Index
of heavy metal emissions to water
TX-4
Dispersion
of Toxic Substances
Pressure
1 Indicator
definition and unit of measurement
Heavy
metals are the metals of environmental interest - e.g. mercury, cadmium, lead -
with few exceptions - e.g
.
aluminium. By
creating an
index, they can be handled in clusters according to sources and emission
patterns. Unit: tox. equivalents/yr.
2 Placement
in the framework
5EAP:
Chapter
5: The themes and targets of the programme, section 5.2: Acidification and air
quality, table 8: Acidification and section 5.4: Management of water resources,
table 11: Water quantity and water quality.
Agenda
21:
Chapter
17: Protection of the oceans, all kinds of seas, including enclosed and
semi-enclosed seas, and coastal areas and the protection, rational use and
development of their living resources.
Chapter
18: Protection of the quality and supply of freshwater resources: application
of integrated approaches to the development, management and use of water
resources.
Chapter
20: Environmentally-sound management of hazardous wastes, including prevention
of illegal international traffic in hazardous wastes (section D).
International
conventions and agreements:
Reductions
of emissions to waters are agreed upon in
OSPARCOM
(Oslo, 1972 and Paris, 1974), HELCOM (Helsinki, 1994) and the North Sea
Ministerial Conference (Esbjerg Declaration, 1995).
Ranking:
Core
ranking:
4
(29%)
Policy
Relevance:
3
(3.3)
Analytical
Soundness:
3
(3.1)
Responsiveness:
21
(2.4)
Most
appropriate related state indicator:
Amounts
of heavy metals in water, sediments and sludge.
3 Significance
Purpose:
The
main purpose of this indicator is to represent the amounts of heavy metals
emitted from different sources and by different processes into water. Better
knowledge of emitted amounts helps activities aiming at decreasing emissions.
Relevance:
Metals
are totally persistent and all amounts emitted to water will accumulate in
water, sediments and, when applicable, sewage plant sludge. Many of the heavy
metals are toxic and an accumulation in these media is, consequently, not
sustainable.
Linkages
to other pressure indicators:
TX-5:
Index of heavy metal emissions to air, TX-7: Emissions of heavy metals by
consumption.
Targets:
5EAP:
1) Surface water: quality improvement towards a better ecological quality and
safeguard of high quality where it exists, 2) Marine water: objectives and
actions similar to the North Sea conference (Bonn, 1983) to other sensitive sea
areas of the EC.
4 Methodological
description and underlying definitions
Underlying
definitions and concepts:
Eight
heavy metals are in environmental focus: mercury, lead, cadmium, chromium,
copper, arsenic, nickel and zinc. The first three are used as indices due to
different principle sources and strategies for emission reduction. By focusing
on these three, the rest of the heavy metals will roughly be considered.
Measurement
methods:
Information
will be generated by emission inventories. Traffic, combustion processes will
be of large importance. A large part of the emissions from products containing
heavy metals will take place not only during production, but also during use
and as waste. Emitted amounts are estimated by the use of emission factors,
describing emission rates of substances from different matrices and uses.
Limitations
of the indicator:
Heavy
metals are a heterogeneous group of metals. Their inherent characteristics,
such as reactivity and toxic potential, differ. The relationship within the
cluster may vary
from
one location to another and from time to time. The emission sources are often
diffuse and the emission factors are in some cases unreliable or non existing.
Alternative
definitions:
Emissions
of each of the three index-linked metals (mercury, lead, cadmium) are singled
out and measured separately, e.g. emissions of cadmium per year.
