<p>The presence of residual nitrate due to the excessive use of nitrogen fertilizers affects both iron mineral and sulfate reduction, potentially impacting cadmium (Cd) mobilization in flooded paddy fields. Soil column experiments with high nitrate (HN) and normal nitrate (CK) were conducted to evaluate cadmium availability on consideration of the reduction of iron minerals and sulfates in paddy soils under flooded conditions. The experimental results can be summarized as follows: the presence of nitrate slows down the Fe(III) reduction rate, which mitigates Cd release from paddy soil; however, the inhibition of sulfate reduction rate in the presence of nitrate contributes to Cd mobilization. As a thermodynamically active electron donor, nitrate increases the relative abundance of denitrifiers (e.g., Bacteroidetes_vadinHA17, Rhodocyclaceae and Opitutaceae) but decreases the relative abundance of sulfate-reducing bacteria (e.g., Defluviicoccaceae), ultimately inhibiting sulfide production required for CdS formation. Thus, the presence of nitrate also results in sulfate accumulation, which promotes the adsorption of Cd by forming Cd-sulfate complexes in paddy soil, as indicated by the experimental and statistical results. Overall, nitrate accumulation in the paddy soil can result in Cd mobilization by inhibiting sulfate reduction.</p> Graphical Abstract <p></p>