively. These concentrations are far below EC 50 values for rainbow trout. Surface/bottom and bottom/porewater activity ratios were calculated. These indicated surface waters as the main source of MTCS, while surface water as well as sediments were sources of t-OP.
Air samples were taken onboard the RRS Bransfield on an Atlantic cruise from the United Kingdom t... more Air samples were taken onboard the RRS Bransfield on an Atlantic cruise from the United Kingdom to Halley, Antarctica, from October to December 1998, with the aim of establishing PCB oceanic background air concentrations and assessing their latitudinal distribution. Great care was taken to minimize pre-and post-collection contamination of the samples, which was validated through stringent QA/ QC procedures. However, there is evidence that onboard contamination of the air samples occurred, following insidious, diffusive emissions on the ship. Other data (for PCBs and other persistent organic pollutants (POPs)) and examples of shipboard contamination are presented. The implications of these findings for past and future studies of global POPs distribution are discussed. Recommendations are made to help critically appraise and minimize the problems of insidious/diffusive shipboard contamination.
Surface seawater and boundary layer atmospheric samples were collected on the FS Polarstern durin... more Surface seawater and boundary layer atmospheric samples were collected on the FS Polarstern during cruise ARKXX in the North Atlantic and Arctic Ocean in 2004. Samples were analyzed for persistent organic pollutants (POPs), with a focus on organochlorine pesticides, including hexachlorocyclohexanes (HCHs), chlordanes, DDTs, hexachlorobenzene (HCB), and polycyclic aromatic hydrocarbons. In addition, the enantiomer fractions (EFs) of pesticides, notably R-HCH and cischlordane (CC), were determined. Concentrations of dissolved HCB increased from near Europe (∼ 1-2 pg/L) toward the high Arctic (4-10 pg/L). For dissolved HCB, strongest correlations were obtained with the average air or water temperature during sampling, not latitude. In the western Arctic Ocean, surface waters with elevated concentrations of HCB (5-10 pg/ L) were flowing out of the Arctic Ocean as part of the East Greenland current. In contrast to dissolved compounds, atmospheric POPs did not display trends with temperature. Air-water exchange gradients suggested net deposition for all compounds, though HCB was closest to air-water equilibrium. EFs for R-HCH in seawater ranged from 0.43 to 0.50, except for two samples from 75°N in the East Greenland Sea, with EFs of 0.31 and 0.37. Lowest EF (0.47) for CC were also at 75°N, other samples had EFs from 0.49 to 0.52. It is suggested that samples from around 75°N in the Greenland Gyre represented a combination of surface and older/deeper Arctic water. FIGURE 5. Ratio of OCPs, PAH, and PCB concentrations near the pole versus near Europe as a function of subcooled liquid vapor pressure.
The extent to which different manufacturing sources and long-range transport pathways contribute ... more The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.
Traffic vehicles are a main source of polycyclic aromatic hydrocarbon (PAH) emission in urban are... more Traffic vehicles are a main source of polycyclic aromatic hydrocarbon (PAH) emission in urban area. It is vital to understand PAH gas-particle partitioning in real traffic environment and assess PAH vehicular emission factors in developing China. Concentrations of particulate matter, carbonaceous products, gaseous and particulate PAHs were measured during 2011-2012 in a road tunnel of Shanghai, China. Time variation of them reflected basic traffic operation of the tunnel. PAHs approached equilibrium between gas and particle phases and the partitioning was predicted better by a dual sorption model combining absorption into organic matter and adsorption onto black carbon. The influence of black carbon adsorption on the partitioning behavior of PAHs was important. The difference in isomer ratios of gaseous and particulate PAHs was attributed to PAH contributions from different traffic-related PAHs sources. Real-world vehicle emission factors of gaseous and particulate PAHs were quantif...
