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Geophysical Research Letters
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Supporting Information for
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Hidden carbon sink beneath desert
Yan Li1 ,
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Yu-Gang Wang1 ,
R.A. Houghton2 ,
Li-Song Tang1
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State Key Lab of Desert and Oasis Ecology, Xinjiang Institute of Ecology and
Geography, Chinese Academy of Sciences, 818 South Beijing Road, Xinjiang
830011, China，2 Woods Hole Research Center, 149 Woods Hole Road, Falmouth,
MA 02540-1644, USA.
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Contents of this file
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Text: text01
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Table: ts01 – ts06
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Figure: fs01
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Introduction
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This document contains 1 text, 6 tables and 1 figure file, as described below.
1. text01.tex Text file with detailed description of soil CO2 flux measurements.
2. ts01.txt Table file with statistics of DIC age and its K-S test in the Tarim Basin
3. ts02.txt Table file with the parameters and prediction errors of models for DIC age
in the Tarim Basin
4. ts03.txt Table file with the parameters for carbon storage of the saline aquifers of
the Tarim Basin for each age group
5. ts04.txt Table file with DIC content in different DIC age groups within the Tarim
Basin
6. ts05.txt Table file with estimated DIC input and storage for three arid basins in
China.
7. ts06.txt Table file with estimated DIC input and storage for three 5 arid basins in
other parts of the world.
6. fs01.tif Diurnal variations (a−g) and daily average (h) of soil CO2 fluxes at different
groundwater depth (GWD) at the center of Taklamagan Desert.
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1
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Text01:
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Detailed Description of soil CO2 flux measurements in the Taklamagan Desert
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Measurements of soil CO2 fluxes were conducted in the hinterland of the
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Taklamagan Desert (39°00ʹN, 83°40ʹE and 1099 m.a.s.l.) during 4–19 August 2013,
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with an LI-8150 Automated Soil CO2 Flux System equipped with six long-term
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monitoring chambers (LI-COR 8150, Lincoln, Nebraska, USA). To capture the
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influence of groundwater depth (GWD) on soil CO2 fluxes, soil collars were arranged
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along a longitudinal sand dune transect, giving a natural gradient of GWD. In total,
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seven sites were measured, with GWD of 4.32, 6.80, 9.58, 11.15, 13.25, 26.16 and
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28.85 m, respectively. Soil CO2 fluxes were measured every 30 min, and each site was
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monitored for at least 2 d with three replicates (Figure S1).
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GWD was determined by artificial digging at the lowest site. Then, based on the
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site, relative altitude was measured with Electronic Total Station (NTS-660R, South
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China Electronic Company, Guangzhou, China) and GWD of other sites could be
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calculated.
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2
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Table S1 Statistics of DIC age and its K–S test in the Tarim Basin.
Sample Mean
170
63
2227
SE
SD
235
3068
CV (%) Min
156.82
1
Max Skewness Kurtosis
16880
2.16
5.25
K–S
3.042
P = 0.000
64
65
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Table S2 The parameters and prediction errors of models for DIC age in the Tarim
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Basin.
Co/Sil
Model
Exponentia
l
68
Co
1.5
Range
l
(Degree)
0.128
0.84
12.3
8
F-valu
R2
Sill
RSS
RMSS
E
0.00
7
1.018
e
0.59
6
ME
0.23
40.58**
9
1
Note: **Means F-test significance at p < 0.01
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Table S3 The parameters for carbon storage of the saline aquifers of the Tarim Basin
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for each age group.
△H (m)
DIC age
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C (mg L–1)
P
(K yr · BP)
A (104 km2)
Mean
SE
Mean
SE
Mean
SE
<1
12.50
4202
1090
0.11
0.03
62.32
3.32
1–2
10.04
5151
958
0.11
0.03
60.83
3.9
2–5
16.83
5933
853
0.11
0.03
68.22
4.31
5–8
6.56
5337
903
0.11
0.03
77.15
19.37
>8
4.65
6621
1547
0.11
0.03
68.48
11.81
△H is the thickness of the aquifer, P the porosity of the aquifer, C the DIC content in
the groundwater, which is taken as sum of carbon in the form of carbonate and
bicarbonate.
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Note: the porosity of the aquifer is 0.09–0.14 in the Tarim Basin, 0.03 was the Adj.
