Search

Assessing metal distributions in cities is an important aspect of urban environmental quality management. Western honeybees (Apis mellifera) and their products are biomonitors that can elucidate small‐scale metal distribution within a city. We compare range and variations in trace element (TE) concentrations and lead (Pb) isotopic compositions of honey, bee tissue, bee pollen, and propolis collected throughout Metro Vancouver (BC, Canada). Honey, bee, and bee pollen results have similar TE and isotopic trends; samples collected in urban and industrialized areas exhibit elevated concentrations of anthropogenically influenced TE (e.g., Pb, Zn, V, and Ti) and a less radiogenic Pb isotopic composition (i.e., lower 206Pb/207Pb and elevated 208Pb/206Pb) relative to their suburban and rural counterparts. For example, 206Pb/207Pb, 208Pb/206Pb in honey range from 1.126, 2.131 and 1.184, 2.063; extremes measured in honey from urban and suburban/rural areas, respectively. Except for propolis, measured and interpolated (kriged) results in all materials reflect the immediate zoning or land use setting near the hive, providing kilometer‐scale geospatial resolution, suitable for monitoring urban systems. Statistical analysis reveals that no systematic variations or intra‐ or inter‐annual trends exist in TE concentrations or Pb isotopic compositions, including among sampling and field methods (i.e., old vs. new hive equipment and honey from the brood nest box vs. honey super). The results of this systematic study using honeybees and hive products in Metro Vancouver provide a robust, current baseline for future comparison of local land use and environmental policy change. Key Points: Honeybees and their products can help monitor metal distributions in urban environmentsPb isotopes and trace element concentrations in hive matrices are geospatially and temporally reproducible over several yearsTypical hive management practices (reusing equipment or splitting hives) do not hinder biomonitoring utility of hive products [ABSTRACT FROM AUTHOR]

The parent magma and mantle source of the Mesoproterozoic Kiglapait intrusion, the largest and youngest troctolitic intrusion in the Nain Plutonic Suite of coastal Labrador, Canada, are evaluated using an integrated Pb–Sr–Nd–Hf isotopic and trace element framework. The bowl-shaped Kiglapait intrusion crystallized mostly as a closed system, forming an 8 km-thick stack of differentiated cumulates from the troctolitic Lower Zone (0–84% solidified or PCS) through the olivine gabbroic to ferrosyenitic Upper Zone (84–100 PCS). Whole-rocks and mineral separates (plagioclase, clinopyroxene, bulk mafic minerals) were analysed from eight different stratigraphic locations from 5 to 89·3 PCS. This new dataset is complemented by Pb–Sr–Nd TIMS isotopic analyses of samples spanning the entire magmatic stratigraphy of the Kiglapait intrusion (29 samples, 0·12 to 99·99 PCS) and from the Nain Plutonic Suite (26 samples) for regional comparisons. There is no significant change in initial Nd and Hf isotopic ratios from the base to the top of the intrusion. In contrast, initial 87Sr/86Sr steadily increases in the Upper Zone due to progressively increasing small amounts of assimilation of country rock with a composition similar to local Proterozoic supracrustal rocks and Archean gneiss. The Pb isotopic analyses, both MC-ICP-MS and TIMS, reveal differences between less radiogenic plagioclase and more radiogenic mafic separates in nearly all samples. This feature is attributed to cryptic alteration from interaction with a high-temperature, externally-derived, hydrothermal fluid in oxygen isotope equilibrium with the host anorthositic rocks. The Pb isotope composition of the Kiglapait parent magma was recovered through systematic analysis of leached plagioclase separates (and corresponding leachate solutions). Trace element modeling combined with Pb–Sr–Nd–Hf isotopic constraints indicate that the Kiglapait parent magma was derived from depleted mantle (∼95%) with a small contribution (∼5%) from the lower crust assimilated during ponding at the Moho or during transit through the crust. This geochemical model is extended to the origin of other troctolitic and anorthositic magmas in the Nain Plutonic Suite at a regional scale. Most of the Pb–Sr–Nd isotopic compositions of the Nain anorthosites are compatible with crystallization from melts that originated from the mantle and that assimilated variable extents of crustally-derived melts (3–30%). The multi-isotopic and trace element geochemical framework developed for the Kiglapait intrusion in this study can be applied to the investigation of the source, parent magma, differentiation processes and post-crystallization changes in layered intrusions and anorthosites throughout the geological record. [ABSTRACT FROM AUTHOR]

