PCB and PCDD/F analysis carried out during assessments of abandoned military sites in the Canadian North allowed an opportunity to test the utility of multivariate statistical techniques in the assignment of source signatures to contaminated soil samples. A combination of principal component analysis (PCA) and polytopic vector analysis (PVA) was used to assess the inputs of PCDD/Fs to soils along with source signatures obtained from the literature. The composition of background samples obtained at least 20 km from any local source contamination showed a clear correlation with combustion sources. Soil samples taken in the vicinity of the military sites showed evidence of PCDD/F contamination associated with the extensive use and spillage of PCBs in transformer fluids and the use of chlorophenols as wood preservatives. There was evidence that significant changes in signature occur with distance from the source. The results of the statistical analysis in assigning source signatures agreed well with field observations.

The results of a PCB weathering experiment (i.e., losses from soil and changes in PCB composition from soil over time) at Cambridge Bay, Northwest Territories, in the Canadian Arctic are presented. Nine plots representing three different general substrate types (dry barren, dry moss, and wet grass) were treated with three different PCB Aroclor formulations (1254, 1260, and a 1:1 mixture). Soil and plant samples were collected annually over a 5-year period and analyzed for individual PCB congeners. The results showed a high degree of variability between treatments that was ascribed to the presence of vegetation as well as non-homogenous PCB application and/or soil heterogeneity (e.g., biomass, organic carbon, and moisture content) within individual plots. Where readily interpretable data were available, the first-order rate constant for the loss of PCBs from the substrate was calculated to be approximately 0.5 yr(-1) (t(1/2) = 1.1 yr) (range = 0.3-1.0 yr(-1) for individual congeners). For the dry barren area, the rate of loss from soil of individual congeners was negatively correlated with the planar total surface area of the congener (or positively correlated with vapor pressure). For a wet grass area or a dry moss area, the rate of loss was not correlated with any of the standard physical constants, suggesting that live and detrital vegetation may play a key role in the release and retention of PCBs. The estimated loss rates for the three plots may or may not be applicable to PCB-contaminated soils in general, where PCB volatility may be reduced by the presence of hydrocarbon-based carriers or influenced by other factors not considered in this study.

Vascular plants collected at background locations in the Canadian Arctic were assessed as biological indicators of the aerial transport of contaminants from nearby military radar sites. Significantly higher levels of lead and PCBs were found in plants from site background areas (collected up to 10 km from any known sources of contamination) than remote locations (collected at least 20 km away from any human activity) which indicates that these contaminants are being aerially redistributed from the sites to plants in surrounding background areas. An analysis of individual PCB congener signatures in plant site background samples using principal components analysis (PCA) revealed that the past use of specific commercial PCB formulations at these sites, such as Aroclor 1260 on the east coast, is reflected in the PCB congener signature present in the plants. The implications of these findings in terms of elucidating sources and the distribution of contaminants in the Canadian Arctic are discussed.

Elevated concentrations of organochlorines in the tissues of large marine predators in the Canadian Arctic are well documented. This paper presents some of the first data on the composition and distribution of chlorinated organic compounds in some arctic coastal animals found at lower levels of the marine food chain. Organisms include bottom-dwelling invertebrates: clams (Mya truncata), mussels (Mytilus edulis), sea urchins (Strongylocentrotus droebachiensis) and fish: sculpins (Myoxocephalus quadricornis). The majority of samples were collected in the vicinity of Cambridge Bay, Northwest Territories (NWT), Canada; however, samples were also collected near another inhabited area (Hall Beach, NWT) and at a reference site (Wellington Bay, NWT). PCBs and other organochlorines typically originate in more industrialized parts of the northern hemisphere, enter the Arctic, and are subsequently biomagnified. In this study, differences in the PCB congener compositions and concentrations, as well as the relative concentrations of a larger suite of organochlorines in biota, allowed the discrimination between local and distant PCB sources. Terrestrial runoff from southern Victoria Island, NWT, has resulted in localized elevation of PCBs and chlorinated pesticides in marine sediment and bottom-dwelling animals. The major inputs of PCBs to coastal waters within Cambridge Bay were derived from local sources (the hamlet dump and DEW Line site). In addition, transport from more distant sources via riverine input accounts for locally elevated concentrations of other organochlorines in upper Cambridge Bay. This process may also account for concentrations of all measured organochlorines that are higher in Wellington Bay than in Queen Maud Gulf. The high PCB concentrations in the whole tissue (excluding liver) or livers of four-horned sculpins in Cambridge Bay (up to 220 ng/g and 1950 ng/g, respectively) and, to a lesser extent, Wellington Bay (3.8 ng/g and 47 ng/g, respectively) reflect a strong tendency for biomagnification of PCBs in coastal benthic communities.

