Silicon Isotope Fractionation in Maize and its Biogeochemical Significance

ABSTRACT

Plants that absorb silicon may induce isotope fractionation that causes relative abundance changes in biogeochemical processes in organisms and environment. Silicon isotopes (²⁸Si, ²⁹Si, and ³⁰Si) were determined with high precision using multicollector inductively coupled plasma mass spectrometer. In the present study, the silicon isotope composition was determined in maize and corresponding soil was collected from Zhejiang Province, China. The δ³⁰Si values were from −2.7 to 3.3‰ in the plant tissues. The isotope fractionation between precipitated and dissolved silicon was 0.9976 and the silicon isotope fractionation in the plants was appeared to be Rayleigh-like process. The fractionation factors between the whole plants and the soil–water-soluble fractions were estimated to be 0.9989, indicating the presence of biochemical silicon isotope fractionation. The active uptake of silicon appeared to play an important role through which the heavy silicon isotopes were preferentially absorbed and transferred to the aboveground plant tissues. However, the roles of a passive mechanism for silicon uptake could not be ruled out through which the light silicon isotopes preferentially precipitated in various plant tissues.

KEYWORDS:

• Isotope fractionation
• multicollector inductively coupled plasma mass spectrometry
• plant tissue
• silicon

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (No. 31572194, 31172032). The authors declare no competing financial interests.