Metal Mining Effluent Research Articles

Exposure and recovery: The effect of different dilution factors of treated and untreated metal mining effluent on freshwater biofilm function and structure

Abandoned mines generate effluents rich in heavy metals, and these contaminants are released uncontrolled into the nearby aquatic ecosystems, causing severe pollution. However, no real solution exists, leaving a legacy of global pollution. In this study, the efficiency of the treatment technologies in reducing the ecological impacts of mining effluents to freshwater ecosystems with different dilution capacities was tested using biofilm communities as biological indicators. The functional and structural recovery capacity of biofilm communities after 21 days of exposure was assessed. With this aim, we sampled aquatic biofilms from a pristine stream and exposed them to treated (T) and untreated (U) metal mining effluent from Frongoch abandoned mine (Mid Wales, UK). Additionally, we simulated two different flow conditions for the receiving stream: high dilution (HD) and low dilution (LD). After exposure, the artificial streams were filled with artificial water for 14 days to assess the biofilm recovery. Unexposed biofilm served as control for biofilm responses (functional and structural) measured throughout time. During the exposure, short term effects on biofilm functioning (photosynthetic efficiency, nutrient uptake) were observed in T-LD, U-HD, and U-LD, whereas long term effects (community composition, chl-a, and diatom metrics) were observed on the structure of all biofilms exposed to the treated and untreated mining effluent. On the other hand, metal accumulation occurred in biofilms exposed to the mining effluents. However, a functional recovery was observed for all treatments, except in the U-LD in which biofilm structure did not present a significant recovery after the exposure period. The results presented here highlight the need to consider the dilution capacity of the receiving stream to assess the real efficiency of treatment technologies applied to mining effluents to mitigate the ecological impact on freshwater ecosystems.

Condition and Sperm Characteristics of Perch Perca fluviatilis inhabiting Boreal Lakes Receiving Metal Mining Effluents

One of the world’s largest, but low-grade, sulfide nickel deposits in northeastern Finland has been exploited by a bioheapleaching technology since 2008. Bioheapleaching is a relatively new, cost-effective technology, but humid climate, e.g., in boreal temperate environments, causes challenges to the management of the water balance in the ore heaps with wide catchment area, and the mining effluents have caused substantial metal and salting contamination of the receiving waterbodies. In our study, the impacts of metal-extracting bioheapleaching mine effluents on muscle and liver element concentrations, body condition, liver and testes mass, and sperm count and motility of male perch Perca fluviatilis were analysed. Liver, testes, and carcass mass of perch in relation to their length were lower in the mining-impacted lakes than in the reference lake, which may be due to the metal contamination, food availability, and energy demand under multistressor conditions. The sperm counts of the males in the mining-impacted lakes were lower, but the endurance of their sperm motility was longer than the endurance of sperm of the reference males. These findings suggested that the condition and sperm characteristics of perch were altered in lakes receiving metal mining effluents. Measured variables seem to be useful indicators for metal mining impacts on freshwater fish but only if high natural variation in these characteristics can be controlled by multiyear monitoring scheme.

Assessing the effects of metal mining effluents on freshwater ecosystems using biofilm as an ecological indicator: Comparison between nanofiltration and nanofiltration with electrocoagulation treatment technologies

Abstract Abandoned mines cause serious environmental damage to their surroundings with considerable impacts on freshwater ecosystems. These impacts occur mainly due to the uncontrolled discharge of polluted effluents, which may contain high concentrations of heavy metals. Currently, no real solution exists for this important environmental problem, leaving a legacy of global pollution. This study aimed to assess the impact of a metal mining effluent from an abandoned mine on freshwater ecosystems, using aquatic biofilms as an ecological indicator. At the same time, the efficiency of different innovative treatment technologies in reducing the ecological impacts caused by mining effluents was evaluated, consisting of nanofiltration and nanofiltration combined with electrocoagulation. To do that, aquatic biofilms obtained from a pristine stream, were exposed, under microcosms conditions, to a metal mining effluent, untreated or treated by the innovative treatment technologies and responses were compared with unexposed biofilm which served as control. The structural and functional responses of the biofilm were measured with throughout time. Biofilms that were exposed to the untreated mining effluent showed significant differences respect to the rest of treatments and the control, particularly exhibiting inhibitory effects on photosynthetic efficiency just after 24 h of exposure and a progressive shift of the photosynthetic community composition throughout the exposure period. The treatment technologies significantly reduced the ecological impact caused by the metal mining effluent. However, metal bioaccumulation in biofilm revealed a potential long-term impact. These observations evidenced the biofilm as a useful ecological indicator to assess the ecological impact caused by metal mining effluents on freshwaters and the efficiency of different treatment technologies to reduce it.

