|
Abstract To investigate the basic characteristics of nitrogen and phosphate nutrient retention in the headwater stream of Shiwulihe, Lake Chaohu basin, a solution containing NH4Cl or KH2PO4 addition and a conservative tracer (NaCl) was used to conduct field experiments by slug injection. According to the data sets of breakthrough curves of chloride and nutrient concentration, the OTIS model code and OTIS-P software, proposed by Runkel (United States Geological Survey, USGS), were employed to estimate hydrological parameters (e.g. D, A, As, a) and first-order uptake rate coefficients (i.e. λ and λs). And on this basis the reach-scale transient storage metrics and nutrient uptake parameters were calculated as well as the fraction of uptake contribute to and SRP between the main channel and transient storage zone was estimated. Study results showed that the mean values of first-order uptake rate coefficients for in main channel and transient storage zone were 3.88×10-6s-1and 8.81×10-4s-1, respectively, and 7.80×10-6s-1and 7.98×10-8s-1for SRP, respectively. The average values of total uptake rate k-NH4 and k-SRP were 1.64×10-4s-1and 7.80×10-6s-1, respectively. The uptake lengths of Sw-NH4 and Sw-SRP were getting pretty big and approach 1632.88m and 25471.32m, respectively, suggesting a low probability to remove the nutrients by physical or biological processes. Relative to mountain headwater streams with low nutrient concentration, the studied reach had lower values of Vf-NH4and Vf-SRP, but higher U-NH4and U-SRP. Estimates of mass loss indicated that 93.82% of the uptake occurred in the transient storage zone, whereas 99.70% of the SRP uptake occurred in the main channel.
|
|
Received: 10 July 2013
|
|
|
|
