Figure S1 Real-time Cd2+, Pb2+and Cu2+fluxrecorded at the root position of 300 μmand 1000 μm from the root apex of Typhalatifolia immediately upon addition of 10 μM Cd, Pb and Cu.

Figure S2 Real-time Cd2+, Pb2+and Cu2+fluxrecorded at the root position of 300 μmand 1000 μm from the root apex of Canna indicaimmediately upon addition of 10 μM Cd, Pb and Cu.

Figure S3 Real-time Cd2+, Pb2+and Cu2+fluxrecorded at the root position of 200 μmand 1000 μmfrom the root apex of Phragmitesaustralis immediately upon addition of 10 μM Cd, Pb and Cu.

Figure S4 Test for pharmaceuticals effect on Pb2+ (A) and Cu2+ (B) microelectrode. The microelectrodes were calibrate with and without different drugs added to the calibration solutions containing0.1mM KNO3, 0.1mMCa(NO3) 2, 0.1mMMgSO4, 1.0 mMNaCl

FigureS5. Response curves of Pb2+ (A) and Cu2+ (B) microelectrode obtained according to Bakker’s methodtoward the interfering ions. The electrodes wereconditioned in 10mMNaCl solutions overnight before measurement.

FigureS6. Pb2+and Cu2+flux measured at each known position with the addition of 0.05 mMZn, Cd and Pb/Cu

Figure S7Measurement of Cd2+, Cu2+ and Pb2+ flux (mean ± standard error) across the root surface ofTypha latifolia. Each point represents the mean of five seedlings and bars represent the standard error of the mean, measured at each position. Roots were scanned in segments of 300 μm from the root tip

Figure S8 Measurement of fluxes (outward positive) of Cd2+, Pb2+ and Cu2+ (mean ± standard error) across the root tips of three common wetland plant species, Typhalatifolia (a)Canna indic (b) and Phragmitesaustralis (c), using Cd2+, Pb2+ and Cu2+ ion selective microelectrodes and the scanning ion-selective electrode technique. Flux measurements were carried out in a extracted solution from soil in the locations where the plants normally grow. Roots were scanned in segments of 100 μm

Figure S9 Potential vs. time dependences recorded for Pb2+(a) and Cu2+ISME (b) in DI water containing 1 × 10−3 M and 1 × 10−4 M Pb2+ or Cu2+ with the addition of 1.0 mM K+ and/ or Mg2+

Figure S10 Calibration curve for Pb2+(a) and Cu2+ISME (b) in DI water and a background containing different concentrations of K+ and Mg2+

Table S1. Composition and slopes for Pb2+ cocktail based on different ionophore. The slopes recorded were based on Pb2+ISME readingin 10 and 100μMPb2+ in DI water.

Ionophore (%) / Solvents (%) / Lipophilic salt (%) / Slope
(mv/decade)
methylene-bis-N,N
-diisobutyldithiocarbamate / tetramethylene-bis-N,N
-diisobutyldithiocarbamate / o-NPOE / DBP / NaTPB / tetradodecyl ammonium tetrakis(4-chlorophenyl) borate
10 / – / 79 / – / 8 / 3 / 29
50 / – / 40 / – / 10 / – / 14
20 / – / 70 / – / 10 / – / 26
5 / – / 90 / – / 5 / – / 22
– / 10 / 80 / – / 8 / 2 / 26
– / 20 / 70 / – / 10 / 24
– / 5 / 90 / – / 5 / 16
15 / – / – / 70 / – / 15 / 25
5 / – / – / 80 / 15 / – / 19
– / 5 / – / 60 / – / – / 18
– / 10 / – / 70 / – / – / 22
– / 20 / – / 60 / 20 / – / 20
– / 5 / – / 80 / – / 15 / 13

Table S2.Composition and slopes for Cu2+ cocktail based on different ionophore. The slopes recorded were based on Cu2+ISME readingin 10 and 100μMCu2+ in DI water.

Ionophore / Solvents / Lipophilic salt / Slope
(mv/decade)
diphenylthiocarbazone / N,N,N′,N′-Tetracyclohexyl
-2,2′-thiodiacetamide / o-NPOE (mg) / DBP (mg) / NaTPB (mg) / tetradodecyl ammonium tetrakis(4-chlorophenyl) borate (mg)
10 / – / 68 / – / 12 / 10 / 28
5 / – / 80 / – / 15 / – / 19
50 / – / 40 / – / 10 / – / 22
– / 5 / 80 / – / 15 / – / 16
– / 10 / 70 / – / 20 / – / 20
– / 20 / 60 / – / 10 / 10 / 23
10 / – / – / 80 / – / 10 / 23
10 / – / – / 70 / 15 / 15 / 13
– / 10 / – / 70 / – / 20 / 24
– / 10 / – / 80 / – / 10 / 25

Soil solution extraction and analysis

Double deionized water was added to bring soil and solution on a mass basis to a ratio of 1:10. The suspensions were stirred in 2-L buckets for 2 h at room temperature using a motor-driven propeller and then allowed to equilibrate for 24h.To separate the soil from the extract,suspensions were filtered through 0.7-mm prefilters made of borosilicate glass fiber filter using a pressure-filter system. Soil extracts were then 0.2μm filtered over mixed cellulose ester membrane filters using vacuum-driven filter units.Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES;IRIS ADVANTAGE, Thermo Fisher Scientific, USA) was used for the analysis ofcations in the soil extracts. Anions were analyzed on a waters liquid ion chromatograph (Milford, MA, USA).

Table S3. The main characteristicsof soil extracted solution

Characteristic / value
pH / 6.5
EC(dS/m) / 5.7
Ca (mM) / 9.8
Mg (mM) / 5.1
K (mM) / 3.0
Na (mM) / 32.0
Cl (mM) / 30.0
NO3(mM) / 7.6
SO4 (mM) / 8.1