Development of environmental effects monitoring protocol in Brazil: a fish guide study of three river estuaries.

In Brazil, there are no unified and effective environmental monitoring models for bodies of water. Thus, several methodologies are used that result in information that is often difficult to compare, especially for stakeholders involved in regional water management. Studies in some countries such as Australia, Chile, the USA, and Sweden use the monitoring model implemented in Canada that was developed in the early 1990s. This model was designed to evaluate whether the current environmental regulations are sufficiently protective for pulp and paper effluents and for metal mining effluents. In this study, the Canadian Environmental Effects Monitoring methodologies were applied to three different Brazilian river basins, with the goal of constructing a framework for monitoring environmental effects. Pilot studies were carried out in the estuarine regions of the Benevente, Jucu, and Santa Maria da Vitória river basins, which are important rivers in the state of Espírito Santo. Evaluations included fish health, bioaccumulation studies, benthic invertebrate survey, and physical-chemical analyses of water and sediment. The quality of the environments was evaluated by means of seasonal samplings and comparisons between discharge, upstream, and downstream areas. This study made it possible to identify appropriate fish species to be used in environmental effects monitoring and the environmental quality of the rivers themselves as well as knowledge and policy gaps to implement such monitoring programs in Brazil. The study raises questions about the adequacy of Brazilian environmental legislation concerning tidal rivers.

Evaluation of Lethal Fish Sampling and the Nonlethal Alternative Under the Canadian Metal and Diamond Mining Environmental Effects Monitoring Program

The Environmental Effects Monitoring (EEM) program, federally mandated to metal and diamond mines and mills in Canada, aims to ensure that fish, fish use, and their environment are sufficiently protected by the Metal and Diamond Mining Effluent Regulations (MDMER). Concerns have been raised regarding lethal fish sampling conducted for the program and the potential risk to fish populations. This study endeavored to calculate the extent of fish sacrificed during lethal EEM fish surveys to provide a more informed characterization for stakeholders. By extrapolating data from 28 studies conducted at 8 metal mines in Saskatchewan between 2004 and 2017, it was conservatively estimated that 60 060 ± 19 978 fish have been sacrificed for the program nationwide since its promulgation in 2002. This is almost 2 times greater than guidance recommendations due to numerous factors. Challenges faced when implementing the nonlethal fish population survey alternative were also evaluated, and some of these included data interpretation inconsistencies due to the lack of critical effect sizes (CES) included in the regulations for nonlethal effect endpoints, and reliance on capturing young of the year fish to assess the prescribed effect endpoints. Finally, a case study conducted to evaluate the congruity of lethal and nonlethal fish population survey results identified that the effect endpoints often produced conflicting conclusions for the same response variable. Ultimately, this study highlights that in order to strengthen and promote the use of nonlethal fish sampling as an alternate to the current standard of conducting lethal fish population surveys under the EEM program, the effect endpoints, study designs, and adoption of CES need to be thoroughly evaluated and included in the MDMER. If nonlethal sampling designs adequately provide the required data and meet program objectives, then there would be no need to continue sacrificing fish for the Canadian metal and diamond mining EEM program. Integr Environ Assess Manag 2019;00:1-10. © 2019 SETAC.

Bench-scale comparison of conventional and high rate clarification treatment processes for acid mine drainage

Acid mine drainage (AMD) is characterized as having low pH and high concentrations of sulfate and dissolved metals. This study compared treated water quality and sludge properties of three process technologies for AMD: conventional sedimentation, high density sludge (HDS), and ballasted flocculation. All three processes were found to be capable of removing regulated metals to concentrations below current Canadian discharge guidelines. However, ballasted flocculation was the only technology found to be able to meet the more stringent federal guidelines proposed for future implementation under the Fisheries' Act's Metal Mining Effluent Regulations. Specifically, arsenic and zinc concentrations in AMD treated by the conventional and HDS processes were above proposed future guidelines of 0.10 and 0.25 mg/L, respectively, while lead, copper, and nickel all met respective guidelines. Concentrations of all regulated contaminants were below proposed guidelines when treated by ballasted flocculation. The HDS process was found to produce a significantly more concentrated sludge than conventional sedimentation (i.e., higher solids content (19 ± 1% versus 7 ± 4% wet solids) and lower sludge volume index (SVI; 8.4 ± 0.8 versus 230 ± 20 mL/g)).

