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Survival and reproduction tests were conducted using two native springtail (subclass: Collembola) species to determine the toxicity of a fine-grained (< 0.005 – 0.425 mm) soil from an industrial site located in the Canadian boreal ecozone. Accidental petroleum hydrocarbon (PHC) release continuously occurred at this site until 1998, resulting in a total hydrocarbon concentration of 12,800 mg/kg (soil dry weight). Subfractions of the PHC-contaminated soil were characterized using Canadian Council of Ministers of the Environment Fractions, which are based on effective carbon numbers (nC). Fraction 2 (> nC10 to nC16) was measured at 8400 mg/kg and Fraction 3 (> nC16 to nC34) at 4250 mg/kg in the contaminated soil. Age-synchronized colonies of Folsomia candida and Proisotoma minuta were subject to 0%, 25%, 50%, 75%, and 100% relative contamination mixtures of the PHC-contaminated and background site soil (< 100 mg/kg total PHCs) for 28 and 21 days, respectively. Survival and reproduction decreased significantly (Kruskal–Wallis Tests: p < 0.05, df = 4.0) in treatments of the contaminated site soil compared to the background soil. In both species, the most significant decline in survival and reproduction occurred between the 0% and 25% contaminated soil. Toxicity responses in the two springtails were ascribed to the standardized test design, short lifespans, and high fecundity in both species. This study showed that 25 + years of soil weathering has not eliminated the toxicity of fine-grained PHC-contaminated soil on two native terrestrial springtail species. Adverse effects to springtail health were attributed to exposure to soils dominated by genotoxic PHC Fraction 2 compounds and slow weathering processes due to the cold climate at the site. [ABSTRACT FROM AUTHOR]

The Arctic faces increasing exposure to environmental chemicals such as metals, posing health risks to humans and wildlife. Biomonitoring of polar bears (Ursus maritimus) can be used to quantify chemicals in the environment and in traditional foods consumed by the Inuit. However, typically, these samples are collected through invasive or terminal methods. The biomonitoring of feces could be a useful alternative to the current metal monitoring method within the Arctic. Here, we aim to 1) quantify the relationship between concentrations of metals in the feces and tissues (muscle, liver, and fat) of polar bears using predictive modeling, 2) develop an easy-to-use conversion tool for use in community-based monitoring programs to non-invasively estimate contaminant concentrations in polar bears tissues and 3) demonstrate the application of these models by examining potential exposure risk for humans from consumption of polar bear muscle. Fecal, muscle, liver, and fat samples were harvested from 49 polar bears through a community-based monitoring program. The samples were analyzed for 32 metals. Exploratory analysis indicated that mean metal concentrations generally did not vary by age or sex, and many of the metals measured in feces were positively correlated with the internal tissue concentration. We developed predictive linear regression models between internal (muscle, liver, fat) and external (feces) metal concentrations and further explored the mercury and methylmercury relationships for utility risk screening. Using the cross-validated regression coefficients, we developed a conversion tool that contributes to the One Health approach by understanding the interrelated health of humans, wildlife, and the environment in the Arctic. The findings support using feces as a biomonitoring tool for assessing contaminants in polar bears. Further research is needed to validate the developed models for other regions in the Arctic and assess the impact of environmental weathering on fecal metal concentrations. [ABSTRACT FROM AUTHOR]

The contamination of the marine environment surrounding coastal Antarctic research stations remains insufficiently understood in terms of its extent, persistence, and characteristics. We investigated the presence of contaminants in marine sediments near Casey Station, located in the Windmill Islands of East Antarctica, during the period spanning from 1997 to 2015. Metals, hydrocarbons, PBDEs, PCBs, and nutrients were measured in sediments at anthropogenically disturbed sites, including the wastewater outfall, the wharf area, two former waste disposal sites, and various control locations. Sampling was carried out at three spatial scales: Locations, which were generally kilometres apart and formed the primary scale for comparison; Sites, which were 100 meters apart within each location; and Plots, which were 10 meters apart within each site. Consistently higher concentrations of most contaminants, and in some cases nutrients, were observed at disturbed locations. Some locations also exhibited an increase in contaminant concentrations over time. The spatial distribution of sediment properties (such as grain size and organic matter) and contaminants displayed intricate patterns of variation. Variation in grain size depended on the size category, with fine grains (e.g., <63 μm) showing the greatest variation at the Location scale, while coarse grains exhibited minimal variation at this scale. Contaminant levels demonstrated significant differences between Locations, accounting for approximately 55% of the overall variation for metals, while the variation within the 10-meter scale generally exceeded that within the 100-meter scale. Residual variation among replicate samples was also very high, demonstrating the need for adequate replication in studies of sediments and contaminants around stations. Some contaminants exceeded international guidelines for sediment quality, including metals, hydrocarbons, and PCBs. We conclude that Antarctic research stations such as Casey are likely to pose a moderate level of long-term ecological risk to local marine ecosystems through marine pollution. However, contamination is expected to be confined to areas in close proximity to the stations, although its extent and concentration are anticipated to increase with time. Raising awareness of the contamination risks associated with Antarctic stations and implementing monitoring programs for marine environments adjacent to these stations can contribute to informed decision-making and the improvement of environmental management practices in Antarctica. [ABSTRACT FROM AUTHOR]

