[Combined remediation of polycyclic aromatic hydrocarbons (PAHs) by plant and immobilized bacteria in contaminated soil]. / 植物-固定化菌剂联合修复多环芳烃污染土壤.

In this study, three dominant bacteria Cellulomonas flavigena (Ⅰ), Cellulomonas flavigena (Ⅱ), Sphingomonas paucimobilis (Ⅲ) from Fire Phoenix rhizosphere soil were used to develop a multi-microbial agent system. For oil-contaminated soil in the Dagang oilfield, the immobilized test bacteria were inoculated into the Fire Phoenix rhizosphere soil to examine the effects of bacterial agents on polycyclic aromatic hydrocarbons (PAHs)-contaminated soil. The results showed that PAHs degradation was promoted under the ⅠⅢ (with an effective number of viable bacteria of 109 cfu·mL-1) and ⅠⅡⅢ (with an effective number of viable bacteria of 107 cfu·mL-1) treatments. The PAHs degradation rates were 32.2% and 41.4%, respectively, being significantly higher than that in the control treatments. The ⅠⅡⅢ treatment significantly promoted the belowground biomass of Fire Phoenix, which was 31.2% higher than that of the control treatment. Our results suggested that the multi-microbial agent constructed by the three dominant bacteria ⅠⅡⅢ could be used as a strengthening method for the remediation of PAHs-contaminated soil by Fire Phoenix, which provided a novel method for microbial enhanced phytoremediation technology.

[Ecotoxicological effects of chlorotetracycline on earthworm in soil].

Eiseniafoetida was selected to investigate the ecotoxicological effects of chlorotetracycline on the earthworm in soil. The results showed that 1, 10 and 100 mg · kg(-1) chlorotetracycline had no significant effects on earthworm's body mass after a 7-d exposure, but it was significantly inhibited by 10, 100 mg · kg(-1) chlorotetracycline after 21 days. The soluble protein content of earthworm was induced by 1, 10 and 100 mg · kg(-1) chlorotetracycline, and showed a positive response as the con- centration increased. Also, the earthworm treated by 1, 10 and 100 mg · kg(-1) chlorotetracycline induced the increases of SOD, POD and CAT activities to different degrees. The gene expression in earthworm changed significantly after a 28-d exposure. It is suggested that chlorotetracycline had a chronic ecotoxicological effect on earthworm, and the body mass, soluble protein, antioxidant en- zyme and gene expression could be used as the biomarkers to estimate chlorotetracycline toxicity.

[Ecological adaptability of Hordeum jubatum to magnesite dust].

Hordeum jubatum was pot-cultured with the soil sprayed with different amounts of magnesite dust (0, 1%, 5%, 10%, 15%, 20%, and 30%) to study the magnesium (Mg) tolerance of the plant. After sprayed onto soil surface, the magnesite dust could rapidly form a crust. When the amount of the sprayed dust was bigger than 20%, soil pH increased significantly, soil conductivity had a gradual decrease, whereas soil organic matter content increased after an initial decrease. With the increasing amount of sprayed magnesite dust, the leaf chlorophyll content of H. jubatum increased first and decreased then, while the leaf soluble protein content showed a trend of increase-decrease-increase. H. jubatum had stronger tolerance to Mg. When the soil Mg content was as high as 4.61 g x kg(-1), H. jubatum could still grow well, indicating that this plant species could be used as an appropriate candidate for the ecological restoration of waste lands in magnesite mining areas.

[Application of wastewater land treatment technique to the construction of ecological engineering in sand land].

In this paper studies on the feasibility of harmlessness and resource of wastewater, which was discharged from a thermal power plant, by using slow rate filtration of land treatment technique for the fast recovery of vegetation in the Kubuqi sand land were carried out. The selected arbor, shrub and herbage in the land treatment system were poplar (Populus alba Var. Pyramidalis bunge), seabuckthorn (Hippophae rhamnoides) and sweet clover (Melilotus suaveolens) respectively. Three levels of wastewater hydraulic loading were designed in the field pilot experiment. They were high plot with 3000 mm/a irrigation (H), medium plot with 1500 mm/a irrigation (M) and low plot (L) with small volume of irrigation only used in the period of transplant seedlings. The performance indicate that the purification function of power plant wastewater by pre-treatment through combination of precipitation pool with storage ponds is effective and therefore the effluent after pretreatment can be used to irrigation vegetation. The experiment results show that the volume of tree crown for poplar in H plot and M plot was up to 1.07 and 2.21 times comparing with L plot respectively. The annual yield (dry weight) of sweet clover in H plot and M plot was up to 2.33 and 3.0 times comparing with L plot respectively. The height of seabuckthorn in H zone and M plot was up to 1.08 and 1.32 times comparing with L plot respectively. There is direct proportion between growth status of vegetation and hydraulic loading of irrigation. The contents of heavy metals for sweet clover (Cd 0.021 mg/kg, Pb<0.001 mg/kg, Cr <0.01 mg/kg, As 0.043 mg/kg) are much lower than the food standards of grain and vegetables, therefore the sweet clover for raising livestock is safe. Wastewater in this area is valuable source. Its reasonable utilization can contribute important benefits in economy and ecology in the ecological construction and developing effective agriculture and animal husbandry.

Greenhouse gas emissions from a constructed wetland for municipal sewage treatment.

The fluxes of greenhouse gases (methane and nitrous oxide) emission from a constructed wetland in the Eastern China as municipal sewage treatment were measured from June 1999 to August 2000 by the closed chamber method. The constructed wetland for municipal sewage treatment is a significant source of methane, up to 976.6 x 10(6) g CH4/a, which was emitted from the constructed wetland with the area of 495,000 m2 and wastewater loading rate of 12,000 m3/d. Its daily mean methane flux reached 5.22 g CH4/(m2.d), 250 times as much as that in natural wetland in the same latitude region. 227.8 mg CH4 was produced from the treatment of 1 liter wastewater, up to 700-1000 times as much as that in the secondary treatment. The emission of nitrous oxide from the constructed wetland is not higher than that from secondary treatment of wastewater, only 0.07 mg N2O/L.