Alan J. Martin

The mobility of radium-226 and trace metals in pre-oxidized subaqueous uranium mill tailings

The exchange of 226Ra and trace metals across the tailings-water interface and the mechanisms governing their mobility were assessed via sub-centimetre resolution profiling of dissolved constituents across the tailings–water interface in Cell 14 of the Quirke Waste Management Area at Rio Algoms Quirke Mine, near Elliot Lake, Ontario, Canada. Shallow zones ( 2 m water depth) fosters stagnant bottom waters and permits the development of anoxia above the benthic boundary. These anoxic tailings are characterized by substantial remobilization of 226Ra, resulting in a relatively large flux of 226Ra from the tailings to the water column. The strong correlation between the porewater profiles of 226Ra and Ba (r2=0.99), as well as solubility calculations, indicate that the mobility of Ra is controlled by saturation with respect to a poorly ordered and/or impure barite phase [(Ra,Ba)SO4]. In the anoxic zones, severe undersaturation with respect to barite is sustained by microbial SO4 reduction. Flux calculations suggest that the increase in 226Ra activity in the water cover since 1995 (from <0.5 to 2.5 Bq l−1) can be attributed to an increase in the spatial distribution of anoxic bottom waters caused by increased density of benthic flora. The anoxic, vegetated areas also exhibit minor remobilization with respect to dissolved As, Ni and Zn. The removal of trace metals in the anoxic bottom waters appears to be limited by the availability of free sulphide. Collectively, the data demonstrate that while the water cover over the U mill tailings minimizes sulphide oxidation and metal mobility, anoxic conditions which have developed in deeper areas have led to increased mobility of 226Ra.

Winter Ciliates in a British Columbian Fjord: Six New Species and an Analysis of Ciliate Putative Prey

ABSTRACT. This work provides the first study of North Pacific planktonic ciliates by quantitative protargol staining. Triplicate water bottle samples were collected at a depth of 2 m (above the shallow pycnocline) at six stations in Indian Arm, British Columbia, on February 15, 1990, and February 26, 1991. Thirty‐six ciliate species were observed. Six new species are described from protargolstained specimens: Strombidium lynni n. sp., Strombidium taylori n. sp., Strombidium basimorphum n. sp., Slrombidiurn ventropinnum n. sp., Strobilidium undinum n. sp., and Urotricha cyrtonucleata n. sp.

Speciation, behavior, and bioavailability of copper downstream of a mine-impacted lake.

A combination of Cu speciation analysis and toxicity testwork was conducted to assess the behavior, speciation, and bioavailability of Cu in a stream system rich in dissolved organic carbon (DOC) downstream of a mine-impacted lake (East Lake, ON, Canada). Elevated levels (approximately 50 microg/L) of Cu exist in the lake due to the release of dissolved Cu to the water column from underlying sediments. Most of the Cu present in East Lake and downstream is present as filterable species that represent 74 to 100% of the total. Measurements of labile Cu as measured by diffusive gradients in thin films (DGT) suggest that most of the Cu is unavailable to aquatic biota. The DGT results indicate that 9 to 24% of Cu within the receiving environment is biologically available. Decreases in the labile Cu fraction with distance downstream of East Lake correlate well with increases in the concentration of DOC (r(2) = 0.79-0.95), presumably due to the progressive importance of Cu-organic complexes. The relationship between filterable Cu and SO(4)(2-) downstream of East Lake was linear (r(2) = 0.99) for all sampling periods, suggesting that decreases in filterable Cu concentration downstream of East Lake could be attributed solely to dilution (i.e., conservative behavior). Variations in the filterable Cu concentration resulting in 50% mortality (LC50 = 96-203 microg/L) and the concentration resulting in an inhibition of reproduction by 25% (IC25 = 75-156 microg/L) with respect to Ceriodaphnia dubia (7-d incubation) in Cu-spiked solutions could be explained by differences in labile-Cu concentrations as determined by DGT. The considerable complexation capacity afforded by lake and stream waters can be attributed to complexation of Cu with abundant DOC (7-17 mg/L). The relevance of the toxicity data to water-effect ratio testwork, and the associated development of site-specific water quality objectives, are discussed.