Assessing the fate and toxicity of Thallium I and Thallium III to three aquatic organisms

Thallium has been shown to significantly increase in both water and aquatic biota after exposure to metal mine effluent, however, there is a lack of knowledge as to its fate and effect in the aquatic environment. The objectives of this project were to assess (1) fate of thallium by conducting speciation analysis and determining the influence of water quality on toxicity and (2) effects of thallium (I) and (III) on three aquatic species; the algae, Pseudokirchneriella subcapitata, the invertebrate Ceriodaphnia dubia and the vertebrate Pimephales promelas.Speciation analysis proved challenging with poor recovery of thallium (I), however analysis with solutions >125μg/L revealed that over a 7-d period, recovery of thallium (III) was less than 15%, suggesting that the majority of thallium (III) was converted to Thallium (I). It was only in fresh solutions where recovery of Thallium (III) was greater than 80%.The lowest IC25s generated during our effects assessment for both Thallium (I) and (III) were more than 10-fold greater than the highest concentration recorded in receiving environments (8μg/L) and more than 100-fold greater than the current guideline (0.8μg/L).To assess the influence of water quality on thallium toxicity, the concentrations of both potassium and calcium were reduced in dilution water. When potassium was reduced for both C. dubia and P. subcapitata tests, the lowest IC25 generated was 5-fold higher than the current guideline, but within the range of concentrations reported in receiving environments for both Thallium (I) and (III). When calcium was reduced in dilution water, toxicity only increased in the Tl (III) tests with C. dubia; the IC25 for Tl(III), similar to the exposures conducted with reduced potassium, was within the range of total thallium concentrations reported in the receiving environment.Without an accurate, repeatable method to assess thallium speciation at low concentrations it is not possible to draw any firm conclusions as to whether the IC25s for Tl (III) are relevant to concentrations present in receiving environments. Based on the results of our study we recommend that any test, to determine Thallium (III) toxicity, use fresh solutions, made daily, to get good recovery and accurate toxicity results. The results generated in our effects and exposure assessment would indicate that the current guideline of 0.8μg/L is protective. Special attention should be placed on the concentration of potassium in receiving environments when estimating thallium toxicity.

Root length of aquatic plant, Lemna minor L., as an optimal toxicity endpoint for biomonitoring of mining effluents.

Lemna minor, a free-floating macrophyte, is used for biomonitoring of mine effluent quality under the Metal Mining Effluent Regulations (MMER) of the Environmental Effects Monitoring (EEM) program in Canada and is known to be sensitive to trace metals commonly discharged in mine effluents such as Ni. Environment Canada's standard toxicity testing protocol recommends frond count (FC) and dry weight (DW) as the 2 required toxicity endpoints-this is similar to other major protocols such as those by the US Environmental Protection Agency (USEPA) and the Organisation for Economic Co-operation and Development (OECD)-that both require frond growth or biomass endpoints. However, we suggest that similar to terrestrial plants, average root length (RL) of aquatic plants will be an optimal and relevant endpoint. As expected, results demonstrate that RL is the ideal endpoint based on the 3 criteria: accuracy (i.e., toxicological sensitivity to contaminant), precision (i.e., lowest variance), and ecological relevance (metal mining effluents). Roots are known to play a major role in nutrient uptake in conditions of low nutrient conditions-thus having ecological relevance to freshwater from mining regions. Root length was the most sensitive and precise endpoint in this study where water chemistry varied greatly (pH and varying concentrations of Ca, Mg, Na, K, dissolved organic carbon, and an anthropogenic organic contaminant, sodium isopropyl xanthates) to match mining effluent ranges. Although frond count was a close second, dry weight proved to be an unreliable endpoint. We conclude that toxicity testing for the floating macrophyte should require average RL measurement as a primary endpoint.

