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摘要
In order to reveal the spatial distribution characteristics and source of heavy metals and Se in potential Se-enriched soils in Zhuanqiao Village, Lujiang County, we collected 430 samples of 0-20 cm top soil in the local and surrounding area. The concentrations of organic matter (OM), total nitrogen (TN), total phosphorus (TP), potassium oxide (K2O), total sulphur (TS), total ferric oxide (TFe2O3), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), nickel (Ni), selenium (Se) and zinc (Zn) in the soils were tested. Geographic information system (GIS), geostatistics and principal component analysis (PCA) were used to analyze the spatial variations and source apportionment of heavy metals. The results show that the heavy metal content varied from 0.23 to 0.80, which belonged to the moderate variability. The concentrations of Cr and Ni were lower than the national guideline values of Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018). However, Cu concentration in most soil samples were high. The same goes for Cd, Pb and Zn in a very few soil samples, and As and Hg in one sample. Copper contaminated soil did not lead to contamination of agricultural products. There was a similarity in spatial distribution between w(Cr) and w(Ni), w(As) and w(Se), as well as w(Cu) and other four elements (w(Pb), w(Zn), w(Hg) and w(Cd)) respectively. The ratio values of nugget to sill of heavy metal elements ranged from 0.168 to 0.637, where Zn, Se, Cu, Cr and Ni had a strong spatial autocorrelation, and Pb, As, Hg and Cd had a medium spatial autocorrelation. PC1 (Cr, Ni, K2O and TP), PC2 (OM, TN and TS), PC3 (Cu, TFe2O3 and Cd), PC4 (Pb, Zn and Hg) and PC5 (As and Se) were extracted by PCA method, with 71.677% of the variance being explained by variations in these values. Se in the soils came from selenium-rich rock. Cu and Zn were mainly related to the geological background (the development of veins), and Cr and Ni were derived from the parent material. Pb, Cd and Hg were affected by the geological background and agricultural activities, and As was affected by selenium-rich rock and agricultural activities. The results indicate that the effects of soil parent materials, the geological background and agricultural activities on heavy metals in farmland soil can be effectively identified by combining the content of soil elements, variation intensity, spatial autocorrelation and the extracted PC. The selenium-rich rock can provide Se source for the soil in this region, and the soil quality can meet the requirements of selenium-rich agriculture development. ? 2019, Editorial Board, Research of Environmental Sciences. All right reserved.
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