Biogeochemical Mechanisms of Selenium Exchange between Water and Sediments in Two Contrasting Lentic Environments

The biogeochemical mechanisms of Se exchange between water and sediments in two contrasting lentic environments were assessed through examination of Se speciation in the water column, porewater, and sediment. High-resolution (7 mm) vertical profiles of <0.45 μm Se species across the sediment-water interface demonstrate that the behavior of dissolved Se(VI), Se(IV), and organo-Se are closely linked to redox conditions as revealed by porewater profiles of redox-sensitive species (dissolved O2, NO3-, Fe, Mn, SO4(2-), and ΣH2S). At both sites Se(VI) is removed from solution in suboxic near-surface porewaters demonstrating that the sediments are serving as diffusive sinks for Se. X-ray absorption near edge spectroscopy (XANES) of sediments suggests that elemental Se and organo-Se represent the dominant sedimentary sinks for dissolved Se. Dissolved Se(IV) and organo-Se are released to porewaters in the near-surface sediments resulting in the diffusive transport of these species into the water column, where between-site differences in the depths of release can be linked to differences in redox zonation. The presence or absence of emergent vegetation is proposed to present a dominant control on sedimentary redox conditions as well as on the recycling and persistence of reduced Se species in bottom waters.

DISSOCIATION BETWEEN SKINFOLD THICKNESS CHANGES AND GROWTH OF ADIPOSE TISSUE VOLUME IN CHILDREN AND YOUTH

The purpose of this investigation was to determine whether there is a divergence in the relationship between skinfold thickness and an adipose tissue volume (ATV) corresponding to the same segment of the body during growth. Anthropometric data from the cross‐sectional Coquitlam Growth Study (COGRO) were used to estimate the ATV of the arm, calf, thigh, and trunk in 6‐ to 18 years old girls (n = 458) and boys (n = 487). Assuring a cylindrical shape for body segments, ATV was calculated by subtracting an inner cylinder of muscle, bone, and residual from the total cylindrical volume of a given segment. Combined graphical analysis of both skinfold growth and growth of ATV reveals that a decrease in skinfold can occur without a concomitant decrease in its corresponding regional ATV. This happens more dramatically in boys than in girls, and in the limbs than in the trunk. This suggests that exaggerated growth in length and/or muscle girth cause a “spreading” and “thinning” of the adipose tissue layer, which does not necessarily reflect fat loss. The meaning of changes in skinfold thicknesses during growth thus needs evaluation.

The biogeochemical behaviour of selenium in two lentic environments in the Elk River Valley, British Columbia

