HR: 0800h
AN: H31D-1333    [Abstracts]
TI: Hydrological control and anthropogenic effect on dissolved nitrogen in stream water from a subtropical mountainous drainage system
AU: * Kao, S
EM: sjkao@gate.sinica.edu.tw
AF: Research Center for Environmental Changes, Academia Sinica, Taiwan, 128, Sec. 2 Academia Rd., Nangang, Taipei, Tai 115 Taiwan
AU: Lee, T
EM: tylee@gate.sinica.edu.tw
AF: Research Center for Environmental Changes, Academia Sinica, Taiwan, 128, Sec. 2 Academia Rd., Nangang, Taipei, Tai 115 Taiwan
AU: Huang, W
EM: r90241403@ntu.edu.tw
AF: Research Center for Environmental Changes, Academia Sinica, Taiwan, 128, Sec. 2 Academia Rd., Nangang, Taipei, Tai 115 Taiwan
AU: Liu, K
EM: kkliu@ccms.ncu.edu.tw
AF: National Central Univ., 38, Wu Chuan Li, Chung-Li, Taoyuang, Tai 111 Taiwan
AB: Spatio-temporal investigation of dissolved inorganic nitrogen (DIN; NH4, NO2, NO3) and dissolved organic nitrogen (DON) in the river water was conducted in the Danshuei River drainage system, which includes uncultivated upstream and polluted downstream with high population density. Human population and water runoff are two major factors determining nitrogen export. On average, NO3 is the dominant form of DIN in river water at upstream stations, while NH4 dominates the middle-down stream river water. Concentrations of three DIN species showed an increasing trend from up to down stream reach. NO3 concentrations range from 10 uM at uncultivated upstream to 80 uM at highly populated downstream stations. Compared to NO3, NH4 shows much more significant downstream increases from 0.1 uM to over 200 uM due to sewage inputs. Inputs from agriculture and urban sewage source significantly affect the spatial pattern of nitrogen speciation and concentration over entire drainage system. For upstream stations, the variability of DIN concentration is much less than that of runoff variability. Thus, the DIN flux is controlled by the water discharge rate. After logarithmic transformation, the yields of total dissolved nitrogen (TDN) can be parameterized as functions of population density and runoff depth (runoff/area) within the watershed of Danshuei River. This empirical function might be applicable to estimate total nitrogen load for other mountainous small watersheds.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1806 Chemistry of fresh water
DE: 1860 Streamflow
DE: 1871 Surface water quality
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005