中文摘要：

为揭示生活污水补给影响下排水沟渠氮、磷滞留特征,以合肥市城郊结合部的关镇河支渠为对象,以NH4Cl和KH2PO4为添加营养盐,以Na Cl为保守型示踪剂,开展5次现场示踪试验.在此基础上,利用OTIS（one-dimensional transport with inflow and storage）模型估算D（扩散系数）、A（渠道过水断面面积）、As（暂态存储区断面面积）、α（暂态存储交换系数）、λ（主流区溶质一阶吸收系数）和λs（暂态存储区吸收系数）;并利用营养螺旋原理,计算营养盐的Sw（吸收长度）、Vf（吸收速度）和U（吸收速率）等.结果表明：①As/A具有随流量减小而增大的变化特征,平均值为0.35;5次试验得到的α均处在10^-3数量级水平,平均值为2.49×10^-3s^-1.②Sw-NH4和Sw-PO4（分别表示NH4-N和PO4-P的Sw,下同）均较大,最大值分别达934 020、47 518 m,意味着关镇河支渠已基本不具备氮、磷滞留能力;而Sw-NH4和Sw-PO4均不同程度地出现负值,表明该支渠还具有＂源＂的作用.③Vf-NH4与河水平均深度、渠道流量均呈显著负相关,Vf-PO4和U-PO4与渠道水面宽度均呈显著正相关.④NH4-N和PO4-P的营养螺旋指标与其相应质量浓度背景值无明显相关性.

英文摘要：

Nitrogen and phosphorus retention for a typical drainage ditch in Guanzhenhe Branch,a first-order stream dominated by domestic sewage in the rural-urban continuum of Hefei,was characterized.Field tracer experiments were carried out for five replications by addition of a conservative tracer（NaCl） and nutrients（NH4Cl and KH2PO4） along the study reach.Based on the experimental data,hydrological parameters（e.g.,dispersion coefficient D,stream channel cross-sectional area A,storage zone cross-sectional area As,and stream storage zone exchange coefficient α） and the first-order nutrient decay coefficients（e.g.,decay coefficient in main channel λ and decay coefficient in storage zone λs）,were estimated with the transient storage OTIS（one-dimensional transport with inflow and storage）model.Nutrient spiraling metrics（i.e.,uptake length Sw,mass transfer coefficient Vf,and nutrient uptake rate U） were subsequently calculated based on the nutrient spiraling theory.Regression and correlation analysis were further conducted with SPSS statistical software.The results showed that：1） The average value of As/A was 0.35,and was significantly negatively correlated with discharge（Q）.2） The order of magnitude of α was 10^-3,while the mean value of α was 2.49 × 10^-3s-1.Sw-NH4 and Sw-PO4（Swof NH4-N and PO4-P）reached their maximum values of 934,020 and 47,518 m,respectively,indicating that Guanzhenhe Branch was not capable of retaining nutrients efficiently.Meanwhile,the negative values of Sw-NH4 and Sw-PO4 suggested that the study reach even acted as a nutrient source.3） Correlation analysis results showed that Vf-NH4 was negatively correlated with water depth and Q,respectively.In addition,both Vf-NH4 and Uf-PO4 increased with stream width.4） Nutrient spiraling metrics were not statistically related to ambient concentrations of NH4-N and PO4-P in regression analysis.In general,high nutrient concentrations restricted the effect of nutrient retention in Guanzhenhe Branch.Excessive nutrient