Influence of elevated alkalinity and natural organic matter (NOM) on tissue-specific metal accumulation and reproductive performance in fathead minnows during chronic, multi-trophic exposures to a metal mine effluent

Metal bioavailability in aquatic organisms is known to be influenced by various water chemistry parameters. The present study examined the influence of alkalinity and natural organic matter (NOM) on tissue-specific metal accumulation and reproductive performance of fathead minnows (Pimephales promelas) during environmentally relevant chronic exposures to a metal mine effluent (MME). Sodium bicarbonate (NaHCO3) or NOM (as commercial humic acid) were added to a Canadian MME [45 percent process water effluent (PWE)] in order to evaluate whether increases in alkalinity (3–4 fold) or NOM (~1.5–3mg/L dissolved organic carbon) would reduce metal accumulation and mitigate reproductive toxicity in fathead minnows during a 21-day multi-trophic exposure. Eleven metals (barium, boron, cobalt, copper, lithium, manganese, molybdenum, nickel, rubidium, selenium, and strontium) were elevated in the 45 percent PWE relative to the reference water. Exposure to the unmodified 45 percent PWE resulted in a decrease of fathead minnow egg production (~300 fewer eggs/pair) relative to the unmodified reference water, over the 21-day exposure period. Water chemistry modifications produced a modest decrease in free ion activity of some metals (as shown by MINTEQ, Version 3) in the 45 percent PWE exposure water, but did not alter the metal burden in the treatment-matched larval Chironomus dilutus (the food source of fish during exposure). The tissue-specific metal accumulation increased in fish exposed to the 45 percent PWE relative to the reference water, irrespective of water chemistry modifications, and the tissue metal concentrations were found to be similar between fish in the unmodified and modified 45 percent PWE (higher alkalinity or NOM) treatments. Interestingly however, increased alkalinity and NOM markedly improved fish egg production both in the reference water (~500 and ~590 additional eggs/pair, respectively) and 45 percent PWE treatments (~570 and ~260 additional eggs/pair, respectively), although fecundity over 21 day exposure consistently remained lower in the 45 percent PWE treatment groups relative to the treatment-matched reference groups. Collectively, these findings suggest that metal accumulation caused by chronic 45 percent PWE exposure cannot solely explain the reproductive toxicity in fish, and decrease in food availability (decrease in C. dilutus abundance in 45 percent PWE exposures) might have played a role. In addition, it appears that NaHCO3 or humic acid mitigated reproductive toxicity in fish exposed to 45 percent PWE by their direct beneficial effects on the physiological status of fish.

The influence of food quantity on metal bioaccumulation and reproduction in fathead minnows (Pimephales promelas) during chronic exposures to a metal mine effluent

Metal mine effluents can impact fish in the receiving environment via both direct effects from exposure as well as indirect effects via food web. The main objective of the present study was to assess whether an indirect effect such as reduced food (prey) availability could influence metal accumulation and reproductive capacity in fish during chronic exposure to a metal mine effluent. Breeding pairs of fathead minnows (Pimephales promelas) were exposed to either reference water (RW) or an environmentally relevant metal mine effluent [45 percent process water effluent (PWE)] for 21 days and fed either low food quantities [LF (a daily ration of 6–10 percent body weight)] or normal food quantities [NF (a daily ration of 20–30 percent body weight)] in artificial stream systems. Fish in RW treatments were fed Chironomus dilutus larvae cultured in RW (Treatments: RW-NF or RW-LF), while fish in PWE treatments were fed C. dilutus larvae cultured in PWE (Treatments: PWE-NF or PWE-LF). Tissue-specific (gill, liver, gonad and carcass) metal accumulation, egg production, and morphometric parameters in fish were analyzed. Fathead minnows that were exposed to LF rations had significantly smaller body, gonad and liver sizes, and were in a relatively poor condition compared to fathead minnows exposed to NF rations, regardless of the treatment water type (RW or PWE) (two-way ANOVA; p<0.05). Although elevated concentrations of copper, nickel, rubidium, selenium, and thallium were recorded in C. dilutus cultured in PWE, only the concentrations of rubidium, selenium and thallium increased in tissues of fish in PWE treatments. Interestingly though, despite the greater abundance of metal-contaminated food in the PWE-NF treatment, tissue metal accumulation pattern were almost similar between the PWE-NF and PWE-LF treatments, except for higher liver barium, cobalt and manganese concentrations in the latter treatment. This indicated that a higher food ration could help reduce the tissue burden of at least some metals and thereby ameliorate the toxicity of metal-mine effluents in fish. More importantly, cumulative egg production in fish was found to be lowest in the PWE-LF treatment, whereas fish egg production in the PWE-NF treatment was not impacted. Overall, these findings suggest that decreased food abundance could have a greater impact than metal accumulation in target tissues on the reproductive capacity of fish inhabiting metal-mine effluent receiving environments.

