Chiquan He

Alkyl Polyglucoside (APG) Amendment for Improving the Phytoremediation of Pb-PAH Contaminated Soil by the AquaticPlant Scirpus triqueter

This study assessed the potential abilities of Scirpus triqueter for phytoremediation of soils contaminated with Pb-PAHs, amended with environment-friendly surfactant alkyl polyglucoside (APG). The effects of APG on the removal of PAHs from soil and the plant uptake and translocation of Pb were tested with plant growth and soil enzymatic activities. Experiments demonstrated that APG has an ability to facilitate PAH degradation and Pb uptake in the plant body at appropriate concentrations (20–40mg L−1). The highest PAH removal rate was observed in 30 mg L−1 APG treatment, and the highest accumulation of Pb was detected as 40 mg L−1 APG. Experiments documented the effects of APG on plant growth, soil enzymatic activity, bioaccumulation and translocation of Pb in Scirpus triqueter. Results indicated that the addition of appropriate APG enhanced PAH removal rate and increased plant uptake and translocation of Pb.

Use of Energy Crop (Ricinus communis L.) for Phytoextraction of Heavy Metals Assisted with Citric Acid

Ricinus communis L. is a bioenergetic crop with high-biomass production and tolerance to cadmium (Cd) and lead (Pb), thus, the plant is a candidate crop for phytoremediation. Pot experiments were performed to study the effects of citric acid in enhancing phytoextraction of Cd/Pb by Ricinus communis L. Citric acid increased Cd and Pb contents in plant shoots in all treatments by about 78% and 18–45%, respectively, at the dosage of 10 mM kg−1 soil without affecting aboveground biomass production. Addition of citric acid reduced CEC, weakened soil adsorption of heavy metals and activated Cd and Pb in soil solutions. The acid-exchangeable fraction (BCR-1) of Pb remained lower than 7% and significantly increased with citric acid amendment. Respective increases in soil evaluation index induces by 14% and 19% under the Cd1Pb50 and Cd1Pb250 treatments upon addition of citric acid resulted in soil quality improvement. Ricinus communis L. has great potential in citric acid-assisted phytoextraction for Cd and Pb remediation.

Potential of Sagittaria trifolia for Phytoremediation of Diesel.

The phytoremediation potential and responses of Sagittaria trifolia to diesel were investigated. In order to elucidate the biochemical and physiological responses of S. trifolia to diesel, the chlorophyll content, root vitality, soluble protein content and antioxidant enzymes activity (peroxidase (POD), catalase (CAT) and antioxidant enzymes superoxide dismutase (SOD)) were determined in the plant tissues after 50 d of diesel treatment. The results showed the presence of S. trifolia significantly improved the removal ratios of diesel, from 21∼36% in the control soils to 54∼85% in the planted soils. The chlorophyll content, root vitality and soluble protein content all increased at low diesel concentration, then decreased at high diesel concentration. The activities of CAT and POD exhibited peak values at 5 g·kg−1 diesel treatment and declined at higher diesel concentrations. However, the activity of SOD kept stable at lower diesel concentration (1 and 5 g·kg−1), and also declined at higher diesel concentration. Collectively, S. trifolia had the ability to tolerate certain amount of diesel, but when the concentration was up to 10 g·kg−1, the growth of S. trifolia would be restrained. The results also showed that variation of antioxidant enzyme activity was an important response in plants to diesel pollution.

The fate of arsenic in contaminated paddy soil with gypsum and ferrihydrite amendments

Ferrihydrite and gypsum (CaSO 4 ∙2H 2 O) are two chemicals which were suggested to reduce the bioavailability of arsenic (As) in agricultural field. The efficiency of those chemicals added in the paddy field was investigated by pot culture in this study. The results showed As uptake by rice under ferrihydrite treatment was significantly lower than that in the control (36% in shoot), however, plants grown in gypsum show no significant difference in As content compared with those in the control. Sequential extraction showed that As was mainly adsorbed to amorphous and crystalline hydrous oxide. The addition of gypsum did not change the As fractionation in comparison with the control, which may be due to restrained sulphur (S) reduction by the high microbially reducible Fe(III) (150–250 mg kg –1 ), which precipitates with sulphide in preference to As. These results suggest that the chemical Fe oxides efficiently reduce As risk in the paddy.