污泥施用土壤对玉米的生态毒性效应

Eco-toxicity of Land Application of Sewage Sludge on Zea Mays

采用盆栽试验方法,研究污泥土地利用后对玉米种子出苗、单株生物量、根伸长、叶片内叶绿素含量和脯氨酸含量及体内重金属含量等指标的生态毒理学效应.结果表明:污泥施用后,玉米生物量显著高于对照,但出苗率和根长受到不同程度的抑制.土壤中的重金属对玉米根长有明显的抑制作用,在施污泥肥时应该重点考虑土壤中重金属对植物根系的影响.玉米叶绿素总含量随着污泥施加量呈先升后降的趋势.玉米叶片的脯氨酸含量与对照相比有大幅的上升,但并未出现阀值.玉米根部Cu、Pb的含量高于地上部分,而地上部分Zn的含量要高于根部.污泥在混配土壤中的干重比低于25%的施用范围内为种植玉米农田的最佳污泥施加量.

The eco-toxicological effects of sewage sludge application on seed germination,root elongation test,biomass,chlorophyll content,proline content and heavy metals content in Zea mays were studied by pot experiments.The results showed that the content of Pb,Cu,Zn in the soil did not exceed the national standard of Environmental Quality Standards for Soils for Grade II（GB-1518-1995）.The biomass of Zea mays was increased significantly and was better than the controlled one after land application of sewage sludge.Zea mays seedling emergence and root length were inhibited in varying degrees due to sewage sludge application,showing the effects of dose-effect relationship with the increased amount of sludge.Zea mays root length was restrained by heavy metals in the soil,and the effects of heavy metals in the soil on plant root system should be considered with land application of sewage sludge.The total chlorophyll content of Zea mays with the amount of sludge application showed a rapid decrease after a increase.The proline content of Zea mays leaves compared with the controlled one showed a big increase after sewage sludge application,which grew nearly eight times,but threshold did not appear.In conclusion,Zea mays on the sludge applied showed a strong adaptability and tolerance in the ratio of sludge in the mixed soil of dry weight lower than 25%.