Abstract: To understand the effects of heavy metal pollution derived from atmospheric dust fall on bacterial community structure under different types of biological soil crusts near mining area, we measured the diversity, community composition, and relative abundance of bacteria communities in three different developmental stages of biological soil crusts (BSCs), including algae (ZB), mixed (HB), and moss (TB) crusts, and control (CK, bare soil) around a typical thermal power plant in Ningdong Energy Industrial Base, using the high-throughput sequencing technique. Environmental factors affecting the bacterial community structure were further investigated. The results showed that there were significant differences in physicochemical properties and heavy metal contents among different BSCs. The BSCs were heavily polluted due to the enrichment of heavy metals from atmospheric dust fall. Among the top ten dominant bacterial phyla, Gemmatimonadetes and Cyanobacteria were significantly distinct among different BSCs. Bacterial α diversity decreased in an order of CK>TB>HB>ZB. The NMDS ordination plots indicated that there were significant differences in the bacteria community composition of the three kinds of BSCs and the CK. The correlation analysis showed that the succession of BSCs significantly affected bacterial community composition in BSCs. Bacterial diversity and composition were closely related to pH, nutrients, and heavy metal contents. The relative abundance of Actinomycetes and Chloroflexi was positively correlated with pH, but negatively correlated with total N, total P, and the contents of heavy metal Pb, Zn, Cd. Results of the redundancy analysis showed that organic carbon, pH, total N, and total P were the major soil factors affecting bacterial α diversity, relative abundance of some dominant phyla, whereas heavy metal contents of Zn, Cd, Pb were the major heavy metals affecting structure of bacterial community which inhibited or stimulated the abundance and diversity of bacterial communities. We concluded that pH, heavy metals, and nutrients were the key factors affecting soil bacteria community composition. The succession of BSCs would improve their physicochemical properties and significantly impacted bacterial community composition. Long term heavy metals enrichment would affect bacterial diversity and community composition of BSCs.

Key words: atmospheric dust fall, heavy metals contamination, biological soil crusts, bacterial community, high-throughput sequencing.