The biogeochemical behaviour of selenium (Se) in two lentic environments (Goddard Marsh (GM) and Fording River Oxbow (FRO)) was assessed through detailed examination of Se speciation in bottom water, porewater and sediment components. The depositional environments at GM and FRO differ with regards to organic matter content, organic matter sources (as revealed by C:N ratios) and redox character. X-ray absorption near edge spectral (XANES) data suggest that elemental Se and organo-Se represent the dominant hosts for Se at GM and FRO. At both sites, the vertical distributions of dissolved Se species in porewater are closely linked to the profiles of redox-sensitive metabolites. Porewater profiles indicate that the sediments at GM and FRO are serving as diffusive sinks for Se through in situ adsorption/precipitation of Se in suboxic horizons. Although the sediments at both sites serve as net sinks for dissolved Se, interfacial peaks in dissolved selenite (Se) and organo-Se demonstrate these species are recycled back into the water column. The conditions present at GM are more favourable for the recycling of reduced Se species. Such observations can be linked to subtle differences in redox conditions as illustrated by profiles of redox-sensitive species (dissolved NO3, Fe, Mn, SO4 and ΣH2S). These differences have important implications to both the recycling of reduced Se species into the water column and Se uptake by aquatic biota. Implications with regards to Se management, bioremediation and biologically availability (food chain transport) are discussed. INTRODUCTION The fine-grained organic-rich substrates typical to lentic systems (e.g., wetlands, ponds, lakes) serve as optimum media for the microbially-mediated transformations of selenate (Se) to reduced forms, including selenite (Se), elemental selenium (Se) and organic species (Masscheleleyn and Patrick 1993; Zhang and Moore 1996; Simmons and Wallschlager 2005). Accordingly, understanding and quantifying mechanisms involved in Se cycling within lentic environments is required to assess the long-term fate of Se and risks to biological receptors. Studies to date conducted through the Elk Valley Selenium Task Force (EVSTF), including assessments of fish, waterbirds, waterfowl and amphibians (McDonald and Strosher 2000; Minnow 2004; Golder 2005), have advanced our understanding of the effects of Se on biological receptors in both lentic and lotic environments. However, there remains a dearth of information with respect to the biogeochemical mechanisms controlling the speciation, accumulation and remobilization of Se within lentic environments in the region. B.C.’32 Annual Mine Reclamation Symposium Technical Paper 8 2 To expand our current understanding of Se behaviour in lentic systems, studies were conducted in two lentic environments in the Elk River Valley of southeastern B.C. This study represents a collaborative effort between the EVSTF, Lorax Environmental Services Ltd., Trent University (Dr. Dirk Wallschlager), University of Saskatoon (Drs. Cheryl Wiramanaden and Ingrid Pickering) and Laurentian University (Dr. Nelson Belzile). The approach focused on the collection of high vertical-resolution profiles of Se species in sediment, bottom water and porewater, with the primary objective being to delineate the biogeochemical processes governing Se behaviour. The results have both local and global relevance to our understanding of Se behaviour in aquatic systems. The preliminary work presented herein, prepared for the EVSTF, has not been fully reviewed nor endorsed by its membership. FIELD AND ANALYTICAL METHODS Environmental Setting Field surveys at Goddard Marsh (GM) (Elkview Coal Operations) and Fording River Oxbow (FRO) (Fording River Operations) were conducted between August 21-23 and September 4-7, 2007. These lentic zones were selected for study based on previous work at these sites, ecological significance, and proximity to mine-related inputs. GM is located immediately downstream of a sediment-pond discharge from Elkview Mine, and comprises a dense cattail (Typha latifolia) marsh with limited areas of open water. Water depths range from ~0.5 to 1.0 m. Sediments at GM are organic rich and fine-grained. FRO is located adjacent to the Fording River ~9 km downstream of the Fording Mine. FRO extends for several hundred metres and comprises narrow channels and open ponds which are hydraulically connected to the Fording River. Water depths at FRO range from 0.5 to 1.5 m. The system is replete in organic matter and hosts fine-grained sediments. Field Methods Duplicate sediment cores were collected by hand from GM and FRO using 8 cm diameter butyrate tubing. Cores were extruded and sliced at intervals ranging from 1 cm in thickness near the sediment-water interface to 5 cm in thickness at deeper sediment depths. Sediment sub-samples were placed in polyethylene bags and frozen prior to transport. The post-depositional behaviour of Se and exchange with the overlying water column was assessed by sampling of the porewaters and bottom waters using dialysis arrays (peepers), as described in Martin et al. (2002, 2003). The peepers afford 7 mm-resolution profiling of dissolved constituents (0.45 μm pore size) from ~20 cm above the benthic boundary to a sub-interface depth of ~30 cm. Dissolved metal samples were acidified to pH <2 with ultrapure nitric acid while samples for nutrients and sulfate analysis were frozen. For hydrogen sulfide analysis, a 2.0 mL sample was taken and spiked with 50 μL of 1 M zinc acetate. Samples for Se speciation analysis were frozen with dry ice immediately upon collection. Analytical Methods Total Se in porewaters was determined by inductively-coupled-plasma dynamic-reaction-cell massspectrometry (ICP-DRC-MS). Inorganic Se species in porewater were determined by anion-exchange B.C.’32 Annual Mine Reclamation Symposium Technical Paper 8 3 chromatography coupled to ICP-DRC-MS (AEC-ICP-DRC-MS), similar to Wallschlager and Roehl (2001). Dissolved organic selenium was converted to selenite (Se) by selective UV-photo-oxidation, and then determined indirectly (by subtraction of the sample’s native selenite (Se) concentration) by hydride generation-atomic fluorescence spectrometry (HG-AFS) (Chen et al., 2005). Determinations of dissolved trace element concentrations were performed using inductively-coupled plasma mass spectrophotometry (ICP-MS) at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. Sulfate and nitrate concentrations in porewaters were measured by ion chromatography and total sulfide (ΣH2S = S, HS and H2S) was measured spectrophotometrically. Total carbon and sulphur concentrations in sediments were determined by combustion/gas chromatography at the University of British Columbia. Carbonate carbon was determined by coulometry. Organic carbon was determined by subtracting carbonate carbon values from the total value. Trace elements were analyzed by inductively-coupled plasma optical emission (ICP-OES) and mass spectrometry (ICP-MS) using solutions prepared by fusing sub-samples in lithium metaborate (LiBO2), followed by dissolution of the quenched glass in 10% nitric acid (HNO3). X-ray absorption near edge spectra (XANES) data were collected using the synchrotron at the Canadian Light Source Saskatoon, SK. XANES probes the absorption characteristics of a particular electron shell using tunable synchrotron light. The geometry of the resulting spectra is valence dependent so it is possible to determine the specific elemental oxidation states present (i.e., Se, Se, Se, Se) (Pickering et al., 1995). As well, XANES spectra can be used to obtain semi-quantitative determinations of the relative abundance of each oxidation state. To quantify the relative contribution of various Se forms, a XANES library of known Se compounds was compared to the sample spectra. RESULTS AND DISCUSSION Sediments Contrasts between the depositional environments at GM and FRO are illustrated by their carbon (C), nitrogen (N) and sulfur (S) content (Figure 1). The greater organic carbon content at GM (25 to 30 wt.%) in comparison to FRO (5 to 7 wt.%) likely relates to differences in the source(s) of organic matter. Specifically, the C-Org:N ratio in GM sediments (mean = 38) is closer to the C:N signature of terrestrial organic matter (45 to 50:1), while the C-Org:N ratio at FRO (mean = 20) is similar to organic matter produced by plankton decomposition (12:1) (Wetzel 1975). The higher C:N at GM indicates that the organic matter content at this site is composed largely of decomposing wetland vascular plants (e.g., Typha sp.). Conversely, the lower C:N contents at FRO imply a greater portion of the organic matter originates from in situ sources such as algal production. These differences likely have relevance to Se accumulation in sediments. Total-Se in sediments at GM range from 7 to 71 mg/kg dry wt. (mean = 37 mg/kg) while deposits at FRO range from 2 to 19 mg/kg dry wt. (mean = 10 mg/kg) (Figure 2). XANES spectra suggest that elemental Se, organo-Se (possibly seleno-methionine) and selenite (sorbed Se), are the dominant hosts for Se at B.C.’32 Annual Mine Reclamation Symposium Technical Paper 8 4 both GM and FRO (Figure 2). Of these, elemental phases and organo-Se contribute most to the total sediment inventory, which account for on average 35% and 50%, respectively, of the total at both sites. Org-C (wt.%) 0 5 10 15 20 25 30 35 0

