Size-Differentiated Chemical Characteristics of Asian Paleo Dust: Records from Aeolian Deposition on Chinese Loess Plateau

Figures & data

Table 1. Description of loess samples collected from the Xi Feng loess profile at the CLP

Strata ^a	Sample ID	Depth from Surface (m)	Age of Loess Deposit (1000 yr B.P.) ^b
L1LL1	ZJC-L1–0	2.2	ca. 12.5 – 28.2
	ZJC-L1–1	2.4
	ZJC-L1–2	2.6
L1LL2	ZJC-L1–34	9	ca. 65 – 73
	ZJC-L1–35	9.2
	ZJC-L1–36	9.4
L2	ZJC-L2–5	14.7	ca. 125 – 198
	ZLC-L2–6	15.1
	ZLC-L2–8	15.5
Notes: ^aL1LL1 and L1LL2 represent two loess horizons in Malan loess (L1) deposited during the last glacial period; L2 represents loess deposited during the penultimate glacial periods. ^bAge of loess deposit is determined by correlation between the magnetism profiles and the SPECMAP time series.36 Paleosol samples (represented by gaps in deposit age) were not collected because strong chemical weathering after deposition means they are non-representative of the original characteristics of paleo dust.

Figure 1. Map of China showing distributions of the CLP as well as major deserts and sand-lands. The loess sampling location is indicated by a black dot.

Table 2. Massfractions in each layer for TSP, PM ₁₀, PM _2.5, and PM₁ size fractions

			L1L1 (n = 3)				L1L2 (n = 3)				L2 (n = 3)				Surface Soil (n = 15)24
Species ^b	Analysis Methods ^c	Unit	TSP	PM10	PM2.5	PM1	TSP	PM10	PM2.5	PM1	TSP	PM10	PM2.5	PM1	TSP	PM10	PM2.5	PM1
Cl^−	IC	%	0.08 ± 0.04	0.12 ± 0.07	0.09 ± 0.09	0.08 ± 0.11	0.15 ± 0.11	0.12 ± 0.08	0.05 ± 0.08	0.04 ± 0.10	0.12 ± 0.09	0.12 ± 0.08	0.03 ± 0.11	0.05 ± 0.21	0.14	0.26	0.37	0.50
NO3 ^−	IC	%	0.03 ± 0.04	0.08 ± 0.07	0.10 ± 0.09	0.10 ± 0.11	0.07 ± 0.11	0.09 ± 0.08	0.06 ± 0.08	0.03 ± 0.10	0.08 ± 0.09	0.04 ± 0.08	0.08 ± 0.11	0.14 ± 0.21	0.00	0.00	0.00	0.00
SO4 ^2−	IC	%	0.06 ± 0.04	0.10 ± 0.07	0.11 ± 0.09	0.14 ± 0.11	0.15 ± 0.11	0.09 ± 0.08	0.09 ± 0.09	0.10 ± 0.11	0.12 ± 0.09	0.11 ± 0.08	0.11 ± 0.11	0.15 ± 0.21	0.04	0.06	0.04	0.04
