Abstract
In soil-rice systems,microbial reduction of iron(Fe)has been recognized as a crucial biogeochemical process that regulates Fe and chromium(Cr)translocation;however,the underlying processes are unknown.To investigate the impacts of biochar on the biochemical cycling of Fe and Cr and their toxicity to rice,maize straw biochar was applied at 1％(weight/weight)to a paddy soil spiked with 300 mg kg-1 Cr under two phosphorus(P)levels(0 or 90 mg kg-1)in a pot experiment.The key microbial groups affecting Fe dissimilatory reduction and their environmental drivers were explored.Biochar inhibited root Cr uptake by 36％,owing to the promoted iron plaque(IP)formation on the rice root surface.Correlation analysis showed that Fe concentration in pore water was strongly linked to the abundances of Geobacter(r=0.81-0.94,P＜0.05)and Clostridium(r=0.83-0.95,P＜0.05),indicating that Geobacter and Clostridium played essential roles in Fe reduction.Redundancy analysis showed that labile carbon and pore water P concentrations were the key determinants influencing Fe-reducing bacterial abundances,accounting for 42％and 32％of the variation in community composition,respectively.Besides,biochar increased Fe and P concentrations in root cell walls,which retained more Cr.Overall,Cr stress in rice under biochar treatment was relieved through increasing IP formation and altering subcellular distribution.These mechanistic insights had important implications for reducing Cr uptake by rice.
基金项目
National Natural Science Foundation of China(42107017)
National Natural Science Foundation of China(32172121)
NETL
NSTL
万方数据