A field calibration study of low density polyethylene (LDPE) for measuring atmospheric concentrat... more A field calibration study of low density polyethylene (LDPE) for measuring atmospheric concentrations of persistent organic pollutants (POPs) was performed in East Providence (RI), USA. LDPE samplers were collected after 3, 7, 10, 14, 17 and 21 days of exposure along with samples from a co-deployed high volume sampler. Uptake kinetics of POPs by LDPEs were confirmed both by using an uptake study over time and the inclusion of performance reference compounds (PRCs). Results indicated that only POPs with log sampler-air partitioning coefficient (KPE-A) ≤ 7.6 were approaching equilibrium by the end of the deployment period, whereas all the other POPs were still in the linear uptake rate. Sampling rates (1.0-80 m(3) per day) were higher for some POPs when compared to literature values possibly due to the open sampler housing design used. Derived KPE-As for the detected POPs in field calibration study were correlated against the compounds' octanol-air partitioning coefficients (log KOA): [log KPE-A = 0.88 ± 0.02 × log KOA + 0.40 ± 0.21 (R(2) = 0.96; n = 59; SE = 0.23)], and their subcooled liquid vapour pressures (log PL/Pa): [log KPE-A = -0.82 ± 0.02 × log PL + 6.22 ± 0.05 (R(2) = 0.96; n = 59; SE = 0.22)] to predict values for all POPs. PL was generally found to be a better predictor of KPE-A for all POPs.
This paper is a comprehensive, critical review of the levels, behaviour and processes affecting p... more This paper is a comprehensive, critical review of the levels, behaviour and processes affecting polychlorinated Ž . dibenzo-p-dioxins and -furans PCDDrFs in air and deposition. Aspects of sampling, analysis and quality assurancercontrol are discussed initially, before a review of the PCDDrF concentrations in ambient air is presented. The Ž . 3 Ž 3 . general trend in ⌺P CDDrF and ⌺TEQ is: remote sites -0.5 pgrm ⌺TEQ -10 fgrm ; rural sites ; 0.5᎐4
1] Accurate knowledge of Henry's law constants (K aw ) is very important for fate and transport s... more 1] Accurate knowledge of Henry's law constants (K aw ) is very important for fate and transport studies of organic chemicals. Here field-derived K aw 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 K aw values were derived from air and seawater samples simultaneously collected at these locations, and their relationship with temperature was determined. The average field-derived K aw 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 K aw values for PCB 149 and PCB 153 were up to 10 times higher than literature values. The comparison of field-and laboratory-derived K aw shows that their temperature dependence is not significantly different (95% confidence) from those reported in the literature.
Freely dissolved and gas phase polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibe... more Freely dissolved and gas phase polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were measured in the water column and atmosphere at five locations within Newark Bay (New Jersey, USA) from May 2008 to August 2009 with polyethylene (PE) passive samplers. Mono- to octa-CDDs and mono- to hepta-CDFs were detected in bottom and surface waters at ≤ 20 pg/L with no clear gradient between sampling locations, suggesting freely dissolved PCDD/Fs are well mixed in Newark Bay. The most concentrated, freely dissolved gas phase congener was 2,7/2,8-dichlorodibenzo-p-dioxin (2,7/2,8-DiCDD), likely originating from photochemical conversion of triclosan in Newark Bay. Air-surface water gradients strongly favored net volatilization of PCDD/PCDFs from Newark Bay. Water-to-air fluxes of 2,7/2,8-DiCDD and 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), the most concentrated and the most toxic PCDD/PCDFs, respectively, were approximately 60 ng/m(2) per month and 14 to 51 pg/m(2) per month. Significant decreases in freely dissolved 2,3,7,8-TCDD concentrations with increasing freshwater near the Passaic River and conservative behavior during the summer of 2009 suggested Passaic sediments as a likely source of 2,3,7,8-TCDD to Newark Bay. Mass balance calculations implied that almost 50% of freely dissolved 2,3,7,8-TCDD delivered to Newark Bay from the Hackensack and Passaic Rivers was lost to volatilization in the summer of 2009.
