The Baseline - Mining and the Environment: From Ore to Metal - page 351

TABLE 8.2
Example of an Indicator Profi le, Adopted from Ward et al. (1998)

Indicator - Sediment Quality (Contaminants)

Description - This indicator documents levels of, and changes in, major contaminants of surface sediments in surface water bodies including estuaries and
coastal areas.

Rationale - Contaminants commonly accumulate in sediments, and measurement of sediment concentrations of contaminants is a useful way to track
long-term trends in concentrations of most contaminants in aquatic systems. These concentrations indicate the extent and magnitude of pressure imposed
by contaminants on the fl ora and fauna of the shallow water ecosystems.

Analysis and interpretation - Contaminants are sometimes anthropogenic materials (such as cyanide) introduced by mining, while others are naturally
occurring materials (such as trace metals) and become contaminants when they occur in higher than usual concentrations. Some fi nd their way into the sur-
face sediments of waterways after various periods (sometimes brief) in the water column. Naturally occurring materials are often in the natural make up of
the sediment material. For both anthropogenic and natural materials, the precise level at which an effect can be expressed in the biological system is diffi cult
to defi ne. Hence, besides using absolute concentration criteria to determine when levels are acceptable, trend assessment becomes important in evaluating
level of stress imposed by contaminants. For anthropogenic materials, levels should be trending downwards, hopefully to near-zero, while for natural materi-
als they should be close to natural background levels and not trending upwards. Monitoring results that do not fi t these objectives may indicate the need for
environmental mitigation and remedial actions. Change can only be detected against a baseline of existing or historic data, and then only with many caveats
about collection and analysis techniques. Since laboratory techniques become increasingly sophisticated and a project may become controversial with time,
data from earlier times may become questionable. Full documentation of procedures, quality assurance and controls is critical if currently collected data are
to be useful in the future.

Monitoring design and strategies - Sediment quality as indicator is measured using traditional fi eld sampling and laboratory analysis protocols
documented in form of an SOP. It includes analysis of major chemical constituents (trace metals relevant for the specifi c mining project and/or as specifi ed
in relevant regulatory standards), organic carbon, and of physical characteristics such as grain size and size distribution. The indicator is monitored annually
(or as otherwise specifi ed in the SOP) in a small number of carefully selected downstream locations and reference areas. Monitoring has three purposes: to
track changes in contaminants that are probably infl uencing waters downstream of the mine site; to provide the basis for control/reference conditions so that
local-scale effects of contamination can be determined more robustly; and to enable rehabilitation programmes to have a relatively undisturbed condition as
a target for the restoration of degraded habitats.

Reporting scale - The data for each year is summarized annually, together with year-to-year changes for each site, and with estimates of uncertainty
(say 95% confi dence limits). The difference between these estimates and any previous (or baseline) estimates will be expressed as an estimate of change,
together with an estimate of the size of change that could be statistically detected with the methods used.

Outputs - The outputs are presented in the form of maps annotated with tables summarizing site-specifi c levels of each contaminant. Changes are
summarized by tables setting out the percentages of signifi cant change (positive or negative change of statistical signifi cance).

Data sources - Often extensive sediment data are collected during exploration. Such data are collected with a specifi c purpose, and are not viewed as
objective data in case of a controversy. Also realistic data on background concentrations over regional areas are seldom available.

Linkages to other indicators - This indicator is closely allied to water quality, fi sh tissue quality, and seabird eggs (contamination).

Using too many indicators risks
diluting their usefulness. Priorities may
become confused and the details may
seem overwhelming for users.

Indicator Species
An indicator species (or bio-indicator) is a plant or animal that indicates, by its presence
in a given area, the existence of certain environmental conditions. Indicator species are
unique environmental indicators as they offer a signal of the biological condition. Using
bio-indicators as an early warning of pollution or degradation in an ecosystem can help
with directing environmental mitigation efforts. While indicator species is a term that is
often used, it is somewhat inaccurate. Indicators are actually often groups or types of bio-
logical resources. Within each group, individual species can be used to calculate metrics
such as percent of species or groups of species or individual orders in an effort to assess
environmental conditions.