Cr(VI) bioreduction by fulvic acid-mineral-microbe interactions: The critical role of nitrogen-centered environmentally persistent free radicals - Cheng Yu; Xuantong Li; Chenchen Qu; Chunhui Gao; Yichao Wu; Jiangrong Xiao; Ke Dai; Peng Cai; Qiaoyun Huang (Journal of Environmental Chemical Engineering, 2026)