Supplemental Information
Arsenic Distribution and Speciation in a Managed Turfgrass System following a
Monosodium Methylarsenate (MSMA) Application
D. J. Mahoney1, T. W. Gannon1, M. D. Jeffries1, and M. L. Polizzotto2
1
D. J. Mahoney, T. W. Gannon, and M. D. Jeffries, Dept. of Crop Science, North Carolina State
Univ., 100 Derieux St., Campus Box 7620, Raleigh, NC 27695. 2M. L. Polizzotto, Dept. of Soil
Science, North Carolina State Univ., 100 Derieux St., Campus Box 7619, Raleigh, NC 27695.
Received __________.

Corresponding author ([email protected]).
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Table S1. Effect of time on clipping arsenic concentrations, contents, and recoveries within
MSMA-treated lysimeters under each clipping management practice.†, ‡, §, ¶, #, ††
_____
WAT
CC _____ _____ CR _____ _____ CC _____ _____ CR _____ _____ CC _____ _____ CR _____
1
2
3
4
5
6
concentration (µg As g-1)
383
109
121
52
54
14
19
7
13
6
7
3
7
8
LSDf
5
_____
4
39 _____
content (µg As lysimeter-1)
160.2
16.7
23.7
9.6
11.1
1.7
4.3
1.3
2.7
1.0
1.6
0.4
2
_____
3
34 _____
0.9
____
1.0
15.7 ____
____
_____
As recovery (%)e _____
9.4
1.0
1.4
0.6
0.7
0.1
0.3
< 0.1
0.2
< 0.1
< 0.1
< 0.1
0.4
< 0.1
< 0.1
0.6
4.0 ____
< 0.1
< 0.1
_
_
†
Clipping As concentrations and contents cannot be compared across management practices because of
unequal sample collections between clippings collected and returned regimes.
‡
Abbreviations: WAT, week after treatment; CC, clippings collected; CR, clippings returned; As,
arsenic; LSD, least significant difference.
§
MSMA provided 1.7 mg As per lysimeter.
¶
Arsenic was not detected in nontreated clipping samples; therefore, it is assumed that As
detected was the result of the MSMA application.
#
Arsenic recoveries are a percent of total As applied.
††
LSD values for comparison within measurement. LSD values not calculated for As recoveries.
Under the clippings collected (CC) regime, clippings were harvested from both weekly
mowing events and homogenized for analysis; however, under clippings returned (CR), only
clippings from the second weekly mowing event were harvest for analysis. Due to unequal
sample timings, clipping As concentration and content cannot be compared across management
practices; therefore, they are presented according to their respective management practice (Table
S1). Arsenic concentration and content trends under both CC and CR were similar, with
decreases over time
2
Table S2. Effect of time on remaining vegetation arsenic concentrations, contents and
recoveries within MSMA-treated lysimeters.†, ‡, §
_______________________
WAT
Pooled over clipping management _______________________
1
2
3
4
5
6
concentration (µg As g-1)
283
145
87
66
41
36
content (µg As lysimeter-1)
936
488
323
216
152
134
As recovery (%)¶
55
29
19
13
9
8
7
24
98
6
94
108 ____________
6
8
LSD#
_____________
24
25 ____________
____________
_
†
Abbreviations: WAT, week after treatment; LSD, least significant difference.
‡
MSMA provided 1.7 mg As per lysimeter.
§
Nontreated remaining vegetation As concentrations and contents were ≤ 0.51 mg As
kg-1 and 1.77 µg lysimeter-1, respectively. This was not subtracted from MSMAtreated content, as it is 1% of the total applied As.
¶
Arsenic recoveries are a percent of total As applied.
#
LSD values for comparison within measurement. A LSD value was not calculated
for percent As recovery.
Arsenic concentrations and contents are pooled across clipping management practices, as
they did not significantly affect As in the remaining vegetation over time (Table S2). Like
clipping As concentrations and contents, remaining vegetation As decreased over time.
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Table S3. Root arsenic concentrations and contents of treated and nontreated turfgrass over
time.†
Treated
Nontreated
Treated
Nontreated
_________________
2 WAT
4 WAT
8 WAT
LSD‡
µg As g-1 _________________
27
1
33
1
31
2
____________________ ____________________
9
____________
µg As lysimeter-1 _____________
234
10
252
8
267
21
___________________
50 ___________________
†
Abbreviations: WAT, week after treatment; LSD, least significant difference.
‡
LSD values for comparison within measurement.
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Figure S1. Arsenic species and total concentration in 5-cm-depth porewater over time following
an MSMA application. The two bars for each time point represent data from two unique CR
lysimeters. Porewater was unable to be collected from one lysimeter 8 WAT.
Porewater was collected from two treated lysimeters from the 5-cm depth under the CR
regime. Although total As concentration varied between lysimeters at each sample date, As
species concentration between lysimeters was consistent (Figure S1). At 4 WAT, a significant
increase in porewater As concentration was detected from one lysimeter. The cause for this
occurrence is unknown, but As from MSMA may conjoin with various plant compounds and
may be subsequently exuded. While the As concentration did not follow the decreasing trend, As
species, as a percent of total As, were similar to the other sample at this time.
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A
B
C
Figure S2. Arsenic micro-XANES spectra of MSMA-treated soil samples under the clippings
collected management practice, with dashed lines to denote peak energies of As(V) and As(III)
reference standards. Cacodylic acid is representative of dimethylarsonic acid. (A) As standards
(bottom 4 spectra) and 2-WAT soil samples (upper 3 spectra), (B) 4-WAT soil samples, and (C)
8-WAT soil samples. In the bottom panels, microscale (1 x 1 mm) X-ray fluorescence maps
show areas of As accumulation (hot colors) within the soil samples (0-5 cm depth) corresponding
to the spectra above.
X-ray absorption spectroscopy indicated that multiple As species were present in soil
samples at the 0- to 5-cm depth (Figure S2). Micro-XRF mapping revealed As hotspots (circled)
of high As content, and these spots were chosen for µ-XANES analysis. Three As hotspots
detected in soil from 2 WAT showed As(V) as the predominant species. There is also evidence
of As(III) in spot 1, as indicated by the spectra shoulder at 11,871.3 eV. Similar results were
detected in soil from 4 WAT. The six spots revealed a predominant presence of As(V), with
As(III) detected at only 1 analyzed hotspot. At 8 WAT, As(V) dominated all hotspots.
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