Abstract: Environmental monitoring and remediation require techniques to identify the source and fate of metals emissions. The measurement of heavy metal isotopic signatures, made possible by the advent of the MC-ICP-MS, is a powerful new geochemical tool, which may be used to trace the source of these metals in the environment. In a multi-tracer study, Cd, Zn and Pb isotopic compositions (MC-ICP-MS) and elemental concentrations (HR-ICP-MS) are used to distinguish between natural and anthropogenic sources of these metals in bivalves collected from western Canada (British Columbia), Hawaii, and the USA East Coast. Variability in the δ114/110Cd values of bivalves (−1.20‰ to −0.09‰) is attributed to differences in the relative contributions of Cd from natural and anthropogenic sources between sites. Cadmium isotopic compositions (δ114/110Cd=−0.69‰ to −0.09‰) identify high Cd levels in B.C. oysters as primarily natural (i.e., upwelling of Cd rich intermediate waters in the North Pacific), with some variability attributed to anthropogenic sources (e.g., mining and smelting). Variability in the δ66/64Zn values exhibited by the B.C. bivalves is relatively small (0.28–0.36‰). Despite the low Pb levels found in B.C. oysters, Pb isotopes are used to identify emissions from industrial processes and the consumption of unleaded gasoline and diesel fuel as significant metal sources. Although the Cd concentrations of the USA East Coast bivalves are primarily lower than those of B.C. oysters, their relatively light Cd isotopic compositions (δ114/110Cd=−1.20‰ to −0.54‰) indicate the significance of anthropogenic Cd sources and are attributed to the high prevalence of industry on this coast. The δ114/110Cd values of USA East Coast bivalves include the lightest ever reported, with the exception of values reported for extraterrestrial materials. In addition, the Pb isotopic compositions of bivalves from the USA East Coast indicate Pb emissions from the combustion of coal are an important source of Pb, consistent with the high consumption of coal for power production on this coast. This study demonstrates the effective use of Cd and Zn isotopes to trace anthropogenic sources in the environment and the benefit of combining these tools with Pb “fingerprinting” techniques. [Copyright &y& Elsevier]

The contemporary academic environment in Canada has undergone reorganization based on neoliberal principles, and has increased attention focused on the importance of supporting interdisciplinary initiatives to address complex problems affecting global society. The purpose of our study was to examine the experience of people participating in a specific university-funded interdisciplinary research initiative. As there is a strong emphasis within this program on reporting on the outcomes of the funding that supports interdisciplinary collaboration, our aim was to explore how participation may shape one's intellectual quality of life (iQoL) and how one's iQoL could be conceptualized and understood. Using a pragmatic constructivist case study, focus group and individual interviews were undertaken with 30 participants involved with university-funded interdisciplinary research teams. Findings illustrate that their iQoL was shaped by their capacity to engage in and achieve what they viewed as their core work and its outcomes. Related sub-themes addressed the social and relational climate, institutional environment and structure, and expectations and resources. We argue that further development of iQoL as a unique construct is required to adequately measure the full range of people's experiences in academia, particularly when aiming to address 'wicked' social and global problems within a predominantly neoliberal context. [ABSTRACT FROM AUTHOR]

Abstract: The Muskox mafic–ultramafic layered intrusion, Nunavut, is part of the widespread 1.27Ga Mackenzie large igneous province in northern Canada. The age and Nd–Hf isotope geochemistry of samples from the marginal zone of the Muskox intrusion and adjacent gneisses allow for an assessment of contamination mechanisms along the floor and walls of the intrusion, relationships between the marginal zone and overlying layered series, and genetic links with the Coppermine River flood basalts and Mackenzie dikes. The marginal zone, intersected in two diamond drill holes at stratigraphically low (West Pyrrhotite Lake) and high (Far West Margin) positions along the western margin of the intrusion, comprises a thick upper subzone (∼100–150m) of olivine and olivine–chromite cumulates and a relatively thin (<10m) lower subzone containing granophyre-bearing gabbronoritic rocks. U–Pb baddeleyite geochronology yields a crystallization age of the marginal zone of ca. 1269Ma based on dating of three samples (1268.8±1.7Ma, chromite-rich peridotite; 1268.7±2.9Ma, gabbronorite; 1271.5±3.4Ma, peridotite), which is synchronous with published ages from the layered series and Mackenzie dikes. The peridotites from both sections mostly span a restricted range of isotopic compositions (initial ɛ Nd =−2.8 to +0.5; initial ɛ Hf =−3.9 to +1.5), which is similar to that observed in the overlying layered series and consistent with the lack of significant chamber-wide crustal contamination of the Muskox parent magmas during differentiation and consolidation. In contrast, the gabbronorites within 10m of the margin of the intrusion (initial ɛ Nd =−13 to −5.5; initial ɛ Hf =−16 to −5.9) were strongly contaminated by melting and exchange with their respective host rocks; the extent of contamination is greater adjacent to paragneiss wallrocks than adjacent to orthogneiss. Crystallization of this thin, contaminated zone along the margin of the Muskox intrusion likely sealed the contacts with the host gneisses and prevented magmas within the interior of the chamber from interacting with the surrounding crustal rocks. Comparison of the Nd isotopic compositions from the marginal zone with published results from the layered series and the Coppermine River flood basalts indicates that only the lowermost portion of the volcanic succession (lower member of the Copper Creek Formation and lowermost part of the middle member) could represent residual magmas that resided and fractionated in the Muskox magma chamber prior to eruption. Construction of the Muskox layered intrusion was thus restricted to the early stages of emplacement of the Mackenzie large igneous province. [Copyright &y& Elsevier]

