The Northern Contaminants Program (NCP) baseline monitoring project was established in 1992 to monitor for persistent organic pollutants (POPs) in Arctic air. Under this project, weekly samples of air were collected at four Canadian and two Russian arctic sites, namely Alert, Nunavut; Tagish, Yukon; Little Fox Lake, Yukon; Kinngait, Nunavut; Dunai Island, Russia and Amderma, Russia. Selected POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides, were analyzed in both the gas and particulate phases. This paper summarizes results obtained from this project in the past 5 years. Temporal trends were developed for atmospheric PCBs and OCs observed at Alert using a digital filtration (DF) technique. It was found that trends developed with 5 years of data (1993–1997) did not differ significantly from those determined with 7 years of data (1993–1999). This implies that with the DF technique, long-term trends can still be developed with less than 10 years of data. An acceleration in decline of OC and PCB air concentrations was noted in 1999 for some compounds, although the reason is unknown. Monitoring efforts must continue to assess the effect of this decline on the long-term trends of POPs in the Canadian Arctic. Occasional high trans-/cis-chlordane ratios and heptachlor air concentrations measured at Alert between 1995 and 1997 suggests sporadic fresh usage of chlordane-based pesticides. However, significant decreasing trends of chlordanes along with their chemical signatures has provided evidence that emission of old soil residues is replacing new usage as an important source to the atmosphere. Measurements of OC air concentrations conducted at Kinngait in 1994–1995 and 2000–2001 indicated faster OC removal at this location than at Alert. This may be attributed to the proximity of Kinngait to temperate regions where both biotic and abiotic degradation rates are faster. The PAH concentrations observed at Alert mimic those at mid-latitudes and are consistent with long-range transport to the Arctic, particularly for the lighter PAHs. A decline in particulate PAH was observed, similar to atmospheric sulphate aerosol and can be attributed to the collapse of industrial activity in the former Soviet Union between 1991 and 1995. Spatial comparisons of OC seasonality at Alert, Tagish, Dunai and Kinngait show elevated air concentrations of some compounds in spring. However, elevated spring concentrations were observed for different compounds at different sites. Potential causes are discussed. Further investigation in the atmospheric flow pattern in spring which is responsible for the transport of POPs into the Arctic is required. OC and PCB air concentrations at Alert were found to be influenced by two climate variation patterns, the North Atlantic Oscillation (NAO) and the Pacific North American (PNA) pattern. Planetary atmospheric patterns must be taken into account in the global prediction and modelling of POPs in the future.

The initial emission rate of volatile organic compounds (VOCs) from consumer products is important for assessing potential human exposure to VOCs in products. The vapor pressure and boundary layer (VB) model developed in the past was used to predict the emission rates of VOCs in the fast decaying phase from petroleum-based wet materials. This study has extended the model to largely water-based products. Study results have shown a good agreement (ratio = 1.01, r2 = 0.89) between model-predicted initial emission rates (ER0) of 2-butoxyethanol (2-BE) based on its equilibrium headspace concentration and experimentally measured ER0 in a small dynamic environmental chamber for 20 consumer products. These water-based products included wood surface treating stains, general cleaning agents, and degreasers with 2-BE concentrations over a wide range. The results also demonstrated a dependency between the headspace concentrations of the target analytes and the water content in the liquid. But dependency on water content had no effect on the use of headspace concentration to predict the ER0. The ER0 of 2-BE in the products ranged from 100 to 3000 mg m-2 h-1. In the majority of cases, the 2-BE concentration range in individual products indicated in the Material Safety Data Sheet agreed with the measured data.

