WEI Xueji1,2，WANG Lei2,3，ZHUO Xiaoxiong2,4
（1. Guangxi Geophysical Survey Institute, Liuzhou, 545005, China；
2. Project Office of Land Quality Geochemical Assessment of Guangxi, Nangning 530023, China；
3. Geology Team No．4 of Guangxi Zhuang Autonomic Region, Nangning 530031, China；
4. Guangxi Geological Survey Institute, Nanning, 530023, China）
Abstract: Selenium is one of the essential trace elements which are of great importance to human health. Rice is a major grain crop in south China. A thorough understanding of selenium contents in the rice and rhizosphere soil system can provide the scientific basis for the cultivation of selenium-rich rice, the development of selenium-rich industry and improving the utilization value of lands. This study chose a typical carbonate area in central Guangxi as the research area and collected 800 samples of rice seed and rhizosphere soil to study the selenium levels and the possible influencing factors. The results showed that: (1)The rhizosphere soils were generally acidic, and their selenium contents ranged from 0.11 to 3.82mg/kg with an average of 0.61mg/kg, which was significantly higher than those of other regions of China. (2) Cd, Cr, Hg and S elements in rhizosphere soils were relatively enriched compared with the soil background value of China, consistent with their high background contents in carbonate rock regions of Guangxi, while high contents of Se and Cd in in rhizosphere soils might be resulted from their secondary enrichments. (3) The minimum, the maximum and the average Se contents in rice seeds were 0.015mg/kg, 0.532 mg/kg and 0.08 mg/kg, respectively, the enrichment rate of Se in rice seeds was as high as 81.5%. (4) The selenium content in rhizosphere soils was controlled mainly by the parent material of the soils and related closely to the widely distributed carbonate and siliceous rocks of Carboniferous, Devonian, Permian and Triassic in the study area. In addition, significant positive correlations were found between heavy metals and soil organic matter contents. The soil organic matter can adsorb and fix Se to enrich Se in the surface soil. The selenium contents in rice seeds were controlled by the selenium contents of rhizosphere soils and correlated negatively with soil organic matter content, S content and pH of the rhizosphere soils.
Key words: rice; root soil; Selenium; influencing factors; carbonate rock area; Central Guangxi
EARTH AND ENVIRONMENT Vol.48, No.3, Tot No.335, 2020, Page 369-376
