生活污泥对滩涂土壤性质和苏丹草生长及重金属累积的影响

Effects of Sewage Sludge Application on the Properties of Mudflat Saline Soil, the Growth and Heavy Metal Accumulation of Sudangrass(Sorghum Sudanense(Piper) Stapf)

滩涂盐土农业利用的主要障碍是盐分含量过高和缺乏有机质。施用生活污泥可快速提高滩涂土壤有机质含量,加快土壤熟化,但由于担心污泥含有一定量的重金属,其施用受到一定的限制。采用盆栽苏丹草的试验方法,研究滩涂盐土施用不同量的生活污泥后对土壤性质、植物生长和对重金属累积的影响。结果表明,生活污泥施用于滩涂盐土后降低了土壤pH值,提高了EC值和总盐含量;苏丹草的出苗率、株高和鲜重增加;施用污泥提高了苏丹草植株中全氮、全磷及叶绿素的含量,且随施用量的增加而增大,但对植株中全钾的含量无显著影响;苏丹草中Zn、Cd含量随着污泥施用量增加呈增长的趋势,但Pb、Ni、Cu含量变化不大。在试验条件下,所施用污泥中重金属向苏丹草体内转移的比例介于0.13%-13.44%之间。就该种土壤而言,要更为注意含Pb量较高的污泥施用,而Cu则是最为安全的。总体考虑,一次性施用干污泥应控制在8t·667m^-2以下。

The main obstacles of mudflat saline soil for agricultural use include high salt content and lack of organic matter. Sewage sludge can be applied to rapidly elevate organic matter content of mudflat saline soil, and to accelerate soil maturation. However, considering that sewage sludge may contain a certain amount of heavy metals, its safety in agricultural use is widely concerned. With sudangrass as material, a pot experiment was carried out to investigate the effects of sewage sludge application in mudflat saline soil on soil properties, plant growth and accumulation of heavy metals. The results showed that：application of sewage sludge decreased the soil pH, increased EC values and the total salt content; and elevated the emergence rate plant height and fresh weight of sudangrass. Sewage sludge also improved the contents of total nitrogen, total phosphorus and chlorophyll content in sudangrass plants. However, sewage sludge had no significant effect on the total potassium content of plants. The contents of Zn and Cd in the sudangrass tended to increase with the sewage sludge application rate, while Pb, Ni, Cu contents remained very low and changed little. In this experiment, approximately 0.13%~13.44% of heavy metals in sewage sludge applied to saline soil was transferred into the plant body of sudangrass. The content of Pb in the sewage sludge applied in this soil should be more concerned than that of Cu in the sludge. General considerations, one-time application of dry sludge per 667 m2 should be less than 8 tons.