Abstract
Nitrogen (N) saturation of upland forests has been assumed to be a substantial N source downstream. However, removal processes of N, including assimilation and denitrification in the downstream area, have not been clarified. To evaluate the N removal processes, nitrate (NO3 -) and organic N concentrations, as well as nitrogen isotope ratio (δ15N) and oxygen isotope ratio (δ18O) of NO3 - were measured along three rivers of Tatara River Basin, Japan where upland forests have already been N-saturated. Geographic information system (GIS) based topographical analysis was also conducted to evaluate the land use as urban area in relation to topography. In two of the three rivers, NO3 - concentrations did not increase from upstream to downstream, despite the potential non-point N sources of urban areas. In another river, NO3 - concentrations rather decreased. The values of δ15N and δ18O of NO3 - and organic N concentrations suggested the presence of denitrification and assimilation over N pollutants in the river whose watersheds have a lower percentage of urban area. The lower percentage of urban area could be explained by the lower topographic index. This study concluded that the NO3 - leaching from upland N-saturated forests was substantially assimilated or denitrified in the downstream area.
| Original language | English |
|---|---|
| Article number | 43 |
| Journal | Hydrology |
| Volume | 4 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Jan 1 2017 |
Fingerprint
All Science Journal Classification (ASJC) codes
- Oceanography
- Water Science and Technology
- Waste Management and Disposal
- Earth-Surface Processes
Cite this
Differences in stream water nitrate concentrations between a nitrogen-saturated upland forest and a downstream mixed land use River Basin. / Shinozuka, Ken'ichi; Chiwa, Masaaki; Tayasu, Ichiro; Yoshimizu, Chikage; Otsuki, Kyoichi; Kume, Atsushi.
In: Hydrology, Vol. 4, No. 3, 43, 01.01.2017.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Differences in stream water nitrate concentrations between a nitrogen-saturated upland forest and a downstream mixed land use River Basin
AU - Shinozuka, Ken'ichi
AU - Chiwa, Masaaki
AU - Tayasu, Ichiro
AU - Yoshimizu, Chikage
AU - Otsuki, Kyoichi
AU - Kume, Atsushi
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Nitrogen (N) saturation of upland forests has been assumed to be a substantial N source downstream. However, removal processes of N, including assimilation and denitrification in the downstream area, have not been clarified. To evaluate the N removal processes, nitrate (NO3 -) and organic N concentrations, as well as nitrogen isotope ratio (δ15N) and oxygen isotope ratio (δ18O) of NO3 - were measured along three rivers of Tatara River Basin, Japan where upland forests have already been N-saturated. Geographic information system (GIS) based topographical analysis was also conducted to evaluate the land use as urban area in relation to topography. In two of the three rivers, NO3 - concentrations did not increase from upstream to downstream, despite the potential non-point N sources of urban areas. In another river, NO3 - concentrations rather decreased. The values of δ15N and δ18O of NO3 - and organic N concentrations suggested the presence of denitrification and assimilation over N pollutants in the river whose watersheds have a lower percentage of urban area. The lower percentage of urban area could be explained by the lower topographic index. This study concluded that the NO3 - leaching from upland N-saturated forests was substantially assimilated or denitrified in the downstream area.
AB - Nitrogen (N) saturation of upland forests has been assumed to be a substantial N source downstream. However, removal processes of N, including assimilation and denitrification in the downstream area, have not been clarified. To evaluate the N removal processes, nitrate (NO3 -) and organic N concentrations, as well as nitrogen isotope ratio (δ15N) and oxygen isotope ratio (δ18O) of NO3 - were measured along three rivers of Tatara River Basin, Japan where upland forests have already been N-saturated. Geographic information system (GIS) based topographical analysis was also conducted to evaluate the land use as urban area in relation to topography. In two of the three rivers, NO3 - concentrations did not increase from upstream to downstream, despite the potential non-point N sources of urban areas. In another river, NO3 - concentrations rather decreased. The values of δ15N and δ18O of NO3 - and organic N concentrations suggested the presence of denitrification and assimilation over N pollutants in the river whose watersheds have a lower percentage of urban area. The lower percentage of urban area could be explained by the lower topographic index. This study concluded that the NO3 - leaching from upland N-saturated forests was substantially assimilated or denitrified in the downstream area.
UR - http://www.scopus.com/inward/record.url?scp=85046879713&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85046879713&partnerID=8YFLogxK
U2 - 10.3390/hydrology4030043
DO - 10.3390/hydrology4030043
M3 - Article
VL - 4
JO - Hydrology
JF - Hydrology
SN - 2306-5338
IS - 3
M1 - 43
ER -