兰州市城市污泥施用对小麦生长和重金属富集的影响

以兰州市安宁区污水处理厂污泥为研究对象,采用盆栽的方法研究污泥土地利用后对土壤中重金属含量以及对3种小麦生长和重金属富集的影响。结果表明,污泥施用后使污泥混合土壤中重金属Pb、Cu、Zn含量显著增加,但3种重金属含量均未超过我国土壤环境质量二级标准(GB15618-1995)中的限制性标准值。污泥土地施用后,小麦获得了良好的生长响应。污泥低施入量(污泥在混配土壤中的干重比为5%、10%、15%)时不同程度的促进了小麦的生长发育,使3种小麦出苗率提高,植株更高,生物量增加。污泥高施入量(污泥在混配土壤中的干重比为25%、35%)时,小麦的出苗率和根长受抑制明显。污泥的施用使小麦籽实中的Pb、Cu、Zn的含量显著升高,呈现递增趋势,污泥在混配土壤中的干重比超过25%时,籽实中Cu和Pb含量相对国家无公害食品标准有超标现象。综合考虑污泥对小麦生长和重金属富集的影响及土壤中重金属含量的变化,对小麦的耕种土壤中一次性施用污泥时,污泥在混配土壤中的干重比应限量在25%以下。

Effects of Municipal Sewage Sludge in Lanzhou Application on Growth of Triticum Aestivum and Accumulation of Heavy Metals

Effects of land utilization of An-ning District of Lanzhou Wastewater Treatment Plant on the heavy metal content in soil,Triticum aestivum growth and accumulation of heavy metals were carried out by using pot scale experiments.The experimental results showed that the contents of Pb,Cu,Zn in the soil were increased significantly after sewage sludge application,Contents of Pb,Cu,Zn in the soil did not exceed stringent Chinese environmental quality standard for soil(GB-1518-1995).Triticum aestivum obtained good growth activities after sewage sludge application.Low land application of sewage sludge(sludge in the mixed soil of dry weight ratio is 5%,10%,15%) promoted growth and development of the three kinds of Triticum aestivum in varying degrees,Triticum aestivum seedling emergence,Triticum aestivum height and Triticum aestivum biomass were increased significantly.High land application of sewage sludge(sludge in the mixed soil of dry weight ratio is 25%,35%) inhibited seedling emergence and root length.Sewage sludge inhibited significantly Triticum aestivum root length along with land application of sewage sludge to increase.After sewage sludge application,the contents of three kinds of heavy metals in Triticum aestivum grain were significantly increased,showing an increasing trend.The contents of Cu and Pb in Triticum aestivum grain exceeded National pollution-free food standards in sewage sludge application more than 25%.The results indicated that sludge in the mixed soil of dry weight ratio for Triticum aestivum should be lower than 25%.