Archived extracts of weekly air samples collected at remote arctic monitoring stations at Alert and Tagish, Canada, and Dunai Island, Russia, in 1994-1995 were combined into 4-week composites and analyzed for levels and seasonal trends of polychlorinated naphthalenes (PCNs) and non- and mono-ortho-substituted polychlorinated biphenyls (PCBs). Mean annual sigmaPCN concentrations were 0.69, 0.82, and 0.38 pg/m3 at Alert, Dunai, and Tagish, respectively. PCNs exhibited a seasonal trend at Alert and Dunai, with higher levels occurring during winter when air masses originating over Eurasia influence the high arctic and coincide with the haze period. Episodic, trans-Pacific transport impacted PCN concentrations at Tagish. A seasonal trend was not evident for the non-/mono-o-PCBs. The contrary PCN and non-/mono-o-PCB trends indicate that the sources of these two compound classes to arctic air differ, and that atmospheric transport from source regions has a greater influence on PCN levels than for non-/ mono-o-PCBs. PCNs apparently originating from combustion sources contribute to levels in winter, as indicated by the presence of combustion marker congeners, but evaporative emissions from source regions are likely the dominant source. PCNs contributed 71 and 75% of dioxin toxic equivalents (TEQ) relative to the non-/mono-o-PCBs at Alert and Dunai and 30% at Tagish during the winter months, demonstrating the toxicological importance of PCNs as a compound class relative to PCBs.

Temperature normalization (TN), multiple linear regression (MLR), and digital filtration (DF) were used to analyze the temporal trends of an atmospheric dataset on organochlorine pesticides (OCs) collected at the Canadian high arctic site of Alert, Nunavut. Details of these techniques have been presented before (Environ. Sci. Technol. 2001, 35, 1303-1311). Both the TN and DF methods revealed that the majority of OC pesticides declined over the 5 years of study, except endosulfan I and several of the pesticide metabolites, including dieldrin and p,p'-DDE. In comparison to studies conducted in the Great Lakes, atmospheric levels in the Arctic were less dependent on temperature, although seasonal variations were apparent. Generally, levels in the winter were lower than during the rest of the year. A notable exception was p,p'-DDE. Many compounds also showed a second minimum in concentrations during June/July and possible explanations are presented to account for this. The estimated first order half-lives for the decline in OC concentrations were generally found to be comparable or slightly longer than those obtained at temperate locations, with the exception of alpha-HCH, which displayed a much longer half-life in the Arctic (approximately 17 yrs). Sporadic increases in heptachlor as well as increases in the ratio of trans- to cis-chlordane suggest episodic input of chlordanes between 1995 and 1997, especially during the winter.

A long-term database of weekly air concentrations was examined to establish temporal trends of PCBs in the Arctic atmosphere. Several methods were employed to reduce the intra-annual variability allowing the elucidation of longterm trends for a selection of congeners at Alert located in the Canadian Arctic. These methods included temperature normalization (TN), multiple linear regression (MLR), and digital filtration (DF). Estimation of the slope (m) resulting from the linear regression between the natural logarithm of the partial pressure in air versus reciprocal temperature (In P = m/T + b), required for TN and MLR, proved difficult due to the poor correlation with temperature experienced forthe majority of congeners. Values of m were considerably lower than those obtained from temperate studies, implying that regional air-surface exchange plays a minor role in supporting the observed air concentrations in the Arctic. The lighter congeners generally showed very low slopes, and some even showed positive correlation with 1/T. This might be a result of their relatively fast reaction rates with OH radicals following the onset of 24-h sunlight in spring. Use of DF (in combination with TN and MLR) revealed declining trends for several of the lower chlorinated congeners in the high Arctic atmosphere, with estimated first-order half-lives, t1/2, ranging from approximately 3 to 20 yr. Declining trends of the lower congeners probably reflect falling levels in source regions, as a result of long-range transport to this Arctic site. There were no apparent trends for the higher chlorinated congeners (penta-substituted and above), exceptfor PCB 180, in marked contrast to temperate studies, indicating a lag time for decline between the Arctic and source regions.

Concentrations of hexachlorocyclohexanes (HCHs), chlordane, and dichlorodiphenyltrichloroethane (DDT) were measured in ambient air samples on a weekly basis between December 1992 and January 1995 at Tagish Yukon, Canada. In winter, unusually high air concentrations of HCHs, DDT, and chlordanes at Tagish were predominantly influenced by transpacific long‐range atmospheric transport from eastern Asia that generally occurred within 5 days. HCH and heptachlor epoxide concentrations were correlated with the time that air spent over eastern Asia prior to arrival at Tagish. Chlordane and DDT, which also increase with transpacific transport, do not show a correlation with the time the upwind airshed included Asia as the composition of these pesticides in the atmosphere is affected by differences in usage patterns, application methods, variable composition of parent pesticides and metabolites in the soil, and rates of volatilization. Air masses originating from North America had the highest concentrations of HCHs and chlordanes when the 5‐day upwind airshed included the western United States. Concentrations of HCHs may also be influenced by lindane usage in Canada.

