Tissue concentrations of some mineral elements appeared to be influenced by plant Fe status. The influence of Fe deficiency on Cu uptake and accumulation in Commelina communis, and the relationship between Cu uptake and root Fe (Ⅲ) chelate reductase (FCR) activity were investigated in this study. The results showed that Cu accumulation in C. communis was increased with the drop of Fe concentration in nutrient solution. Cu uptake in C. communis was significantly enhanced by Fe deficiency. Cu uptake in Fe-deficient plants were still higher than that of Fe-sufficient plants when P-type ATPase inhibitor Na3VO4 was added in the solution, which demonstrated that Fe deficiency induced stimulation of the plasma membrane H+-ATPase did not play a role in the enhanced Cu uptake. Fe and Cu deficiency could induced root Fe (Ⅲ) chelate reductase activity in C. communis. Both Fe (Ⅲ) chelate reductase activity aud Cu concentration in roots inhibited distinctly by cycloheximide, a kind of protein synthesis inhibitor. In the time course of Fe deficiency, there simultaneously appeared Cu concentration and FCR activity peaks in roots at day 9. All above evidences demonstrated Cu uptake aud accumulation in C. communis were probably related to the root FCR activity.

Phytotoxicity of dredged sediment from Hangzhou section of the Grand Canal as land application was evaluated by pakchoi (Brassica chinensis L.) germination tests and pot experiments. Germination rates of pakchoi in the dredged sediment and in sediment-applied soils were both significantly higher than that in the soil controls, while the germination rate between the sedimentapplied soils was no significant difference. In pot experiments, plant height and biomass were increased by the dredged sediment application rate in the rate of lower than 540t ha 1, but decreased when the application rate was over this rate. Concentrations of Zn and Cu in pakchoi were linearly increased with the increasing of the application rate of the dredged sediment. Both plant height and biomass of pakchoi in sediment-treated red soil were higher than that in sediment-treated paddy soil, regardless the application rate. The results suggest that plant biomass of pakchoi may be used as an indicator of the phytotoxicity of the dredged sediment. It also showed that red soil is more suitable to accept the dredged sediment than paddy soil, and 270 t ha 1 is a safe application rate both in red soil and paddy soil.

Titanium dioxide mediated photocatalytic degradation of polyvinyl alcohol (PVA) was studied in an annular photoreactor with two 6W (Emax=365nm) UV lamps as light source. In the presence of both TiO2 and light, and initial concentration of 30mg/l, 55.3% of PVA was found to degrade after an hour. The effects of initial concentration, pH and the addition of H2O2 on the rate of degradation of PVA were studied. The results showed that it was more effective for PVA to be degraded under acidic or alkaline condition. The order of reaction rates was pH10>pH9>pH4>pH5> pH7. Proper amount of H2O2 could improve the photodegradation rate of PVA. However, the further increase of H2O2 might inhibit the system efficiency. Fourier transformed infrared spectroscopy (FTIR) indicated that several carbon-carbon bonds were scissored, which led to the formation of short-chain compounds during the photocatalytic oxidation of PVA. These intermediates were also degraded with prolonged reaction.

Physiological experiments on plant roots exposed to cadmium were conducted on carrot and radish using a liquid culture and a pot experiment with a series of cadmium applications. Activities of four enzymes (catalase, peroxidase, polyphenol oxidase, superoxide dismutase), and concentrations of free proline and malonaldehyde in the roots of both plants were investigated. Results showed that the germination rate and growth of roots of both plants were inhibited at the concentration of 20mg Cd/l, and the inhibition was increased with the increasing concentrations of cadmium, both in the liquid culture and in the pot experiment; activities of the four enzymes declined similarly in both species. The concentration of proline in roots reached the maximum when the application of cadmium was at the level of 20mg/l in the liquid culture (or 20mg/kg in soil), and then it declined slowly with the increasing concentration of cadmium. However, the reverse trend was observed for the concentration of malonaldehyde. All of bio-indicators measured here was quite sensitive to the addition of cadmium.

To gain information on organic pollutants in wateresediment systems, a compartment model was applied to study the sorption course of phenanthrene and pentachlorophenol (PCP) in sediments. The model described the time-dependent interaction of phenanthrene and PCP with operationally defined reversible and irreversible (or slowly reversible) sediment fractions. The interactions between these fractions were described using first order differential equations. By fitting the models to the experimental data, apparent rate constants were obtained using numerical optimization software. The model optimizations showed that the amount of reversible phase increased rapidly in the first 10d with the sorption time, then decreased after 10d, while the amount of irreversible phase increased in the total sorption course. That suggested the mass transport between reversible phase and irreversible phase. The extraction efficiency with hot methanol ranged from 36% to 103% for phenanthrene and from 65% to 101% for PCP, with the trend of decreasing with sorption time.