Climate Effects on Stream Nitrate Concentrations at 16 Forested Catchments in South Central Ontario

2004 ◽  
Vol 38 (8) ◽  
pp. 2383-2388 ◽  
Author(s):  
Shaun A. Watmough ◽  
M. Catherine Eimers ◽  
Julian Aherne ◽  
Peter J. Dillon
Keyword(s):  
Forested Catchments ◽  
Climate Effects ◽  
South Central ◽  
Nitrate Concentrations ◽  
Stream Nitrate

scholarly journals Export flux of unprocessed atmospheric nitrate from temperate forested catchments: A possible new index for nitrogen saturation

2018 ◽  
Author(s):  
Fumiko Nakagawa ◽  
Urumu Tsunogai ◽  
Yusuke Obata ◽  
Kenta Ando ◽  
Naoyuki Yamashita ◽  
...  
Keyword(s):  
Soil Water ◽  
Nitrogen Saturation ◽  
Weighted Average ◽  
Deposition Flux ◽  
Forested Catchments ◽  
Export Flux ◽  
Stable Isotopic ◽  
Nitrate Concentrations ◽  
Atmospheric Nitrate ◽  
Stream Nitrate

Abstract. To clarify the biological processing of nitrate within temperate forested catchments using unprocessed atmospheric nitrate exported from each catchment as a tracer, we continuously monitored stream nitrate concentrations and stable isotopic compositions including 17O-excess (Δ17O) in three forested catchments in Japan (KJ, IJ1, and IJ2) for more than two years. The catchments showed varying flux-weighted average nitrate concentrations: 58.4, 24.4, and 17.1 µmol L−1 in KJ, IJ1, and IJ2, respectively. In addition to stream nitrate, nitrate concentrations and stable isotopic compositions in soil water were determined for comparison in the most nitrate-enriched catchment (the KJ site). While 17O-excess of nitrate in soil water showed significant seasonal variation, ranging from +0.1 to +5.7 ‰, stream nitrate showed small variation, from +0.8 to +2.0‰ in KJ, +0.7 to +2.8 ‰ in IJ1, and +0.4 to +2.2‰ in IJ2. We concluded that the major source of stream nitrate in each forested catchment was nitrate in groundwater, which buffered the seasonal variations in soil water nitrate. The estimated annual export flux of unprocessed atmospheric nitrate accounted for 9.4 ± 2.6 %, 6.5 ± 1.8 %, and 2.6 ± 0.6 % of the annual deposition flux of atmospheric nitrate in KJ, IJ1, and IJ2, respectively. The export flux of unprocessed atmospheric nitrate relative to the deposition flux showed a clear normal correlation with the flux-weighted average concentration of stream nitrate, indicating that reductions in the biological assimilation rates of nitrate in forested soils, rather than increased nitrification rates, are likely responsible for the enrichment of stream nitrate, probably due to nitrogen saturation. The export flux of unprocessed atmospheric nitrate relative to the deposition flux in each forest ecosystem is applicable as an index for nitrogen saturation.

scholarly journals Export flux of unprocessed atmospheric nitrate from temperate forested catchments: a possible new index for nitrogen saturation

2018 ◽  
Vol 15 (22) ◽  
pp. 7025-7042 ◽  
Author(s):  
Fumiko Nakagawa ◽  
Urumu Tsunogai ◽  
Yusuke Obata ◽  
Kenta Ando ◽  
Naoyuki Yamashita ◽  
...  
Keyword(s):  
Nitrogen Saturation ◽  
Weighted Average ◽  
Deposition Flux ◽  
Forested Catchments ◽  
Export Flux ◽  
Significant Seasonal Variation ◽  
Stable Isotopic ◽  
Nitrate Concentrations ◽  
Atmospheric Nitrate ◽  
Stream Nitrate

