Remediation Of Cadmium And Pyrene Contaminated Soil By Monoculture And Intercropping Of Glycine Max And Solanum Nigrum

Wastewater irrigation is one of the most important way of wastewater reused in China by far, but the environmental problems caused by sewage irrigation has become very serious. In recent years, heavy metal and PAHs pollution has restricted the development of grain production and economy in our country. Heavy metal and PAHs contamination control has become one of important directions of soil contamination control at present. Through the pot experiment in greenhouse, this study investigated the remediation of cadmium and pyrene contaminated soil by Glycine Max and Solanum Nigrum in different planting pattern. The results showed that:(1)In the process of repairing the single cadmium polluted soil, cadmium inhibited the growth of Glycine Max, the biomass was greater in the intercropping treatment than in the monoculture treatment. Cd concentration in Glycine Max and Solanum Nigrum decreased in the order root>shoot>seed, shoot>root, respectively. Cd concentration in the shoot of Solanum Nigrum was 8.98 %~19.93 % greater in the intercropping treatments than in the monoculture treatments. The dissipation rate of Cd in soil by different planting pattern decreased in the order intercropping of Glycine Max and Solanum Nigrum>monoculture of Solanum Nigrum>monoculture of Glycine Max, and the dissipation rate was 10.68%~19.07% in the intercropping treatments. Cd concentration in the seed of Glycine Max was above the limit standard of food when Cd addition was 1 mg?kg-1, the oil of seed can bring some economic benefits. Therefore, intercropping of Glycine Max and Solanum Nigrum is an effective way to repair Cd contaminated soil which can make full use of the contaminated land simultaneously.(2)In the process of repairing the single pyrene polluted soil, low concentration of pyrene(10mg?kg-1) promoted the growth of Glycine Max, but high concentration inhibited its growth. The effect of pyrene in this experiment on the growth of Solanum Nigrum was not significant. The biomass of Glycine Max and Solanum Nigrum was higher in the intercropping treatments than in the monoculture treatment. The distribution of pyrene in Glycine Max and Solanum Nigrum(mature period) was root > shoot. There was no significant difference in the pyrene concentration of plants between monoculture and intercropping treatment. The remediation effect under the same contamination level decreased in the order: intercropping of Glycine Max and Solanum Nigrum>monoculture of Glycine Max>monoculture of Solanum Nigrum>the control treatment.(3)In the process of repairing cadmium and pyrene combined polluted soil, the growth of Glycine Max was inhibited, but the effect on the growth of Solanum Nigrum was not significant. The biomass of Solanum Nigrum was greater in the intercropping treatment than in the monoculture treatment. The interaction of cadmium and pyrene enhanced the Solanum Nigrum toxicity, and Solanum Nigrum showed a good patience to compound pollution of cadmium and pyrene. Cd concentration in Glycine Max in the compound pollution treatment was lower than that in the single pollution treatment, but Cd concentration in Solanum Nigrum in the compound pollution treatment was higher than that in the single pollution treatment, which indicated that pyrene have different effects on the absorption of cadmium by Glycine Max and Solanum Nigrum. The the dissipation rate in the compound pollution treatment was lower than that in the single pollution treatment.(4)The distribution of cadmium in each part of the Glycine Max under the same contamination level was in the order: root > stem > grain, monoculture treatment >intercropping treatment. The cadmium content in soybean seeds were exceed evaluation standard, cannot be eaten directly, its use deserve further research.