Reclamation has been widely accepted to restore abandoned lands. Most studies focused on the improvement of land reclamation in soil nutrients and microbial activities. However, the effects of reclamation time on bacterial communities of abandoned salt pans are still unclear. The object of this study is to: i) assess the successional change of soil physicochemical properties and bacterial communities in reclaimed abandoned salt pans with different reclamation histories, and ii) figure out the main limit factors on the improvement of soil quality in reclaimed abandoned salt pans. The soils in a farmland (RTBL) and six abandoned salt pans with 1 year (RT1), 2 years (RT2), 3 years (RT3), 4 years (RT4), 8 years (RT8), and 9 years (RT9) of reclamation were sampled to investigate the temporal variation of soil properties, heavy metal content, bacterial community composition, and diversity. Results showed that the soil bulk density (BD), total dissolved salt (SS), median particle size (MMAD) decreased with the increase of reclamation time, while soil nutrient (soil organic matter, total nitrogen, available phosphorus, available potassium) showed an opposite trend. The bacterial α-diversity increased first, then decrease. Land reclamation enhanced the relative abundances of Acidobacteria, Chloroflexi, and Actinobacteria but reduced the relative abundances of Proteobacteria, Gemmatimonadetes, and Bacteroidetes. Compared with RTBL, the soil nutrients and bacterial community structure in RT1, RT2, RT3, and RT4 showed a significant difference.Therefore, reclamation time is a vital driving force for restoring soil physicochemical properties and bacterial communities in abandoned

Soil oil-pollution is one of the most severe environmental issues at present. Shifts of soil metallome and microbiome are essential indicators for risk assessment and remediation of field soil pollutions, but not well studied undergoing the petroleum contamination. In this research, soil samples were collected from a short-term and long-term petroleum-contaminated oil field. The soil physicochemical properties, metallome, microbial community, and polluted and unpolluted soil network were testified. Results showed that the contents of soil total petroleum hydrocarbon, total carbon, total nitrogen, total sulfur, total phosphorus, calcium, copper, manganese, lead, and zinc were increased by petroleum contamination. In contrast, the soil pH was decreased by petroleum contamination regardless of the pollution duration. Petroleum-contamination also reduced bacterial and fungal α-diversity indices. In contrast, bacterial α-diversity was negatively correlated with soil TPH and EC, and fungal α-diversity was negatively correlated with soil EC. Moreover, the relative abundances of Proteobacteria, Ascomycota, Oleibacter, and Fusarium in soil were increased by petroleum contamination. Network analysis showed that number of links, modules and the network invulnerability decreased in PS, followed by the OS group. These results demonstrate that short-term heavy petroleum contamination can cause shifts in soil physicochemical properties, metallome, and microbiome and assemble a less complex and vulnerable soil microbial network. Moreover, natural restoration can hardly amend soil properties and microbial network structure. This research emphasizes that the uncommonly studied soil metallome may play a vital part in the reaction of soil microbial communities to petroleum-contamination and potential application value of synthetic community in bioremediation.