European experience in chemicals management: integrating science into policy.

The European Union (EU) adopted the first legislation on chemicals management in 1967 with the Dangerous Substances Directive (DSD). Over time the underlying concepts evolved: from hazard identification over risk assessment to safety assessment. In 1981 a premarketing notification scheme was introduced. Approximately 10 years later a risk assessment program started for existing substances following a data collection and prioritization exercise. Integration of science into EU chemicals legislation occurred via several technical committees managed by the European Chemicals Bureau (ECB) and resulted in the Technical Guidance Document on Risk Assessment (TGD), which harmonized the risk assessment methodology. The TGD was revised several times to adapt to scientific developments. The revision process, and the risk assessments for new and existing substances, led to scientific research on chemical risk assessment and thus increased in complexity. The new EU chemicals policy REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) builds on previous experiences and aims to further enhance health and safety. REACH places the burden of proof for chemical safety on industry focusing on managing risks. REACH formalizes the precautionary principle. Furthermore, it underlines a continued scientific underpinning in its implementation, also via stakeholder involvement, and a focus on aligning with international fora.

Seasonality of PCDD/Fs in the ambient air of Malopolska region, southern Poland.

BACKGROUND, AIM, AND SCOPE: The aim of the study was to identify the impact of polychlorinated dibenzo-p-dioxin and furan (PCDD/F) emission sources on ambient air concentrations in the Malopolska Region, southern Poland. Three sites were selected: the city center of Krakow (Aleje), an industrial area (Nova Huta), and a rural site (Zakopane). In order to investigate the annual variations of PCDD/F sources, summer and winter time samples were taken. MATERIALS AND METHODS: Ambient air particulate matter (PM10) was collected using an Anderson High-Volume sampler during June and December 2002 in the three mentioned sites. Analysis of PCDD/Fs was based on isotope dilution using high-resolution gas chromatography-high-resolution mass spectrometry for quantification. RESULTS AND DISCUSSION: Total concentrations of 2,3,7,8-PCDD/Fs in air particulate phase from Malopolska region ranged from 0.6 to 37 pg m(-3) (0.04-3.2 pg WHO(98)-TEQ per cubic meter, 0.037-2.9 pg I-TEQ per cubic meter). Higher PCDD/F concentrations were measured at all three sites during winter. A linear correlation among PCDD/F concentrations, benzo(a)pyrene (B(a)P) and PM10 concentrations, was found in Aleje and Zakopane, which suggested that all compounds were originating from the same source, solid fuel domestic heating. Instead, PCDD/F levels in Nova Huta did not correlate with the seasonality of B(a)P or PM10 levels and 2,3,7,8-PCDD/F congener patterns for this site were significantly different from the other sites. CONCLUSIONS: Domestic solid fuel combustion is likely the main PCDD/F source in winter in this part of Poland for urban and rural sites. PCDD/F fingerprints in the industrial site remained almost identical during summer and winter, confirming the yearly prevalence of the emissions from the nearby metal industry. RECOMMENDATIONS AND PERSPECTIVES: PCDD/F concentrations found in Malopolska Region are in the upper range of ambient air concentrations of PCDD/Fs reported worldwide. However, further research is needed in order to study the impact of the deposition of these PCDD/F emissions on the region. A more extended study is being conducted in the area to analyze soil samples, such as sink of atmospheric deposition, and spruce needles, as indicator of PCDD/F availability.

Seasonal air-water exchange fluxes of polychlorinated biphenyls in the Hudson River Estuary.

Polychlorinated biphenyls (PCBs) were measured in the air and water over the Hudson River Estuary during six intensive field campaigns from December 1999 to April 2001. Over-water gas-phase SigmaPCB concentrations averaged 1100 pg/m3 and varied with temperature. Dissolved-phase SigmaPCB concentrations averaged 1100 pg/L and displayed no seasonal trend. Uncertainty analysis of the results suggests that PCBs with 5 or fewer chlorines exhibited net volatilization. The direction of net air/water exchange could not be determined for PCBs with 6 or more chlorines. Instantaneous net fluxes of SigmaPCBs ranged from +0.2 to +630 ng m(-2) d(-1). Annual fluxes of SigmaPCBs were predicted from modeled gas-phase concentrations, measured dissolved-phase concentrations, daily surface water temperatures and wind speeds. The net volatilization flux was +62 microg m(-2) yr(-1), corresponding to an annual loss of +28 kg/yr of SigmaPCBs from the Hudson River Estuary for the year of 2000.

