Water quality of a coastal river receiving nutrient inputs: Ammonium nitrogen transformations

The influence of ammonium, nitrate, and dissolved oxygen concentrations on uptake, nitrification, and denitrification rates associated with prairie stream substrata

“…Factors that regulate nitrification are integral to ecosystem function and, thus, to eutrophication and health concerns related to elevated NO concentrations in freshwaters because Ϫ 3 nitrification is central to the accumulation and loss of NO Ϫ 3 (DeLaune et al 1991;Henriksen et al 1993). Recent studies have also identified nitrification as an important regulator for N retention due to coupling with denitrification (DeLaune et al 1991;An and Joye 2001).…”

“…Recent studies have also identified nitrification as an important regulator for N retention due to coupling with denitrification (DeLaune et al 1991;An and Joye 2001). Despite the importance of nitrification and denitrification, few studies have explored the factors regulating these processes in streams, and no single set of factors has emerged consistently as the key regulator.…”

“…In streams, the benthos represents a potentially important biotic sink for nutrients because uptake and transformation rates within the benthos may control movement and removal of N in the stream channel (DeLaune et al 1991;Henriksen et al 1993;Peterson et al 2001). Possible fates of ammonium (NH ) within the benthos include biotic uptake, nitri-ϩ 4 fication, volatilization, and adsorption.…”

Ammonium Availability Affects the Ratio of Ammonia-Oxidizing Bacteria to Ammonia-Oxidizing Archaea in Simulated Creek Ecosystems

“…AOB predominance was established more rapidly in flow channels incubated at 350 M NH 4 ؉ than in those incubated at 50 or 20 M NH 4 ؉ . Biofilm-associated potential nitrification activity was first detected after 28 days and was positively correlated with bacterial but not archaeal amoA gene copy numbers.Nitrogen transformation processes in small-river ecosystems are primarily associated with the sediment or epilithic biofilms (4,5,18). Here, nitrification as the first step in coupled nitrification-denitrification is a key step in the removal of the allochthonous nitrogen load, preventing the eutrophication of downstream ecosystems (1,5,29,39).…”

“…Nitrogen transformation processes in small-river ecosystems are primarily associated with the sediment or epilithic biofilms (4,5,18). Here, nitrification as the first step in coupled nitrification-denitrification is a key step in the removal of the allochthonous nitrogen load, preventing the eutrophication of downstream ecosystems (1,5,29,39).…”