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Papers by Alan Martin

The bioremediation of selenium (Se) from mine waters using passive systems (those requiring negli... more The bioremediation of selenium (Se) from mine waters using passive systems (those requiring negligible management) and semi-passive systems (those requiring active management to sustain desired conditions and processes) is reviewed. Examples of passive systems include natural wetlands, constructed surfaceflow wetlands, constructed subsurface-flow wetlands and permeable reactive barriers (PRB). Examples of semi-passive systems, such as in situ pit lake treatment, require active management that may involve periodic amendments (e.g., organic carbon, nutrients) to stimulate desired microbial mechanisms. In all cases, Se bioremediation relies primarily upon microbial and/or biological processes to remove Se from solution, including plant uptake, precipitation (e.g., in situ formation of elemental Se), adsorption, microbial/algal assimilation and biological volatilization (e.g., release of dimethyl selenide to atmosphere). Case studies that describe field-scale examples of passive and sem...

The distributions of Fe, Mn, Ni, Cu, Zn and As in the water column, interstitial waters and assoc... more The distributions of Fe, Mn, Ni, Cu, Zn and As in the water column, interstitial waters and associated solid phases in Balmer Lake, Ontario, were determined from samples collected in July and October of 1993, and March and May of 1994, in order to assess the seasonal biogeochemical controls governing trace metal behaviour and mobility. The basin has served as a repository for tailings pond effluents since 1967, and as a result, hosts elevated levels of contaminants in the sediments and lake waters. During the ice-free periods of summer, fall and spring, the water column is characterized by fully oxygenated bottom waters and homogeneous distributions of all measured parameters. However, reducing conditions develop in deeper areas during the period of ice cover in response to the high biological demand of the organic-rich sediments coupled with restricted atmospheric exchange. Trace metal profiles collected during winter exhibit considerable lakewide variation and appear to reflect va...

The large volume of pit lakes and their potential role in mine water management make them a focal... more The large volume of pit lakes and their potential role in mine water management make them a focal point of closure planning. In this paper, the modelling of pit lake physical structure and water quality for the Aitik Pit (Aitik Mine, northern Sweden) is used to illustrate: 1) the importance of developing robust site-specific model inputs for the development of defensible pit lake predictions; and 2) how pit lake water quality predictions can be used to inform and refine mine closure plans.

The biogeochemical behaviour of selenium (Se) in two lentic environments (Goddard Marsh (GM) and ... more 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 t...

Integrated Environmental Assessment and Management, 2008

ICES Journal of Marine Science, 2001

A field study was carried out on the central coast of British Columbia in March 1999 to determine... more A field study was carried out on the central coast of British Columbia in March 1999 to determine particle fluxes arising from a salmonid net-pen during feeding. Water samples were collected within, beside, and at two depths relative to a net-pen and analysed for suspended particulate matter (SPM), major and minor elemental abundance, carbon/nitrogen content, and stable carbon isotopes. Sediment traps were also deployed immediately beside the bottom of the net-pen. The highest mean concentration of SPM (0.6 mg l 1) during the feeding cycle was observed within the central region of the net-pen. Approximately 87% and 30% of the mean SPM were observed at depth and beside the net-pen, respectively, suggesting that transport of suspended particulates was predominantly in the vertical direction. Sediment trap deployments revealed that sedimentation fluxes of total SPM, carbon, and nitrogen were higher below the farm than at the control site located 500 m away. Major and minor elemental analyses of feed pellets and sediment trap contents showed that calcium, phosphorus, sulphur, and strontium were removed within the net-pen system. The feed-specific carbon isotope signature (13 C= 21.4 to 22.0‰) was not evident in the trap samples deployed beside the bottom of the net-pen (13 C= 23.4‰), suggesting the relative absence of feed pellet particles, isotopic alteration through fish assimilation and/or dilution of the isotope signature with other carbon sources. However, a feed-signature was evident in samples collected in the upper water column (depth 5 m), suggesting that 13 C might serve as a useful tracer of feed particles.

