Ammonium uptake in alpine streams in the High Tatra Mountains (Slovakia)

Abstract

Uptake of NH4 -N by streambed biota of mountain brooks was studied in the alpine zone of the High Tatra Mountains . Experiments were performed involving in situ dosing of ammonium directly to the acidified stream and incubations of ammonium and streambed bryophytes in enclosures within a range of pH from 4 .45 to 8 .10 .NH4 -N uptake length decreased with decreasing stream discharge, while comparable values of dischargenormalized uptake lengths were found during two in situ experiments .Maximum uptake rates of NH4 -N obtained during the incubation of bryophytes (6 to 11 mg m -2 h -1 ) were comparable with results of two in situ experiments (8 and 12 mg m -2 h -1 ) . The average NH4 -N uptake rates observed during incubations lasting 3 to 5 hours (4 .3 mg m -2 h-1 ) were not related to the pH of stream water. Nitrification of about 50% of the NH4 -N added was observed in non-acidified streams, but was negligible in acidified streams . Significant photoinhibition of nitrification was observed in non-acidified streams during enclosure experiments . 157

Chemical composition of the Tatra Mountain lakes: Response to acidification

“…Low NO (Fig. 5), as well as in the alpine streams (Kopáček & Blažka, 1994), suggest that a large portion of the Tatra alpine zone is in an advanced stage of N saturation according to Stoddard (1994).…”

“…The elevated atmospheric deposition of S and N compounds also affected the nutrient status of the Tatra Mts surface waters: (i) lake water concentrations of phosphorus was related to the acidification status of lakes (Vyhnálek et al, 1994), (ii) nitrification of ammonium was reduced in strongly acidified Tatra streams (Kopáček & Blažka, 1994), and (iii) concentrations of nitrate increased in lakes situated in nitrogen-saturated catchment areas (Kopáček et al, 1995(Kopáček et al, , 2000.…”

The Role of Bryophytes in Carbon and Nitrogen Cycling

“…Liverworts such as Jungermannia vulcanicola and Scapania undulata used NH 4 ϩ as their major N source, with uptake rates ranging from 0.019-0.058 mg N per g dry weight hr Ϫ1 (Miyazaki & Satake 1985). Aquatic alpine bryophytes took up NH 4 ϩ at average rates of 4.3 mg m Ϫ2 hr Ϫ1 (Kopacek & Blazka 1994). Kahl et al (1997) used 15 N-NMR to show that Sphagnum fallax incorporated 15 NH 4 ϩ into glutamine and glutamate amino acids.…”

Stream ecosystem response to chronic deposition of N and acid at the Bear Brook Watershed, Maine

“…Nitrogen transformations such as nitrification (Kopáček and Blazka 1994;Strauss and Lamberti 2000) can be reduced by acidification, although this has not received much direct attention in streams. Acidification may further suppress biological activity by mobilizing metals that may be directly toxic and can precipitate when stream water pH rises, leading to reduced primary production and decreased leaf decomposition (Niyogi et al 2002).…”