A Single Metal, Metal Mixture, and Whole-Effluent Approach to Investigate Causes of Metal Mine Effluent Effects on Fathead Minnows (Pimephales promelas)

Although many studies have examined effects of metal mine effluents (MMEs) on receiving environments, few have compared the roles of individual and mixed metals relative to whole effluents. The objective of the present set of studies was to examine whether Cu, Ni, or Se, alone or in a mixture, causes comparable effects to those observed in fathead minnows (Pimephales promelas) exposed to an environmentally relevant MME (45 % process water effluent [PWE]). Metal bioaccumulation, fathead minnow (FHM) morphometrics, and egg production were compared between treatments over a 21-day exposure. FHMs were exposed to similar waterborne concentrations and species of metals in single and mixed metal treatments relative to 45 % PWE. FHMs were also exposed to similar concentrations of metals in single and mixed metal treatments relative to 45 % PWE through the diet (Chironomus dilutus — a representative prey species). However, only FHMs exposed to 45 % PWE had reduced egg production (60–80 % less than controls). Our findings indicate that Cu, Ni, and Se exposures and bioaccumulation did not contribute to decreased reproductive output in FHMs under the conditions that were examined. We also found no evidence to believe that these metals were responsible for decreased egg production in PWE. It is therefore reasonable to suggest that these metals have limited potential to cause reproductive effects in MMEs with similar composition and water chemistry conditions. Overall, this study highlights the importance of examining single and mixed metal exposures prior to suggesting that adverse effects in fish exposed to MMEs occur due to bioaccumulation of metal(s).

Can natural variability trigger effects on fish and fish habitat as defined in Environment Canada's metal mining environmental effects monitoring program?

The Metal Mining Effluent Regulations (MMER) took effect in 2002 and require most metal mining operations in Canada to complete environmental effects monitoring (EEM) programs. An "effect" under the MMER EEM program is considered any positive or negative statistically significant difference in fish population, fish usability, or benthic invertebrate community EEM-defined endpoints. Two consecutive studies with the same statistically significant differences trigger more intensive monitoring, including the characterization of extent and magnitude and investigation of cause. Standard EEM study designs do not require multiple reference areas or preexposure sampling, thus results and conclusions about mine effects are highly contingent on the selection of a near perfect reference area and are at risk of falsely labeling natural variation as mine related "effects." A case study was completed to characterize the natural variability in EEM-defined endpoints during preexposure or baseline conditions. This involved completing a typical EEM study in future reference and exposure lakes surrounding a proposed uranium (U) mine in northern Saskatchewan, Canada. Moon Lake was sampled as the future exposure area as it is currently proposed to receive effluent from the U mine. Two reference areas were used: Slush Lake for both the fish population and benthic invertebrate community surveys and Lake C as a second reference area for the benthic invertebrate community survey. Moon Lake, Slush Lake, and Lake C are located in the same drainage basin in close proximity to one another. All 3 lakes contained similar water quality, fish communities, aquatic habitat, and a sediment composition largely comprised of fine-textured particles. The fish population survey consisted of a nonlethal northern pike (Esox lucius) and a lethal yellow perch (Perca flavescens) survey. A comparison of the 5 benthic invertebrate community effect endpoints, 4 nonlethal northern pike population effect endpoints, and 10 lethal yellow perch effect endpoints resulted in the observation of several statistically significant differences at the future exposure area relative to the reference area and/or areas. When the data from 2 reference areas assessed for the benthic invertebrate community survey were pooled, no significant differences in effect endpoints were observed. These results demonstrate weaknesses in the definition of an "effect" used by the MMER EEM program and in the use of a single reference area. Determination of the ecological significance of statistical differences identified as part of EEM programs conducted during the operational period should consider preexisting (background) natural variability between reference and exposure areas.