Atmospheric measurements of organohalogen pesticides (OCs) have been made in both the Canadian and Russian Arctic. A full quality-controlled database of weekly samples is now available for the years 1992–94. Hexachlorobenzene (HCB) and the hexachlorocyclohexanes (HCHs) were the most predominant compounds in the atmosphere, followed by the chlordanes and endosulfan. Evidence of a seasonality in air concentrations was apparent particularly for the pesticide metabolites, compounds such as oxychlordane, heptachlor epoxide and dieldrin showing a significant positive correlation with temperature (p<0.01). An exception to this was p, p′-DDE which showed elevated levels during the winter. Large spatial differences in mean annual concentrations of most OCs were not evident; however, spatial differences were apparent in α/γ-HCH ratios between the high Arctic site of Alert and the Yukon site of Tagish. The influence of both the European sector and the regional effect of the Arctic Ocean on the high Arctic probably accounted for this difference. A decline in the trans-chlordane/cis-chlordane ratio compared to studies during the 1980s may indicate a more weathered source of chlordane to be present in the Arctic by the mid-1990s. Slopes generated from plots of partial pressure (ln P) versus 1/T for selected compounds were considerably less steep than those derived from temperate studies. It is inferred here that long-range transport has a large influence on contaminant levels in the arctic atmosphere.

In the first multi-year arctic air sampling program, PAI-ls were sampled (vapor and particulate) every week at three locations in the Canadian and Russian Arctic. Data are presented here for the years 1992-1994. The geometric mean Sigma PAH concentrations (where Sigma=16 compounds) for 1993 ranged from 249 to 508 pg/m(3) for the three sites. Clear seasonality was evident with the highest concentrations occurring during the colder months of October-April, coinciding with the arctic haze period. PAH concentrations during this period were highest in the order of Dunai (Russian) > Alert (high Arctic) > Tagish (Pacific). Air mass back trajectories computed for February 1994 revealed long-range transport from Eurasia into the high Arctic. Short periods of high concentrations were also evident during the warmer months, most notably at the Tagish site, where elevated levels of retene (a marker for soft wood combustion) matched forest fire records. Initial findings suggest that the gas/particle partitioning of some of the lighter PAHs, examined during the colder haze period, is similar to remote temperate studies and in reasonable agreement to the Junge-Pankow adsorption model.

In 1992, a long term program was established to measure the airborne concentrations of persistent organic pollutants (POPs) in the Arctic. To maximize spatial variation over a wide geographical area, three Arctic locations were selected; two sites in Canada, Alert on Ellesmere Island and Tagish in the western Yukon, and one in Russia at Dunai Island in eastern Siberia. PCB data is presented here for the years 1992-1994. Mean Sigma PCB concentrations for 1993, the year when all three sites were running simultaneously, were 27.4, 17.0, and 34.0 pg/m(3) at the Alert, Tagish, and Dunai sites, respectively. With the exception of the Tagish site in 1993, where Sigma PCB concentrations were found to be weakly correlated with mean monthly temperatures, no correlation with temperature was observed. However, changes in the homolog group profile with temperature were apparent. On an annual basis, the trichlorinated congeners made the largest single contribution to the atmospheric concentrations of Sigma PCB, however, this contribution declined with the onset of warmer months. This temperature-dependent homolog pattern was most clearly evident at Dunai, where the contribution of the pentachlorinated congeners matched or exceeded that of the trichlorinated congeners during May, June, and July of 1993. It was also evident at Alert and Tagish, but not to the same degree. Spatial and year-to-year differences at these Arctic sites were attributed to both the site's proximity to source areas (where different PCB mixtures and quantities have been used) and to the influence of air mass movement from these source regions.