Purpose: Risks to native soil-dwelling organisms in terrestrial ecosystems contaminated by petroleum hydrocarbons (PHCs) are difficult to assess due to the range of compounds and their varying toxicity. Weathering of PHCs in soil has been shown to alter their chemical composition and decrease their associated toxicity. Hence, generic regulatory guidelines may inadequately predict risks and exposure scenarios at some sites. Methods: In this study, the toxicity of both coarse- and fine-grained subarctic soils contaminated with weathered PHCs was assessed using two soil invertebrates, Folsomia candida and Proisotoma minuta. In addition to survival and reproduction tests, avoidance behavior was investigated using F. candida, P. minuta, Oppia nitens, and Folsomia bisetosa. Reference toxicant tests using boric acid were conducted to provide confidence in the interpretation of the results and verified the sensitivity of F. candida and P. minuta to contaminants. Results: Despite exceeding the Canada-wide generic guidelines for PHC fraction 3 (F3), weathered contaminated soils at concentrations between 1140 and 5880 mg/kg had no significant negative impacts on the reproduction or mortality rates of F. candida or P. minuta. Furthermore, all four soil invertebrates preferred to inhabit the contaminated soils during the 48 h avoidances tests. Conclusion: Natural weathering processes to PHC-impacted soils at a Canadian Subarctic site have led to a decrease in toxicity on four native soil invertebrates. [ABSTRACT FROM AUTHOR]

Remedial guidelines for petroleum hydrocarbons (PHCs) in soil aid in the mitigation of risks to human health and the environmental. However, some remediation guidelines may overestimate the potential for adverse effects to native plant species, contributing to unnecessary remedial efforts in attempts to meet the guidelines. At sites where PHC-contaminated soils undergo weathering, some PHCs may persist but with decreased bioavailability to organisms. In this study, the toxicity of both coarse and fine-grained subarctic soils, contaminated with weathered PHCs were assessed using five native plant species (Picea mariana, Achillea millefolium, Alnus viridis, Elymus trachycaulus and Salix bebbiana). Soil toxicity tests were conducted in a growth chamber with parameters set to simulate the site's subarctic climate conditions. Reference toxicant tests using boric acid were conducted to provide confidence in the interpretation of the results for the PHC-contaminated soils, and also provide new information on the sensitivities of the four boreal species to boric acid. All plants exhibited reduced growth and germination rates as boric acid concentrations increased. Despite exceeding the Canada-wide standard guidelines for Fraction 3 PHCs, field-collected contaminated soils had no significant negative impacts on the growth (i.e., length, dry weight and emergence) of any of the plant species tested. [ABSTRACT FROM AUTHOR]

Historical (or legacy) contaminants, such as metals and persistent organic pollutants (POPs; e.g., polychlorinated biphenyls) have been measured in circumpolar subpopulations of polar bears, especially from Hudson Bay, East Greenland, and Svalbard, but substantially less is currently known about new and/or emerging contaminants such as polychlorinated naphthalenes, current-use pesticides, organotins, and polycyclic aromatic compounds (PACs). The polar bear (Ursus maritimus) is an apex Arctic predator that accumulates high levels of bioaccumulative POPs and mercury (Hg), but there is currently no comprehensive profiling of the present knowledge on contaminants in tissue and body compartments in polar bears. Based on current literature reports and data, and including archived museum samples (as far back as the 1300s) and up to 2018, the aim of this review is to utilize available data to examine the comparative distribution and burden of mainly lipophilic contaminants in kidney, liver, fat, and other body compartments, such as milk, blood, and brain. Highlight outcomes from this review include the following: (1) the kidneys are one of the most important tissue depots of contaminants in polar bears; (2) there is a critical lack of data concerning the presence of metals of concern (other than Hg); and (3) there currently are no data available on the concentrations of many newer and emerging contaminants, such as PACs, which is especially relevant given the increasing oil and gas development in regions, such as the Beaufort Sea (Canada). Additionally, given the vulnerability of polar bear populations worldwide, there is a need to develop non-invasive approaches to monitor contaminant exposure in polar bears. [ABSTRACT FROM AUTHOR]