Occurrence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Lake Maggiore (Italy and Switzerland).

Samples of air (gas and particulate phases), bulk deposition, aquatic settling material and sediments were collected in Lake Maggiore (LM) in order to determine their content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Air (gas and particulate phases) concentrations were 0.5 pg m(-3), 80 pg m(-3), 13 pg m(-3) and 106 pg m(-3) for SigmaPCDD/Fs, SigmaPCBs, Sigma dioxin-like PCBs (DL-PCBs) and SigmaPBDEs, respectively. Deposition fluxes ranged from 0.7 ng m(-2) d(-1) for SigmaPCDD/Fs to 32 ng m(-2) d(-1) for SigmaPCBs. Aquatic settling material presented concentrations of 0.4 ng g(-1) dry weight (dw) for SigmaPCDD/Fs, 13 ng g(-1) dw for SigmaPCB, 3.4 ng g(-1) dw for SigmaDL-PCBs and 5.7 ng g(-1) dw for SigmaPBDEs. Mean sediment concentrations were 0.4 ng g(-1) dw for SigmaPCDD/Fs, 11 ng g(-1) dw for SigmaPCB, 3 ng g(-1) dw for SigmaDL-PCBs and 5.1 ng g(-1) dw for SigmaPBDEs. Similar PCDD/F and DL-PCB congener patterns in all the environmental compartments of LM point to an important, if not dominant, contribution of atmospheric deposition as source of these pollutants into LM. In contrast, PBDE congener distribution was not similar in the different environmental compartments. BDE 47 dominated air and settling material, while BDE 209 was the predominant congener in the bulk atmospheric deposition. Moreover, sediments showed two distinct PBDE congener profiles. Lower PBDE concentrated sediments were dominated by congeners 47 and 99, while BDE 209 dominated in higher PBDE concentrated samples. This suggests the influence of local sources as well as atmospheric input of PBDEs into LM.

LC-MS-MS analysis and occurrence of octyl- and nonylphenol, their ethoxylates and their carboxylates in Belgian and Italian textile industry, waste water treatment plant effluents and surface waters.

Alkylphenols (APs), alkylphenol ethoxylates (APEOs), ethoxycarboxylate metabolites (APECs) and bisphenol A were determined in surface water using solid-phase extraction (SPE) followed by triple-quadrupole LC-MS-MS. APs were separated by LC from APECs using an acetonitrile-water-gradient without the addition of any buffer. Nonylphenol ethoxycarboxylates (NPECs) interfere in the detection of nonylphenols (NPs) when using an acidic mobile phase, because they produce the same MS-MS fragment ions (219>133 and 147). 4n-NP shows the characteristic transition 219>106; it is well suited as internal standard. Nonylphenol ethoxylates NPE(n)Os (n=1-17) were analysed separately in a second run by positive ionization using an ammonium acetate mobile phase. Textile industry discharges, the corresponding wastewater treatment plant (WWTP) effluents and the receiving rivers in Belgium and Italy were analysed. Among the substances investigated, NPE1C and NPE2O exhibited the highest concentrations in the water samples, up to 4.5 microg l(-1) NPE1C in a WWTP effluent and 3.6 microg l(-1) NPE2O in a river. The highest NP levels were found in the receiving rivers (max. 2.5 microg l(-1)). The predicted no-effect concentration (PNEC) for NP of 0.33 microg l(-1) for water species was frequently exceeded in the surface waters investigated, suggesting potential adverse effects to the aquatic environment.

Direct and indirect atmospheric deposition of PCBs to the Delaware River watershed.

Atmospheric deposition can be an important source of PCBs to aquatic ecosystems. To develop the total maximum daily load (TMDL) for polychlorinated biphenyls (PCBs) for the tidal Delaware River (water-quality Zones 2-5), estimates of the loading of PCBs to the river from atmospheric deposition were generated from seven air-monitoring sites along the river. This paper presents the atmospheric PCB data from these sites, estimates direct atmospheric deposition fluxes, and assesses the importance of atmospheric deposition relative to other sources of PCBs to the river. Also, the relationship between indirect atmospheric deposition and PCB loads from minor tributaries to the Delaware River is discussed. Data from these sites revealed high atmospheric PCB concentrations in the Philadelphia/Camden urban area and lower regional background concentrations in the more remote areas. Wet, dry particle, and gaseous absorption deposition are estimated to contribute about 0.6, 1.8, and 6.5 kg year-(-1) sigmaPCBs to the River, respectively, exceeding the TMDL of 0.139 kg year(-1) by more than an order of magnitude. Penta-PCB watershed fluxes were obtained by dividing the tributary loads by the watershed area. The lowest of these watershed fluxes are less than approximately 1 ng m(-2) day(-1) for penta-PCB and probably indicates pristine watersheds in which PCB loads are dominated by atmospheric deposition. In these watersheds, the pass-through efficiency of PCBs is estimated to be on the order of 1%.