The Distant Early Warning (DEW) Line, a series of radar stations spanning the Canadian Arctic, is closing. In order to determine the environmental status of these installations, the Canadian Department of National Defence has sponsored an assessment of soil contamination, the partial results of which are presented here. A comparison of PCB concentrations in background samples taken from pristine areas near the radar sites and samples taken in remote locations (> 20 km distant) provides evidence for short-range redistribution of PCBs. Principal component analysis, which was used to highlight differences in congener composition, provided confirmation of this observation. The PCB congener signatures for background samples taken at the radar sites correlated well with PCB signatures from contaminated locations at the radar sites. In contrast, the congener signature attributed to long-range transport, contained a relatively higher proportion of more volatile congeners, which can be attributed to the increased atmospheric residence time.

Arsenic concentrations in freshwater macrophytes were examined in relation to arsenic loadings in sediments (solid phase and pore water) and surface waters for a group of lakes contaminated by the discharge of mine tailings near Yellowknife, N.W.T. Lakes closest to the current discharge were highly contaminated with arsenic (up to 18 650 μg g−1 in sediments) compared with other areas. Macrophytes tended to bioconcentrate arsenic relative to sediment concentrations (up to a factor of ten), with submerged species containing much higher levels of arsenic than emergents. Differences in levels between the most common submerged (Potamogeton pectinatus L.) and emergent species (Typha latifolia L.) were attributed to differences in growth form and possible differences in the ability to exclude arsenic with increasing sediment concentrations. High environmental arsenic concentrations appeared to have negative effects on Typha latifolia, as suggested by decreased stand height, necrosis of leaf tips and reduced micro-nutrient concentrations in root tissues of copper, managanese, and zinc. Phytotoxic symptoms in Typha were generally observed at sediment and water concentrations exceeding 300 μg g−1 and 400 μg l−1, respectively. The lack of relationships between tissue concentrations of arsenic and environmental concentrations of phosphorus (as pore water PO−34, particulate total extractable P, or As:P ratios) did not support the hypothesis that arsenic bioavailability (as arsenate) and toxicity is related to its competition for uptake with phosphate.

The presence of abnormally high concentrations of arsenic in sediment and water samples collected from a chain of small lakes afforded a unique opportunity to investigate the environmental partitioning and speciation of inorganic arsenic in fresh water. The distribution of arsenic in water, surface sediment (0-5 cm depth) and associated pore water downstream of the discharge differed from that expected due to conservative dilution and/or sediment adsorption from a point-source. Inorganic arsenic in the water column, sediment particulates and pore water exhibited a maximum concentration similar to 4-6 km downstream of the gold-mine input. Arsenite (As(III)) was the predominant arsenical in the sediment pore water throughout the watershed, whereas arsenate (As(V)) comprised the vast majority of dissolved arsenic in water column samples. Arsenite was not detected in the mine effluent, but was found in increasing concentrations in the water column with increasing downstream distance from the discharge pipe. There are two possible mechanisms for the downstream redistribution of historical arsenic inputs in this system: (1) bulk movement via sediment/particulate transport; and (2) redissolution from sediments during early diagenesis, followed by upward diffusion and transport to downstream areas. Sediment distributions of other substances which are 'tracers' of the gold-mine effluent (e.g. antimony, copper, gold, nickel, zinc, sulphate and chloride ion) were examined in order to distinguish between these mechanisms. Collectively, the data indicate that the arsenic distribution in surficial sediments of the study area is controlled partially by the bulk movement of sediments, followed by burial with less contaminated sediments in the upper reaches of the watershed. Particulate concentrations of arsenic contributed significantly to the total arsenic concentrations in the water column downstream of the gold-mine discharge (up to 70% of total As concentration). The extremely high concentrations of arsenicals in sediment pore water (up to 68.9 mu M) and the overlying water column (up to 7.3 mu M in dissolved form) in areas further removed from the input, however, are attributable to remobilization from sediments through redox-related dissolution. This release of dissolved arsenic during sediment diagenesis may be enhanced by anthropogenically-enhanced sulfate deposition, also associated with gold-mining activity.