Bacterial response to sharp geochemical gradients caused by acid mine drainage intrusion in a terrace: Relevance of C, N, and S cycling and metal resistance.

•Unique terrace with sharp geochemical gradients contaminated by AMD was selected.•Microbial communities and metabolisms in various geochemical gradients were compared.•AMD contamination impaired processes such as nitrogen fixation and DNRA.•pH, TOC, Fe- and S-species were identified as drivers for community and metabolism.