Environmental Science & Technology, 2003

The post-depositional behavior of Cu in a gold-mining polishing pond (East Lake, Canada) was asse... more The post-depositional behavior of Cu in a gold-mining polishing pond (East Lake, Canada) was assessed after mine closure by examination of porewater chemistry and mineralogy. The near-surface (upper 1.5 cm) sediments are enriched in Cu, with values ranging from 0.4 to 2 wt %. Mineralogical examination revealed that the bulk of the Cu inventory is present as authigenic copper sulfides. Optical microscopy, energy-dispersion spectra, and X-ray data indicate that the main Cu sulfide is covellite (CuS). The formation of authigenic Cu-S phases is supported by the porewater data, which demonstrate that the sediments are serving as a sink for dissolved Cu below sub-bottom depths of 1-2 cm. The zone of Cu removal is consistent with the occurrence of detectable sulfide and the consumption of sulfate. The sediments can be viewed as a passive bioreactor that permanently removes Cu as insoluble copper sulfides. This process is not unlike that which occurs in other forms of bioremediation, such as wetlands and permeable reactive barriers. Above the zone of Cu removal, dissolved Cu maxima in the interfacial porewaters range from 150 to 450 µg L-1 and reflect the dissolution of a Cubearing phase in the surface sediments. The reactive phase is thought to be a component of treatment sludges delivered to the lake as part of cyanide treatment. Flux calculations indicate that the efflux of dissolved Cu from the sediments to the water column (14-51 µg cm-2 yr-1) can account for the elevated levels of dissolved Cu in lake waters (∼50 µg L-1). Implications for lake recovery are discussed.

The removal of selenium (Se) from water using passive technologies at mine sites is challenging a... more The removal of selenium (Se) from water using passive technologies at mine sites is challenging as a result of associated high flow rates. However, the chemical and hydraulic conditions of backfilled pits offer a potential means to bioremediate large volumes of water passively. Specifically, the oxidation demand associated carbonaceous waste materials in conjunction with long water residence times within backfilled pits can produce the suboxic conditions required to support the removal of Se from solution through a suite of microbially-mediated processes. Evidence for Se removal is provided from a study of a backfilled pit at a coal mine in Northern Canada. Redox conditions within the saturated backfill are mildly-suboxic, as inferred from low levels of oxygen, nitrate and the presence of dissolved Mn and Fe. Results show pronounced removal of dissolved Se within the saturated backfill, with concentrations decreasing from 40 μg/L (upgradient of saturated zone) to <1 μg/L within t...

Water Research, 2004

The relationship between lake trophic status, sedimentary redox conditions and As mobility was ex... more The relationship between lake trophic status, sedimentary redox conditions and As mobility was examined in mineimpacted Balmer Lake, Canada. Under the current redox regime, the reductive dissolution of As-bearing Fe(III) oxyhydroxides occurs in close proximity to the sediment-water interface, resulting in the remobilization of dissolved As in the shallow porewaters to values as high as 8.5 mg L À1. The shallow depth of the oxic zone limits the extent to which As can be re-sorbed in the interfacial horizons, and as a result, a proportion of the remobilized As escapes into the water column where it poses a water quality concern. Examination of the relationship between summer average chlorophyll a and total P at spring overturn in the lake water column demonstrates that Balmer Lake is currently eutrophic as a result of mining-derived inputs of P (domestic waters) and N (blasting residues and cyanide breakdown products). The results suggest that actively pushing the system towards oligotrophy by reducing non-natural P loadings to the system will decrease rates of in situ production and associated sediment oxygen demand, which will in turn result in increased thickness of the aerobic zone and enhanced As scavenging. Such conclusions are supported by porewater data which indicate that the flux of As to the water column is significantly reduced when the Fe(III) redox cline is situated at deeper sediment depths. In the absence of detailed P-loading data, it is recommended that P inputs be reduced to 1010% of the estimated pre-mining P loading of 10200 kg yr À1. This implies reducing the collective P-loadings from the two mine sites adjacent to the lake from the approximate current value ($150 kg yr À1) to $20 kg yr À1. It is proposed that establishment of oligotrophy in the lake should significantly mitigate the current level of dissolved As in lake waters.

Marine Pollution Bulletin, 2007

Marine sediment samples were collected in the Broughton Archipelago, British Columbia, to assess ... more Marine sediment samples were collected in the Broughton Archipelago, British Columbia, to assess the use of a geochemical normalization technique in the identification of a chemical tracer of aquaculture waste material. Zinc and copper were suggested as tracers of feed pellets, while copper was considered an indicator of anti-foulant agents used on netpen systems. The sediment samples were analyzed for carbon, nitrogen, organic matter, water, trace-element, and free sulfide concentrations, and sediment grain-size distribution. Sediment texture analysis revealed a wide range of substrate types from sand to silty loam categories. Strong relationships between sediment texture, sediment porosity, and organic content were observed across both near-field and far-field stations. Excess zinc and copper sediment concentrations, identified using a lithium-normalization technique, were restricted to near-field sampling stations (0 and 30m from netpen systems). The relationships between these metal tracers and organic content and sulfur concentrations were explored to account for variations in sediment concentrations of zinc and copper.