The Arctic is considered a pristine environment with few direct inputs of persistent organic pollutants (POPs). However, significant concentrations of POPs have been observed in both the North American and European Arctic regions. Atmospheric circulation, ocean currents, and riverine inputs are considered the primary routes of transport for these compounds to the Arctic. A long-term measurement program has been established in the Canadian and Russian Arctic regions to measure airborne concentrations of POPs and to provide information on pathways and fates of these compounds. The first station, at Alert in the Northwest Territories of Canada, was established in January 1992, and air concentration results for a subset of compounds monitored in the first year are presented in this chapter. Seasonal variations in concentrations are similar to those observed for Arctic haze which peaks in the period from December to March, the coldest part of the year. For example, in cold periods, benzo[a]pyrene concentrations were found to average 20 pg/m(3). In contrast, during warm periods (May to September) average levels were ca. 1.0 pg/m(3). For organochlorine compounds (OCs), the seasonal cycle was not as pronounced as that for the polycyclic aromatic hydrocarbon (PAH) compounds but appears to peak in summer months. It is postulated that air concentrations may be influenced by advection from distant source regions as well as by exchange with local (Arctic Ocean) surfaces which is influenced strongly by temperatures of air and ocean surfaces. The concentrations of a subset of the compounds measured in the first year of monitoring at Alert are discussed in light of both exchange processes and long-range transport.

The Arctic is generally considered to be a pristine environment and has few direct inputs of organochlorine compounds (OCs), including pesticides, herbicides, polychlorinated biphenyls, or polycyclic aromatic hydrocarbons (PAHs). In spite of this, airborne concentrations of persistent organic pollutants (POPs) are comparable to those in more populated and industrialized regions of North America and Europe. Atmospheric transport and condensation of compounds at low temperature conditions are important factors contributing to the presence of contaminants in the Arctic. A long-term program has been established to measure the airborne concentrations of POPs in the Arctic. The first station at Alert was established in January 1992. The concentrations measured in the first year of monitoring for 18 compounds that are representative of different compound classes are presented. Seasonal variations for PAHs are similar to those for Arctic haze and peak during winter. For example, in the coldest period, October to April, benzo[a]pyrene concentrations were found to average 20 pg/m(3), whereas, in contrast, during the relatively warm May to September period, average levels were 1.0 pg/m(3). For OCs, the seasonal cycle was not as pronounced as that for PAH compounds. For example, alpha-hexachlorocyclohexane was found at Alert at average concentrations of 62 and 57 pg/m(3), respectively, during cold and warm periods. It is postulated that air concentrations are influenced by advection from distant source regions as well as exchange with local (Arctic Ocean) surfaces.

Seven different samplers were evaluated for collection of C-1-C-4 hydrocarbons in air. The passivated canister proved to be suitable for 17 target compounds and also 3 heavier hydrocarbons (hexane, benzene, and toluene). The Carbotrap(R) 200 sorbent tube was effective for sampling hydrocarbons with three or more carbons and some of the C-2 hydrocarbons.

Hexachlorocyclohexanes (HCHs) are the most abundant organochlorine pesticides in the arctic atmosphere and ocean surface water. A compilation of measurements made between 1979–93 from stations in the Canadian and Norwegian Arctic and from cruises in the Bering and Chukchi seas indicates that atmospheric concentrations of α‐HCH have declined significantly (p < 0.01), with a time for 50% decrease of about 4 y in summer‐fall and 6 y in winter‐spring. The 1992–93 levels of about 100 pg m−3 are 2–4 fold lower than values in the mid‐1980s. The trend in γ‐HCH is less pronounced, but a decrease is also suggested from measurements in the Canadian Arctic and the Bering‐Chukchi seas. HCHs in ocean surface water have remained relatively constant since the early 1980s. The decline in atmospheric α‐HCH has reversed the net direction of air‐sea gas exchange to the point where some northern waters are now sources of the pesticide to the atmosphere instead of sinks.

