Contribution of residential wood combustion and other sources to hourly winter aerosol in Northern Sweden determined by positive matrix factorization

[摘要] The combined effect of residential wood combustion (RWC)emissions with stable atmospheric conditions, which frequently occurs inNorthern Sweden during wintertime, can deteriorate the air quality even insmall towns. To estimate the contribution of RWC to the total atmosphericaerosol loading, positive matrix factorization (PMF) was applied to hourlymean particle number size distributions measured in a residential area inLycksele during winter 2005/2006. The sources were identified based on theparticle number size distribution profiles of the PMF factors, the diurnalcontributions patterns estimated by PMF for both weekends and weekdays, andcorrelation of the modeled particle number concentration per factor withmeasured aerosol mass concentrations (PM₁₀, PM₁, andlight-absorbing carbon M_LAC) Through these analyses, the factors wereidentified as local traffic (factor 1), local RWC (factor 2), and local RWCplus long-range transport (LRT) of aerosols (factor 3). In some occasions,the PMF model could not separate the contributions of local RWC frombackground concentrations since their particle number size distributionspartially overlapped. As a consequence, we report the contribution of RWC asa range of values, being the minimum determined by factor 2 and the possiblemaximum as the contributions of both factors 2 and 3. A multiple linearregression (MLR) of observed PM₁₀, PM₁, total particle number, andM_LAC concentrations is carried out to determine the source contributionto these aerosol variables. The results reveal RWC is an important source ofatmospheric particles in the size range 25–606 nm (44–57%), PM₁₀(36–82%), PM₁ (31–83%), and M_LAC (40–76%) massconcentrations in the winter season. The contribution from RWC is especiallylarge on weekends between 18:00 LT and midnight whereas local trafficemissions show similar contributions every day.

[学科分类] 大气科学