Selenium speciation and localization in chironomids from lakes receiving treated metal mine effluent

A lake system in northern Saskatchewan receiving treated metal mine and mill effluent contains elevated levels of selenium (Se). An important step in the trophic transfer of Se is the bioaccumulation of Se by benthic invertebrates, especially primary consumers serving as a food source for higher trophic level organisms. Chironomids, ubiquitous components of many northern aquatic ecosystems, were sampled at lakes downstream of the milling operation and were found to contain Se concentrations ranging from 7 to 80mgkg−1dry weight. For comparison, laboratory-reared Chironomus dilutus were exposed to waterborne selenate, selenite, or seleno-DL-methionine under laboratory conditions at the average total Se concentrations found in lakes near the operation. Similarities in Se localization and speciation in laboratory and field chironomids were observed using synchrotron-based X-ray fluorescence (XRF) imaging and X-ray absorption spectroscopy (XAS). Selenium localized primarily in the head capsule, brain, salivary glands and gut lining, with organic Se species modeled as selenocystine and selenomethionine being the most abundant. Similarities between field chironomids and C. dilutus exposed in the laboratory to waterborne selenomethionine suggest that selenomethionine-like species are most readily accumulated, whether from diet or water.

Environmental Pursuits In Nanomaterial Systems Science With Indian Exemplars

AbstractThe behavior and pattern of NPs of minerals in the evolutionary history of the earth vis – a –vis the environmental context are inquired into, with a riverine system as a model. The study of fractal dimensions of NPs of interest serves as an aid to obtain a comprehensive view of natural NPs in the model system. The present study combines inputs from work done on nanoparticles, derived from the Subanarekha River System and products of base metal mine effluents that are rich in NPs of minerals. The authors believe this study would help to establish certain universalities about NPs and provide an updated framework for understanding the current state of nanomineral science.

Examining waterborne and dietborne routes of exposure and their contribution to biological response patterns in fathead minnow ( Pimephales promelas)

The objectives of the current study were: (i) to gain a better understanding of the relative importance of water and diet as routes of exposure causing toxicity in fathead minnow (FHM) exposed to metal mining effluents (MME) using a full factorial water/food experimental design (Experiment 1), and (ii) to assess differences in the effects of food quality on toxicity by comparing FHM fed both a live and frozen diet of Chironomus dilutus (Experiment 2). The results showed significant increases in general water quality parameters (e.g., hardness, conductivity) and various metals in the effluent treatment waters compared to control waters, with maximum increase seen in the multi-trophic streams. Metals accumulation (Rb, Al, Se, Sr, Tl, Ce, Co, Cu, Pb) effects of both waterborne and multi-trophic exposures were significant in one or more fathead minnow tissue type (muscle, gonads, liver, larvae) relative to those in the control systems. Condition factor and liver somatic index (LSI) of FHM were also significantly affected in both exposures by one or both routes of exposure (water and/or diet). In addition, cumulative total egg production and cumulative spawning events were significantly affected by both waterborne and dietborne exposures, with maximum effect found in the multi-trophic streams. These results suggest that under environmentally relevant exposure conditions, trophic transfer of metals may lead to greater reproductive effects and increased metal toxicity in fish. It also indicates that metals are assimilated in tissues differently depending on the quality of the food (live vs. frozen). Overall, it appears that the multi-trophic bioassay provides an important link between the laboratory and field, which may allow for a more realistic assessment of the true impact of MME's in the environment.

Environmental Pursuits In Nanomaterial Systems Science With Indian Exemplars

AbstractThe behavior and pattern of NPs of minerals in the evolutionary history of the earth vis – a –vis the environmental context are inquired into, with a riverine system as a model. The study of fractal dimensions of NPs of interest serves as an aid to obtain a comprehensive view of natural NPs in the model system. The present study combines inputs from work done on nanoparticles, derived from the Subanarekha River System and products of base metal mine effluents that are rich in NPs of minerals. The authors believe this study would help to establish certain universalities about NPs and provide an updated framework for understanding the current state of nanomineral science.

Examining the effects of metal mining mixtures on fathead minnow ( Pimephales promelas) using field-based multi-trophic artificial streams