Abstract: A large part of the accreted Middle to Late Triassic Wrangellia oceanic plateau is exposed as a linear belt (<30 km×300 km) in southwest Yukon. The first major- and trace-element, and isotopic compositions of the Nikolai Formation in Yukon are presented here, along with compositions for underlying Paleozoic arc rocks. The Nikolai Formation in Yukon is predominantly massive tholeiitic subaerial flows (~1000 m) with no intervening sediments and a thin zone of pillow breccia along the base (<100 m). The Nikolai basalts unconformably overlie Late Paleozoic volcanic arc and marine sedimentary sequences and are overlain by Late Triassic limestone, which grades upwards into pelagic sediments. The Nikolai Formation is comprised of two distinct lava types: low-titanium basalts form most of the lower stratigraphy and high-titanium basalts form the upper parts of the volcanic stratigraphy. All of the low-titanium basalts (0.5–1.0 wt.% TiO2; 5.6–11.3 wt.% MgO) have prominent negative HFSE anomalies, whereas the high-titanium basalts (1.4–2.3 wt.% TiO2; 5.8–8.7 wt.% MgO) do not have HFSE anomalies and are more LREE-enriched. The low-titanium basalts are characterized by mostly higher initial ε Hf (+11.1 to +15.8) and lower initial ε Nd (+2.3 to +6.8) than the high-titanium basalts (initial ε Hf =+10.4 to +12.0; initial ε Nd =+6.6 to +9.0), and their Pb isotopic compositions overlap. Incongruent dynamic melting modeling of trace element compositions indicate the low-titanium basalts could have been derived from small degrees of melting (<5%) of Paleozoic sub-arc lithospheric mantle that was HFSE-depleted and evolved with high 176Hf/177Hf. The high-titanium basalts formed from melting of Pacific plume-type mantle, similar to the source of the Caribbean Plateau. Plume-derived melts dominated the upper stratigraphy of the oceanic plateau as a result of increased decompression melting of the underlying mantle plume in response to thinning of the lithosphere. [Copyright &y& Elsevier]

The Alpha–Mendeleev ridge complex is a prominent physiographic and geological feature ofthe Arctic Amerasia Basin. The Alpha and Mendeleev ridges are, respectively, the eastern andwestern components of a continuous seafloor high that is approximately 2000 km long and200–400 km wide. A surge of interest in the tectonic evolution of Arctic submarine featureshas led to a wealth of new geophysical data collected from the Alpha Ridge. Currentinterpretations of its origin vary but there is compelling evidence that the Alpha Ridge mayhave formed as an oceanic plateau during the Late Cretaceous. Geological samples are rarebut most samples recovered indicate a genetic link with the High Arctic Large IgneousProvince (HALIP). In August 2016, Canada&#x2019;s Extended Continental Margin-United Nations Convention onthe Law of the Sea Program dredged approximately 100 kg of volcanic rocks from the AlphaRidge. The large size and pristine state of the samples enabled the first comprehensive studyof a single eruptive event in the volcanic record of the Alpha Ridge. The dredgesample is a lapilli tuff containing vitric and basaltic clasts. Textural evidence and thecoexistence of juvenile and cognate clasts suggest a phreatomagmatic eruption. Thevitric fragments consist of sideromelane glass with abundant plagioclase microlites.Texturally, these basaltic glass lapilli display a fresh glassy core surrounded byFe- and Ti-rich zones and a palagonite rim. Major and trace element analyses ofglassy cores indicate remarkably uniform, mildly alkaline basaltic compositions. Theplagioclase-bearing glass yielded a 40Ar/39Ar plateau age of 90.40 ± 0.26 Ma (2σ error)which included 89% of 39Ar released. We interpret this result to represent the eruption age ofthe plagioclase microlites and consequently, of the host basaltic glass lapilli inthe tuff. Volatile species analyses by infrared spectroscopy on the fresh basalticglass suggests that the melt was effectively degassed to shallow level. Assumingequilibrium degassing, the homogeneous resulting values of H2Ototal in the range0.1 to 0.19 wt.% (1σ error) indicate subaerial or shallow eruption (surface to 80m). The new 40Ar/39Ar age for the sample is consistent with a 40Ar/39Ar age of 89 ± 1 Maobtained for a sample of tholeiitic basalt dredged from the central part of the Alpha Ridge,and with the range of ages reported for HALIP igneous rocks exposed onshore in theCanadian Arctic Archipelago (130-80 Ma). Our new data provide evidence for localemergence of the Alpha Ridge in the Late Cretaceous. A comparison of the Alpha Ridge andKerguelen Plateau–Broken Ridge Large Igneous Province (LIP) provides new insights on theepisodic nature of LIP magmatism and variations in eruptive style through time. [ABSTRACT FROM AUTHOR]