Mercury emissions from cement-stabilized dredged material.

Upland placement of dredged materials from navigation channels in the New York/New Jersey Harbor is currently being used to manage sediments deemed inappropriate for open water disposal. Although upland placement sites are equipped with engineering controls (leachate collection and/or barrier walls), little is known of the potential impacts of this approach to air quality. The aim of this study was to estimate the flux of mercury to the atmosphere from New York/New Jersey Harbor stabilized dredged material (SDM) that was used for land reclamation at a site in northeastern New Jersey. Total gaseous mercury (TGM) was measured at a site receiving SDM in August and October 2001 and May and November 2002. TGM was also monitored at an urban reference site 3.5 km west of the SDM site in September 2001 and from February 2002 to July 2002 and from October 2002 to February 2003. The concentration of TGM at the urban reference site averaged 2.2 +/- 1.1 ng m(-3), indicating some local contribution to the Northern Hemisphere background. TGM concentrations exhibited seasonality with the highest values in summer (3.3 +/- 2.1 ng m(-3) in June 2002) and the lowest in winter (1.7 +/- 0.6 ng m(-3) in January 2003). TGM concentrations at the SDM placement site ranged from 2 to 7 ng m(-3) and were significantly higher (p < 0.001) than those at the urban reference site. Sediment-air fluxes of Hg at the SDM placement site estimated by the micrometeorological technique ranged from -13 to 1040 ng m(-2) h(-1) (sediment to air fluxes being positive) and were significantly correlated to solar radiation (r2 = 0.81). The estimated contribution of Hg emissions from land-applied SDM to local TGM concentrations was found to be negligible (<4%). However, the estimated annual volatilization rate of TGM atthe SDM site (130 kg y(-1))was comparable to those of other industrial sources in New Jersey (140-450 kg y(-1)).

Atmospheric concentrations and deposition of polycyclic aromatic hydrocarbons to the Mid-Atlantic East Coast region.

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured at urban/industrial, suburban, coastal, and rural areas in New Jersey as part of the New Jersey Atmospheric Deposition Network. Concentrations of 36 PAH compounds were measured in the gas and particle phases in air and in precipitation at nine sites at regular intervals from October 1997 through May 2001. Gas-phase and particle-phase sigma36PAH concentrations ranged from 0.45 to 118 ng m(-3) and from 0.046 to 172 ng m(-3), respectively, and precipitation concentrations ranged from 11 to 16200 ng L(-1). PAH concentrations vary spatially across the region, with the highest concentrations occurring at the most heavily urban and industrial locations. Average gas absorption deposition ranged from 0.004 (naphthacene) to 5040 (methylphenanthrenes) ng m(-2) d(-1), and dry particle deposition PAH fluxes ranged from 0.11 (naphthacene) to 300 (benzo[b+k]fluoranthene) ng m(-2) d(-1) at the nine sites. Average atmospheric wet deposition PAH fluxes at the seven sites ranged from 0.40 (cyclopenta[cd]pyrene) to 140 (methylphenanthrenes) ng m(-2) d(-1). These represent the first comprehensive estimates of PAH deposition to New Jersey and the Mid-Atlantic East Coast.

Chlordanes in the mid-Atlantic atmosphere: New Jersey 1997-1999.

To characterize the atmospheric dynamics and behavior of chlordane compounds in the mid-Atlantic region of the United States, atmospheric concentrations were measured in 1997-1999 at three New Jersey locations as part of the New Jersey Atmospheric Deposition Network (NJADN) project. Observed concentrations of sigma-chlordanes (cischlordane + trans-chlordane + cis-nonachlor + transnonachlor) are log-normally distributed, with a geometric mean concentration of 77.1 pg m(-3) and range from 6.1 to 481 pg m(-3). Gas-phase species comprised 83% (+/-23%) of the sigma-chlordanes species across all samples at all location. Gas-phase sigma-chlordane concentrations are inversely proportional to temperature, with higher concentrations during periods of warmer air temperatures. Observed concentrations do not correlate with wind direction or air mass history, which suggests that observed concentrations in the New Jersey atmosphere are due to volatilization from soils and surfaces on the regional scale.