We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6... more We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6)-C(14) perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (∑PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). ∑PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L ∑PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, ∑PFAAs were <210 pg/L. PFOA/PFOS ratios were typically ≥1 in the northern hemisphere, ∼1 near the equator, and ≤1 in the southern hemisphere. In the Canadian Arctic, ∑PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically ≫1) decreased from Baffin Bay to the Amundsen Gulf, possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.
Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon ... more Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon (BC), and their δ 13 C isotope ratios. Sediments displayed high OC (20-25%) and increasing BC concentrations from ∼0.40% (in 1800 C.E.) to ∼0.60% dry weight (in 2000 C.E.). Petrographic analysis confirmed the presence of fire-derived carbonaceous particles/BC at ∼2% of total OC. Natural fires were the most likely cause of both elevated polycyclic aromatic hydrocarbon (PAH) concentrations and enhanced sorption in Oriole Lake sediments prior to 1850, consistent with their tree-ring-based fire history. In contrast to other PAHs, retene and perylene displayed decreasing concentrations during periods with natural fires, questioning their use as fire tracers. The occurrence of natural fires, however, did not result in elevated concentrations of black carbon or chars in the sediments. Only the 1912-2007 sediment layer contained anthropogenic particles, such as soot BC. In this layer, combining OC absorption with adsorption to soot BC (using a Freundlich coefficient n = 0.7) explained the observed sorption well. In the older layers, n needed to be 0.3 and 0.5 to explain the enhanced sorption to the sediments, indicating the importance of natural chars/inertinites in sorbing PAHs. For phenanthrene, values of n differed significantly between sorption to natural chars (0.1-0.4) and sorption to anthropogenic black carbon (>0.5), suggesting it could serve as an in situ probe of sorbents.
Passive polyethylene (PE) samplers were deployed at six locations within Narragansett Bay (RI, US... more Passive polyethylene (PE) samplers were deployed at six locations within Narragansett Bay (RI, USA) to determine sources and trends of freely dissolved and gas-phase polycyclic aromatic hydrocarbons (PAHs) from May to November 2006. Freely dissolved aqueous concentrations of PAHs were dominated by fluoranthene, pyrene, and phenanthrene, at concentrations ranging from tens to thousands of pg/L. These were also the dominant PAHs in the gas phase, at hundreds to thousands of pg/m3. All stations mostly followed the same temporal trends, with highest concentrations (up to 7300 pg/L for sum PAHs) during the second of 11 deployments, coinciding with a major rainstorm. Strong correlations of sum PAHs with river flows and wastewater treatment plant discharges highlighted the importance of rainfall in mobilizing PAHs from a combination of runoff and atmospheric washout. PAH concentrations declined through consecutive deployments III to V, which could be explained by an exponential decay due to flushing with cleaner ocean water during tides. The estimated residence time (tres) of the PAH pulse was 24 days, close to an earlier estimate of tres of 26 days for freshwater in the Bay. Air-water exchange gradients indicated net volatilization of most PAHs closest to Providence. Further south in the Bay, gradients had changed to mostly net uptake of the more volatile PAHs, but net volatilization for the less volatile PAHs. Based on characteristic PAH ratios, freely dissolved PAHs at most sites originated from the combustion of fossil fuels; only two sites were at times affected by fuel spill-derived PAHs.
Ship-board air samples collected between The Netherlands and South Africa in January-February 200... more Ship-board air samples collected between The Netherlands and South Africa in January-February 2001 were analyzed for PCBs and selected organochlorine compounds. Broad latitudinal trends in compound concentrations were influenced by proximity to source areas, land, and air mass origin. Lowest concentrations were observed in the remote south Atlantic (1-32°S), where ∑ 7 PCB concentrations were ∼10 pg m -3 . Here, a diurnal cycle was noted for some PCB congeners, with the daytime concentrations higher than the nighttime concentrations, typically by a factor of 1.5-2.5. The data are consistent with a close coupling of air-open ocean concentrations, which has important implications for future rates of POP removal from the global "recyclable pool". The observations are discussed in the context of the potential controlling variables. Interactions between the phytoplankton and the dissolved phase are implicated in controlling the observations made here and a hypothesis to explain the cycling trends is presented. However, the precise mechanisms remain unclear; further studies are urgently required to elucidate them.
Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of ... more Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of persistent organic pollutants (POPs). A new methodology that combines aerosol remote sensing measurements with measured POP aerosol-phase concentrations is presented to derive dry particulate depositional fluxes of POPs to the oceans. These fluxes are compared with those due to diffusive airwater exchange. For all polychlorinated biphenyl (PCB) congeners and lower chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), air-water exchange dominates the dry deposition mechanism. However, this tendency reverses in some areas, such as in marine aerosol influenced areas and dust outflow regions, consistent with the important variability encountered for the depositional fluxes. Seasonal variability is mainly found in mid-high latitudes, due to the important influence of wind speed enhancing dry deposition fluxes and temperature as a driver of the gasparticle partitioning of POPs. The average dry aerosol deposition flux of ΣPCBs and ΣPCDD/Fs to the Atlantic Ocean is calculated to be in the order of 66 ng m -2 yr -1 and 9 ng m -2 yr -1 respectively. The total dry aerosol deposition of ∑PCBs and ∑PCDD/Fs to the Atlantic Ocean is estimated to be 2200 kg yr -1 and 500 kg yr -1 , respectively, while the net air-water exchange is higher, 22000 kg ∑PCBs yr -1 for PCBs and 1300 kg ∑PCDD/Fs yr -1 . Furthermore, it is suggested that marine aerosol plays an important role in scavenging atmospheric contaminants.
Air samples were taken concurrently for four sampling events in the winter of 1998 at three contr... more Air samples were taken concurrently for four sampling events in the winter of 1998 at three contrasting sites: an urban center and two rural sites. The rural sites were characterized by the extensive usage of coal and wood for space heating. Samples were analyzed for PCDD/Fs, PCBs, and PAHs. Recently measured octanol-air partition coefficients (K oa ) for PCDD/Fs enabled a comparison of the K oa -based versus the subcooled liquid vapor pressure (p L )based partition model for all three compound classes. Both K oa and p L were found to be excellent descriptors of the gas-particle partitioning of PCDD/Fs, PCBs, and PAHs. However, regressions for log K p -log p L gave higher regression coefficients than for log K p -log K oa . Both models showed roughly similar relative states of equilibrium for PCDD/Fs, PCBs, and PAHs. PCBs were closest to equilibrium at the urban site. It is argued that newly released particles at the rural sites caused nonequilibrium partitioning at those sites for PCBs. PAHs were released at all sites and were, in line with expectations, approaching equilibrium. The K oa -based and the p L -based model gave contradictory results for PCDD/Fs: according to the p L -model, PCDD/Fs were in equilibrium for event I but not for the other events, whereas the K oa -model showed the PCDD/ Fs not being in equilibrium for event I. A simple K oa -model, combining advective transport and locally released PCDD/ Fs and PAHs, can explain the observed nonequilibrium partitioning for the first sampling event.
Surface water and atmospheric samples were collected across the tropical Atlantic Ocean on a tran... more 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.
Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large ... more Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large section of the tropical Atlantic suggested net volatilization of PCBs to the atmosphere. Only for the higher chlorinated PCB 153 and hexachlorobenzene (HCB) were gradients near equilibrium detected. The use of passive samplers also enabled the detection of dichlorodiphenyltrichloroethane (DDT) and its transformation products across the tropical Atlantic, indicating net deposition. There were clear differences between the southern and northern hemisphere apparent in terms of atmospheric concentrations: Once the ship moved from the southern into the northern hemisphere air, concentrations of HCB and other organochlorine pesticides increased several-fold. For large swaths of the tropical Atlantic Ocean, neither PCB nor organochlorine pesticide dissolved concentrations varied much longitudinally, probably due to efficient mixing by ocean currents. In selected samples, dissolved concentrations reflected the influence of river plumes and major ocean currents far away from the continents. Dissolved concentrations of PCBs 28, 52, 101, 118, and HCB increased in the Amazon plume and the Gulf Stream. While the Amazon plume flushed only a few kg of PCBs and HCB, the Gulf Stream is potentially delivering tons of PCBs into the North Atlantic annually.
The environmental distribution and fate of microplastic in the marine environment represents a po... more The environmental distribution and fate of microplastic in the marine environment represents a potential cause of concern. One aspect is the influence that microplastic may have on enhancing the transport and bioavailability of persistent, bioaccumulative, and toxic substances (PBT). In this study we assess these potential risks using a thermodynamic approach, aiming to prioritize the physicochemical properties of chemicals that are most likely absorbed by microplastic and therefore ingested by biota. Using a multimedia modeling approach, we define a chemical space aimed at improving our understanding of how chemicals partition in the marine environment with varying volume ratios of air/water/organic carbon/polyethylene, where polyethylene represents a main group of microplastic. Results suggest that chemicals with log KOW > 5 have the potential to partition >1% to polyethylene. Food-web model results suggest that reductions in body burden concentrations for nonpolar organic chemicals are likely to occur for chemicals with log KOW between 5.5 and 6.5. Thus the relative importance of microplastic as a vector of PBT substances to biological organisms is likely of limited importance, relative to other exposure pathways. Nevertheless, a number of data-gaps are identified, largely associated with improving our understanding of the physical fate of microplastic in the environment.
The extent to which different manufacturing sources and long-range transport pathways contribute ... more The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.
Polyethylene (PE)-water equilibrium partitioning constants, K(PEw), were reviewed for trace hydro... more Polyethylene (PE)-water equilibrium partitioning constants, K(PEw), were reviewed for trace hydrophobic organic contaminants (HOCs). Relative standard deviations were <30% for phenanthrene, anthracene, fluoranthene, and pyrene implying excellent reproducibility of K(PEw) across laboratories and PE sources. Averaged K(PEw) values of various HOCs were best correlated with aqueous solubility, logC(w)(sat)(L): logK(PEw) = -0.99(±0.029)logC(w)(sat)(L) + 2.39(±0.096) (r(2) = 0.92, SE = 0.35, n = 100). For 80% of analytes, this equation predicted logK(PEw) within a factor of 2. A first-order estimation of K(PEw) can be obtained assuming constant solubility of the compounds in the PE, such that the variation in C(w)(sat)(L) determines the differences in K(PEw). For PE samplers, K(PEw) values do not change with the thickness of the PE sampler. The influence of temperature on K(PEw) seems dominated by solubility-changes of the compound in water, not in PE. The effect of salt is rather well understood, using a Schetschenow-style approach. The air-PE partitioning constant, K(PEa), can be approximated as the ratio of K(PEw)/K(aw) (the air-water partitioning constant). A critical review of diffusivities in PE, D(PE), suggests that best results are obtained when using the film-stacking method. A good correlation is then found between D(PE) and molar volume, V(m) (Ǻ(3)/mol): logD(PE) (m(2)/s) = 0.0145(±0.001)V(m) + 10.1(±0.20) (r(2) = 0.76, SE = 0.24, n = 74).
