Assaying the Activity of Nitrate and Nitrite Reductases in Sediment from a Eutrophic Lake

Sediment, sampled from Meiliang Bay in Lake Taihu, Eastern China, was employed to investigate the activities of nitrate reductase (Nar) and nitrite reductase (Nir) and their response to toluene. The optimum incubation times for assaying the activity of Nar and Nir in the sediment were 24-27 h and 21-24 h, respectively. Nir activity is easily inhibited by toluene while the Nar activity shows tolerance to toluene. The nitrate or nitrite consumed by potential denitrification in the sediment is 2-5 times greater than that by the dissimilatory reduction of nitrate to ammonia pathway during the incubations.