Distribution Characteristics of Soil Selenium and Its Influencing Factors in Tangchang Town of Chengdu City, Sichuan Province

Abstract

BACKGROUND Selenium is one of the essential trace elements for humans. Eating agricultural products containing selenium is an important way for humans to obtain selenium. It is of great significance for the utilization of selenium-enriched soil resources and the development of selenium-enriched agricultural products to investigate the content characteristics of soil selenium, delimit selenium-enriched soil areas, and determine the influencing factors of soil selenium spatial distribution, migration and enrichment. OBJECTIVES To discuss the content, distribution characteristics and influencing factors of soil selenium in the study area. METHODS Tangchang Town in the Pidu District of Chengdu City was chosen as the study area. 788 surface soil samples (0-20cm) and 46 profile soil samples (100-150cm) were collected. The pH values and contents of Se, As, Hg, Cu, Pb, Zn, Ni, Cr, CD, TP, TK, TN and TOC in soil were determined by AFS, XRF and ICP-MS/OES. Geostatistical analysis, variance analysis, correlation analysis and geographic detectors were applied to systematically determine the content, distribution characteristics and influencing factors of soil selenium. RESULTS (1) Results showed that surface soil selenium content of Tangchang Town ranged from 0.082 to 1.10mg/kg, with an arithmetic mean value of 0.337mg/kg, which was 1.47, 4.02 and 1.16 times the average Se content of soil in Chengdu, Sichuan and China, respectively. (2) The Se-sufficient and Se-enriched topsoil reached 99.2% of Tangchang Town. In the profile soil samples, the soil selenium content decreased with increasing depth. In the spatial distribution, high selenium concentrate areas generally showed a northwest zonal distribution trend in Zhanqi Village, Baimu Village, Dayun Village, and Zhulin Village. (3) Correlation analysis showed that lead, chromium, nickel, cadmium, mercury, arsenic, total potassium, total nitrogen, pH, TOC and altitude were factors affecting spatial distribution variability of the soil selenium but varied in extent (P < 0.01). (4) The factor detection showed that TOC was the highest in the effect, explaining 0.29 of the variability, followed by Zn, which was 0.18, and the third was Cd, which was 0.16. Interaction detection showed the interpretation degree of the interaction between soil TOC and 17 influencing factors was more than 0.30, which was the dominant factor of spatial differentiation of selenium in topsoil. CONCLUSIONS The town is characterized by selenium-enriched soil resources; it is suggested to organically combine the selenium-enriched area with the characteristic industries of chives in Tangyuan to build an ecological chain of selenium-enriched industry, and further carry out collaborative analysis on the influencing factors of selenium migration and enrichment in soil crops.

Keywords

• soil
• selenium
• atomic fluorescence spectrometry
• inductively coupled plasma-optical emission spectrometry/mass spectrometry
• distribution characteristics
• influencing factors
• geographic detector
• tangchang town