Nitrite formation in sediment cores from nitrate-enriched running waters
Stief, Peter; Neumann, Dietrich
published: May 26, 1998
ArtNo. ESP141014202007, Price: 29.00 €
1. A laboratory simulation was used to investigate nitrite formation within anoxic and nitrate-impacted sediments of nitrogen-enriched running waters. Natural sediment cores were perfused from below with nitrate-enriched, hypoxic water. The nitrate concentrations (14 and 28 mg 1-1 NO3-N) were in the range of groundwaters, as they occur in catchment areas of small rivers in Central Europe. 2. In sediment layers with detectable nitrate consumption, nitrite generated in physiologically detrimental concentrations of 0.5 -2.5 mg 1-1 NO2-N. Experimental manipulations of temperature, flow rate, oxygen saturation and ammonium concentration of the perfused water were correlated with changes in the nitrite concentrations occurring in the interstitial water. 3. High nitrite concentrations of up to 2.5 mg · 1-1 NO2-N were measured at 15 °C, at a flow rate of 0.25 ml m-2 s-1, and at O2-concentrations of between 0.5 and 1.5 mg 1-1 Supplementing the cores with ammonium led to a decrease in nitrite concentrations. 4. The results are discussed in relation to (a) denitrification processes, (b) the natural occurrence of comparable nitrite concentrations in nitrate-enriched streams and rivers, and (c) the detrimental consequences for the benthic fauna of such biotopes.