重金属离子对不同非水溶性有机物含量土壤胶体上十溴联苯醚迁移行为的影响

Effects of Heavy Metal Ions on Transport of Deca-Brominated Diphenyl Ether by Soil Colloids with Insoluble Organic Matter

为了研究复杂土壤环境中非水溶性有机物和重金属离子对BDE-209(十溴联苯醚)的时空迁移过程和变换规律,在旋转混匀仪[转速为(30±1.0)r/min、温度为(25.0±0.5)℃]内避光试验条件下,分析V_水∶m_土为5、pH为6.8±0.1条件下,森林土壤和农田土壤中非水溶性有机物含量(分别为2.2%和4.7%)和重金属离子(Fe^(3+)、Cu^(2+)、Zn^(2+))含量对土壤中BDE-209环境迁移行为的影响.结果表明:重金属离子在森林土和农田土土壤胶体上的平衡时间和平衡含量分别为40、32 h和(49.4±1.2)(81.7±1.9)mg/g.重金属离子对森林土(重金属负荷为0~60 mg/g)和农田土(重金属负荷为0~80 mg/g)土壤胶体混凝沉降强弱作用均依次为Fe^(3+)最强,其次为Cu^(2+)、Zn^(2+);而当森林土重金属负荷为60~100 mg/g、农田土重金属负荷为80~100 mg/g时,森林土和农田土土壤胶体质量浓度分别稳定在(49.3±1.3)和(50.4±1.1)mg/L,致使上清液中ρ(BDE-209)由(388.5±13.2)ng/L分别降至(24.7±21.7)和(25.4±18.8)ng/L.此外,重金属离子未实现BDE-209由土壤胶体向重金属胶体的再分配过程[上清液中ρ(BDE-209)与土壤胶体质量浓度比值保持在(493.1±6.8)ng/g],仅通过改变土壤胶体环境行为来影响BDE-209迁移过程,进而导致土壤环境中BDE-209时空迁移过程与土壤胶体迁移行为一致.

To illustrate the transport behaviors of deca-brominated diphenyl ether（ BDE-209） in soils with different contents of insoluble organic matter,the heavy metal ions Fe-（3＋）,Cu^2＋and Zn^2＋with loads of 0-100 mg/g were investigated. The verities of the forest soil colloids（ ≤1 μm,insoluble organic matters of 2. 2%） and the farmland soil colloids（ ≤1 μm,insoluble organic matters of 4. 7%） with BDE-209 were carried out to check their transport behaviors with rotary mixers under the conditions of r =（ 30. 0 ± 1. 0） r/min,T =（ 25. 0 ± 0. 5） ℃,ratio value of Vwaterand msoil= 5 and p H = 6. 8 ± 0. 1. The balance times and the equilibrium contents of the heavy metal ions（ Fe-（3＋）,Cu^2＋and Zn^2＋） were 40 h and（ 49. 4 ± 1. 2） mg/g for the forest soil colloids and 32 h and（ 81. 7 ± 1. 9） mg/g for the farmland soil colloids,respectively. For the forest soil colloids（ loads of 0-60 mg/g） and farmland soil colloids（ loads of 0-80 mg/g）,the flocculation effects of Fe-（3＋）on the soil colloids were best compared with those of Cu^2＋and Zn^2＋. For the forest soil colloids with the loads of 60-100 mg/g and the farmland soil colloids with the loads of 80-100 mg/g,the concentrations of the soil colloids were maintained at（ 49. 3 ± 1. 3） mg/L and（ 50. 4 ± 1. 1） mg/L,respectively. Simultaneously,the BDE-209 concentrations in the supernatants were obviously decreased from（ 388. 5 ± 13. 2） ng/L to（ 24. 7 ± 21. 7） ng/L for the forest soil colloids and to（ 25. 4 ± 18. 8） mg/L for the farmland soil colloids.Moreover,the heavy metal ions did not directly change the BDE-209 transport behaviors by calculating the BDE-209 contents（（ 493. 1 ± 6. 8） ng/g） in those soil colloids. The heavy metal ions affected the BDE-209 transport behaviors in the soil environmentmainly by changing the behaviors of soil colloids to move the contaminated soil colloids,freely passing through the porous soil matrix to potentially pollute and threaten other clean and safe districts.