Four natives Canadian recretohalophytic species: Atriplex canescens, Armeria maritima, Spartina pectinata, and Distichlis spicata were examined to determine their relative uptake and excretion of chloride in the context of phytoremediation. Adult plants were grown in soils contaminated with either sodium chloride or potassium chloride at various concentrations, then manually washed to collect the excreted salts. Atriplex canescens which has salt bladders, was found to have negligible excretions, suggesting that these structures release minimal amounts of salt onto the leaf's surface. Chloride excretions of S. pectinata and D. spicata increased with higher soil chloride concentrations. A. maritima showed minimal excretion until a threshold soil salinity was reached. This species shifted from a reliance on internal sequestration to secretion at higher soil salinity. The salt used in the media did not impact these trends, but D. spicata excreted significantly more chloride under sodium chloride conditions. While all four species studied were able to translocate significant amount of salt to their shoots, only S. pectinata, D. spicata, and A. maritima are suitable candidates for remediation by haloconduction. Among these, A. maritima showed the greatest potential and significantly reduced the soil chloride concentration by up to 60% in the highest concentration treatment (4 mg/g). Armeria maritima, Spartina pectinata, and Distichlis spicata are suitable species for remediation via haloconduction. Armeria maritima had the highest total extraction capacity at high soil chloride. Spartina pectinata had the most consistent excretion capacity and is the most suitable for remediation of soils with lower soil chloride. [ABSTRACT FROM AUTHOR]

Point Pelee National Park (PPNP) is highly contaminated with dichlorodiphenyltrichloroethane (DDT) due to the historical use of this persistent organochlorine pesticide. Hydroxypropyl-β-cyclodextrin (HPβCD) has previously been investigated for its role in the remediation of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In the present study, HPβCD's ability to promote DDT microbial degradation, enhance DDT phytoextraction by two native grasses (Schizachyrium scoparium and Panicum virgatum), and increase DDT bioavailability to redworms (Eisenia fetida) was investigated. Using a range of HPβCD concentrations (2.5% to 10%), it was determined that it did not promote DDT microbial degradation in PPNP soils, however, it was able enhance the DDT phytoextraction ability of S. scoparium plants due to the increased water solubility of DDT. Although HPβCD application to PPNP soil did not increase DDT bioavailability to redworms, its enhanced solubility allowed it to move through the soil column, and hence groundwater contamination is a possibility. Due to this important issue, in situ use of HPβCD to remediate DDT contamination is not recommended unless measures are in place to mitigate movement into groundwater. [ABSTRACT FROM AUTHOR]

Diluted bitumen (dilbit) spilled to rivers has the potential to sink and become trapped in coarse bed sediments. Hyporheic flow through the river bed can then lead to the dissolution of hydrocarbons from this trapped oil, and subsequent risks to water quality and aquatic life. It is important to understand the concentrations of dissolved hydrocarbons in water, relative to aqueous solubility, that may result from mass transfer under these conditions, particularly under conditions where coarse sediments lead to faster hyporheic flow that could promote rate-limited mass transfer conditions. In this study, the dissolution of dilbit (Cold Lake Blend) trapped in gravel was measured using one-dimensional columns at flow rates representative of fast hyporheic flow. Dissolved concentrations in the column effluent were found to be less than 20% of effective solubility (equilibrium) concentrations and decreased with increasing flow rate, indicative of rate-limited conditions. These results show that risks posed by the contamination of gravel-bedded rivers by trapped dilbit may be lower, but persist for a longer period of time, than those estimated assuming dissolution at concentrations near solubility limits. [ABSTRACT FROM AUTHOR]

