Quantification of Airborne Elemental Carbon by Digital Imaging

Figures & data

FIG. 1 Light intensities of red (R), green (G), and blue (B) of a filter with activated carbon.

FIG. 2 Organic carbon (OC) loadings with different light intensities discrepancy.

TABLE 1 The red (R), green (G), and blue (B) values of combusted field samples and their differences

Sample number	R	G	B	R – G	R – B
1	247.4	244.4	241.2	3.0	6.2
2	246.1	236.0	229.3	10.1	16.8
3	246.9	245.6	244.0	1.3	3.0
4	246.7	243.3	239.9	3.4	6.8
5	197.7	177.8	178.4	19.8	19.3
6	243.5	226.9	217.0	16.5	26.4
7	247.4	242.7	237.6	4.7	9.8
8	247.1	243.1	239.4	4.0	7.7
9	246.3	245.3	243.4	1.0	2.8
10	241.6	232.0	227.4	9.5	14.2
11	245.8	244.7	241.5	1.2	4.4
12	245.4	241.6	238.7	3.9	6.8
13	245.8	240.0	237.1	5.8	8.7
14	244.8	235.6	229.3	9.2	15.5

FIG. 3 Elemental carbon (EC) loadings on filters with different maximum value of transformed R, G, and B (max{R’,G’,B’}).

FIG. 4 Linear regression between log [EC] and log (max{R’,G’,B’}) with the dotted lines represent the 95% confidence interval of the regression.

FIG. 5 The estimation curve and the actual values of EC loading determined by thermal-optical method. The dotted lines correspond to the 95% confidence interval of the linear regression in the log-log plot.

FIG. 6 Verification of the estimation model with 24 high volume samples. Circles (•) represent the measured EC loading while the solid line and dashed lines represent the estimation model and its 95% confidence interval.