NH4 ^+	AC	%	0.02 ± 0.02	0.04 ± 0.04	0.05 ± 0.06	0.05 ± 0.09	0.03 ± 0.05	0.02 ± 0.04	0.02 ± 0.06	0.03 ± 0.08	0.04 ± 0.05	0.04 ± 0.04	0.04 ± 0.09	0.06 ± 0.17	0.05	0.12	0.21	0.22
NA^+	AAS	%	0.02 ± 0.01	0.05 ± 0.01	0.08 ± 0.05	0.07 ± 0.08	0.04 ± 0.01	0.03 ± 0.01	0.07 ± 0.06	0.06 ± 0.08	0.04 ± 0.01	0.08 ± 0.03	0.05 ± 0.09	0.06 ± 0.16	0.04	0.07	0.13	0.12
K^+	AAS	%	0.10 ± 0.02	0.19 ± 0.03	0.46 ± 0.08	0.37 ± 0.10	0.17 ± 0.03	0.17 ± 0.03	0.41 ± 0.08	0.31 ± 0.10	0.12 ± 0.02	0.10 ± 0.03	0.26 ± 0.09	0.26 ± 0.17	0.09	0.15	0.31	0.26
CA2 ^+	AAS	%	8.66 ± 0.90	12.18 ± 1.20	10.33 ± 1.03	12.63 ± 1.75	13.07 ± 1.21	11.80 ± 1.07	12.15 ± 1.40	9.69 ± 1.53	13.28 ± 1.16	11.00 ± 1.07	9.27 ± 1.22	8.90 ± 1.18	NA	NA	NA	NA
0C1	TOR	%	0.04 ± 0.07	0.01 ± 0.10	0.07 ± 0.37	0.09 ± 0.60	0.00 ± 0.11	0.06 ± 0.14	0.04 ± 0.41	0.10 ± 0.58	0.05 ± 0.12	0.03 ± 0.17	0.02 ± 0.60	0.15 ± 1.17	0.01	0.02	0.09	0.00
0C2	TOR	%	0.25 ± 0.12	0.35 ± 0.18	0.48 ± 0.42	0.25 ± 0.62	0.34 ± 0.22	0.33 ± 0.21	0.26 ± 0.44	0.39 ± 0.61	0.45 ± 0.22	0.32 ± 0.23	0.28 ± 0.62	0.29 ± 1.18	0.15	0.33	0.51	0.09
0C3	TOR	%	0.47 ± 0.25	0.91 ± 0.43	1.53 ± 0.69	0.57 ± 0.76	1.08 ± 0.64	1.34 ± 0.54	0.66 ± 0.59	0.83 ± 0.76	1.05 ± 0.55	0.80 ± 0.48	0.82 ± 0.78	0.87 ± 1.44	0.49	0.94	1.44	1.07
0C4	TOR	%	0.24 ± 0.13	0.46 ± 0.24	0.83 ± 0.50	0.40 ± 0.62	0.29 ± 0.25	0.47 ± 0.27	0.39 ± 0.45	0.67 ± 0.64	0.41 ± 0.26	0.36 ± 0.26	0.73 ± 0.67	0.71 ± 1.21	0.32	0.73	1.19	0.81
OP	TOR	%	0.32 ± 0.19	0.24 ± 0.22	0.79 ± 0.65	0.36 ± 0.68	0.52 ± 0.36	1.04 ± 0.70	0.37 ± 0.50	0.70 ± 0.71	0.00 ± 0.15	0.18 ± 0.25	0.14 ± 0.61	0.00 ± 1.15	0.48	1.11	0.73	0.73
OC	TOR	%	1.29 ± 0.54	1.91 ± 0.84	3.44 ± 1.72	1.22 ± 1.92	2.16 ± 1.12	3.15 ± 1.26	1.36 ± 1.41	2.28 ± 1.96	1.90 ± 0.95	1.55 ± 0.92	1.55 ± 1.93	1.35 ± 3.51	1.44	3.13	3.96	2.70
EC1	TOR	%	0.21 ± 0.08	0.67 ± 0.24	1.13 ± 0.40	0.51 ± 0.25	0.44 ± 0.19	1.02 ± 0.34	0.39 ± 0.18	0.86 ± 0.35	0.31 ± 0.15	0.30 ± 0.13	0.65 ± 0.28	0.64 ± 0.40	0.33	0.75	1.28	0.53
