3 Results

3.1  Identification of Relevant Sources

Based on the approach described in Section 2.1 all relevant nickel emission sources were identified in the nickel EU RA (Table 1).

Table 1:  Nickel emission sources reported 
in the nickel EU RA

3.2  Selection of Appropriate Emission Quantification Methods

Following the general methodology described in Section 2.2, the appropriate emission quantification approach was selected for each identified source (Table 2).

(1)  Indicates that first the emissions are quantified from data from The Netherlands (known region) and are then extrapolated to the EU-15
(2)  Full details can be found in background report on the assessment of point and diffuse sources of nickel (compounds) (ECOLAS, 2005)
(3)  Additional information is available in a report from RIVM/RIZA (Elzenga et al., 1998)

Table 2:  Overview of the emission quantification methods used in the nickel EU RA


As indicated in Section 2.3, data gathering is the most important step in setting up an emission inventory. Many different sources need to be evaluated to select the appropriate data. Table 3 provides an overview of the most important sources of nickel for which activity data and emission factors were used to complete the emission estimation formulas.


Table 3:  Overview of important data sources


Total nickel emissions in the EU27 (defined as the “continental region”) to the air, water, and soil compartments are estimated as direct emissions from the source. The results are shown in Table 4 and Figure 3.


Table 4:  Total nickel emissions in the EU27



Figure 3:  Total nickel emissions in EU27
(in tons per year)

For the EU27, total nickel emissions are estimated at about 1,790 tons nickel/year (745 tons nickel/year to surface water, 612 tons nickel/year to air, and 433 tons nickel/year to soil). For the water compartment, the most important source categories are “waste management” and “industry.” Within the “waste management” category 83% of the emissions are the result of emissions from sewage treatment plants. Emissions to soil are almost exclusively a result of the use of manure and mineral fertilizers on agricultural soil. Traffic and industrial processes were identified as important sources for emissions to air. Within the category “traffic,” the biggest share in total nickel emissions are caused by the fuel combustion by ships.

The EU Risk Assessment process evaluates risk at both regional and continental scales, where the continental scale is built on emission for the EU 27. Emissions are extrapolated from the continental scale to the regional scale by assuming that a typical European region comprises 10% of continental emissions. This equates to about 180 tons nickel/year of which 74.5 tons nickel/year to surface water, 61.2 tons nickel/year to air, and 43.3 tons nickel/year to soil.

Another approach for estimating regional scale emissions is to calculate emissions for a well-characterized region that is representative of Europe as a whole. The Netherlands were selected because it meets the criteria defined by the EU for a typical region (i.e., 20 million inhabitants and 40,000 km²) and, furthermore, constitutes a country with significant information on diffuse uses and releases. The Netherlands is therefore an appropriate reference for checking and comparing diffuse releases.

The results from this estimation are shown in Table 5 and Figure 4. Total emissions in The Netherlands are about 124 tons nickel/year and thus significantly lower than the extrapolated regional emissions.

For The Netherlands, total releases per year are about 20 tons to surface water, 72 tons to air, and 32 tons to soil.

About 70% of the emissions to water relate to “waste management” sources, of which 70% can be allocated to “wastewater treatment” activities. About 20% is emitted by industry. Other sources are related to overflows and the emissions through separate sewage systems.

From the total emissions to air, 56% can be allocated to “industry,” of which 96% come from combustion processes. More specifically, 43% can be allocated to traffic emissions from shipping. The emissions to air in The Netherlands are higher than those determined by EU-27 extrapolation because of the importance of inland shipping in The Netherlands.

From the total nickel emissions to soil, about 97% can be allocated to agricultural sources, of which in particular about 50% from the use of mineral fertilizers, about 40% from the use of manure, and about 10% for the use of sewage sludge on agricultural soil.


 Table 5:  Total nickel emissions in the selected region

(The Netherlands)


 Figure 4:  Total nickel emissions in the selected region
(The Netherlands) (in tons per year)