Fig. 3. Solid-state ¹⁵N nuclear magnetic resonance (NMR) spectra of a [¹⁵N]- and [¹⁴C]-TNT spiked soil incubated for 4 d under anaerobic conditions. Sample P2a represents the bulk sample, P2b its residue after methanol extraction. Samples P2a-HF and P2b-HF are the residues of P2a and P2b after extraction with 10% hydrofluoric acid