An organic vapour concentrator with Tenax-TA as the adsorbent or a gas- sampling valve was used in combination with a transportable gas chromato graph (GC) for measurement of indoor airborne organics in the range of 5- 15,000 μg/m3. With the gas-sampling valve, detection limits were, approxi mately 50-200 and 10-100 μg/m3 with flame ionisation (FID) and photo-ion isation detectors (PID), respectively. By substituting the concentrator for the valve, detection limits were improved significantly. The detection limits, based upon a signal-to-noise ratio of 3 : 1, were approximately 2, 3 and 4 μg/m3, respectively, for toluene, α-pinene and 1,4-dichlorobenzene with an air sample of 100 ml collected with the concentrator and analysed with the GC/FID. The respective detection limits were improved by factors of 5, 6 and 8, with the PID. Instrument response was linear over the range of 2-2,000 μg/m3 with the GC/FID and 0.2-2,000 μg/m3 with the GC/PID for the test compounds. The precision of the method determined by repeat injections of a gas standard was better than 5% relative standard deviation. The instrument response factor varied by less than 15 % over a 12-day period as determined with a certified gas mixture of test compounds.

A gas chromatography-based automated method was developed for direct aqueous injection analysis of trace gases dissolved in water samples to support studies on air-water exchange processes of chemicals. Initial efforts were focused on the determination of dissolved gases such as Ar and N-2 because of their potential to serve as ''tracer'' species (or as ''surrogates'') for the air-water exchange process. Direct injection of water samples eliminated time-consuming sample preparation procedures and enabled short analysis cycles. The method employed a GC equipped with a helium ionization detector (HID) to achieve sensitivity sufficient for water analysis with direct injection of 10 mu L water via a liquid sample valve. Analytes were isolated from the water matrix using a column switching technique prior to the separation and detection. Chromatographic separation of Ar, O-2 and N-2 was achieved with a long, 30-foot molecular sieve column. However, a short, 6-foot column combined with a chemical scrubber for O-2 was selected in order to ensure accurate quantitation of Ar and shorten the analysis cycle to 15 minutes. The precision for determination of Ar and N was 1% RSD, with a method detection limit of ca. 30 mu g/L Ar or N-2 in water and a linear range of ca. 2.5 orders of magnitude.

A nationwide study of indoor air concentrations of 26 VOCs was conducted in Canada in 1991. The study design was based upon random selection of private residences from 1986 Census data and incorporated a temporal stratification feature that allowed sampling of residences in each of four regions of the country at different times of the year with equal probability. Average 24 h concentrations of 26 VOCs in 754 residences were obtained by a passive monitoring method. Initially, climatic parameters were found to have the second highest relative weight among 14 factors identified by factor analysis. Further analysis by linear regression showed that individual VOC concentrations and average outdoor temperature or relative humidity were poorly correlated (r > 0.13). Detailed analysis of the data from four regions of Canada also gave poor correlations between household VOC concentrations and temperature or relative humidity. Concentrations of all 26 VOCs averaged 7.8 μg m−3 in winter, 10.3 μg m−3 in spring, 4.4 μg m−3 in summer and 10.8μ m−3 in fall. The highest concentrations of individual compounds averaged 84μm−3 for toluene in the spring and 42 μg m−3 in the fall, and 44 μg m−3 for decane in the spring and 48 μg m−3 in the fall. Segregation of the results into outdoor temperature ranges of ⩽ 0°C, 0–15 and > 15°C gave mean indoor VOC concentrations of 10.3, 9.8 and 50μgm−3, respectively. Further examination of the results revealed that the likely presence of sources within homes had a far greater influence on indoor concentrations than ventilation which is partly influenced by climate.

Stored extracts of passive samplers exposed in 757 randomly selected Canadian residences provided a unique opportunity for retrospective determination of the occurrence of airborne volatile organic compounds (VOCs). Aliquots of the individual extracts were pooled to form a composite exposure sample and a corresponding blank sample. To identify and quantitate potentially hazardous organics in the samples, GC-MS analyses were conducted by several approaches. The amounts of 52 target compounds in the composite sample were estimated based on selected ion monitoring (SIM) results, extraction recoveries, average air volume sampled, and 3M OVM 3500 passive sampling rates. Forty of the organics were detected and were present in amounts equivalent to airborne concentrations ranging from < 1 to 104 mu g m(-3). Several other compounds were also tentatively identified by full scan analysis. Many of the detected organics have been reported to be associated with activities such as tobacco smoking and the presence of consumer products and plastic materials indoors. The analytical results have been useful in risk assessments and establishment of a new Canadian priority substances list (PSL).