连续施用城市污泥后林地土壤中重金属的含量变化及生态风险

将堆肥污泥施用于林地能够增加土壤肥力,促进林木增长,具有广阔的应用前景,但污泥中所含重金属进入土壤环境后的积累特征及所引起的生态风险问题亦备受关注.连续5年将污泥堆肥产品施用于林地并对相应林地土壤重金属含量进行了同步监测,采用单因子指数法和潜在生态危害指数法分析评价了污泥堆肥泥质、污泥堆肥不同施用比例以及是否连续施肥等...

Eco-environmental risk assessment of urban sludge application in forest land

The usage of sludge as fertilizers for forest land can improve the soil fertility and the plant growth, but the environmental risks of sludge usage are still unclear due to the relative high concentration of heavy metals in the sludge. Based on the five-year data of heavy metal concentration in the soil after the use of sludge as fertilizers, the single-factor index method and the potential risk hazard index method were used to investigate the effects of sludge properties, sludge dosage and continuous fertilization on the environmental risks of heavy metal in this study. The correlation analysis was also conducted to investigate the relationship between the change of heavy metal in soil and the use of sludge. The results showed that Hg, Cd, Zn, As and Pb in sludge had greater environmental risks, compared to other heavy metals. When the sludge dosage was 10% and 20%, the environmental risks were low. However, the risk to the environment was greater when the sludge dosage was 30% and 40%. The monitoring results showed that the heavy metals in the soil has accumulated but not exceeded Soil Environmental Quality Risk Control Standards for Soil Contamination of Agricultural Land (GB 15618-2018) (6.5≤pH<7.5) in five years. According to the prediction model of soil pollutant accumulation, it showed that the heavy metal concentration in the soil would exceed the standard in the 11th year when the fertilization ratio was 10%, indicating that fertilization was safer in 10 years. Based on the correlation analysis, heavy metals in soil might be affected by various factors such as fertilizer sludge, atmospheric sedimentation, precipitation, and soil parent material. This study can provide a reference for the application of sludge products in forest land to avoid the risk of heavy metals.