Biocrusts, as the dominant green strips in arid continents, potentially sever as a useful tool for immobilizing Pb in contaminated land under extreme constraints such as water resource. Artificially created biocrusts ensure the expansion of biocrusts in the short period. In this study, Microcoleus steenstrupii and montmorillonite (MMT) were used to construct artificial cyanobacterial biocrusts (ACBs) on the surface of Pb-containing dunes and cultured in compliance with the water conditions of the arid climate. Results suggested that MMT induced bulk productions of protective substances such as exopolysaccharides (EPS) and soluble proteins and reduced the overall oxidative damage of ACBs weakened by malondialdehyde. Biomineralization was identified as a possible pathway for ACBs to diminish Pb(II) effectiveness. The inoculum not only converted Pb(II) into Pb 3(CO 3) 2(OH) 2 and Pb 5(PO 4) 3OH, but also triggered the evolution of different cyanosphere communities that each accomplished a complicated biomineralization and precipitation process. This study revealed the feasibility of remediation of Pb-contaminated surfaces and provided an effective approach for the utilization of wasted land in arid regions.

The establishment of biological soil crusts is widely perceived as a main method to control ecological environment in arid and semi-arid regions. However, artificial biocrusts are insufficient to face with some stress from environment by using traditional established methods. Hence in this study, kaolin, a common clay mineral, was introduced as a stabilizer by mixing with Microcoleus steenstruppi of different mass ratios for inoculating onto sand to establish artificial biocrust. The results showed that the addition of kaolin exhibited a significantly positive effect on promoting biocrust formation, and accelerating the biocrust development. Moreover, the artificial biocrust from 1:500 (algae:kaolin) inoculant achieved the best performances with coverage of 98%, and thickness of 5.62 mm after 86 days of incubation. The highest contents of chlorophyll a, exopolysaccharides, and soluble protein were also observed in 1:500 mass ratio of algae:kaolin throughout the biocrust development process. As for the water retention performances, the results of contact angle, water drop penetration time (WDPT), and repellency index (RI) illustrated that biocrusts improve water utilization in kaolin-treated groups by delaying the time of water infiltration, especially in 1:500 group. After 86 days post inoculation, a series of common bacteria appeared in the biocrusts such as actinobacteria and acidobacteria and decomposed metabolites from cyanobacteria as energy source to supply their own life activities. This study gains new insights on clay minerals on biocrust development and puts forward a new approach for rapid artificial biocrust establishment to reverse desertification.

Salt-tolerant superabsorbent polymer (SAP) was synthesized to improve the water retention properties of saline-alkali soil. The Lop Nur saline-alkali soil of Xinjiang with high salinity (total dissolved salt: 18.13wt%) was the object of improvement. The good swelling capacity of SAP (69.04 g/g) under high salinity condition contributed to the superb slow-release water property and further [showed](https://www.wordhippo.com/what-is/another-word-for/build.html) [excellent](https://www.wordhippo.com/what-is/another-word-for/excellent.html) water retention property of SAP-saline-alkali soil (28 days), which showed a good application potential of SAP in saline-alkali land. The swelling mechanism under high salt condition was also explored. Notably, owe to the complexation reaction between and three hydrophilic groups of SAP, the swelling capability of SAP tended to keep steady when the concentration of CaCl 2 exceeded 0.55wt%. Interestingly, the distribution of the calcium salt in SAP was directly displayed by the maximum intensity projection of computed tomography.