Chlordanes in the indoor and outdoor air of three U.S. cities.

Indoor and outdoor concentrations of six chlordane components (trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, oxychlordane, and MC5) were measured at 157 residences, all of which were inhabited by nonsmoking individuals, in three urban areas during June 1999-May 2000. The analyses were conducted on a subset of 48 h integrated samples collected in Los Angeles County, CA, Houston, TX, and Elizabeth, NJ within the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study. Both particle-bound (PM2.5; quartz fiber filter) and vapor-phase (PUF sorbant) chlordane concentrations were separately measured by GC/EI MS after solvent extraction. The outdoor (gas + particle) total chlordane (trans-chlordane + cis-chlordane + trans-nonachlor + cis-nonachlor) concentrations ranged from 0.036 to 4.27 ng m(-3) in Los Angeles County, from 0.008 to 11.00 ng m(-3) in Elizabeth, and from 0.062 to 1.77 ng m(-3) in Houston. The corresponding indoor total chlordane concentrations ranged from 0.037 to 112.0 ng m(-3) in Los Angeles County, from 0.260 to 31.80 ng m(-3) in Elizabeth, and from 0.410 to 38.90 ng m(-3) in Houston study homes. Geometric mean concentrations were higher in indoor air than outdoor air (1.98 vs 0.58 ng m(-3) in CA; 1.30 vs 0.17 ng m(-3) in NJ; 4.18 vs 0.28 ng m(-3) in TX), which suggests there are significant indoor sources of chlordane species in a subset of homes in each of the three cities. Calculated source strengths relate to home age, with the highest apparent indoor source strengths occurring in unattached single-family homes built during the period from 1945 to 1959. Principle indoor sources of chlordanes likely include volatilization from residues of indoor application of chlordanes and infiltration from subsurface and foundation application of chlordane-containing termiticides during home construction.

Persistent organic pollutants in dusts that settled indoors in lower Manhattan after September 11, 2001.

The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol impacting many residents, workers, and commuters after September 11, 2001. In all, 12 bulk samples of the settled dust were collected at indoor locations surrounding the epicenter of the disaster, including one sample from a residence that had been cleansed and was once again occupied. Additionally, one sample was collected from just outside a fifth story window on the sill. These samples were analyzed for many components, including inorganic and organic constituents as well as morphology of the various particles. The results of the analyses for persistent organic pollutants on dusts that settled at indoor locations are described herein, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and select organo-chlorine pesticides. The Sigma(86)-PCB concentrations, comprising less than one part per million by mass of the bulk in the two samples analyzed, indicated that PCBs were of limited significance in the dust that settled at indoor locations across lower Manhattan. Likewise, organo-chlorine pesticides, Hexachlorobenzene, Heptachlor, 4,4'-DDE, 2,4'-DDT, 4,4'-DDT and Mirex were found at even lower concentrations in the bulk samples. Conversely, Sigma(37)-PAHs comprised up to 0.04% (<0.005-0.036%) by mass of the bulk indoor dust in the 11 WTC impacted bulk indoor samples. Analysis of one sample of indoor dusts collected from a vacuum cleaner of a rehabilitated home shows markedly lower PAH concentrations (<0.0005 mass%), as well as differing relative contributions for individual compounds. In addition to similar concentrations, comparison of PAH concentration patterns (i.e. chemical fingerprints) shows that dusts that settled indoors are chemically similar to previously measured WTC dusts found at outdoor locations and that these PAH analyses may be used in identifying dusts of WTC origin at indoor locations, along with ascertaining further needs for cleaning.

Multi-component analysis of polar water pollutants using sequential solid-phase extraction followed by LC-ESI-MS.

