胡敏素-赤铁矿复合物对外源添加镉污染富硒土壤的钝化

Passivation effect of humin-hematite complexes on exogenous cadmiumcontaminated selenium-enriched soil

以本地富硒土壤提取的胡敏素(humin,HM)、制备的赤铁矿(hematite,α-Fe2O3)和胡敏素-赤铁矿复合物(HM-α-Fe2O3)作为钝化剂,对富硒土壤中的镉(Cd)进行钝化研究。结果表明,有效态Cd浓度与pH呈显著负相关(r=?0.729)(0.01<P<0.05)。与空白对照组(CK)处理对比,添加3种不同水平用量的HM(H1~H3),α-Fe2O3(F1~F3)和HM-α-Fe2O3[(F-H)1^(F-H)3]处理并培养60 d后,土壤中有效Cd浓度分别降低14.21%~22.96%、21.25%~37.55%和13.45%~27.75%;可交换态Cd的浓度分别降低17.77%~23.34%、33.93%~45.39%和18.56%~22.07%。比较不同钝化剂的钝化效果,发现单独钝化剂中最佳处理组为F2(20 d),有效态Cd浓度的降低幅度最大(37.55%),但施加量也最大,易导致土壤碱性化;HM钝化剂在5 d达到最佳效果(H2);HM-α-Fe2O3中最佳处理组为(F-H)3(60 d),有效态Cd浓度的降低量与钝化剂用量、钝化时间都呈极显著正相关(r=0.631,0.428)(P<0.01),说明其钝化效果与钝化剂用量、钝化时间呈现较好的线性增长关系,施用率低且效果明显。因此,HM适用于短期修复,而HM-α-Fe2O3适用于长期修复。HM与α-Fe2O3复合应用为充分利用土壤腐殖质和控制重金属流动性提供了新途径。

The cadmium(Cd)in selenium-enriched soil was passivated by using the following passivating agents:humin(HM)extracted from local selenium-enriched soil,prepared hematite(α-Fe2O3)and huminhematite complex(HM-α-Fe2O3).The results showed that pH was negatively correlated(r=?0.729)with the concentration of available Cd(0.01<P<0.05).In comparison with control(CK)group,the concentrations of available Cd in the soils subjected to 60 d incubation after additions of HM(H1~H3),α-Fe2O3(F1~F3)and HM-α-Fe2O3[(F-H)1^(F-H)3]at three dosages decreased by 14.21%~22.96%,21.25%~37.55%and 13.45%~27.75%,respectively.And the concentrations of exchangeable Cd decreased by 17.77%~23.34%,33.93%~45.39%and 18.56%~22.07%,respectively.Through the passivation effect comparison among different repair agents,F2(20 d)group was the best treatment one in individual repair agents with the maximum reduction ratio of 37.55%for available Cd,but the dosage was also the largest which easily led to soil alkalization.HM achieved the best passivating effect in 5 days(H2).The best treatment group in HM-α-Fe2O3 was(F-H)3(60 d),and the decrease of available Cd concentration of was significantly positively correlated(r=0.631,0.428)with the dosage of passivation agent and passivation time(P<0.01),which indicated that the passivation effect presented a good linear growth relationship with the dosage and time,and low application and marked effect.Therefore,HM was suitable for a short-term repair,while HM-α-Fe2O3 were the best choice for a long-term repair.The application of HM combined withα-Fe2O3 as repair agents provided a new way for both making full use of humus and controlling metal mobility.