EXECUTIVE SUMMARY

The Canadian Government committed to review the Metal Mining Liquid Effluent Regulations (MMLERs) in the early 1990’s. Discussions established the need to identify tools that could be used to monitor the effects of effluents from mining operations on the aquatic environment. This provided the impetus for the Aquatic Effects Technology Evaluation (AETE) program.

The mandate for the AETE program was twofold:
1) to evaluate environmental monitoring technologies that could be used to assess the impacts of mine effluents, and
2) to recommend specific methods or groups of methods that will permit accurate characterization of environmental impacts in as cost-effective a manner as possible.

The AETE program was a joint initiative of the Canada Centre for Mineral and Energy Technology (CANMET) and the Mining Association of Canada (MAC). Other federaland provincial departments participated on the management and technical committees. The $3.4M program ran from 1994 to 1998 and supported over 30 individual studies and projects. This Synthesis Report provides a summary and overview of the program, major findings and final recommendations.

The program consisted of three main technical areas:
a) acute and sublethal toxicity test methods,
b) water and sediment monitoring methods, and
c) biological monitoring methods in receiving waters

The tools and methods recommended in this report should be suitable for use in a routine monitoring program to document existing environmental conditions and to determine if there is a measurable effect. The federal government is also developing an Environmental Effects Monitoring (EEM) program for the mining sector in Canada under the federal Fisheries Act. The AETE Synthesis Report provides a list of recommended tools that could be adopted in the EEM program.

Monitoring tools considered by the AETE program had to address at least one of the following guiding questions:
1) are contaminants getting into the system?
2) are contaminants bioavailable?
3) is there a measurable biological response?
4) are the contaminants in the system causing the observed response?

Over 100 potential monitoring tools were considered through initial screening, literature(technical) reviews, laboratory and field testing. Tools were evaluated using several criteria including ability to answer one or more of the four guiding questions, demonstrated performance in the AETE program, cost, practicality and availability of standardized protocols.

Only tools evaluated within the context of AETE were recommended, although it is recognized that other monitoring methods may be available for more detailed studies. Furthermore, although some tools were not considered suitable for use in routine monitoring programs, their potential application in detailed site-specific investigations is recognized by AETE.

The toxicity testing component examined five rapid micro-toxicity tests as potential alternatives to the commonly used Rainbow trout and Daphnia magna acute lethality tests for examination of liquid effluents. Secondly, nine sublethal toxicity test methods were evaluated for their ability to detect sublethal effluent effects. In addition, the ability of sublethal toxicity test results to predict downstream biological effects was examined. Four sediment toxicity test methods were also evaluated to determine their ability to detect effects from mine discharges.

The mandate of the water and sediment monitoring component of AETE was to evaluate methods of assessing effects of mine effluents to receiving waters and their underlying sediments. The tools and methods evaluated included total versus dissolved metal concentrations in water, filtering methods, analytical detection limits, methods of sediment collection and analysis of total or partial metal levels in sediments.

The biological monitoring component evaluated tools to determine if contaminants were bioavailable, and to measure biological responses in receiving waters. A wide range of tools were considered including metal levels and biochemical indices in plant and animal tissues, metallothionein levels in fish tissues, various measures of benthic invertebrates and surveys of fish including abundance, growth, histopathology, reproduction and organ size.

A series of thirteen formal hypotheses were also developed that could be tested during field studies conducted in 1997. The hypotheses were based on the four guiding questions but helped clarify comparisons of individual monitoring tools (e.g. total versus dissolved metals in water). In addition, a number of integration hypotheses were developed to examine the relationships between different tools or monitoring results (e.g. relationship between sediment toxicity and benthic invertebrates).

Field trials of the candidate tools comprised a significant portion of the AETE program during three different years. A pilot program was conducted in 1995 at one mine site to evaluate 10 specific monitoring tools. The 1996 field program included a preliminary evaluation of seven (7) mine sites across Canada that incorporated toxicity testing as well as environmental measurements. The purpose of the 1996 program was to select four mine sites for further detailed testing, and to prepare a study design for the detailed investigations. The criteria to select four sites for detailed evaluation included:
¨ presence of a well defined gradient of water, sediment, toxicity and biological effects
¨ availability of adequate reference stations, and
¨ suitability of the site to test hypotheses

The 1997 field program included two phases:
1. detailed field and laboratory evaluation and hypothesis testing at four mine sites, and
2. data interpretation and comparative assessment of the monitoring methods.

To examine the question “are the contaminants in the system causing the observed response?”, a weight-of-evidence approach was investigated. Specifically, the sediment quality triad was used to examine the statistical relationships between water and sediment chemistry, toxicity and in-stream (or lake) biological responses.

The various technical evaluations, laboratory testing and field surveys all produced individual reports for the AETE program that included recommendations pertaining to monitoring tools. Where there were discrepancies between a technical review and the field survey observations, greater weight was given to the field results when considering a recommendation. In the end, only the tools recommended in this Synthesis Report are endorsed by AETE. Sixteen individual tools are recommended as suitable candidates in a routine mine monitoring program. An additional six tools are recognized as having potential application in more detailed site specific investigations.