A multi-component screening analysis method for polar to medium-polar water pollutants was developed. Sample clean-up and group separation are performed by sequential solid-phase extraction (SSPE) using automated SPE with C18 and polymeric sorbent materials. Analyses are performed by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) using a single-quadrupole instrument. More than 90 priority compounds of environmental interest--comprising the most important chemical and substance classes: phenols, carboxylic acids, aromatic sulfonates, aromatic amines, pharmaceuticals, surfactants, dyes, and pesticides--have been chosen for the experiments. The compounds are divided by the SSPE procedure into 3 different polarity classes. The extraction recoveries were determined in the 3 fractions for every single substance, and were for most of the analytes in the range of 50-100%. A mixture of hexane-dichloromethane was used for the elution of nonpolar compounds like alkylphenols from C18. Methanol and acetone are well suited for the elution of more polar substances. The limits of detection (LODs) were determined for all compounds. Effluents from municipal and industrial wastewater treatment plants (WWTPs) treating waste water from textile industries; and the corresponding receiving waters (rivers and lakes) have been analysed with the developed method. Urban and industrial pollution was observed in rivers and streams in the area north of Milan, Italy. In the water samples different phenols (nitrophenols, bisphenol A, nonylphenol), alkylphenol ethoxylate surfactants, their metabolites with endocrine disrupting potential, aromatic sulfonates, linear alkylbenzenesulfonate surfactants, dyes, pesticides, pharmaceuticals, and a dichlorobenzidine compound were identified.

Reevaluation of air-water exchange fluxes of PCBs in Green Bay and southern Lake Michigan.

Air-water exchange of persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) is an import process for the delivery of contaminants to water bodies, as well as for their removal, and is thus a pivotal parameter in the construction of mass balances in aquatic systems. Simultaneous measurements of PCB concentrations in the gas and dissolved phases conducted in Green Bay in 1989 and in southern Lake Michigan in 1994-1995 were used to estimate air-water exchange fluxes. In this work, improved Henry's law constants for PCBs and new mass-transfer rates across the air-water interface were used to update the previous calculations. The new model calculations suggest that the net volatilization flux of PCBs out of Green Bay ranges from +170 to +5300 ng m(-2) day(-1), which is 2-20 times larger than previous estimates. The flux of PCBs in southern Lake Michigan exhibits net volatilization of +0.5 to +230 ng m(-2) day(-1) throughout the study period (May and July 1994, January 1995), whereas previous estimates reported that the net flux was seasonally absorptive. Thus, water-to-air fluxes are more important for the removal of PCBs from both Green Bay and Lake Michigan than previously recognized.

Oceanic biogeochemical controls on global dynamics of persistent organic pollutants.

Understanding and quantifying the global dynamics and sinks of persistent organic pollutants (POPs) is important to assess their environmental impact and fate. Air-surface exchange processes, where temperature plays a central role in controlling volatilization and deposition, are of key importance in controlling global POP dynamics. The present study is an assessment of the role of oceanic biogeochemical processes, notably phytoplankton uptake and vertical fluxes of particles, on the global dynamics of POPs. Field measurements of atmospheric polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), and furans (PCDFs) are combined with remote sensing estimations of oceanic temperature, wind speed, and chlorophyll, to model the interactions between air-water exchange, phytoplankton uptake, and export of organic matter and POPs out of the mixed surface ocean layer. Deposition is enhanced in the mid-high latitudes and is driven by sinking marine particulate matter, rather than by a cold condensation effect. However, the relative contribution of the biological pump is a function of the physical-chemical properties of POPs. It is concluded that oceanic biogeochemical processes play a critical role in controlling the global dynamics and the ultimate sink of POPs.

Wet deposition of polychlorinated biphenyls in urban and background areas of the Mid-Atlantic States.

Spatial and temporal trends of polychlorinated biphenyl (PCB) concentrations in precipitation were measured at urban and background sites as part of the New Jersey Atmospheric Deposition Network (NJADN). The volume weighted mean concentration (VWM) of sigmaPCBs (sum of PCBs) based on precipitation measurements at three background sites was in the range of 0.30-0.50 ng/L. Concentrations in precipitation at two urban-industrial sites were on average 7-43 times higher than background concentrations. Wet deposition fluxes of sigmaPCBs at the two urbanized sites were 16 +/- 3.4 and 3.9 +/- 0.72 microg/m2-yr, while the background flux was approximately 0.30 microg/m2-yr. On average, 97% of the total atmospheric washout (WT) of PCBs resulted from particle scavenging. The fraction of atmospheric PCBs on particles was the best predictor of atmospheric washout in both urban (log WT = 0.71 (+/- 0.049) log psi + 4.9 (+/- 0.11); r2 = 0.81) and nonurban areas (log W(T) = 0.77 (+/- 0.083) log psi + 5.6 (+/- 0.16); r2 = 0.64). Wet deposition fluxes of sigmaPCBs are of the same order of magnitude as dry-particle deposition fluxes in all land-use regimes.