Hydrological and biogeochemical controls governing the speciation and accumulation of selenium in a wetland influenced by mine drainage

Controls governing the speciation and accumulation of Se in a 3.7-ha marsh influenced by mine drainage were assessed through examination of water balance, water quality, sediment, and plant tissue components. Over the 8-mo study period (April through November, 2009), mean monthly flows ranged from 1600 to 2300 m3  d-1 (hydraulic retention time of 1-3 d). Total Se concentrations in the marsh outflow were lower than the inflow by 0.4 to 6.2 μg L-1 (mean difference = 3.3 μg L-1 ), illustrating Se removal. The Se accumulation pathways are illustrated by elevated concentrations of Se in sediments (3-35 mg kg-1 dry wt) as well as in below-ground (2-41 mg kg-1 dry wt; mean = 10 mg kg-1 dry wt) and above-ground (0.8-6.3 mg kg-1 dry wt; mean = 2 mg kg-1 dry wt) emergent plant tissues. Redox stratification in the shallow water column had a marked effect on Se speciation and behavior, illustrating bottom water removal of dissolved selenate in suboxic horizons and increased mobility of dissolved organo-Se. Mass balance data yielded inflow and outflow loading rates for Se of 27 and 23 g d-1 , respectively (net accumulation rate of 4 g d-1 or 0.11 mg m2  d-1 ). The rate of accumulation as calculated from the mass balance agrees with independently measured rates of Se accumulation in sediments for the site (3.6-8.1 g d-1 or 0.10-0.22 mg m-2  d-1 ). Environ Toxicol Chem 2018;37:1824-1838.

Application of High-Resolution Microscopy Methods to the Analysis of Fine-Grained and Amorphous Treatment Sludges

Lime addition is a common method for the treatment of acid mine drainage (AMD) whereby neutralization promotes a reduction in acidity and the precipitati on of metals as voluminous sludges that may contain gypsum, calcite and a spectrum of other phases. Due to the extremely fine-grained and often amorphous ( i.e ., non crystalline) character of sludge solids, the compos ition of these materials has been difficult to eluc idate. Traditional methods, such as X-Ray Diffraction (XRD) and optical microscopy, have proved largely ineff ective. In order to provide further insight into the solid- phase characterization of neutralization sludges, s amples from mine sites across Canada were examined by high resolution microscopy techniques, including Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and X-ray Absorption Spectroscopy (XAS). The results revealed sludge-specific host phases, including relatively pure Feoxyhydroxide, amorphous Mg-Al-(Fe) hydroxysulphate and amorphous metal hydroxides. The data indicate that the nature of metal phase associations is stro ngly dependent on AMD influent composition.