We use 3487 surface soil samples, 35 soil profile samples, and 93 agricultural products and root soil samples obtained from the southeastern Tarim basin, Xinjiang, northwestern China (Ruoqiang County and Qiemo County, Bayingguo Mongolia Autonomous Prefecture, and Minfeng County and Yutian County, Hetian Prefecture) to assess As contamination. Multivariate statistical analysis, geostatistics, and global information system (GIS) techniques are used to study:the spatial distribution characteristics of soil As, the effects of various agricultural products on As enrichment, and to compare the characteristics of the As content of agricultural products and root soils in spatially significantly and non-significantly autocorrelated regions. The As content of soil samples were relatively low, and the average As contents determined for agricultural land and non-agricultural land were 9.81 mg·kg-1 and 7.94 mg·kg-1, respectively. We found that 568 surface soil samples (16.3% of all samples) had an As content that exceeded Xinjiang soil background values (11.2 mg·kg-1) and that five samples exceeded the risk screening values (25 mg·kg-1). The Moran's indexes of spatial autocorrelation were>0, and the main aggregation types of spatial autocorrelation of soil As were high-high and low-low types, with the zone of the high-high type being mainly located in the agricultural land of each county. A GIS spatial distribution map showed that the high value area of soil As content presented a flaky or island-like scattered distribution. The standard deviation ellipses showed that the trend direction of soil As content in:Ruoqiang County was from north to south, Qiemo County and Minfeng County were both from southwest to northeast, and Yutian County was from northwest to southeast. The As content of the vertical profiles of the agricultural land in Ruoqiang County fluctuated from the surface to depth, whereas those of other counties were relatively stable. The As enrichment ability of crops was ranked as:root vegetables > walnuts > wheat > corn > red dates. The As contents of corn and red dates showed a significant positive correlation with that of the root soil. There was no significant difference in the As content of agricultural products between significant autocorrelation zones and non-significant autocorrelation zones, whereas there was a significant difference in the As content of root soils.
Keywords: enrichment characteristics of crop arsenic; geostatistics; soil arsenic; southeastern Tarim Basin; spatial autocorrelation; spatial distribution; standard deviation ellipse.