Identifying and modelling fugitive nickel dust emissions from a steelworks site in Sheffield, UK

Ni in PM₁₀ can contribute to health problems such as cardiovascular mortality at low ambient concentrations, and in the UK is measured through the Heavy Metals Network. Localised concentrations of nickel in PM₁₀ have resulted in a Sheffield air quality monitoring station exceeding the EU target value of 20 ng/m³. Two localised sources of nickel have been identified; one relating to point source emissions, and one relating to fugitive dust emissions. Fugitive dust emissions from a Sheffield steelworks have therefore been assessed using a novel approach, with six months of sticky pad and PM₁₀ dust monitoring, and subsequent elemental characterisation of dust and control samples using ICP-OES and ICP-MS used to inform dust dispersion modelling. Three new fugitive dust source areas on-site were identified from the dust monitoring and characterisation results. Emission rates of Ni were estimated from each source, with adjustments made based on the dust monitoring and characterisation results. Dispersion modelling was undertaken using the new and existing Ni dust sources and results compared favourably to previous studies. Source apportionment of measured concentrations was investigated with regard to the modelling and characterisation results and showed that on-site fugitive dust sources were not significantly different to a fugitive nickel source identified in previous research. However, both source apportionment results and dust monitoring results show that Ni concentrations at the local monitoring station were not increased when fugitive emissions from the study site were highest, or when the winds from the direction of the site were most frequent, indicating that fugitive dust emissions that caused increased concentrations throughout this study period were derived from sources in the area other than the study site.