Polycyclic aromatic hydrocarbons in the indoor and outdoor air of three cities in the U.S.

The indoor and outdoor concentrations of 30 polycyclic aromatic hydrocarbons (PAHs) were measured in 55 nonsmoking residences in three urban areas during June 1999-May 2000. The data represent the subset of samples collected within the Relationship of Indoor, Outdoor, and Personal Air study (RIOPA). The study collected samples from homes in Los Angeles, CA, Houston, TX, and Elizabeth, NJ. In the outdoor samples, the total PAH concentrations (sigmaPAH) were 4.2-64 ng m(-3) in Los Angeles, 10-160 ng m(-3) in Houston, and 12-110 ng m(-3) in Elizabeth. In the indoor samples, the concentrations of sigmaPAH were 16-220 ng m(-3) in Los Angeles, 21-310 ng m(-3) in Houston, and 22-350 ng m(-3) in Elizabeth. The PAH profiles of low molecular weight PAHs (3-4 rings) in the outdoor samples from the three cities were not significantly different. In contrast, the profiles of 5-7-ring PAHs in thesethree citieswere significantlydifferent, which suggested different dominant PAH sources. The signatures of 5-7-ring PAHs in the indoor samples in each city were similar to the outdoor profiles, which suggested that indoor concentrations of 5-7-ring PAHs were dominated by outdoor sources. Indoor-to-outdoor ratios of the PAH concentrations showed that indoor sources had a significant effect on indoor concentrations of 3-ring PAHs and a smaller effect on 4-ring PAHs and that outdoor sources dominated the indoor concentrations of 5-7-ring PAHs.

Evidence for destruction of PCBs by the OH radical in urban atmospheres.

Evidence for reaction of polychlorinated biphenyl (PCB) congeners with the hydroxyl (OH) radical in the troposphere was observed in diurnal variations in ambient gas-phase PCB concentrations at three urban sampling sites located in the Chicago, IL; Baltimore, MD; and Jersey City, NJ urban/industrial areas. The magnitude of the depletion of individual PCB congeners decreased by about 10-20% for each additional chlorine substituent, reflecting slower reaction rates for higher MW congeners with the OH radical. Octa- and nonachlorobiphenyls, which are largely unreactive with the OH radical, were used as tracers to investigate the effects of dilution on diurnal variation. The environmental rate constants for disappearance of the PCBs range from about 1.0 day(-1) for trichlorobiphenyls to about 0.3 day(-1) for hexachlorobiphenyls. Assuming a OH radical concentration of 3 x 10(6) molecules cm (-3), the second-order rate constants for reaction of specific congeners with the OH radical are consistent with laboratory measurements. More importantly, the relative reactivity of PCB homologues agrees well with the relationship predicted by other researchers from laboratory measurements, suggesting that losses of PCBs during daytime tropospheric transport are due at least in part to reactions with the OH radical.

Air-water exchange of polycyclic aromatic hydrocarbons in the New York-New Jersey, USA, Harbor Estuary.

Polycyclic aromatic hydrocarbons (PAHs, n = 36) were measured in the gas and particle phases in the atmosphere and the dissolved and particle phases in the waters of the New York-New Jersey Harbor Estuary, USA, during a weeklong intensive field campaign in July 1998. Mean total (gas + particulate) phenanthrene and pyrene concentrations were 3.3 and 0.33 ng/m3, respectively, over Raritan Bay, and 14 and 1.1 ng/ml, respectively, over New York Harbor. Similar PAH profiles (p values < 0.01) in the atmospheric gas phase and the dissolved phase in water demonstrate the close coupling of the air and water compartments. Air-water exchange fluxes of PAHs estimated using shore-based air data lead to erroneous flux estimates when compared to those derived using over-water air samples. The gross absorptive air-water flux dominates atmospheric loadings (wet, dry particle, gas absorption) to the estuary for PAHs of molecular weight < 234 g/mol. Dry particle deposition is increasingly more important for the higher-molecular-weight, particle-bound PAH species. Gross volatilization dominates gross absorption for the majority of PAHs in the New York-New Jersey Harbor Estuary.