EC2	TOR	%	0.11 ± 0.11	0.25 ± 0.21	0.29 ± 0.26	0.13 ± 0.21	0.12 ± 0.17	0.23 ± 0.25	0.14 ± 0.18	0.34 ± 0.31	0.11 ± 0.16	0.05 ± 0.13	0.33 ± 0.37	0.34 ± 0.51	0.14	0.31	0.42	0.20
EC3	TOR	%	0.00 ± 0.02	0.09 ± 0.10	0.03 ± 0.10	0.00 ± 0.14	0.01 ± 0.05	0.01 ± 0.04	0.00 ± 0.10	0.06 ± 0.15	0.15 ± 0.17	0.00 ± 0.05	0.30 ± 0.34	0.27 ± 0.41	0.04	0.07	0.02	0.11
EC	TOR	%	0.00 ± 0.24	0.76 ± 0.40	0.66 ± 0.84	0.28 ± 0.85	0.04 ± 0.44	0.23 ± 0.81	0.16 ± 0.63	0.55 ± 0.93	0.57 ± 0.32	0.17 ± 0.33	1.14 ± 0.93	1.25 ± 1.59	0.02	0.03	0.99	0.12
CC	TOR	%	4.21 ± 0.99	4.60 ± 1.16	3.40 ± 0.96	3.22 ± 1.05	4.62 ± 1.37	3.66 ± 1.02	3.96 ± 1.06	3.63 ± 1.09	4.63 ± 1.28	3.65 ± 1.03	2.91 ± 0.97	2.71 ± 1.46	1.77	3.38	2.45	2.13
TC	TOR	%	5.49 ± 1.13	7.25 ± 1.54	7.39 ± 2.17	4.53 ± 2.72	6.80 ± 1.65	7.00 ± 1.52	5.34 ± 2.10	6.27 ± 2.78	7.08 ± 1.56	5.32 ± 1.39	5.40 ± 2.78	4.75 ± 4.94	1.46	3.16	4.95	2.81
Na	XRF	%	0.35 ± 0.08	0.38 ± 0.12	0.43 ± 0.16	0.53 ± 0.17	0.28 ± 0.15	0.60 ± 0.16	0.65 ± 0.18	0.44 ± 0.16	0.25 ± 0.14	0.57 ± 0.16	0.49 ± 0.19	0.38 ± 0.29	0.16	0.42	0.27	0.67
Mg	XRF	%	1.15 ± 0.14	1.71 ± 0.22	2.46 ± 0.31	2.37 ± 0.35	1.54 ± 0.23	2.01 ± 0.25	2.15 ± 0.29	2.24 ± 0.33	1.27 ± 0.20	1.81 ± 0.25	2.29 ± 0.36	2.34 ± 0.44	0.17	0.35	0.48	0.42
Al	XRF	%	4.37 ± 0.44	6.06 ± 0.56	8.01 ± 0.78	8.09 ± 1.02	5.37 ± 0.47	6.79 ± 0.60	7.47 ± 0.80	7.46 ± 0.94	4.63 ± 0.40	6.34 ± 0.60	8.16 ± 1.03	8.08 ± 1.05	5.58	9.14	5.02	4.90
Si	XRF	%	20.09 ± 11.2	12.32 ± 1.14	14.28 ± 1.40	14.99 ± 1.89	24.84 ± 13.7	13.68 ± 1.21	13.17 ± 1.43	14.33 ± 1.81	20.62 ± 11.4	12.94 ± 1.23	14.68 ± 1.86	15.17 ± 1.96	17.54	27.41	14.58	14.27
K	XRF	%	1.79 ± 0.63	2.33 ± 0.80	2.27 ± 0.21	2.34 ± 0.29	2.26 ± 0.78	2.69 ± 0.93	2.19 ± 0.23	2.30 ± 0.28	1.80 ± 0.62	2.48 ± 0.86	2.33 ± 0.29	2.31 ± 0.29	1.72	2.52	2.30	2.17
Ca	XRF	%	10.41 ± 3.13	15.33 ± 4.49	12.97 ± 1.24	14.33 ± 1.80	11.03 ± 3.22	13.88 ± 4.06	11.98 ± 1.28	14.05 ± 1.76	10.86 ± 3.24	14.84 ± 4.43	12.03 ± 1.53	13.38 ± 1.78	6.78	9.83	9.74	9.99
