Sources of nitrite in streams of an intensively cropped watershed.
The sources of high in-stream nitrite (NO2(-)) concentrations were investigated in two major streams located in an intensively cropped watershed in Quebec, Canada. Nitrogen retention was determined to evaluate the dynamics in relation to nitrogen transport along both stream branches during summer-low-water and fall-recharge regimes. In the first stream branch, NO2(-) and ammonium (NH4(+)) showed removal patterns during summer-low-water and fall-recharge periods, whereas, in the second branch, NO2(-) and NH4(+) exports occurred during both hydrologic regimes. The study also demonstrated that seepage water is a source of NO2(-) instream, which varies within the watershed stream branches and with the hydrologic regime. The results highlighted a significant reductive microbial activity in seepage water from either denitrification or dissimilatory nitrate reduction to ammonium (DNRA), leading to nitrate (NO3(-)) consumption. Differences in groundwater NO3(-) concentrations feeding each stream branch may have significantly influenced NH4(+) and NO2(-) concentrations found in seepage water, which potentially resulted in quantitatively significant NO2(-) formation.
Corriveau
J
J
Institut national de la recherche scientifique-Eau, terre et environnement, Quebec, Canada.
van Bochove
E
E
Cluis
D
D
D002849:Chromatography, Gas; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry; D009573:Nitrites / Q000032:analysis*
D009573:Nitrites