21
Can wetland plants take up two pharmaceutical compounds under hydroponic
conditions?
Y. Zhang
1
, T. Lv
1
, P. N. Carvalho
1
, C. A. Arias
1
, Z. Chen
2
and H. Brix
1
1
Department of Bioscience, Aarhus University, Aarhus 8000C, Denmark.
2
College of Life Science, South China Normal University, Guangzhou 510631, PR China.
Abstract
Constructed wetland (CW) systems is an attractive and economic alternative technology, which
enables wastewater to be treated in an effective but cost-efficient way (1). Recently, as
pharmaceuticals and personal care products (PPCPs) were detected in various water bodies, even
in drinking water, CWs have been applied for the removal of PPCPs with promising results (2).
The uptake of pharmaceuticals by crop plants is a known fact widely reported in the literature (3).
Although there is a significant research on the application of wetlands systems to remove PPCPs
from polluted water (4), the studies about uptake of pharmaceuticals in wetland plants are scarce.
A few studies have shown that some pharmaceuticals can enter both roots and leaves of wetland
plants. However, plant uptake depends on the characteristics of the pharmaceuticals, on the
pharmaceutical concentration and on the plant species (3). Therefore, more information is
required on the factors influencing plant uptake of pharmaceuticals, in order to fully understand
its implications for the use of constructed wetland system.
In this study, five constructed wetland plant species,
Typha latifolia
,
Phragmites australis
,
Iris
pseudacorus
,
Berula erecta
and
Juncus effusus
were selected to study the uptake of two
pharmaceuticals, ibuprofen (IBU) and iohexol (IOH), at a concentration of 10 mg/L in
hydroponic culture. Each pharmaceutical treatment (three replicates) and control samples (three
replicates without IBU and IOH) were kept in a growth chamber with day:night cycles (25:22°C;
16:8h light; 70%:80% relative humidity). Aqueous samples were analyzed throughout the
duration of the experiment to study the removal. After 24 days, the plants were harvested and
separated into root, stem and leaf and further lyophilized before being stored at -20 °C until
analysis. The plant samples (0.2 g dry weight) were extracted by 10 mL of methanol/acetone
(95:5, v/v) in an ultrasonic bath for 30 min. After extraction, the supernatant was cleaned-up
using 0.25 g of activated charcoal. Cleaned extract was dried under nitrogen gas and re-dissolved
in water:methanol (1:1). The IBU and IOH in the aqueous samples and the extracts were
analyzed by high-performance liquid-chromatography equipped with a diode away detector
(HPLC-DAD; Thermo Scientific Ultimate 3000). The analytes were separated on a Synergy 4μ
Polar 80 Å column (150 mm × 2.0 mm ID) using water:0.2% formic acid as mobile phase A and
methanol:0.2% formic acid as mobile phase B. Mobile phase gradient started with 100% of A
(hold 2 min), linearly decreased to 35% of A (65% of B) within 2 min, linearly decreased to 0%
of A (100% of B) within 9 min (hold 3 min) and finally returned to the initial conditions in 1 min
and hold for extra 3 min. The flow rate was 0.25 mL min
-1
for 16 min, linearly increasing to 0.30
mL min
-1
within 1 min (hold 2 min) and finally returned to 0.25 mL min
-1
in 1 min. The column
oven was set to 20°C, and the sampler temperature was set to 8 ºC. The sample injection volume
was set at 10 μL and the detector signal was monitored at λ = 220 nm and 240 nm.
The results showed that for IBU, all plant species got nearly 100 % removal efficiency except
B
.
erecta
(only 70% removal) during the 24 days experiment. Regarding IOH, only
P. australis
and
