Positive Matrix Factorization of 47 Years of Particle Measurements in Finnish Arctic

Forty seven years of weekly total suspended particle filters collected at Kevo, Finland from October 1964 through 2010 by the Finnish Meteorological Institute were analyzed for near-total trace elements, soluble trace elements, black carbon, major ions and methane sulfonic acid (MSA). The chemical composition dataset was analyzed by Positive Matrix Factorization using EPA PMF5. The entire dataset (1964–2010) was modeled as well as three separate time periods, 1964– 1978, 1979–1990, and 1991–2010. The dataset was split in 1979 due to a change from Whatman 42 cellulose filters to a glass fiber filters, and in 1990 due to drops in concentrations related to the economic collapse of the Soviet Union. Two factors representing non-ferrous metal smelters were found for all time periods. One factor was dominated by Cu and the other by Ni and Co. Each of the time periods contained a factor describing stationary fuel combustion with high percentages of V, BC, and nss-SO 4 = ; a ferrous metal factor dominated by Fe and some Mn; a biogenic sulfate factor; a factor containing the majority of Mo and W; and a factor dominated by Sn. The 1979–1990, 1991–2010, and 1964–2010 results contained a factor for As and Re, and a factor with the majority of Mn and Cd, which were not observed in 1964– 1978. The 1964–1978 time period results contain three unique factors, a factor dominated by Ag, a factor dominated by Au, and a sea salt factor characterized by a high percentage of Na and Mg. The 1964–2010 period contains an Ag and Au factor as well. Ag and Au both have high concentrations in the late 1960s that decrease dramatically starting in the early 1970s. The increased uncertainty due to the high blanks in the glass fiber filters may account for the inability to determine a sea salt factor in the later time periods.