Individual Particle Morphology and Acidity

Figures & data

TABLE 1 Summary of PAQS ambient concentrations for CCSEM analysis of the selected samples for CCSEM analysis (OC, organic carbon; EC, elemental carbon)

	PM 2.5 ^(1)	OC^(2)	EC^(2)	Sulfate^(3)	Nitrate^(3)
Date	(μ g m^− 3)	(μ g m^− 3)	(μ g m^− 3)	(μ g m^− 3)	(μ g m^− 3)	Sample^(4)
07/04/01	21.6	2.01	0.29	9.08	0.44	S6
07/08/01	22.0	3.52	0.33	8.84	0.61	S8
07/12/01	10.2	2.14	0.49	2.04	0.67	S10
07/15/01	15.2	3.63	0.34	5.73	0.55	S7
07/18/01	44.4	4.33	0.67	22.00	0.95	S1
07/19/01	36.3	3.85	0.42	17.28	0.85	S5
07/22/01	31.1	3.55	0.32	14.36	0.19	S4
07/24/01	35.8	3.46	0.66	13.21	0.49	S2
07/26/01	11.5	1.80	0.29	3.55	0.35	S9
08/03/01	42.6	4.20	0.82	20.92	0.86	S3
01/03/02	15.9	3.67	0.81	3.99	3.87	W3
01/04/02	10.9	1.69	0.27	2.46	3.93	W6
01/07/02	11.8	1.77	0.24	2.99	0.83	W1
01/09/02	10.6	1.40	0.27	2.43	1.33	W2
01/18/02	10.8	2.04	0.23	2.92	3.85	W4
01/19/02	15.6	4.15	0.49	3.40	4.90	W5
^(1) Wittig et al. (2004a); ^(2) Cabada et al. (2004), Subramanian et al. (2004); ^(3) Wittig et al. (2004b); ^(4)summer (S) and winter (W) samples are acidity ranked.

FIG. 1 Examples of the morphological groups for HRSEM analysis: (a–f) group A, particles with signs of a primary liquid state: (a–b) droplet-like, (c–e) needle-like, and (f) others; (g–h) group B, soot-like; (i–l) group C, regular-shaped particles; (m–n) group D, minerals, biogenic and others; and (o–p), group E, mixed particles. Particle geometric diameter, shape parameter values and HRSEM type also shown in the pictures.

TABLE 2 Daily acidity, CCSEM shape parameters, and HRSEM groups (columns A–E described in section 2.4) for particles below 1 μ m

		CCSEM				HRSEM group
Sample	H^+ (1) (ng m^− 3)	Sp 1 St. Dev.		Sp 2 St. Dev.		A	B	C	D	E
S1	41.1	0.612 ± .003		0.340 ± .004		70–90%	5–15%	< 5%	< 5%	< 5%
S2	30.6	0.702 ± .005		0.403 ± .007		50–70%	5–15%	5–15%	< 5%	30–50%
S3	26.4	0.643 ± .006		0.371 ± .008		70–90%	5–15%	< 5%	< 5%	< 5%
S4	29.1	0.691 ± .005		0.387 ± .007		50–70%	5–15%	5–15%	< 5%	30–50%
S5	20.3	0.653 ± .008		0.349 ± .011		70–90%	5–15%	< 5%	< 5%	< 5%
S6	3.8	0.750 ± .002		0.497 ± .003		< 5%	15–30%	30–50%	< 5%	15–30%
S7	2.4	0.731 ± .005		0.495 ± .008		< 5%	30–50%	15–30%	< 5%	< 5%
S8	1.9	0.757 ± .004		0.499 ± .007		< 5%	15–30%	50–80%	< 5%	< 5%
S9	1.6	0.715 ± .004		0.444 ± .007		< 5%	30–50%	15–30%	5–15%	< 5%
S10	1.5	0.755 ± .004		0.520 ± .006		< 5%	30–50%	15–30%	5–15%	< 5%
W1	9.20	0.754 ± .002		0.501 ± .004		15–30%	15–30%	15–30%	15–30%	5–15%
W2	1.70	0.718 ± .005		0.468 ± .007		< 5%	15–30%	30–50%	< 5%	15–30%
W3	0.30	0.737 ± .004		0.479 ± .007		< 5%	15–30%	30–50%	5–15%	5–15%
W4	0.30	0.769 ± .004		0.543 ± .006		< 5%	15–30%	30–50%	5–15%	5–15%
W5	0.30	0.726 ± .004		0.446 ± .006		< 5%	15–30%	30–50%	5–15%	5–15%
W6	0.10	0.745 ± .004		0.495 ± .007		< 5%	15–30%	30–50%	< 5%	15–30%
^1 Takahama et al. (2006).
^2A—droplet-like, needle like, or mixtures of both types; B—soot-like; C—regular-shaped; D—minerals, biogenic and others; E—Mixed particles that do not fall in any type.

TABLE 3 Sp ₂ and Sp ₃ mean value and standard deviation of the mean: summer acidic, summer neutral, and winter samples for particles below 1μ m

	Summer
	Acidic		Neutral		Winter
	Mean St. Dev.		Mean St. Dev.		Mean St. Dev.
Sp 1	0.643 ± .002		0.745 ± .001		0.745 ± .001
Sp 2	0.361 ± .003		0.493 ± .002		0.492 ± .002

TABLE 4 Sp ₂ and Sp ₃ mean value and standard deviation of the mean for the summer acidic, summer neutral, and winter periods in three size ranges: 0.2–0.5 μ m, 0.5–1 μm, and 1.0–2.5 μ m

	Summer
	Acidic		Neutral		Winter
Size range	Mean St. Dev.		Mean St. Dev.		Mean St. Dev.
Sp 1
0.2–0.5 μ m	0.575 ± 0.003		0.720 ± 0.002		0.725 ± 0.002
0.5–1.0 μ m	0.736 ± 0.002		0.792 ± 0.002		0.799 ± 0.002
1.0–2.5 μ m	0.727 ± 0.002		0.778 ± 0.002		0.778 ± 0.001
Sp 2
0.2–0.5 μ m	0.259 ± 0.003		0.438 ± 0.003		0.448 ± 0.003
0.5–1.0 μ m	0.498 ± 0.004		0.592 ± 0.004		0.611 ± 0.004
1.0–2.5 μ m	0.495 ± 0.003		0.579 ± 0.002		0.574 ± 0.002

FIG. 2 Number distribution of particles classified based on sulfur content (relative X-ray counts) in the submicrometer range: Very low (non detectable S), Low (2–11%), Intermediate (12–21%), and High (22–33%) for summer samples, taken on acidic (a) and neutral days (b), and winter (c). The numbers in brackets on the top of each bar correspond to the median values of Sp ₁ and Sp ₂ in each group.

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