石膏/蚯蚓粪肥对赤泥团聚体结构稳定性的影响

Effects of ameliorants on aggregate stability of bauxite residue

赤泥是氧化铝工业生产过程中排放的高碱性固体废弃物,迄今尚无经济有效的处置方法。以华中地区某堆场赤泥为研究对象,通过土培实验研究改良剂(石膏、蚯蚓粪肥、石膏+蚯蚓粪肥)对赤泥团聚体稳定性的影响。结果表明:石膏的添加能显著降低赤泥pH,而蚯蚓粪肥能显著增加赤泥有机碳含量。土培60d时,石膏添加后赤泥pH由10.54降到8.75,蚯蚓粪肥添加后赤泥有机碳含量由3.54g·kg-1增加至14.31g·kg^-1。土培180d时,石膏、蚯蚓粪肥、石膏+蚯蚓粪肥添加后赤泥水稳性团聚体含量由12.04%分别增加到23.49%、29.24%、33.94%;团聚体平均重量直径由0.15mm分别增加到0.26、0.30、0.34mm;可蚀性因子由0.36分别降低到0.31、0.30、0.29。石膏和蚯蚓粪肥的添加促进水稳性团聚体形成,提高赤泥团聚体稳定性。基质改良对赤泥团聚体稳定性的影响效果依次为:石膏+蚯蚓粪肥>蚯蚓粪肥>石膏。研究结果对赤泥土壤化处置和规模化消纳研究有科学参考意义。

Bauxite residue is a highly alkaline waste produced during the production of alumina and there is no economical and effective disposal strategy at the present.In this study,gypsum and vermicompost were selected as the ameliorants to investigate their effects on aggregate stability of bauxite residue in the laboratory incubation experiments with different incubation periods.After 60 d incubation,2%(w/w)gypsum addition reduced the pH from 10.54 to 8.75,whilst 8%(w/w)vermicompost addition increased organic carbon content(TOC)from 3.54 g/kg to 14.31 g/kg.After 180 d incubation,additions of gypsum,vermicompost,and the combination increased the contents of water-stable aggregates from 12.04%to 23.49%,29.24%,and 33.94%,increased the mean weight diameters(MWD)from 0.15 mm to 0.26,0.30,and 0.34 mm,and decreased the erodibility factors(K)from 0.36 to 0.31,0.30,and 0.29,respectively.This study demonstrated that gypsum and vermicompost amendments stimulate water-stable aggregate formation and improve aggregate stability of bauxite residue.Effectiveness of the ameliorants on aggregate stability of bauxite residue decreased in the order:the combination>vermicompost>gypsum.The results provide scientific information for soil formation and large-scale disposal of bauxite residue.