Fe	XRF	%	3.56 ± 0.35	4.38 ± 0.39	5.22 ± 0.49	5.46 ± 0.68	4.29 ± 0.36	4.84 ± 0.41	4.83 ± 0.51	5.33 ± 0.66	3.41 ± 0.28	4.46 ± 0.41	5.24 ± 0.65	5.29 ± 0.67	3.12	4.40	5.01	4.72
Ti	XRF	%	0.31 ± 0.03	0.36 ± 0.03	0.40 ± 0.07	0.42 ± 0.09	0.36 ± 0.03	0.38 ± 0.04	0.35 ± 0.07	0.40 ± 0.09	0.28 ± 0.03	0.37 ± 0.04	0.40 ± 0.10	0.41 ± 0.16	0.30	0.41	0.41	0.40
Mn	XRF	%	0.09 ± 0.01	0.12 ± 0.02	0.12 ± 0.02	0.14 ± 0.03	0.10 ± 0.02	0.11 ± 0.02	0.11 ± 0.02	0.12 ± 0.03	0.09 ± 0.02	0.12 ± 0.02	0.12 ± 0.03	0.13 ± 0.04	0.07	0.11	0.13	0.12
P	XRF	PPM	68 ± 39	36 ± 74	195 ± 106	40 ± 103	94 ± 102	101 ± 88	239 ± 105	227 ± 107	66 ± 90	108 ± 94	0 ± 124	104 ± 205	328	509	550	761
S	XRF	PPM	115 ± 17	152 ± 29	209 ± 58	147 ± 69	98 ± 30	131 ± 30	172 ± 60	139 ± 67	95 ± 28	155 ± 35	122 ± 80	85 ± 130	295	509	448	503
Cl	XRF	PPM	185 ± 39	310 ± 69	408 ± 155	376 ± 195	88 ± 79	145 ± 74	92 ± 162	115 ± 186	95 ± 71	297 ± 96	97 ± 225	171 ± 371	587	757	646	749
V	XRF	PPM	45 ± 23	87 ± 53	80 ± 262	62 ± 354	41 ± 42	120 ± 64	63 ± 295	80 ± 349	68 ± 42	53 ± 106	95 ± 422	81 ± 697	107	161	173	178
Cr	XRF	PPM	51 ± 32	61 ± 61	62 ± 102	69 ± 116	56 ± 82	46 ± 72	102 ± 105	69 ± 114	48 ± 74	62 ± 79	70 ± 139	60 ± 227	71	95	143	120
Co	XRF	PPM	65 ± 17	43 ± 30	75 ± 43	57 ± 46	76 ± 40	74 ± 35	46 ± 43	72 ± 45	39 ± 36	72 ± 37	36 ± 54	58 ± 89	60	86	85	75
Ni	XRF	PPM	22 ± 24	27 ± 46	21 ± 60	52 ± 59	17 ± 63	24 ± 54	31 ± 58	32 ± 57	27 ± 55	25 ± 56	20 ± 70	24 ± 116	32	48	63	56
Cu	XRF	PPM	32 ± 18	59 ± 36	56 ± 50	49 ± 51	149 ± 52	108 ± 44	98 ± 50	55 ± 49	44 ± 44	48 ± 44	45 ± 61	95 ± 100	31	50	68	58
Zn	XRF	PPM	86 ± 27	120 ± 50	142 ± 66	157 ± 65	102 ± 67	140 ± 60	131 ± 63	142 ± 63	82 ± 59	98 ± 60	100 ± 74	222 ± 124	97	163	182	156
Ga	XRF	PPM	25 ± 76	38 ± 146	75 ± 186	15 ± 173	61 ± 200	16 ± 172	16 ± 176	46 ± 171	0 ± 177	65 ± 180	36 ± 207	51 ± 342	0	1	5	74
As	XRF	PPM	0 ± 20	8 ± 39	18 ± 65	4 ± 74	0 ± 53	28 ± 46	0 ± 67	8 ± 73	14 ± 47	0 ± 50	13 ± 89	8 ± 147	15	28	46	96
