Effects of Fe-Mn-Ce oxide-modified biochar on As accumulation, morphology, and quality of rice [Oryza sativa L)

摘要

The fluidity of arsenic (As) in soil used for rice cultivation under flooding conditions is the main reason for its high accumulation in rice, which poses a serious threat to human's health. Biochar can immobilize heavy metal (for example lead) of soil because of the strong binding of heavy metals to the inner biochar particles. We conducted a pot experiment to evaluate the effects of biochar (BC) and Fe-Mn-Ce oxide-modified biochar composites (FMCBCs) on the morphology, As accumulation, and grain quality of rice grown in As-contaminated soils. The biochar and FMCBC treatments significantly increased the dry weight of roots, stems, leaves, and rice grains grown in As-contaminated soil (P < 0.05). The As concentration in different parts of rice was significantly lower with treatment FMCBC_(3.2) (BC, Fe, Mn, and Ce weight ratio of 24:2:3:10) than with the BC and control (no BC) treatments. The application of FMCBC_(3.2) maximized the yield and quality of rice grains: rice grain yields were 61.45-68.41% higher over control and the proportion of essential amino acids in the rice grains was 31.01-44.62%. The application of FMCBCs also increased the concentration of Fe-Mn plaques, which prevent the uptake of As by rice, thereby mitigating the toxic effects of As-contaminated soil on rice. In summary, Fe-Mn-Ce oxide-modified BC composites fixed As, reducing its fluidity and the As concentration in rice. Our results show that FMCBC_3 could play an important role in reducing As accumulation and increasing the grain yield and quality of rice, thus ensuring food safety in regions contaminated with As.