Honey from Apis mellifera is a useful and inexpensive biomonitor for mapping metal distributions in urban centers. The sampling resolution of a biomonitoring survey (e.g., city versus global scale) determines which geochemical processes are reflected in the results. This study presents Pb isotopic compositions and metal concentrations in honey from around the world, sampled at varying resolutions: honey from Canada (n = 21), the United States (n = 111), Belgium (n = 25), and New Zealand (n = 10), with additional samples from Afghanistan, Brazil, Cuba, Germany, Liberia, Taiwan, and Turkey. Honey was sampled at high resolution in two uniquely different land-use settings (New York Metro Area and the Hawaiian island of Kaua'i), at regional-scale resolution in eastern North America (including the Great Lakes region), and Pb isotopic compositions of all samples were compared on a global scale. At high sampling resolution, metal concentrations in honey reveal spatially significant concentration gradients: in New York City, metals associated with human activity and city infrastructure (e.g., Pb, Sb, Ti, V) are more concentrated in honey collected within the city compared to honey from upstate New York, and metal concentrations in honey from Kaua'i suggest polluting effects of nearby agricultural operations. At lower resolution (regional and global scales), lead isotopic compositions of honey are more useful than metal concentrations in revealing large-scale Pb processes (e.g., the enduring legacy of global leaded gasoline use throughout the twentieth century) and the continental origin of the honey. Lead isotopic compositions of honey collected from N. America (especially from the eastern USA) are more radiogenic ( 206 Pb/ 207 Pb: 1.132-1.253, 208 Pb/ 206 Pb: 2.001-2.129) compared to European honey, and honey from New Zealand, which has the least radiogenic isotopic compositions measured in this study ( 206 Pb/ 207 Pb: 1.077-1.160, 208 Pb/ 206 Pb: 2.090-2.187). Thus, biomonitoring using honey at different resolutions reflects differing processes and, to some extent, a honey terroir defined by the Pb isotopic composition. The data presented here provide important (and current) global context for future studies that utilize Pb isotopes in honey. Moreover, this study exhibits community science in action, as most of the honey was collected by collaborators around the world, working directly with local apiarists and hobby beekeepers., (Copyright © 2021 Elsevier Inc. All rights reserved.)

To evaluate metallurgical processing as a source of Zn and Cd isotopic fractionation and to potentially trace their distribution in the environment, high-precision MC-ICP-MS Zn, Cd and Pb isotope ratio measurements were made for samples from the integrated Zn-Pb smelting and refining complex in Trail, B.C., Canada. Significant fractionation of Zn and Cd isotopes during processing of ZnS and PbS ore concentrates is demonstrated by the total variation in delta(66/64)Zn and delta(114/110)Cd values of 0.42 per thousand and 1.04 per thousand, respectively, among all smelter samples. No significant difference is observed between the isotopic compositions of the Zn ore concentrates (delta(66/64)Zn=0.09 to 0.17 per thousand; delta(114/110)Cd=-0.13 to 0.18 per thousand) and the roasting product, calcine (delta(66/64)Zn=0.17 per thousand; delta(114/110)Cd=0.05 per thousand), due to approximately 100% recovery from roasting. The overall Zn recovery from metallurgical processing is approximately 98%, thus the refined Zn metal (delta(66/64)Zn=0.22 per thousand) is not significantly fractionated relative to the starting materials despite significantly fractionated fume (delta(66/64)Zn=0.43 per thousand) and effluent (delta(66/64)Zn=0.41 to 0.51 per thousand). Calculated Cd recovery from metallurgical processing is 72-92%, with the majority of the unrecovered Cd lost during Pb operations (delta(114/110)Cd=-0.38 per thousand). The refined Cd metal is heavy (delta(114/110)Cd=0.39 to 0.52 per thousand) relative to the starting materials. In addition, significant fractionation of Cd isotopes is evidenced by the relatively light and heavy isotopic compositions of the fume (delta(114/110)Cd=-0.52 per thousand) and effluent (delta(114/110)Cd=0.31 to 0.46 per thousand). In contrast to Zn and Cd, Pb isotopes are homogenized by mixing during processing. The total variation observed in the Pb isotopic compositions of smelter samples is attributed to mixing of ore sources with different radiogenic signatures., (Copyright 2010 Elsevier B.V. All rights reserved.)