Enzymatic calcification to solidify desert sands for sandstorm control

Abstract

Sandstorms have been recognized as severe natural disasters worldwide and are increasingly occurring due to land desertification. In this study, an effective and environmentally friendly method (enzymatically induced calcite precipitation-polyvinyl acetate, EICP-PVAc) was proposed for sandstorm control. The technique was applied in a large-scale desert sand solidification experiment (50000 m2) to study the wind-erosion resistance of the technology in the Tengri desert. Due to the straw checkerboard barrier zone and the sand control belt with low barriers zone are easily buried by shifting sands. These engineering methods cannot be reset based on actual field status; so, they easily loss the function of sand proof. The EICP-PVAc method proposed for shifting sand solidification can adapt to the change of different terrain conditions and is suitable for shifting sands with changeable wind direction. After treatment, the straw checkerboard barriers zone and the sand control belt with low barriers zone had larger surface strengths, thicker cemented crust layers and larger CaCO3 contents. The surface strength increased exponentially with increasing thickness of crust layer. In addition, the network structure of PVAc not only increased the ability of solidifying sand stabilization to resist rain erosion, but also enhanced the intensity of sand stabilization. Therefore, the treatment ensured a long-term rainfall-erosion resistance. Moreover, the wind-erosion resistance of the treated area was significantly improved, and the desert sands in this area were not blown by wind in 60 days. The results demonstrated that EICP-PVAc treatment significantly controlled sandstorm, which presents promising potential for anti-desertification.