. . . . . . "SDN:S04::S04271" . "" . "nanomolar ammonium system after Jones (1991)"@en . "accepted"@en . "Ammonium analysis protocol described in Jones RD (1991) An improved fluorescence method for the determination of nanomolar concentrations of ammonium in natural seawaters. Limnol. Oceanogr. 36:814-819."@en . . . . .