Abstract. To clarify the biological processing of nitrate within temperate forested catchments using unprocessed atmospheric nitrate exported from each catchment as a tracer, we continuously monitored stream nitrate concentrations and stable isotopic compositions, including 17O excess (Δ17O), in three forested catchments in Japan (KJ, IJ1, and IJ2) for more than 2 years. The catchments showed varying flux-weighted average nitrate concentrations of 58.4, 24.4, and 17.1 µmol L−1 in KJ, IJ1, and IJ2, respectively, which correspond to varying export fluxes of nitrate: 76.4, 50.1, and 35.1 mmol m−2 in KJ, IJ1, and IJ2, respectively. In addition to stream nitrate, nitrate concentrations and stable isotopic compositions in soil water were determined for comparison in the most nitrate-enriched catchment (site KJ). While the 17O excess of nitrate in soil water showed significant seasonal variation, ranging from +0.1 ‰ to +5.7 ‰ in KJ, stream nitrate showed small variation, from +0.8 ‰ to +2.0 ‰ in KJ, +0.7 ‰ to +2.8 ‰ in IJ1, and +0.4 ‰ to +2.2 ‰ in IJ2. We conclude that the major source of stream nitrate in each forested catchment is groundwater nitrate. Additionally, the significant seasonal variation found in soil nitrate is buffered by the groundwater nitrate. The estimated annual export flux of unprocessed atmospheric nitrate accounted for 9.4 %±2.6 %, 6.5 %±1.8 %, and 2.6 %±0.6 % of the annual deposition flux of atmospheric nitrate in KJ, IJ1, and IJ2, respectively. The export flux of unprocessed atmospheric nitrate relative to the deposition flux showed a clear normal correlation with the flux-weighted average concentration of stream nitrate, indicating that reductions in the biological assimilation rates of nitrate in forested soils, rather than increased nitrification rates, are likely responsible for the elevated stream nitrate concentration, probably as a result of nitrogen saturation. The export flux of unprocessed atmospheric nitrate relative to the deposition flux in each forest ecosystem is applicable as an index for nitrogen saturation.

REGIONAL COHERENCE OF STREAM NITRATE CONCENTRATIONS: IMPLICATIONS FOR THEORY AND MANAGEMENT

2018 ◽  
Author(s):  
Lauren E. Koenig ◽  
◽  
William H. McDowell ◽  
Lisle E. Snyder ◽  
Jody D. Potter
Keyword(s):  
Nitrate Concentrations ◽  
Stream Nitrate

scholarly journals Reduction of stream nitrate concentrations by land management in contrasted landscapes

2019 ◽  
Vol 114 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Laurène Casal ◽  
Patrick Durand ◽  
Nouraya Akkal-Corfini ◽  
Cyril Benhamou ◽  
François Laurent ◽  
...  
Keyword(s):  
Land Management ◽  
Nitrate Concentrations ◽  
Stream Nitrate

Long-term declines in phosphorus export from forested catchments in south-central Ontario

2009 ◽  
Vol 66 (10) ◽  
pp. 1682-1692 ◽  
Author(s):  
M. Catherine Eimers ◽  
Shaun A. Watmough ◽  
Andrew M. Paterson ◽  
Peter J. Dillon ◽  
Huaxia Yao
Keyword(s):  
Stream Flow ◽  
Seasonal Patterns ◽  
Forested Catchments ◽  
Annual Average ◽  
Temporal And Spatial Patterns ◽  
South Central ◽  
Hydrologic Event ◽  
Temporal And Spatial ◽  
Shield Lakes

Total phosphorus (TP) levels in many Canadian Shield lakes in central Ontario have declined over recent decades, despite increases in human activity in most watersheds. To investigate the contribution of changes in catchment export to long-term declines in lake TP, we examined temporal and spatial patterns in TP concentrations and export (1980–1981 to 2001–2002) across 11 subcatchments that drain into three lakes in which average ice-free TP levels have declined by approximately 35%. Annual stream export of TP decreased significantly by 30%–89% in eight of the 11 subcatchments, and decreases in export were driven by declines in TP concentration, not changes in stream flow. Annual average TP concentrations varied fivefold among adjacent subcatchments, and temporal patterns in annual average TP concentrations were poorly correlated. Seasonal patterns of TP concentration were most similar among streams in the spring (March–April–May), and TP export in the spring declined significantly in 10 of the 11 subcatchments. Because spring melt is the principal hydrologic event in these seasonally snow-covered basins, decreases in TP export during the spring were primarily responsible for declines observed in annual export. The drivers of changes in TP over time are unclear at this point but are the focus of current research.

Drainage Effects on Stream Nitrate-N and Hydrology in South-Central Minnesota (USA)

2004 ◽  
Vol 91 (1-3) ◽  
pp. 183-198 ◽  
Author(s):  
J. A. Magner ◽  
G. A. Payne ◽  
L. J. Steffen
Keyword(s):  
South Central ◽  
Nitrate N ◽  
Stream Nitrate
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