It often is of interest to understand the relative importance of the different sources contributing to the concentration c(w) of a contaminant in a stream; the portions related to sources 1, 2, 3, etc. are denoted c(w,1), c(w2), c(w3), etc. Like c(w), the fractions alpha1 = c(w,1)/c(w), alpha2 = c(w,2)/c(w), alpha3 = c(w,3)/c(w), etc. depend on location and time. Volatile organic compounds (VOC...

A primary objective of current air pollution research is the assessment of health effects related to specific sources of air particles or particulate matter (PM). Quantifying source-specific risk is a challenge because most PM health studies do not directly observe the contributions of the pollution sources themselves. Instead, given knowledge of the chemical characteristics of known sources, i...

This paper compares property taxation to a corporate income tax based on formula apportionment in a model where identical countries compete to attract capital. We find that if countries can pair a residence-based capital tax with a property tax (source tax on capital) the tax equilibrium is efficient. In contrast, the use of a 2-factor FA scheme based on sales and capital combined with a reside...

Authors Reply. Accepted. We reworded the sentence into the following: PMF is becoming common for organic source apportionment (Zhang et al., 2005; Lanz et al., 2007) and factor analysis of AMS data using PMF in its diverse implementations (including e.g. ME-2) has extracted biomass burning organic aerosol (BBOA) factors in multiple sites (Aiken et al., 2010; Elsasser et al., 2012; Crippa et al....

1. "The authors are interested in quantification of the contribution of woodsmoke to PM2.5. Source apportionment always depends on the assumptions of the method employed to determine the sources. The authors make the statement that PM2.5 is dominated by woodsmoke on p. 5 (lines 12-13) and p. 10 (line 14). This should be the result of the work, not an initial assumption, which cannot be tested w...

Hyphens were incorrectly omitted from the first three authors’ first names. The correct names are: Jheng-Jie Jiang, Chon-Lin Lee, and Meng-Der Fang. The correct citation is: Jiang J-J, Lee C-L, Fang M-D, Boyd KG, Gibb SW (2015) Source Apportionment and Risk Assessment of Emerging Contaminants: An Approach of Pharmaco-Signature in Water Systems. PLoS ONE 10(4): e0122813. doi:10.1371/journal.pone...