To be able to use polyethylene passive samplers (PE) in the field, the partitioning constants bet... more To be able to use polyethylene passive samplers (PE) in the field, the partitioning constants between PE and water (K PEw ) of the compounds examined must be known. The K PEw s of triclosan (TCS), methyl-triclosan (MTCS), n-nonylphenol (n-NP), nonylphenol-technical mix (NP-tech), n-octylphenol (n-OP), and t-octylphenol (t-OP) were measured as a function of pH, temperature, and salinity, and a salt effect was calculated for TCS, n-OP, and t-OP. Log K PEw s used for calculating dissolved concentrations were taken from 20°C studies taking salt into account: 3.42 (TCS), 4.53 (MTCS), 4.20 (n-NP), 3.69 (n-OP), and 2.87 (t-OP). The K PEw of hydroxyl-group containing compounds were strongly affected by pH, whereas MTCS with its methoxy-group was not. Measured K PEw s could not be estimated from octanol-water partitioning constants due to the semipolar makeup of the compounds investigated. Instead, a good correlation (K PEw = 0.679 Â K hdw þ 1.033, r 2 = 0.984, p = 0.001) was obtained with hexadecane-water partitioning constants (K hdw ) predicted from COSMOtherm. During deployments in Narragansett Bay (RI) in the fall of 2009, concentrations of MTCS and t-OP in surface and bottom waters ranged from 40-225 pg L -1 and 3.5-11 ng L -1 , respectively. These concentrations are far below EC 50 values for rainbow trout. Surface/bottom and bottom/porewater activity ratios were calculated. These indicated surface waters as the main source of MTCS, while surface water as well as sediments were sources of t-OP.
Air samples were taken onboard the RRS Bransfield on an Atlantic cruise from the United Kingdom t... more Air samples were taken onboard the RRS Bransfield on an Atlantic cruise from the United Kingdom to Halley, Antarctica, from October to December 1998, with the aim of establishing PCB oceanic background air concentrations and assessing their latitudinal distribution. Great care was taken to minimize pre-and post-collection contamination of the samples, which was validated through stringent QA/ QC procedures. However, there is evidence that onboard contamination of the air samples occurred, following insidious, diffusive emissions on the ship. Other data (for PCBs and other persistent organic pollutants (POPs)) and examples of shipboard contamination are presented. The implications of these findings for past and future studies of global POPs distribution are discussed. Recommendations are made to help critically appraise and minimize the problems of insidious/diffusive shipboard contamination.
Surface seawater and boundary layer atmospheric samples were collected on the FS Polarstern durin... more Surface seawater and boundary layer atmospheric samples were collected on the FS Polarstern during cruise ARKXX in the North Atlantic and Arctic Ocean in 2004. Samples were analyzed for persistent organic pollutants (POPs), with a focus on organochlorine pesticides, including hexachlorocyclohexanes (HCHs), chlordanes, DDTs, hexachlorobenzene (HCB), and polycyclic aromatic hydrocarbons. In addition, the enantiomer fractions (EFs) of pesticides, notably R-HCH and cischlordane (CC), were determined. Concentrations of dissolved HCB increased from near Europe (∼ 1-2 pg/L) toward the high Arctic (4-10 pg/L). For dissolved HCB, strongest correlations were obtained with the average air or water temperature during sampling, not latitude. In the western Arctic Ocean, surface waters with elevated concentrations of HCB (5-10 pg/ L) were flowing out of the Arctic Ocean as part of the East Greenland current. In contrast to dissolved compounds, atmospheric POPs did not display trends with temperature. Air-water exchange gradients suggested net deposition for all compounds, though HCB was closest to air-water equilibrium. EFs for R-HCH in seawater ranged from 0.43 to 0.50, except for two samples from 75°N in the East Greenland Sea, with EFs of 0.31 and 0.37. Lowest EF (0.47) for CC were also at 75°N, other samples had EFs from 0.49 to 0.52. It is suggested that samples from around 75°N in the Greenland Gyre represented a combination of surface and older/deeper Arctic water. FIGURE 5. Ratio of OCPs, PAH, and PCB concentrations near the pole versus near Europe as a function of subcooled liquid vapor pressure.
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Papers by Rainer Lohmann