P-SE.
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Table S4 DIC content in different DIC age groups within the Tarim Basin (mg L–1)
DIC age
(K yr · BP) N
Min
Max
Mean
SE
<1
68
18.1
165.44
62.32
3.32
1–2
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18.3
124.5
60.83
3.9
2–5
51
19.28 149.51
68.22
4.31
5–8
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22.66 183.62
77.15
19.37
>8
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34.23 108.43
68.48
11.81
170
18.1
64.68
2.25
Basin
183.62
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Table S5: DIC input to and DIC storage in three closed arid basins in China, with DIC
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stands for dissolved inorganic carbon. Data in bold are data used in the
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current study, with input rate inversely calculated from the DIC storage and
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age, averaged for a long history (more than 10 000 years). Other data
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(including data in Table S6) are summarized from literatures as noted,
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averaged for the last few decades.
DIC Input for active recharging area
Runoff
Recharge
Area
Input
DIC Storage for whole basin
Mean
Area
Pool
DIC
Basin
8
3
8
3
-1
4
2
12
-1
-2
-1
4
2
(10 m )
(10 m yr )
(10 km )
(10 gC yr )
(gC m yr )
(10 km )
(PgC)
(gC m-3)
-――
335.5
16.82
2.17±1.08
12.88±6.43
50.58
19.84±5.35
64.68±2.25
Tarim*a
479.85
203.65
3.52
1.49±0.49
42.38±13.84
51.63
22.59±5.13
73.19±3.2
Junggar*b
127.08
51.27
2.63
2.91±0.97
11.06±3.69
17.57
2.39±1.35
56.70±2.81
Qaidam*c
50.08
17.96
0.37
1.53±0.19
41.22±5.01
14.16
2.36±1.19
85.24±10.35
Sum/Mean
657.01
272.88
6.52
5.93±2.73
29.68±9.25
83.36
16.57±7.02
67.76±2.23
Tarim
(in this study)
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*a, *b, and *c indicate data source as listed below.
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*a Li, W. P, P. X. Jiao, Z. X. Zhao. (1995), Study of groundwater chemistry and
environmental isotopic hydrogeology from north to south in Taklimakan desert,
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journal with English abstract)
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97
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*a Zhang, H. F., W. H. Li, H. T. Ge, Y. Chen. (2003), Compositor analysis on
correlation between groundwater level and water chemical contents in low reaches of
Tarim river, Arid Land Geography., 26, 260-263. (Chinese journal with English
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chemical tests in Hotian area and countemeasures for exploitation. Journal of Water
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*a & *b Groundwater in Xinjiang province. 1965. Science Press, Beijing, China.
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*b Guo, L., B. Zhang, J. Guo. (2007), Analysis of natural groundwater reservoir
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129
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Table S6: DIC input to and DIC storage for 5 basins in Australia, USA, Arabian
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Peninsula and Sahara, with DIC stands for dissolved inorganic carbon.
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Data are summarized from available literatures.
Runoff
Recharge
Area
Input
Storage
DIC
(108m3)
(108m3 yr-1)
(104km)
(1012g yr-1)
(PgC)
(g m-3)
Murray Basin in AU*a
158.98
54.76
30
2.75±0.28
0.41±0.26.
50.20±5.03
Great Basin in USA*b
>100
50.22
36
3.01±0.22
0.62±0.44
59.86±4.48
Rub Al Khali watershed
in Arabian Peninsula*c
400
40-100
65
1.55±0.77
1.88±0.90
22.16±2.71
North-Western
Sahara Basin*d
——
10
103
0.28±0.01
3.06±1.12
28.11±0.91
Nubian Basin
of North Africa*e
——
7<
217.58
0.31±0.02
23.90±1.29
44.08±2.39
Region
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*a,*b,*c,*d&*e indicate data sources as listed below.
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*a Cartwright, L., T. R. Weaver, C. T. Simmons, et al. (2010), Physical hydrogeology
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Figure S1. Diurnal variations (a–g) and daily average (h) of soil CO2 fluxes at
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different groundwater depth (GWD) at the center of the Taklamagan Desert. The daily
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averages of soil CO2 fluxes were all no different from zero, indicating no net CO2
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release/absorption.
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