Se	XRF	PPM	0 ± 17	0 ± 33	0 ± 48	0 ± 50	0 ± 46	0 ± 40	0 ± 47	0 ± 49	0 ± 41	0 ± 42	0 ± 59	0 ± 98	2	2	9	9
Br	XRF	PPM	0 ± 20	26 ± 38	41 ± 52	19 ± 52	20 ± 52	25 ± 45	50 ± 51	43 ± 51	3 ± 46	7 ± 47	12 ± 61	46 ± 102	3	2	3	3
Rb	XRF	PPM	65 ± 20	76 ± 37	116 ± 51	126 ± 52	110 ± 50	77 ± 43	67 ± 49	139 ± 53	55 ± 43	70 ± 45	107 ± 61	44 ± 98	79	108	107	109
Sr	XRF	PPM	277 ± 53	367 ± 93	319 ± 114	372 ± 113	180 ± 118	212 ± 102	227 ± 106	299 ± 107	337 ± 108	332 ± 111	343 ± 129	377 ± 205	166	232	293	246
Y	XRF	PPM	20 ± 28	13 ± 55	15 ± 74	74 ± 73	6 ± 76	22 ± 65	54 ± 72	65 ± 72	42 ± 67	22 ± 68	85 ± 88	52 ± 144	24	39	51	35
Zr	XRF	PPM	116 ± 62	163 ± 117	123 ± 148	133 ± 139	110 ± 158	47 ± 136	122 ± 140	189 ± 139	113 ± 140	169 ± 143	164 ± 166	215 ± 273	86	112	126	92
Mo	XRF	PPM	7 ± 63	15 ± 123	0 ± 163	29 ± 160	48 ± 169	40 ± 145	28 ± 158	72 ± 158	4 ± 148	38 ± 151	0 ± 190	48 ± 315	10	12	51	11
Pd	XRF	PPM	13 ± 87	9 ± 169	68 ± 280	22 ± 315	9 ± 227	15 ± 200	41 ± 286	64 ± 311	19 ± 202	13 ± 215	55 ± 376	0 ± 620	5	11	59	7
Ag	XRF	PPM	30 ± 69	11 ± 133	36 ± 275	100 ± 337	82 ± 177	58 ± 159	72 ± 294	37 ± 332	132 ± 158	16 ± 180	108 ± 402	157 ± 664	8	11	16	47
Cd	XRF	ppm	22 ± 76	59 ± 149	9 ± 297	97 ± 361	38 ± 196	5 ± 175	120 ± 317	16 ± 355	47 ± 174	79 ± 197	85 ± 431	8 ± 710	16	20	9	149
In	XRF	ppm	19 ± 74	1 ± 146	57 ± 317	42 ± 393	92 ± 192	58 ± 172	82 ± 341	75 ± 387	138 ± 171	50 ± 198	106 ± 469	46 ± 774	12	23	34	37
Sn	XRF	ppm	54 ± 90	21 ± 176	19 ± 403	0 ± 505	27 ± 227	15 ± 207	29 ± 435	0 ± 497	0 ± 203	0 ± 243	0 ± 601	0 ± 994	20	12	82	31
Sb	XRF	ppm	0 ± 83	2 ± 164	65 ± 432	60 ± 553	0 ± 208	29 ± 195	44 ± 472	25 ± 545	0 ± 187	0 ± 238	45 ± 659	17 ± 1088	4	5	6	3
Ba	XRF	ppm	507 ± 226	375 ± 446	310 ± 1448	726 ± 1906	603 ± 530	614 ± 532	592 ± 1608	396 ± 1877	103 ± 474	620 ± 706	805 ± 2271	425 ± 3748	239	298	785	290
Au	XRF	ppm	23 ± 86	24 ± 165	0 ± 215	25 ± 206	38 ± 226	46 ± 195	51 ± 206	19 ± 203	2 ± 199	34 ± 203	18 ± 245	0 ± 405	3	1	8	53
Hg	XRF	ppm	0 ± 32	0 ± 63	0 ± 94	0 ± 101	0 ± 85	7 ± 74	0 ± 94	0 ± 99	0 ± 76	0 ± 79	0 ± 120	0 ± 198	6	10	39	22
