Baseflow concentrations of nitrogen and phosphorus in forested headwaters in Japan.
A comprehensive investigation on all dissolved nitrogen and phosphorus components at both local and regional scales in the headwaters from forested watersheds is valuable to improve our understanding of the factors controlling water quality. Here, we investigated the baseflow concentrations of dissolved nitrogen and phosphorus components, N:P ratio, and their associations with region and vegetation type in forested headwaters in fives regions of Japan. We found that inorganic nitrogen and phosphorus were the dominant components in the 26 temperate forested streams, rather than organic forms. There were significant positive correlations between the concentrations of N and P components. Furthermore, the regional patterns of the concentrations of nitrate, dissolved inorganic P (DIP), and dissolved total N (DTN) and P (DTP) were similar. Our results suggest that the regional patterns of the concentrations of N and P components should be related to the regional atmospheric deposition of both N and P nutrients. We also found that the nitrate and DTN concentrations were higher in man-made evergreen conifer (EC) than those in the natural deciduous broadleaf (DB). In contrast, the DIP and DTP concentrations in EC were lower than those in DB. The uniformly higher N:P ratio in EC- than in DB-forested streams for each region suggest that EC-forested streams could be more affected by P-limited than DB-forested streams when N inputs from atmospheric sources increased.
State Key Laboratory of Earth Surface Processes and Resource Ecology, Beiing Normal University, Beijing 100875, China. zhzhao22@yahoo.com
Zhao
Z
Zhang
Takehiko
T
Fukushima
Peijun
P
Shi
Fulu
F
Tao
Yuichi
Y
Onda
Takashi
T
Gomi
Shigeru
S
Mizugaki
Yuko
Y
Asano
Ken'ichirou
K
Kosugi
Shinya
S
Hiramatsu
Hikaru
H
Kitahara
Koichiro
K
Kuraji
Tomomi
T
Terajima
Kazuo
K
Matsushige
D004784:Environmental Monitoring; D005618:Fresh Water / Q000032:analysis*; D005843:Geography; D007564:Japan; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D012621:Seasons; D014197:Trees; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
D009566:Nitrates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen