Abstract: In order to understand the status of heavy metal contents in Yanqi basin, a typical oasis basin in arid region, we collected soil samples and measured the contents of Pb, Mn, As, Zn, Ni and Hg. The multivariate statistical analysis and geostatistical analysis methods in combination with administrative division, land use types and the National Standard of Soil Quality (GB 15618-1995) were applied to study the spatial distribution characteristics, source, and regional differences of heavy metals in the soils of Yanqi basin. The results showed that the average contents of the six heavy metals in Yanqi basin was in order of Zn > Pb > Mn > As > Ni > Hg. The maximum contents of Zn, Pb, Ni and As exceeded the soil background values of Xinjiang, but were still within the second grade of the national standard. Geostatistical analysis showed that the contents of As, Pb, Hg and Zn were higher in the northwestern Yanqi county and Hejing county, while Mn and Ni had higher contents in southeastern and southwestern Heshuo county and Bohu county. The contents of As, Hg, Pb and Zn in different land use types were in order of cropland > grassland > bare land > wetland, while the contents of Mn and Ni were in order of bare land > grassland > wetland > cropland. According to the background of the sampling sites, As, Pb, Hg and Zn mainly originated from anthropogenic pollution, while Mn and Ni mainly originated from natural environment. Our results suggested that recent economic development had negative influences on heavy metal contents in the cropland and some other land use types of the west of the basin. Therefore, we should pay more attention on such influence and take measures to prevent the pollution of heavy metals in soils of Yanqi basin.

Key words: rhizosphere soil, fungal community, poplar plantation, high-throughput sequencing, root orders