生物质促进赤泥成土化的生物驱动机理及其潜在生态风险分析

土壤化修复是当前规模化解决赤泥大量堆存问题，实现区域生态环境安全的最可行措施之一。针对赤泥中苛性碱转化及其成土化发育的生物驱动机理等科学问题，本项目以拜耳法赤泥为研究对象，分别以腐化和未腐化处理玉米秸秆为生物质材料，拟通过实验室研究与场地示范相结合方法，探究生物质改良促进赤泥碱性转化及成土发育的生物驱动机制及其生态可持续性。其中，1）利用高通量测序分析、IC/HLPC-MS分析以及结合Na分布表征阐释有机质微生物代谢产酸对赤泥碱性调控作用机制及其可行性；2）采用光谱分析、生态化学计量分析等手段表征赤泥土壤化过程中C、N、P的累积特征，结合颗粒团聚体表征阐释赤泥土壤化发育的生物驱动机制；3）采用微束分析技术、生物毒性试验等手段表征赤泥土壤化发育过程中Na、Al、Cr、V等污染元素的潜在生态风险及其控释机制。项目研究将为生物质用于赤泥堆场生态复垦及其工程的管理提供可靠的理论依据和技术支持。

Soil amelioration of bauxite residues, by-products of bauxite-processing, is the most feasible way to solve the problem caused by the large-scale storage of bauxite residues and realize regional ecological environment security of the bauxite residues disposal area. However, the limited knowledge on the alkalinity transformation and pedogenesis of bauxite residues admixed with organic matters has hindered the wide application of BSRA rehabilitation in practice. In this project, the soil amelioration of bauxite residues from Bayer-processing of Shandong Aluminum Co., Ltd was investigated after admixing biomass materials from corn straw treated with or wthout septicization. Both the laboratory microcosm and in-site rehabilitation experiments were conducted in this study, to explore the biological driving mechanism and ecological sustainability of an eco-engineered soil from bauxite residues. The main investigated items including: 1) DNA high-throughput sequencing analysis of functional microbial community, IC/HLPC analysis of organic acid from biomass biodegradation and XRD/EDS/STXM analysis of Na bonded to solid phase of bauxite residues were used to investigate the effect and driving mechanism of microbial metabolic acid on the morphological transformation of Na bonded in bauxite residues and to explain the feasibility of bauxite residues alkaline regulation with microbiome steered by biomass admixing; 2) to investigate the microbial driving function on soil amelioration of bauxite residues admixed with biomass, the FTIR/NMR analysis, ecological chemical metrology analysis and aggregates morphological analysis was used to characterize the accumulation characteristics of carbon, nitrogen and phosphorus, and to explain biological mechanism of the bauxite residues pedogenesis; 3) the biogeochemical characteristics of Na, Al, Cr, V and their potential ecological risks in the process of loam development were characterized by means of elemental morphology analysis, microbeam technology and biological toxicity test. The research results will provide a reliable theoretical basis for the application of biomass in bauxite residues disposal area rehabilitation and its engineering management.