Lower Hunter particle characterisation study Final Report to the NSW Environment Protection Authority

The Lower Hunter Particle Characterisation Study (LHPCS) provides details about the composition and major sources of PM2.5 (fine airborne particles)and PM2.5-10(coarse airborne particles). Measurements were made for one year from March 2014 to February 2015 at two air quality monitoring stations representative of regional population exposures (Newcastle and Beresfield) and two stations near the Port of Newcastle (Mayfield and Stockton). Annual average PM2.5 concentrations were very similar at Newcastle, Mayfield and Beresfield (6.4–6.7 μg m-3) but about 40% higher at Stockton (9.1 μg m-3). The higher levels at Stockton were mainly due to both more sea salt and to the primary ammonium nitrate, which was only detected at Stockton. The ammonium nitrate, which contributed on average 19% of the PM2.5 mass (and ~40% in winter), was identified as very likely to be due to primary emissions from Orica’s ammonium nitrate manufacturing facility on Kooragang Island. Other than the ammonium nitrate, PM2.5 composition and sources were found to be fairly similar across the four sites. Key results on the sources and their contributions are: fresh sea salt particles: 24% at Newcastle, decreasing to 13% at Beresfield; pollutant-aged sea salt: ~23% at all sites; this is sea salt reacted with industrial, commercial, road and non-road transport emissions from local and regional sources; wood smoke: 15% at Beresfield, decreasing to 6% at Stockton; secondary ammonium sulfate: ~10% at all sites; soil dust: ~10% at all sites; vehicles: ~10% at three sites, but only 5% at Stockton; industry factors: ~12% at three sites but 24% at Stockton; mixed shipping/industry: ~3% at all sites; nitrate: 19% ammonium nitrate at Stockton and secondary nitrate at other sites (6-11%). On an annual average basis, there is an approximately 50:50 split between primary and secondary particles at three sites (Newcastle, Beresfield and Mayfield) and a 65:35 split at Stockton because of the significant contribution from the primary ammonium nitrate. PM2.5-10 composition and sources were only determined at the stations near the Port of Newcastle. The 2½ times higher annual average PM2.5-10 concentration at Stockton (21.5 μg m-3) than at Mayfield (8.3 μg m-3) was found to be mainly due to a much higher contribution by fresh sea salt particles at Stockton. The PM2.5-10 factors and their contributions were identified as:  fresh sea salt: 13.6 μg m-3 at Stockton, 3.3 μg m-3 at Mayfield  industry plus pollutant-aged sea salt: 2.4 μg m-3 at both sites  light-absorbing carbon: 2.2 μg m-3 at Stockton, 0.9 μg m-3 at Mayfield  soil: 2.3 μg m-3 at Stockton, 1.2 μg m-3 at Mayfield  bioaerosol: 1.1 μg m-3 at Stockton, 0.5 μg m-3 at Mayfield. Most PM2.5-10 particles are primary particles or physical combinations of primary emissions, but there is evidence of chemical reactions in the pollutant-aged sea salt factor. Coal particles could contribute up to 10% of PM2.5-10 particles. Further investigations are needed to clarify the contribution of coal