Dianbo Dong

Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO(2) under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO(2) (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO(2) accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36h, corresponding to the TiO(2) amounts from 0% to 4%, respectively. The effects of H(2)O(2), light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H(2)O(2), light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO(2) was an advisable choice for the treatments of PAHs polluted soil in the future.

Effects of aging and freeze-thawing on extractability of pyrene in soil

The effects of soil freezing and thawing on the extractability by dichloromethane of pyrene from two Chinese soils are investigated. The soils were collected from the Northeast region of China where heavy pollution of soils by Polycyclic Aromatic Hydrocarbons (PAH) is common. Two soils were considered: a burozem obtained from the Shenfu irrigated region in Liaoning province and a phaeozem collected from the Hailun area in Haerbin province. The soils were collected from areas free from PAH pollution. Pyrene was aged in sterilized soil, and autoclaved deionized water was then added to adjust the soil to different moisture levels. The combined dichloromethane extractions of pyrene in soils at various periods showed that the quantity of pyrene extracted with dichloromethane could be divided into two stages: the initially rapid period and a longer, slower period. The frequency of freeze-thawing cycles had different and contradictory effects on pyrene extractability between the two soil types. Soil moisture also was found to have different and opposite effects on pyrene extractability. Freeze-thawing cycles had great influence on pyrene extractability both in aged and unaged soils. The changes in unaged soil were more significant than those in 1-year aged soil and attributed to changes in the soil organic matter. Our research shows that the effect of freezing and thawing on pyrene extraction is complicated due to the differences in physical and chemical properties of soils as well as the aging process.

WITHDRAWN: Studies on the interaction between triphenyltin and bovine serum albumin by fluorescence and CD spectroscopy

The interaction between triphenyltin (TPT) and bovine serum albumin (BSA) in physiological buffer (pH=7.4) was investigated by the fluorescence quenching technique. The results of fluorescence titration revealed that TPT could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The apparent binding constants K and number of binding sites n of TPT with BSA were (7.04±0.0057)×10(2) and (0.77±0.016) which were obtained by the fluorescence quenching method. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) were positive, which indicated that the interaction of TPT with BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance r between donor (BSA) and acceptor (TPT) was calculated to be 3.05nm based on Forsters non-radiative energy transfer theory. The results of synchronous fluorescence, three-dimensional fluorescence and Circular Dichroism (CD) spectra showed that the triphenyltin induced conformational changes of BSA.

CADMIUM ACCUMULATION OF TAGETES ERECTA L. AFFECTED BY PLANT GROWTH INHIBITORS AND GLUTATHIONE

The effect of two plant growth inhibitors maleic hydrazide (MH) and cyeloheximide (CHI) on cadmium (Cd) accumulation was investigated in Tagetes erecta L. The relative growth rate (RGR) as well as Cd content in shoots of Tagetes erecta L. was obviously decreased by the two inhibitors, indicating that there was close relationship between Cd accumulation in shoots and the plant growth. When the sulfur (S)-containing compound glutathione (GSH) was applied to the leaves of Tagetes erecta L. under the MH or CHI treatment, the decreased Cd content in shoots affected by MH was alleviated, but there was no effect of the GSH on Cd content in shoots under CHI treatment, suggesting that GSH has an counter-effect on Cd accumulation in shoots of Tagetes erecta L. under the MH treatment. All the results suggested that plant growth and S-containing compounds play an important role in Cd accumulation in Tagetes erecta L.