| Several stabilization meterials such as containing Fe, Mn, Al, S agents and alkaline, clay, organic meterials were used to stabililze the simulated polluted soil with arsenic. And selected their best matching. Additionally, five influence factors contained soil moisture, pH, competitive ion, reaction time and pollution concentration were discussed about the stabilization effects. After that, mechanisms of the stabilized soil were revealed by methods including bio-availability, extraction toxicity, morphology and phase component. At last, in order to provide theoretical basis for the stabilization skill in reality, simulated acid rain experiment according to the elements and amounts from Nanning was carried out. The main study results as follows:(1)The stabilization efficiency reached 90.53% and leaching concentration was 2.09 mg·L-1 by the stabilization material containing one main stabilization agent FeS with dosage Fe/As=15, and carbide slag named pH adjuster with dosage 0.5%, and mushroom dreg called soil conditioner with 6%, the leaching concentration was under the Identification standards for hazardous wastes-Identification for extraction toxicity.(2)Soil moisture was suited to 30%, it would hinder the mixing with soil and agents when lacked of water, and it would become more venomous and mobile, as well as more expensive, when exceeded some water. The stabilization efficiency kept balance when soil pH between 2.20-9.85, and best at about pH=6, but decomposed obviously between 9.85-12.01. Competitive ion PO43-was extremely good at desorbing arsenic, and SO42- and NO3- had inhibiting effect to some extent, but Cl- hardly effected arsenic stabilization. The stabilization efficiency reached 93.28% when the polluted soil reacted 15 days, and it maintained balance within 120 days. It achieved 90.53% and 93.28% respectively when the polluted concentrations were 506 mg·kg-1 and 833 mg·kg-1, but declined to 55.57% and 47.54% when the polluted concentration rose at 2951 mg·kg-1 and 5290 mg·kg-1, the higher polluted concentration, the lower stabilization efficiency.(3)The amounts of effective arsenic state and provided content in organism by chemical extraction and PBET amony the three kind of polluted soils were original polluted soil at most, deionized water in the second place, and stabilization one far behind the first two.Stabilizing treatment could weaken arsenic desorbed remarkable.(4)The leaching concentration by national standard (HJ/T299-2007) and TCLP amony the three kind of polluted soils were original polluted soil at most, deionized water in the second place, and stabilization one far behind the first two. Stabilizing treatment could weaken arsenic desorbed remarkable.(5)The readily soluble arsenic after stabilizing treatment reduced 18.61%, and Fe-As and Ca-As increased 10.36% and 5.81% respectively. Stabilizing treatment could turned readily soluble arsenic into Fe-As and Ca-As efficiently.(6)The polluted soil newly increased four mineral substances containing CaAl2Si208 · 4H2O, Ca3Fe4+3(AsO4)4(OH)8 · 3H2O, Fe2(AsO4)(SO4)OH. 5H2O and (Al,Fe+3)3AsO4(OH)8 · 5H2O Stabilizing treatment promoted arsenic in soil into mineral state.(7)The leaching concentrations of stabilizing treatmen soil kept between 0.88 mg·L-1 and 1.01 mg·L-1, far behind the one between 17.79 mg·L-1 and 7.31 mg·L-1 from the original polluted soil. Stabilizing treatment could control arsenic desorption efficiently. What is more, the gross of arsenic after stabilizing treatment decreased 9.63%, far below the 28.93% coming from original polluted soil. The main reason was because of Fe-As and Ca-As being generated, and soil buffering ability enhanced with mushroom dregs, as a result of boosting the power to restrain scour. |
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