[Simultaneous Determination of Hydroquinone and Catechol Based on L-Histidine-Erythrosine Composite Film Modified Glassy Carbon Electrode].

By using cyclic voltammetry method, L-histidine and erythrosine was electrodeposited on the surface of glassy carbon electrode (GCE) to obtain the modified electrode (denoted as L-His-Erythrosine/GCE). The morphology of L-His-Erythrosine/GCE was characterized by scanning electron microscopy (SEM), and the electrochemical property characterization of L-His-Erythrosine/ GCE was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The electrocatalytic oxidation of hydroquinone (HQ) and catechol (CC) on the modified electrode was discussed by differential pulse voltammetry (DPV) in this study. The L-His-Erythrosine/GCE had shown an excellent electrocatalytic activity for HQ and CC. The oxidation overpotentials of HQ and CC decreased significantly and the corresponding oxidation currents increased remarkably. Due to the large separation of oxidation peak potentials (108 mV), concentrations of HQ and CC can be easily determined simultaneously. Under the optimum conditions, the oxidation peak currents for both HQ and CC increased linearly with the respective concentrations in the 1.2 x 10(-6) to 1.1 x 10(-4) mol x L(-1) concentration range, with the detection limits of 0.19 and 0.16 µmol x L(-1) (S/N = 3), respectively. Furthermore, the modified electrode exhibited good reproducibility and selectivity. The modified electrode was successfully applied to the simultaneous determination of HQ and CC in actual water samples, the recoveries got by standard addition method were in ranges of 99.9% - 100.6% (HQ) and 99.2% - 100.2% (CC).

[Influence of perennial flooding and drought on growth restoration of Acorus calamus in water-level-fluctuation zone of the Three Gorges Reservoir].

Acorus calamus L. is a common kind of wetland plant species in the Three Gorges Reservoir. In this study, we investigated the influence of perennial flooding on growth restoration of A. calamus in the lightless conditions and the drought stress on this plant species' growth after flooding. Our research provided the scientific basis for the selection of candidate species for vegetations restoration in water-level-fluctuation zone of the Three Gorges Reservoir. A. calamus plants were exposed to waters in the lightless conditions in September 2009 and September 2010 respectively and taken away from the waters and grew in natural conditions in the following March, April and May (named as S1, S2, S3). All plants in the control, S1 and S2 groups were challenged with drought stress in May for 20 days. During the experiment, the plant number and leaf number were recorded regularly, as well as leaf length and leaf width. The results showed that flooding restrained the germination of the plants with much less plant in flooding groups than the control, and the plant germination rate had inverse relation to the flooding time. Flooding promoted formation and elongation of the leaves in S1 and S2 groups, which showed higher leaf growth parameters, such as leaf length, leaf number, total leaf length of one plant and total leaf length of all plants than the control. However, all of these growth parameters in S3 group had significantly lower values compared to the control. The survival rate of the plants after flooding decreased significantly with longer flooding time. Besides, the leaf length and leaf width in S1 and S2 groups increased significantly but with decreased leaf number. Additionally, all growth parameters (leaf length, leaf width, leaf number, total leaf number, total leaf length of one plant, total leaf length of all plants) in S3 group decreased remarkably. Furthermore, drought decreased the values of all growth parameters and the plant number in the control, S1 and S2 groups notably. When drought stress was removed for 25 days, the leaf number in the control, S1 and S2 groups increased by 67.0% (P < 0.05), 66.7% (P < 0.05) and 36.2% (P < 0.05), respectively, and the total leaf length of one plant, total leaf length of all plants and total leaf number in S1 and S2 groups increased by 48.2%, 18.1%, 66.7%, 35.0%, 75.0% and 64.3%, respectively (P < 0.05). Therefore, A. calamus exhibited not only strong adaption and tolerance to flooding,but also robust growth restoration ability after flooding, as well as good restoration ability to the drought stress. In summary, A. calamus could be used as one kind of restoration or reconstruction species in water-level-fluctuation zone (especially not exposed to flooding in March or April) of the Three Gorges Reservoir.