Tl	XRF	ppm	0 ± 66	0 ± 127	0 ± 166	26 ± 159	32 ± 173	7 ± 150	14 ± 158	0 ± 156	0 ± 154	0 ± 156	20 ± 189	35 ± 312	5	8	5	22
Pb	XRF	ppm	45 ± 63	41 ± 123	59 ± 166	47 ± 164	80 ± 168	67 ± 145	78 ± 161	94 ± 161	55 ± 148	38 ± 151	26 ± 195	111 ± 323	45	69	221	65
U	XRF	ppm	47 ± 84	50 ± 163	17 ± 208	68 ± 195	12 ± 223	112 ± 193	50 ± 197	100 ± 193	26 ± 197	89 ± 199	3 ± 232	32 ± 384	4	4	16	19
La	ICP-MS	ppm	18.49 ± 0.86	30.74 ± 1.31	34.50 ± 1.72	33.93 ± 2.01	21.83 ± 1.24	29.02 ± 1.54	31.49 ± 1.84	31.80 ± 1.64	22.61 ± 1.34	27.46 ± 1.50	29.42 ± 1.35	42.11 ± 2.47	NA	NA	NA	NA
Ce	ICP-MS	ppm	36.59 ± 1.40	60.02 ± 2.15	67.25 ± 2.87	65.70 ± 2.46	43.83 ± 1.62	57.77 ± 2.12	62.43 ± 2.26	62.56 ± 2.15	43.68 ± 2.30	53.28 ± 1.58	56.88 ± 2.52	81.34 ± 3.30	NA	NA	NA	NA
Pr	ICP-MS	ppm	4.43 ± 0.24	7.31 ± 0.27	8.18 ± 0.32	8.12 ± 0.44	5.29 ± 0.30	7.04 ± 0.60	7.62 ± 0.36	7.56 ± 0.44	5.06 ± 0.25	6.28 ± 0.29	6.84 ± 0.46	9.65 ± 0.62	NA	NA	NA	NA
Nd	ICP-MS	ppm	17.01 ± 0.73	28.00 ± 2.00	31.61 ± 2.65	30.98 ± 2.55	20.41 ± 1.73	27.06 ± 2.35	29.63 ± 1.84	29.82 ± 2.24	20.21 ± 1.44	24.96 ± 1.79	26.56 ± 1.67	38.77 ± 3.39	NA	NA	NA	NA
Sm	ICP-MS	ppm	3.31 ± 0.34	5.58 ± 0.57	6.40 ± 0.65	6.24 ± 0.58	4.12 ± 1.09	5.50 ± 0.64	5.98 ± 0.65	6.21 ± 0.56	4.03 ± 0.67	4.94 ± 0.44	5.57 ± 0.66	7.64 ± 0.66	NA	NA	NA	NA
Eu	ICP-MS	ppm	0.69 ± 0.20	1.19 ± 0.41	1.30 ± 0.46	1.29 ± 0.41	0.79 ± 0.33	1.10 ± 0.39	1.25 ± 0.43	1.28 ± 0.21	0.84 ± 0.13	1.01 ± 0.14	1.32 ± 0.45	1.63 ± 0.21	NA	NA	NA	NA
Gd	ICP-MS	ppm	3.24 ± 0.40	5.44 ± 0.63	6.44 ± 0.89	6.26 ± 1.29	4.02 ± 0.84	5.49 ± 0.88	6.22 ± 0.85	6.33 ± 0.82	4.21 ± 0.81	5.05 ± 0.68	6.02 ± 1.20	8.34 ± 1.95	NA	NA	NA	NA
Tb	ICP-MS	ppm	0.42 ± 0.03	0.75 ± 0.13	0.86 ± 0.10	0.81 ± 0.08	0.51 ± 0.12	0.71 ± 0.18	0.81 ± 0.20	0.87 ± 0.21	0.54 ± 0.13	0.68 ± 0.15	0.87 ± 0.23	1.07 ± 0.14	NA	NA	NA	NA
Dy	ICP-MS	ppm	2.20 ± 0.15	3.79 ± 0.20	4.55 ± 0.33	4.38 ± 0.33	2.75 ± 0.29	3.81 ± 0.48	4.42 ± 0.63	4.46 ± 0.29	2.64 ± 0.36	3.34 ± 0.49	3.91 ± 0.49	5.45 ± 0.48	NA	NA	NA	NA
