Diffuse emissions of dust from LKAB Narvik

NILU has, on behalf of LKAB Norge AS, carried out emission and dispersion calculations for combined emissions from point sources and diffuse sources from the facility in Narvik. The purpose of the project was to develop dispersion calculations that indicate LKAB’s contribution to the pollution situation in Narvik.

LKAB Norge AS in Narvik is responsible for loading iron ore from Sweden onto ships at LKAB’s port in Narvik, as well as unloading additives for transport back to LKAB in Sweden. This process involves both controlled point source emissions and emissions from diffuse sources. Several factors, including correlation between loading activity and measured deposition, suggest that the loading and unloading operation is the most significant diffuse source.

The dispersion calculations have been conducted using FLEXPART-WRF, an atmospheric dispersion model based on meteorological data from the weather forecasting model WRF. FLEXPART models particles that follow the turbulent air movements of the atmosphere and are deposited on the surface through dry and wet deposition. In this analysis, total emissions are estimated on inverse calculations from  the relationship between measured and calculated dust deposition, rather than from generic emission factors such as the EEA/EMEP air pollutant emission inventory Guidebook (2019).

This, along with an assumption about the size distribution of dust emissions, yields a resulting field of ground concentrations for PM₁₀ and PM_2.5. The concentration field can be extracted from the model at the desired time and spatial resolution.

The figure shows three snapshots of the PM₁₀ concentration field along with the temporal variation at a given point over a period in February. A full calendar year is calculated, providing annual mean, daily mean, and hourly mean concentrations.