Straw addition increases enzyme activities and microbial carbon metabolism activities in bauxite residue

• Published in: Journal of environmental sciences (China) 2024-01, Vol.135, p.332-344
• Main Authors: Wu, Hao, Sun, Wei, Zhu, Feng, Jiang, Yifan, Huang, Shiwei, Goloran, Johnvie, Xue, Shengguo
• Format: Article
• Language: English
• Subjects: Bauxite residue; Community-level physiological profiles; Enzyme activities; Labile organic carbon fractions; Soil formation in bauxite residue
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2022.11.021

•The effect of phosphogypsum and straw on microbial functional diversity in bauxite residue was evaluated by using Biolog EcoPlate.•The relationship of carbon fractions and microbial carbon metabolism under different remediation strategies were revealed.•The straw addition significantly promoted the development of microbial functions, whereas phosphogypsum inhibit the microbial activity in bauxite residue. Recovery of microbial functions is one of the critical processes in the nutrient cycling of bauxite residue for improving revegetation. Straw is considered to be effective to increase microbial diversity and drive the development of the microbial community, but its effect on microbial carbon metabolism has not been illustrated. The present study evaluated the effects of phosphogypsum (PG), straw (SF) and phosphogypsum plus straw (PGSF) on physicochemical properties, enzyme activities, and microbial carbon metabolism activities in bauxite residue. After 180 days incubation, PG, SF and PGSF treatment significantly reduced the residue pH from 10.85 to 8.64, 9.39 and 8.06, respectively. Compared to CK treatment, SF treatment significantly increased the content of total organic carbon (TOC) and organic carbon fractions (DOC, MBC, EOC, and POC). In addition, straw addition significantly increased glucosidase, cellulose, urease, and alkaline phosphatase by 7.2-9.1 times, 5.8-7.1 times, 11.1-12.5 times, and 1.1-2.2 times, respectively. The Biolog results showed that straw addition significantly increased microbial metabolic activity (AWCD) and diversity in bauxite residue. Redundancy analysis indicated total nitrogen (TN) and carbon fractions (POC, MBC and DOC) were the most important environmental factors affecting microbial metabolic activity and diversity in bauxite residue. These findings provided us with a biogeochemical perspective to reveal soil formation in bauxite residue and suggested that nutrient supplement and regulation of salinity-alkalinity benefit the establishment of microbial communities and functions in bauxite residue. [Display omitted]