1. Why the marine environment needs protection from heavy metals
Heavy metals are natural constituents of the Earth's crust. Human activities have drastically altered the biochemical and geochemical cycles and balance of some heavy metals. Heavy metals are stable and persistent environmental contaminants since they cannot be degraded or destroyed. Therefore, they tend to accumulate in the soils and sediments. Excessive levels of metals in the marine environment can affect marine biota and pose risk to human consumers of seafood.
Metals and their compounds, both inorganic and organic, are released to the environment as a result of a variety of human activities. A wide range of metals and metallic compounds found in the marine environment pose risks to human health through the consumption of seafood where contaminant content and exposure are significant. Many metals are essential to life and only become toxic when exposures to biota become excessive (i.e., exceed some threshold for the introduction of adverse effects). While certain non-essential metals do not have explicit exposure thresholds for the introduction of effects, the nature of biological responses to metal exposure are a direct consequence of exposure and are defined through dose-effect relationships. This differs from the dose-response relationship associated with many synthetic organic contaminants and radionuclides where risk of adverse effects is assumed to be proportional to exposure. Accordingly, it is desirable to minimize such exposures. In contrast, the predominant challenge in the case of heavy metals is one of limiting exposure to levels that do not cause adverse effects.
The main anthropogenic sources of heavy metals are various industrial point sources, including present and former mining activities, foundries and smelters, and diffuse sources such as piping, constituents of products, combustion by-products, traffic, etc. Relatively volatile heavy metals and those that become attached to air-borne particles can be widely dispersed on very large scales. Heavy metals conveyed in aqueous and sedimentary transport (e.g., river run-off) enter the normal coastal biogeochemical cycle and are largely retained within near-shore and shelf regions.
2. What is the objective of the GPA in relation to heavy metals ?
The objective/proposed target is to reduce and/or eliminate anthropogenic emissions and discharges in order to prevent, reduce and eliminate pollution caused by heavy metals.
3. Which actions does the GPA suggest ?
National actions, policies and measures
Actions, policies and measures of States within their national capacities should include:
(a) Development, compilation and maintenance of inventories on significant sources, including natural sources, of priority heavy metals and their compounds and subsequent assessment of inputs and establishment of priority (geographic or subject) areas for action. They should also, where appropriate, take into account input from long-range transport of these pollutants;
(b) Development of comprehensive national programmes of action for reduction and/or elimination of emissions and discharges of heavy metals from anthropogenic sources could include:
(i) Targets, timetables and sector-specific measures, respecting the precautionary principle, best available techniques (BAT), best environmental practice (BEP) and integrated pollution prevention and control (IPPC);
(ii) Fiscal and economic incentives and measures, including voluntary agreements to encourage reduction and/or elimination of emissions and discharges of heavy metals;
(iii) Appropriate regulatory measures and establishment of facilities for environmentally sound collection and disposal of hazardous wastes containing heavy metals taking into account the technical document on landfill agreed upon within the framework of the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal;
(iv) Promotion of technical solutions, such as the use of unleaded petrol and filter systems for smelters;
(v) Means to ensure effective implementation of the programme of action;
(vi) The establishment of cleaner production programmes in cooperation with industry;
(c) Establishment of an environmental monitoring programme for heavy metals including the development of assessment criteria and the adoption of internationally accepted quality control and quality assurance procedures;
(d) Formulation and implementation of awareness and education campaigns for the public and industry, to gain general recognition of the need to reduce and eliminate pollution by heavy metals and in particular to further reduce diffuse inputs through waste systems, including sewerage systems;
(e) Establishment of information services for industry on technology and ways and means to prevent, reduce and eliminate pollution by heavy metals, including best environmental practice (BEP), best available techniques (BAT) and integrated pollution prevention and control (IPPC);
(f) Promotion of private initiatives for the establishment and implementation of systems of internal environmental management within industry.
Regional actions
States within a region should cooperate in the following action:
(a) Encouraging existing regional agreements and programmes of action dealing with the prevention and elimination of pollution of the marine and coastal environment from land-based activities, to develop or continue to develop and implement programmes and measures to reduce and/or eliminate emissions and discharges of heavy metals and material containing these substances from the appropriate industrial sectors, products and groups of products;
(b) Development and implementation of monitoring programmes and regular assessments of levels, inputs and effects based on regionally agreed quality control and quality assurance procedures and harmonized assessment criteria;
(c) Encouraging States, including land-locked States, that are not already parties to regional seas arrangements regarding the protection of the marine and coastal environment from land-based activities to join such cooperation and to cooperate on bilateral and multilateral basis in the control of pollution from heavy metals;
(d) Promotion of cooperation in the development of cleaner production programmes.
International actions
International actions should include:
(a) Strengthening and extending existing international quality assurance, standardization and classification mechanisms for heavy metals and their compounds to ensure that inventories and assessments are both reliable and intercomparable. Such existing mechanisms include those co-sponsored by IOC, UNEP and IAEA under the GIPME programme and the associated activities of the Marine Environmental Studies Laboratory in Monaco;
(b) Participation in a clearing-house for information on best available techniques (BAT), best environmental practice (BEP) and integrated pollution prevention and control (IPPC) to reduce and/or
eliminate emissions and discharges of heavy metals;
(c) Cooperation with countries in need of assistance, through financial, scientific and technical support to maximize the best practicable control and reduction of anthropogenic emissions and discharges of heavy metals.