This study illustrates the use of a mesocosm approach for assessing the independent effects of three treated metal mine effluents (MME) discharging into a common receiving environment and regulated under the same regulation. A field-based, multi-trophic artificial stream study was conducted in August 2008 to assess the effects of three metal mining effluents on fathead minnow ( Pimephales promelas) in a 21-day reproduction bioassay. The nature of the approach allowed for assessment of both dietary and waterborne exposure pathways. Elements (e.g. Se, Co, Cl, Cu, Fe) were analyzed in several media (water, sediments) and tissues (biofilm, Chironomus dilutus, female fathead minnow (FHM) body, ovary, liver, gills). Significant increases in metal and micronutrient concentrations were observed in the water and biofilm tissues in all MME treatments [20% surface water effluent (SWE), 30% mine water effluent (MWE), and 45% process water effluent (PWE)], compared to reference. However, copper was the only element to significantly increase in the sediments when exposed to PWE. Co and Ni increased significantly in C. dilutus tissues in SWE (1.4- and 1.5-fold, respectively), Cu and Se also increased in chironomid tissues in PWE (5.2- and 3.3-fold, respectively); however, no significant increases in metals or micronutrients occurred in chironomid tissues when exposed to MWE compared to reference. There were no significant increases in metal concentrations in female FHM tissues (body, liver, gonads, gills) in any of the treatments suggesting that metals were either not bioavailable, lost from the females via the eggs, or naturally regulated through homeostatic mechanisms. Cumulative number of eggs per female per day increased significantly (∼127%) after exposure to SWE and decreased significantly (∼33%) after exposure to PWE when compared to reference. Mean total number of days to hatch was reduced in PWE compared to reference. This study shows the importance of isolating treatment streams in cumulative discharge environments to assess aquatic effects due to the different nature of the effluents.

Guidance for Site-Specifically Assessing the Health of Fish Populations with Emphasis on Canada's Environmental Effects Monitoring Program

Abstract Techniques have been developed over the past two decades to site-specifically assess effects of contaminants on the health of fish populations using a sentinel species approach. National environment effects monitoring (EEM) programs have been implemented in Canada for pulp and paper effluents since 1992 and liquid metal mining effluents since 2002 to monitor effects of these discharges on the health of fish populations. The major criticisms of past EEM fish population surveys can be separated into concerns about the adequacy of the reference sites, the potential impacts of confounding factors, the ecological relevance of endpoints used, the influences of natural variability, concerns over statistical design issues, and potential genetic influences on species characteristics. This paper provides input to deal with these issues and guidance on the selection of sentinel species, timing of sampling, and nonlethal sampling methods to evaluate the health of fish populations. Sample size requirements, effect sizes, and power analysis are also discussed as well as data analysis guidance needed to obtain reliable results.

Growth and energy storage in juvenile fathead minnows exposed to metal mine waste water in simulated winter and summer conditions

Juvenile fathead minnows ( Pimephales promelas) were exposed from 10 to 100 days post-hatch (dph) to metal mining effluent under simulated summer (20 °C and 16/8 light/dark) or winter (4 °C and 8/16 light/dark) conditions in order to test the winter stress syndrome hypothesis. The condition factor of fish at 100 dph was similar between seasons, and was greater in the summer effluent exposure group compared to the summer control. Whole body triglycerides were lower in the effluent exposure group compared to control under winter conditions, but not summer. Whole body burdens of several trace metals, notably Cu, Rb and Se, were greater in the effluent exposed fish at 100 dph and displayed seasonal differences in bioaccumulation. Fathead minnows were also exposed from 10 to 100 dph to graded concentrations of ammonia (0.02–0.40 mg unionized NH 3/L) under summer conditions in order to investigate potential effects of this component of the effluent. There was no effect of ammonia exposure on growth parameters, but an increase in whole body triglycerides was observed at the highest exposure. The seasonal differences in bioaccumulation and biological responses suggest that winter conditions may be an important modifying factor in aquatic toxicological studies.

Sublethal Toxicity Testing of Canadian Metal Mining Effluents: National Trends and Site-Specific Uses

ABSTRACT As part of the Canadian Environmental Effects Monitoring program under the National Metal Mining Effluent Regulation, there is a requirement to conduct sublethal toxicity tests twice per year for the first three years. These first three years (2003 to 2005) were considered a period of initial monitoring and resulted in test endpoints for each of the required standardized methods on a fish, an aquatic plant, an invertebrate, and an algal species. On a national level (based on 1648 valid results), the test from most to least sensitive was: the inhibition of reproduction with Ceriodaphnia dubia, the growth inhibition (frond number) with Lemna minor, the inhibition of cell yield with Pseudokirchneriella subcapitata, the growth inhibition (dry weight) with Lemna minor, the growth inhibition of fathead minnows, and the effect on embryo viability with rainbow trout. This sensitivity ranking changed when tests were further evaluated on a geographical region and mine-type basis (e.g., base metal, precious metal, uranium, iron ore). Site-specific examples show how sublethal toxicity data are being used to track changes in effluent quality, choosing a final discharge point, monitoring multiple discharges to the same watercourse, and to identify study design weaknesses by comparing laboratory results to field survey conclusions.