Ho	ICP-MS	ppm	0.39 ± 0.04	0.70 ± 0.11	0.83 ± 0.09	0.78 ± 0.08	0.51 ± 0.12	0.68 ± 0.07	0.78 ± 0.06	0.83 ± 0.15	0.47 ± 0.06	0.62 ± 0.05	0.80 ± 0.24	0.99 ± 0.14	NA	NA	NA	NA
Er	ICP-MS	ppm	1.11 ± 0.15	1.94 ± 0.20	2.39 ± 0.28	2.24 ± 0.22	1.44 ± 0.23	1.96 ± 0.30	2.26 ± 0.33	2.32 ± 0.33	1.38 ± 0.21	1.75 ± 0.30	2.09 ± 0.56	2.81 ± 0.46	NA	NA	NA	NA
Tm	ICP-MS	ppm	0.15 ± 0.03	0.30 ± 0.11	0.33 ± 0.11	0.29 ± 0.08	0.17 ± 0.04	0.28 ± 0.10	0.30 ± 0.07	0.30 ± 0.08	0.19 ± 0.06	0.24 ± 0.06	0.43 ± 0.33	0.40 ± 0.14	NA	NA	NA	NA
Yb	ICP-MS	ppm	1.00 ± 0.14	1.70 ± 0.29	2.08 ± 0.29	1.95 ± 0.34	1.22 ± 0.28	1.68 ± 0.38	2.03 ± 0.63	1.97 ± 0.37	1.20 ± 0.42	1.52 ± 0.32	2.01 ± 0.76	2.55 ± 0.53	NA	NA	NA	NA
Lu	ICP-MS	ppm	0.14 ± 0.03	0.27 ± 0.11	0.29 ± 0.10	0.27 ± 0.07	0.18 ± 0.05	0.24 ± 0.05	0.28 ± 0.05	0.33 ± 0.11	0.20 ± 0.06	0.23 ± 0.05	0.42 ± 0.27	0.40 ± 0.13	NA	NA	NA	NA
Notes: ^aAverage ± standard deviation of the number (n) indicated. ^b0C1, 0C2, 0C3, and 0C4 are organic carbon produced at 120, 250, 450, and 550 °C, respectively, in a He atmosphere; EC1, EC2, and EC3 are elemental carbon produced at 550, 700, and 800 °C, respectively, in a 2% 02/98% He atmosphere; OP is the pyrolyzed carbon fraction, determined when reflected laser light attained its original intensity after 02 was added to the combustion atmosphere; C03-C was measured as carbon by acidification of sample. ^cAAS = atomic absorption spectrophotometry, AC = automatic colorimeter, IC = ion chromatography, ICP-MS = inductively coupled plasma-mass spectrometry, XRF = X-ray fluorescence spectrometry, NA = not analyzed, ppm = parts per million

Figure 2. Relationship between carbonate carbon (CO₃ ²-C) and water-soluble calcium (Ca²⁺) for the TSP, PM₁₀, PM_2.5, and PM₁ fractions of loess.

Figure 3. UCC⁵⁵-normalized abundances for TSP, PM₁₀, PM_2.5, and PM₁ of loess. Samples for each size fraction represent the average of nine source profiles.