Point Pelee National Park (PPNP) is highly contaminated with dichlorodiphenyltrichloroethane (DDT) and dieldrin due to the historical use of these two persistent organochlorine pesticides. Zero-valent iron (ZVI) technology with and without amendments has been successfully used in the past to promote organochlorine pesticides degradation in several locations in North America and Europe. In this study, the use of two commercially available ZVI products, DARAMEND® and EHC®, to promote DDT and dieldrin degradation in PPNP's soil and groundwater were investigated. DARAMEND® was applied to PPNP's soil in a laboratory experiment and in an in situ pilot-scale plot. In both cases, DARAMEND® did not significantly increase DDT or dieldrin degradation in treated soils. The effectiveness of EHC® was tested in a laboratory experiment that simulated the park's groundwater environment using PPNP's pesticide contaminated soil. The result was consistent with the one reported for DARAMEND®, in that there was no significant increase in DDT or dieldrin degradation in any of the samples treated with EHC®. These results demonstrate that both of these ZVI commercially available products are not suitable for in situ remediation at PPNP. ©2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Greenhouse and in-situ field experiments were used to determine the potential for phytoextraction to remediate soil contaminated with Cd from municipal solid waste (MSW) and sewage sludge (SS) compost application at a Peterborough (Canada) site. For the greenhouse experiment, one native (Chenopodium album) and three naturalized (Poa compressa, Brassica juncea, Helianthus annuus) plant species were planted in soil containing no detectable Cd (<1.0 μg·g−1), and soil from the site containing low (5.0 ± 0.3 μg·g−1Cd), and high (16.5 ± 1.2 μg⋅g−1Cd) Cd concentrations. Plant uptake was low (root BAFs ≤0.5) for all species exceptP. compressain the low Cd treatment (BAF 1.0). OnlyB. junceaaccumulated Cd in its shoots, though uptake was low (BAF ≤0.3). For the field experiment,B. junceawas planted in-situ in areas of low and high Cd concentrations.Brassica junceaCd uptake was low (root and shoot BAFs <0.2) in both treatments. Sequential extraction analysis indicated that Cd is retained primarily by low bioavailability soil fractions, and phytoextraction is therefore not feasible at this site. Though low Cd bioavailability has negative implications for Cd phytoextraction from MSW/SS compost-based soils, it may limit receptor exposure to Cd sufficiently to eliminate the potential for risk at this site. [ABSTRACT FROM AUTHOR]

H NMR metabolomics was used to measure earthworm sub-lethal responses to polychlorinated biphenyls (PCBs) in historically contaminated (>30 years) soils (91-280 mg/kg Aroclor 1254/1260) after two and 14 days of exposure. Although our previous research detected a distinct earthworm metabolic response to PCBs in freshly spiked soil at lower concentrations (0.5-25 mg/kg Aroclor 1254), the results of this study suggest only weak or non-significant relationships between earthworm metabolic profiles and soil PCB concentrations. This concurs with the expectation that decades of contaminant aging have likely decreased PCB bioavailability and toxicity in the field. Instead of being influenced by soil contaminant concentration, earthworm metabolic profiles were more closely correlated to soil properties such as total soil carbon and soil inorganic carbon. Overall, these results suggested that H NMR metabolomics may be capable of detecting both site specific responses and decreased contaminant bioavailability to earthworms after only two days of exposure, whereas traditional toxicity tests require much more time (e.g. 14 days for acute toxicity and >50 days for reproduction tests). Therefore, there is significant opportunity to develop earthworm metabolomics as a sensitive tool for rapid assessment of the toxicity associated with contaminated field soils. [ABSTRACT FROM AUTHOR]

Introduction: A greenhouse experiment was conducted to determine if Cucurbita pepo ssp. pepo (pumpkin) root exudates could increase the uptake of polychlorinated biphenyls (PCBs) into plants. Contaminated soil was pre-treated with pumpkin root exudates by first growing pumpkins in the soil. Plants (pumpkins and weeds) were grown in the pre-treated (root exudate group) and non-treated (control group) contaminated soils. Seeds from five weed species collected from two contaminated sites were germinated in sufficient quantities ( n ≥ 6) for three seedlings to be planted in two groups. Discussion: Plants from both the control group and the root exudate group extracted a combined total of ∼1.2% PCBs from soil. Differences in root concentrations between groups were observed for Bidens cernua (beggar's tick) and in total PCBs extracted into the roots for pumpkins. This is the first report of significant changes in the PCB phytoextraction ability of multiple plant species due to the presence of root exudates. In addition, slight differences were also observed for root and shoot concentrations and extractions by several other species, though these were not statistically different at α = 0.05. While the mechanism of phytoextraction is still unknown, this study indicates that the root exudates of C. pepo ssp. pepo can affect the uptake and transport of contaminants within specific plant species. [ABSTRACT FROM AUTHOR]

