纳米羟基磷灰石对电子垃圾拆解地农田土壤Pb生物可利用性的影响

Effect of nano-particle hydroxyapatite on the bioavailability of Pb in the farmland soils around the e-waste dismantling site

为了研究钝化剂对电子垃圾拆解地农田土壤中重金属Pb生物可利用性的影响,采用盆栽试验,在种植油菜和白菜的土壤中加入不同质量比的纳米羟基磷灰石（n-HAP）,研究Pb形态、油菜和白菜生物量、油菜和白菜中Pb的累积量,评价纳米羟基磷灰石对Pb生物可利用性的影响。结果表明,加入5 g/kg、10 g/kg、15 g/kg、20 g/kg和25 g/kg纳米羟基磷灰石后,油菜和白菜生物量增加,且油菜生物量大于白菜生物量;油菜内Pb累积量小于白菜内Pb累积量;土壤中残渣态Pb质量比增加,可交换态Pb质量比减少,有效态Pb质量比与Pb生物可利用性显著降低（p〈0.05）,与对照组相比,种植油菜和白菜土壤中Pb的生物可利用性分别降低了25.53%~82.77%和45.79%~71.68%。当纳米羟基磷灰石质量比为20 g/kg时,油菜和白菜生物量较大,而且对Pb的累积量最低,种植油菜和白菜土壤中Pb的生物可利用性分别降低了81.84%和70.89%。研究表明,纳米羟基磷灰石的适宜投加量为20 g/kg,而油菜为理想植物。

The present paper intends to evaluate the effects of nano-particle hydroxyapatite（ n-HAP） on the bioavailability of Pb in the farmland soils near the e-waste dismantling site. For this purpose,we have laid out experiments at different mass ratios（ e. g. 0,5 g/kg,10 g/kg,15 g/kg,20 and 25 g/kg） of n-HAP and two kinds of plants（ rape and cabbage） for testing the effects of n-HAP on the biomass of rape and cabbage,the form of Pb and the accumulation of Pb in the rape and cabbage. Results have shown that the biomass of rape and cabbage increases,the residual form of Pb increases and exchanged form of Pb decreases by nHAP with 5 g / kg,10 g / kg,15 g / kg,20 g / kg and 25 g / kg with the biomass in the order of rape cabbage. The exchanged form of Pb tends to drop significantly（ p 0. 05） and the bound to the carbonate form of Pb turns out to drop by 66. 67%- 91. 67% and20. 02%- 73. 34% in the rape and cabbage planted soil,respectively（ p 0. 01）. What is more,the bound to iron and manganese oxides form of Pb is expected to be reduced by 18. 01%-50. 00% and 19. 07%- 49. 92% in the rape and cabbage planted soil,respectively. In addition,the bound to organic matter form of Pb is likely to decrease whereas the residual form of Pb tends to rise by 17%- 167. 0% and 10. 0%- 250. 0% in the cabbage and rape planted soil,respectively. As to the accumulation of Pb in the rape and cabbage by different concentrations of n-HAP,the accumulation order should be taken as that of rape cabbage. The bioavailability values of Pb in the soils planting rape and cabbage turn to drop by 25. 53%- 82. 77% and45. 79%- 71. 68%,respectively because of the significant decrease of the content of availability form of Pb. When the mass ratio of n- HAP is 20 g / kg,the biomass of the rape and cabbage is higher,the accumulation of Pb in the rape and cabbage is lower,and the maximum reduction of the bioavailability values of Pb are 81. 84% and 70. 89% in the rape and cabbage planted soil,respectively. Thus,a conclusion can be drawn that the optimized dosage of n- HAP should be 20 g / kg whereas the rape should be a potential desirable passivator in the farmland near the e-waste dismantling site.