Explanation of Key Trends - Heavy Metals

Last updated on 10 Feb 2017 12:31 (cf. Authors)

Please note: Data for heavy metals may have issues such as missing sources. It features considerably higher uncertainties then data for other pollutants covered in this report.


The 1998 Aarhus Protocol on Heavy Metals under the CLRTAP entered into force late in 2003. It targets three particularly harmful metals: cadmium, lead and mercury. According to one of the basic obligations, Germany has to reduce its emissions for these three metals below their levels in 1990. The Protocol aims to cut emissions from industrial sources (iron and steel industry, non-ferrous metal industry), combustion processes (power generation, road transport) and waste incineration. It defines stringent limit values for emissions from stationary sources and suggests best available techniques (BAT) for these sources, such as special filters or scrubbers for combustion sources or mercury-free processes. The Protocol requires Parties to phase out leaded petrol. It also introduces measures to lower heavy metal emissions from other products, such as mercury in batteries, and proposes the introduction of management measures for other mercury-containing products, such as electrical components (thermostats, switches), measuring devices (thermometers, manometers, barometers), fluorescent lamps, dental amalgam, pesticides and paint.

Main drivers

Emission of priority heavy metals (cadmium, lead and mercury) decreased significantly since 1990. Values show reductions by about 70 to 90% compared to the base year. Most of the achievements originate from the early 1990's though. Recent years saw hardly any improvements in heavy metal emissions.

The main sources for all heavy metals is fuel combustion. For arsenic, cadmium, chromium, mercury and nickel Energy Industries (NFR 1.A.1) owns the biggest share. Lead, copper and zinc emissions are governed by the Transport (NFR 1.A.3) sector resulting mostly from brake and tyre wear. Thus, trends are connected directly with the annual mileage. Selenium originates mainly from both energy industries and transport. Metal Production (NFR 2.C) adds to some totals. Other sources are still to be investigated but generally expected to add little to the total trend.


The figure below shows emission trends for heavy metals:

The table below depicts the heavy metal emission trends as total values in tons:

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