Childhood cancer is the leading cause of disease-related death in children aged 1–14 years in Canada and the USA and it has been hypothesized that transplacental exposure to environmental carcinogens such as benzene may contribute to the etiology of these cancers. Our objectives were to determine if transplacental benzene exposure increased tumor incidence in mouse offspring and assess fetal benzene metabolism capability. Pregnant CD-1 and C57Bl/6N mice were given intraperitoneal injections of corn oil, 200 mg/kg, or 400 mg/kg benzene on gestational days 8, 10, 12 and 14. A significant increase in tumor incidence was observed in CD-1, but not C57BL/6N, 1-year-old offspring exposed transplacentally to 200 mg/kg benzene. Hepatic and hematopoietic tumors were predominantly observed in male and female CD-1 offspring, respectively. Female CD-1 offspring exposed transplacentally to 200 mg/kg benzene had significantly suppressed bone marrow CD11b+ cells 1 year after birth, correlating with reduced colony-forming unit granulocyte/macrophage numbers in 2-day-old pups. CD-1 and C57Bl/6N maternal blood benzene levels and fetal liver benzene, t, t-muconic acid, hydroquinone and catechol levels were analyzed by gas chromatography/mass spectrometry. Significant strain-, gender- and dose-related differences were observed. Male CD-1 fetuses had high hydroquinone levels, whereas females had high catechol levels after maternal exposure to 200 mg/kg benzene. This is the first demonstration that transplacental benzene exposure can induce hepatic and hematopoietic tumors in mice, which may be dependent on fetal benzene metabolism capability. [ABSTRACT FROM PUBLISHER]

Greenhouse studies were conducted to assess the impact of organic matter additions on plant uptake of DDT [2,2-bis(chlorophenyl)-1,1,1-trichloroethane] from weathered soil. Cucurbita pepo ssp. pepo cv. Howden pumpkins were grown in 100 g of DDT contaminated soil ([DDT] ∼1100 ng/g) mixed with equal volumes of either clean soil, perlite, vermiculite, peat, potting soil, or granular activated carbon (GAC) to give total organic carbon contents of 2.4%, 2.5%, 2.6%, 11.5%, 12.2%, and 27.3%, respectively. As in other studies, root DDT concentrations were significantly lower in soils with high organic matter. Root bioaccumulation factors (BAF = [DDT]root/[DDT]soil) approximated this trend. Root concentrations correlated with organic matter concentrations and not with soil DDT concentrations. Conversely, shoot DDT concentrations, shoot BAFs and translocation factors (TLF = BAFshoot/BAFroot) were not significantly different between treatment groups, except for plants grown in GAC/DDT soil. This suggests that amendments with a range of organic matter contents may be added to improve soil conditions at industrial sites without significant adverse effects on phytoextraction potential of C. pepo ssp. pepo. [ABSTRACT FROM AUTHOR]

Weathered soils contaminated with commercial-grade Aroclor 1260 from three sites in Canada were used to investigate the polychlorinated biphenyl (PCB) phytoextraction potential of nine plant species ( Festuca arundinacea , Glycine max , Medicago sativa , Phalaris arundinacea , Lolium multiflorum , Carex normalis , and three varieties of Cucurbita pepo ssp. pepo ) under controlled greenhouse conditions. The soils used varied in PCB concentration (90–4200 μg/g) and total organic content (0.06–2.02%). Greenhouse experiments controlled for PCB volatilization through the use of a vented enclosure and by isolating the contaminated soils with parafilm. After 8 wks, PCB concentrations of 47–6700 μg/g were observed in root tissues. Although PCB concentrations in shoot tissues were lower ( Overall, the results indicate that varieties of C. pepo were more effective at extracting PCBs from soil than other plants screened. The evidence suggests that this was mainly due to root uptake of PCBs and tranlocation to the shoots, rather than volatilization of PCBs from soil. All plants screened showed signs of stress in the most highly contaminated soil (4200 μg/g), but not in the two lower PCB contaminated soils (250 and 90 μg/g, respectively). No detectable decreases in soil PCB concentrations were observed in these short-term greenhouse experiments, but the results suggest that this may be achievable through multiple plantings. [ABSTRACT FROM AUTHOR]

Clean-up sites in cold climates present unique challenges for the analytical chemist, primarily because of transportation constraints and limited infrastructure. Excavation of chemically contaminated soils and dumps requires a quick turnaround for analytical results. This is mainly due to the cost factors involved in having expensive heavy equipment idle and the short working seasons, but also because of melting of exposed permafrost during excavation. Three options are available for conducting analyses at remote polar sites. These are off-site determinations, the use of on-site test kits (or simple procedures), and the deployment of a mobile laboratory. This paper discusses these options and provides details of available on-site techniques as well as specific examples of their application in remote northern sites. The design and operation of a mobile laboratory at Resolution Island, Nunavut, is described, and available test kits are compiled and reviewed. [ABSTRACT FROM PUBLISHER]