再生水灌溉对4类土壤Cd生物有效性的影响

Effects of recycled municipal wastewater irrigation on the bioavailability of Cd in different soils

根据国家土壤环境质量标准,选取重金属Cd含量为二级水平的4类土壤(红壤、潮土、土、黑土)进行土培试验,研究再生水灌溉与小白菜生物量及Cd含量、土壤有效态Cd含量、pH、微生物群落的关系,以及不同类型土壤间的差异性。结果表明,再生水灌溉在不同类型土壤上对小白菜生物量及Cd含量、土壤有效态Cd含量、土壤pH和微生物数量的影响不同:1)红壤、潮土、土上小白菜生物量增加显著,分别增加9.09%、16.08%、9.92%,黑土上增加不显著;2)小白菜Cd含量在红壤上显著降低,由对照的0.29 mg/kg降低到0.22 mg/kg,在黑土上比对照增加了18.75%,在潮土和土上影响不大;3)有效态Cd含量在红壤没有变化,但在潮土、土、黑土上增加显著;4)4类土壤微生物数量增加显著;5)潮土、土、黑土的pH值有所降低。

Field experiments were carried out to clarify the effects of reducing nitrogen topdressing with reclaimed water irrigation on rootlayer soil nitrogen residual of greenhouse tomato. Rootlayer soil mineral nitrogen residual, total nitrogen residual, plant biomass, tomato yield, partial factor productivity from applied N and apparent N loss of all treatments were analyzed. The results indicated that soil mineral nitrogen consumption of greenhouse tomato was mainly concentrated in 0 to 30 cm rootlayer, and compared with the conventional topdressing application with reclaimed water irrigation treatment, the yield and partial factor productivities from the applied N of the reducing nitrogen topdressing treatments were significantly improved. After the postharvest of tomato, soil apparent N loss of the reducing topdressing was significantly less than that of the conventional topdressing. Tomato yield is therefore notably improved under reducing nitrogen topdressing with reclaimed water irrigation, maintaining soil fertility, and which is an effective nitrogen management strategy of alleviating soil environment.