School of Agriculture and Food Sciences/CRC CARE, The University of Queensland, St Lucia, QLD, 4072, Australia.
Rio Tinto Alcan, Queensland Research and Development Centre, 1 Technology Court, Pullenvale, Brisbane, QLD, 4069, Australia.
Environ Sci Pollut Res Int. 2018 Sep;25(25):25476-25485. doi: 10.1007/s11356-018-2564-3. Epub 2018 Jun 27.
Laboratory and greenhouse experiments were carried out to investigate the chemical, physical, and microbial properties of seawater-neutralized bauxite residues and the effects of additional leaching (1 pore volume of deionized water versus an additional 6 pore volumes) and amendment with gypsum (5%) and/or cattle manure (6%) on its properties and on the growth of Rhodes grass (Chloris gayana). Additional leaching resulted in a decrease in EC, exchangeable Na, SAR, and ESP. For unamended control treatments, additional leaching induced a rise in pH from 8.5 to 9.6 and pH from 9.1 to 10.1 due to dissolution of residual alkalinity. Addition of gypsum arrested this pH increase resulting in a final pH of 7.5 and pH of 8.8. In control treatments, additional leaching resulted in a pronounced decrease in Rhodes grass yields. However, in gypsum and cattle manure-amended treatments, it led to substantial yield increases and decreases in tissue Al and Na concentrations and increased K/Na ratios. Upon drying for the first time, bauxite residue was shown to contract and form a solid massive structure. The aggregates formed from crushing this material were water stable (as measured by wet sieving). Additions of cattle manure or gypsum to residue aggregates did not affect pore size distribution. Addition of cattle manure increased organic C and microbial biomass C content and basal respiration rate while additional leaching increased basal respiration and metabolic quotient. It was concluded that a combination of drying and crushing the residue, amending it with gypsum and organic manure followed by extensive leaching results in the formation of a medium that supports plant growth.
进行了实验室和温室实验，以研究海水中和后的铝土矿残渣的化学、物理和微生物特性，以及额外淋洗（相对于额外的 6 倍孔隙体积用去离子水 1 倍孔隙体积）和添加石膏（5%）和/或牛粪（6%）对其性质和兰地珠草（Chloris gayana）生长的影响。额外淋洗导致 EC、可交换 Na、SAR 和 ESP 降低。对于未经改良的对照处理，由于残余碱度的溶解，额外淋洗导致 pH 从 8.5 升高到 9.6 和 pH 从 9.1 升高到 10.1。添加石膏阻止了这种 pH 升高，最终 pH 为 7.5 和 pH 为 8.8。在对照处理中，额外淋洗导致兰地珠草产量明显下降。然而，在添加石膏和牛粪的处理中，它导致产量大幅增加，组织中 Al 和 Na 浓度降低，K/Na 比值增加。第一次干燥时，铝土矿残渣被证明会收缩并形成坚固的块状结构。从该材料粉碎形成的团聚体是水稳定的（通过湿筛测量）。向残渣团聚体中添加牛粪或石膏不会影响孔径分布。添加牛粪增加了有机 C 和微生物生物量 C 含量以及基础呼吸速率，而额外淋洗增加了基础呼吸和代谢商。结论是，干燥和粉碎残渣，用石膏和有机肥料改良，然后进行大量淋洗，会形成一种支持植物生长的介质。
