Showing papers by "Yanzheng Gao published in 2004"

Promoted dissipation of phenanthrene and pyrene in soils by amaranth (Amaranthus tricolor L.)

Abstract: A study was conducted to investigate the performance of amaranth, a known hyperaccumulator of cesium, on the promotion of the dissipation of soil phenanthrene and pyrene, which are PAHs (polycyclic aromatic hydrocarbons). Amaranthus tricolor L. ‘een choi’ was the cultivar used. The presence of Amaranthus tricolor L. evidently enhanced the dissipation of these PAHs in soils with initial phenanthrene concentrations of 7.450–456.5 mg/kg dw (dw, dry weight) and pyrene of 8.010–488.7 mg/kg dw. At the end of the experiment (45 days), the residual concentrations of phenanthrene and pyrene in spiked soils with plants were generally higher than those with no plants. The loss of phenanthrene and pyrene in vegetated soils was 87.85–94.03% and 46.89–76.57% of the soil with these chemicals, which was 2.55–13.66% and 11.12–56.55% larger than the loss in non-vegetated soils, respectively. The accumulation of phenanthrene and pyrene by the plant was evident. Root and shoot concentrations of these chemicals monotonically increased with increasing soil PAH concentrations. Bioconcentration factors (BCFs), defined as the ratio of chemical concentrations in plants and in the soils (on a dry weight basis), of phenanthrene and pyrene by roots were 0.136–0.776 and 0.603–1.425, while by shoots were 0.116–0.951 and 0.082–0.517, respectively. BCFs of phenanthrene and pyrene tended to decrease with the increasing concentrations of soil phenanthrene and pyrene. Plant accumulation only accounted for less than 0.32% (for phenanthrene) and 0.33% (for pyrene) of the total amount enhancement of the dissipated PAHs in vegetated vs. non-vegetated soils. In contrast, plant-promoted microbial biodegradation was the predominant contribution to the plant-enhanced dissipation of soil phenanthrene and pyrene. These results suggested the feasibility of the radionuclide hyperaccumulator in phytoremediating the soil PAH contaminants.

Influence of dissolved organic matter (DOM) on environmental behaviors of organic pollutants in soils

Abstract: Dissolved organic matter (DOM) is an important component of solutions in terrestrial and aquatic ecosystems through its influence on acidity, nutrient availability, and toxicity. DOM could enhance the apparent solubility of organic pollutants and alter adsorption-desorption equilibrium of organic pollutants on soil. The enhancement of organic pollutants desorption in the presence of DOM could facilitate the mobility of organic pollutants in soil. On the other hand, the sorption of DOM by solid sorbents in soil could also enhance the retention of DOM-associated organic pollutants in soil. Furthermore, as a photosensitizer, DOM could promote the photogradation of organic pollutants in soil. And under certain condition, DOM also affected the hydrolysis of organic pollutants in soil solution. The effects of DOM on environmental behaviors of organic pollutants in soils were related to the physico-chemical characteristics of organic pollutants, DOM, and soil.