污泥施用对土壤及小麦生理特性的影响

Effects of Sewage Sludge Application on Soil and Physiological Property of Triticum Aestivum

以兰州市安宁区污水处理厂污泥为研究对象,采用盆栽方法研究污泥施用后对土壤pH值的影响,对土壤中重金属Cu、Zn、Pb含量的影响以及对小麦叶片叶绿素含量和脯氨酸含量特性的影响。结果表明,污泥施用后土壤的pH值显著下降,并呈递减趋势。不同污泥施加量土壤中3种重金属元素的含量均远低于我国土壤环境质量二级标准(GB15618—1995)中碱性土壤的限制性标准值。3种小麦叶片的叶绿素总含量随污泥浓度的增加而增加,污泥在混配土壤中的干重比为15%时3种小麦均达到最大值,随着污泥施加量的进一步加大出现下降。污泥施用后3种小麦叶绿素a/b值与对照相比无显著变化,小麦叶片中脯氨酸含量比对照有大幅的增加。低污泥施加量时(5%、10%和15%),3种小麦叶片中脯氨酸含量随施加量增加而增加,但高污泥施加量时(25%和35%)的脯氨酸含量无显著增加,污泥中污染物胁迫超过小麦耐受限值后,小麦生理代谢出现反常。土壤中3种重金属元素的含量与3种小麦体内脯氨酸含量均呈极显著正相关关系,土壤的pH值与3种小麦的叶绿素总含量和脯氨酸含量均呈负相关关系。综合考虑污泥施用对小麦生理特性的影响,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15%以下。

The application of sewage sludge on agricultural soils is a promising disposal and utilizable method and this has been shown to improve soil properties and increase plant productivity. This paper took the sewage sludge in wastewater treatment plant of Anning District in Lanzhou as research subject and studied the effects of land utilization on pH value, the heavy metal content in soil, chlorophyll and proline content in Triticum aestivum leaves by using pot scale experiments. The results showed that pH value in the soil declined significantly with the increase of the sewage sludge application. The content of Pb, Cu, Zn in the soil was far below the national standard of environmental quali- ty standards for soils for Grade II （GB 1518--1995 ）. The amount of total chlorophyll in these three kinds of Triticum aestivum increased with the increase of sewage sludge application, rose to the maximum as the ratio of sludge in the mixed soil of dry weight becomes 15%, and de- creased with a further increase of sewage sludge. Compared with the control, the a/b value in chlorophyll showed little change, whereas the content of proline in Triticum aestivum leaves showed significant increase after the application of sewage sludge. While the content of proline in Triticum aestivum increased with the increase of sewage sludge in low land application of sewage sludge（the ratio of sludge in the mixed soil of dry weight was 5%, 10% and 15%）, there was no significant increase in the content in high land application of sewage sludge（the ratio of sludge in the mixed soil of dry weight was 25% and 35% ）. The physiological metabolism of Triticum aestivum showed abnormality as the stress of pollutants from sludge was beyond the tolerance of Triticum aestivum. The content of Pb, Cu, Zn in the soil had significantly positive correlation with the content of proline in the three kinds of Triticum aestivum leaves, whereas pH value in the soil was negatively correlated with the content of chlorophyll and proline. The study took the effects of sewage sludge application on physiological property of Triticum aes-tivum into consideration, and concluded that the ratio of sludge in the mixed soil of dry weight should be lower than 15%.