Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species' upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32°C); and (iii) the effects of wastewater (at 27 and 32°C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7°C and 33.1°C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC 50s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000)μgL -1, respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC 50s>100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species.
Harford, A., Hogan, A., Tsang, J., Parry, D., Negri, AP., Adams, M., ... Van Dam, R. (2011). Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 1. The tropical diatom Nitzschia closterium. Marine Pollution Bulletin, 62(3), 466-473. https://doi.org/10.1016/j.marpolbul.2011.01.013