Yue-Ming Chen

Aluminium and nutrients induce changes in the profiles of phenolic substances in tea plants (Camellia sinensis CV TTES, No. 12 (TTE))

BACKGROUND Tea plants are always cultivated in acid soils in hilly regions and their growth can be dependent on to soluble aluminium (Al). The mechanism of Al detoxification and the influence of Al on phenolic compounds (i.e. catechin) in the roots of tea plants has remained obscure. This study aimed to investigate the influence of Al changes on the concentrations of phenolic substances in tea plants through hydroponic experiments. RESULTS Tea plants were cultivated in nutrient solution containing 1.5 and 2.5 mmol L(-1) Al, and these treatments enhanced the growth of new buds and roots. Aluminium stimulated the uptake of Ca, Mg, K and Mn, whereas the uptake of Fe, Cu and Zn was retarded. Moreover, total phenol concentrations in tea plant tissues increased with increasing Al concentrations. In general, catechin concentrations in leaves increased with increasing Al concentrations in the hydroponic experiments. High correlation coefficients were obtained between Al and (-)-ECG (r(2) = 0.85, P < 0.01) and between Al and total phenols (r(2) = 0.92, P < 0.01). CONCLUSIONS The Al concentration in tea plants indeed increases catechin concentrations and plays an important role in the growth of tea plants.

Dynamics of cadmium concentration in contaminated rice paddy soils with submerging time

This study examined the change in the speciation of cadmium (Cd) in contaminated rice paddy soils with prolonged submergence. Three Changhua soils (CH1, CH2, and CH3) from central Taiwan and three Taoyuan red soils (TY1, TY2, and TY3) from northern Taiwan with different levels of heavy metal contamination were selected for the study. The Cd, Fe, Mn, soil pH, and Eh in soil solutions were determined as a function of submerging time. During submergence, the Fe and Mn concentration increased, while the SO42− concentration decreased. The concentrations of Cd immediately increased in the soil solutions after a short submerging time and then decreased with further submergence. The sequential extraction showed that the exchangeable fraction decreased and the oxide-bound fraction increased after submergence. According to preliminary calculations of the MinteqA2 program, sulfate cannot be reduced to sulfite or sulfide under the soil Eh and pH values observed for the soils after prolonged submergence. Thus, the observed decreases of sulfate concentration may result from sulfate reduction in the micro-environments, which cannot be accounted for by the thermodynamic calculation. The reduction of sulfate to sulfide may subsequently result in the formation of CdS precipitate, which attributes to the decreases of Cd concentrations in the soil solutions after prolonged submergence.

Removal of methylene blue from aqueous solution using wine-processing waste sludge

Dye wastewaters usually contain toxins and high chroma, making them difficult to treat with biological methods. The adsorption process plays an important role in removing dyes from wastewaters. This study aimed to explore the methylene blue (MB) adsorption mechanism by wine-processing waste sludge (WPWS). The WPWS contains a high cation-exchange capacity (64.2 cmol(c) kg(-1)) and organic matter (52.8%). The parameters affecting MB adsorption included pH, initial concentration of MB, reaction temperature, particle size and dosage of WPWS. The WPWS adsorption isotherms of MB were only well described by Langmuir adsorption isotherm. The maximum adsorption capacity (Q(m)) of MB was 285.7 mg g(-1) at 25 °C. The activation energy determined by Arrhenius equation is 29.995 kJ mol(-1). Under steady-state reaction conditions, the Gibb free energy (ΔG°) ranged from -24.607 to -27.092 kJ mol(-1) and ΔH° was -8.926 kJ mol(-1), indicating that lower reaction temperature would favor MB adsorption. Therefore, MB adsorption by WPWS was a spontaneous, exothermic and physisorption reaction.

CLAY MINERALOGY AND MAJOR ELEMENT CHEMISTRY OF THE EARLY QUATERNARY AND LATE MIOCENE PALEOSOLS ON PENGHU ISLANDS (PESCADORES), TAIWAN

Clay mineralogy and whole-soil major element chemistry of an early Quaternary red soil and two late Miocene paleosols between basalt lavas on Penghu Islands (Pescadores), Taiwan, were studied to compare properties of soils from the different periods. The early Quaternary red soil consists of a kaolinite and smectite clay assemblage. The late Miocene paleosols are rich in kaolin minerals. The amounts of Si, Fe, and Al in the three profiles are the mineralogical differences. The depth distributions for clay and free Fe oxide contents suggest that the early Quaternary red soil formed in at least two stages. The early Quaternary red soil was classified as fine, mixed, hyperthermic, Typic Rodustalf. The late Miocene paleosols were classified as fine, kaolinite, hyperthermic, Typic Rhodic Paleustalf. The late Miocene paleosols contain more clay, lower SiO2/Al2O3 and SiO2/(Al2O3 + Fe2O3) molar ratios, averages of 2.5 and 1.7, respectively, and higher chemical indexes of weathering than the early Quaternary paleosol. The SiO2/Al2O3 and SiO2/(Al2O3 + Fe2O3) molar ratios and Mn2+ and Mg2+ distributions showed zigzag patterns, suggesting that changes in sea level influenced the early Quaternary profile during the soil formation.

Adsorption of Cadmium on Aluminum Precipitates in the Absence or Presence of Catechins

The products of Al hydrolysis play significant roles in terrestrial and aquatic environments, particularly through their binding of nutrients and pollutants. However, the effect of catechins on the crystallization of Al precipitates and the resultant surface alteration of Al transformation products on their kinetics and mechanisms of adsorption of Cd still remain to be uncovered. The objective of this paper was to investigate the kinetics of Cd adsorption on the Al precipitates formed under the influence of catechin. The experiments were conducted with initial catechin/Al molar ratios, interaction time, concentration of Cd ions, and temperature as the variables. Six kinetic models were employed to investigate adsorption mechanisms, and data resembled more closely a second-order process. The structural perturbation of Al precipitates by catechin, resulting in the development of their microporosity and alteration of surface and charge properties, substantially enhanced the rate constants of both fast and slow reaction processes of Cd adsorption. The role of catechins, which vary in the structure and functionality and are common in natural environments in exerting the structural perturbation of Al transformation products and the impact on the dynamics and mechanisms of Cd transformation and transport in soils and waters, deserves increasing attention.