Combined Effects of Bacteria and Hydroxyapatite on Rice and Microorganisms in Cadmium Contaminated Soil

Abstract

Cadmium (Cd) has caused serious soil environmental problems and directly harming plants, microorganisms, and even humans. It is vital and necessary to develop effective methods to solve the problem of soil Cd pollution and improve soil environment. In this study, alkali-producing bacteria combined with hydroxyapatite (HAP) to explore their effects on rice Cd accumulation, rice yield, soil available Cd, and soil microorganisms. Results showed that the soil available Cd content decreased in all groups. The bacteria combined with 0.5% and 2% ratio HAP treatment groups decreased soil available Cd by 7.17% and 0.58%, respectively. However, Cd content of grains in the former treatment group was as high as 0.27 mg/kg, and the latter treatment group was 0.18 mg/kg, they were lower than control group (0.31 mg/kg). As to the rice yield, most treatment groups can increase rice yield comparing to control group, and the bacteria combined with 2% ratio HAP increased by 13.79%. On the soil microorganisms, treatment groups had no obvious impact on diversity of soil microbial communities (p > 0.05), but there were significant differences in phylum classification, and the bacteria combined with 2% ratio HAP had more complex network of soil microorganisms. Besides, the bacteria could to adapt to this soil environment and colonize. So, the bacteria combined with 2% ratio HAP had great potentials for Cd contaminated soil remediation.