Table 3. Comparison of elemental ratios (uncertainties) for loess PM and dust-dominated aerosol in source regions

	CLP				Mu Us Desert	Tenggeli Desert				Takalamagan Desert	Hunshan Daka Sand-Land		Horqin Sand-Land
	Xi Feng ^a	Xi Feng ^a	Xi Feng ^a	Xi Feng ^a	Zhenbeitai20	Zhenbeitai14	Zhenbeitai19	Zhenbeitai15	Shapotou20	Aksu21	Sunite Zuoqi16	Sanggen Dalai16	Tongliao18
Size	TSP (n = 9)	PM10(N=9)	PM25(n = 9)	PM, (n = 9)	TSP (n = 58)	PM9 (n = 24)	PM25	PM25(n = 22)	TSP (n = 1)	TSP (n= 18)	TSP	TSP	PM25
fractions
Mg/AI	0.28 (0.08)	0.29 (0.08)	0.29 (0.09)	0.29 (0.11)	0.31	0.32 (0.03)	0.28	0.35	NA	0.48	0.31	0.25	0.19
Si/AI	4.56 (1.05)	2.03 (0.46)	1.79(0.49)	1.88 (0.59)	4.18	2.79 (0.04)	NA	1.9	2.37	4.18	NA	NA	4.06
K/AI	0.41 (0.25)	0.39 (0.24)	0.29 (0.08)	0.29 (0.09)	0.27	0.31 (0.02)	0.56	0.32	0.51	0.52	0.8	0.47	0.44
Ca/AI	2.25(0.2)	2.29(0.12)	1.56(0.24)	1.77 (0.25)	0.86	0.79(0.15)	0.92	1	1.95	2.05	0.4	0.53	0.76
Fe/AI	0.69 (0.03)	0.65 (0.01)	0.71 (0.02)	0.79 (0.07)	0.52	0.63 (0.04)	0.71	0.59	0.78	1	1.07	1.03	0.78
Ti/AI	0.052	0.048	0.058	0.067 (0.005)	0.078	0.054 (0.004)	0.08	0.051	0.096	0.086	0.12	0.078	0.063
Mn/AI	0.02 (0.002)	0.015(0.002)	0.018(0.002)	0.02 (0.002)	0.014	0.015(0.002)	0.027	0.015	0.012	0.017	0.02	0.019	0.02
P/AI	0.0016(0.001)	0.0019(0.002)	0.0012(0.001)	0.0015(0.001)	0.096	0.013	NA	NA	NA	0.085	NA	NA	0.05
V/Al	0.001 (0.004)	0.001 (0.002)	0.001 (0.001)	0.001 (0.0007)	0.0007	NA	0.0027	0.011	0.005	0.001	0.0036	0.0036	0.01
Cr/AI	0.0009 (0.001)	0.001 (0.0009)	0.0009 (0.0007)	0.001 (0.0008)	0.001	NA	0.0017	0.019	NA	0.0017	NA	NA	0.01
Co/AI	0.0003 (0.00008)	0.0002 (0.00004)	0.0003 (0.00004)	0.0002 (0.00005)	NA	NA	NA	0.0008	0.016	NA	NA	NA	NA
Ni/AI	0.0007 (0.0002)	0.0007 (0.0002)	0.0008 (0.0005)	0.0006 (0.0001)	0.0062	NA	NA	0.003	0.0063	0.0075	0.0012	0.0053	0.003
Cu/AI	0.0009 (0.0004)	0.0016(0.001)	0.0018(0.002)	0.001 (0.001)	0.0034	NA	0.001	0.0062	0.012	0.0037	0.0027	0.0016	0.01
Zn/AI	0.0016(0.001)	0.002 (0.001)	0.0016(0.001)	0.003 (0.004)	NA	NA	0.0098	0.035	0.01	0.0018	0.004	0.0055	0.09
Rb/AI	0.0016(0.0004)	0.0015(0.0003)	0.0015(0.0002)	0.0014(0.0003)	NA	NA	NA	NA	NA	NA	NA	NA	NA
Sr/AI	0.0039 (0.002)	0.0032 (0.0006)	0.0037 (0.0008)	0.0035 (0.001)	NA	NA	0.006	0.005	NA	NA	NA	NA	NA
Zr/AI	0.0023 (0.0014)	0.0017(0.001)	0.002(0.0015)	0.002 (0.0015)	NA	NA	NA	NA	NA	NA	NA	NA	NA
Ba/AI	0.0065 (0.019)	0.0073(0.013)	0.0084 (0.005)	0.0085 (0.006)	NA	NA	0.011	0.009	NA	NA	NA	NA	NA
Pb/AI	0.0005 (0.0002)	0.0005 (0.0002)	0.0005 (0.0001)	0.0004 (0.0001)	0.01	NA	0.007	0.025	0.005	0.0057	0.0022	0.0079	0.02
Notes: aSamples collected during this study. NA = not analyzed.

Figure 4. The percentages of crustal and non-crustal origin for elements Pb,Zn, Cr, V, Ni, Cu, and Co of PM_2.5 aerosol samples acquired from the ZBT station.15 The fraction of non-crustal origin (f _{non-crustal origin}, in percent) for element X was calculated as follows: f _{non-crustal origin} = 100 × [1 - (Al _sample × X _loess)/(Al _loess × X _sample)].

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