中文关键词排水沟渠硝态氮吸收养分螺旋指标TASCCM-M方程 英文关键词drainage ditchnitrate uptakenutrient spiraling metricstracer additions for spiraling curve characterization (TASCC)Michaelis-Menten (M-M) model

作者	单位	E-mail
李如忠	合肥工业大学资源与环境工程学院, 合肥 230009	Lrz1970@163.com
殷齐贺	合肥工业大学资源与环境工程学院, 合肥 230009
高苏蒂	安徽新华学院土木与环境工程学院, 合肥 230088
陈广洲	安徽建筑大学环境与能源工程学院, 合肥 230022

中文摘要 为揭示农业排水沟渠NO₃^--N吸收动态变化特征，选择溴化钠（NaBr）为保守示踪剂、硝酸钾（KNO₃）为添加营养盐，于2016年10月至2017年4月在合肥地区某一源头溪流开展5次示踪试验，并以TASCC方法和Michaelis-Menten（M-M）方程模拟NO₃^--N吸收动力学特征，结果表明，背景浓度条件下排水沟渠完全混合子渠段U_amb和V_f-amb的变化范围分别为11.40~69.13 μg·（m²·s）^-1[均值为34.45 μg·（m²·s）^-1]、0.07~0.43 mm·s^-1（均值为0.24 mm·s^-1），相应地S_w-amb变化范围为92.51~405.74 m（均值为199.06 m），明显小于排水沟渠长度（也就是2.5 km），表明沟渠具有较强的NO₃^--N滞留潜力.M-M方程较好地拟合了NO₃^--N吸收动力学特征，参数U_max变化范围为158~1280 μg·（m²·s）^-1[均值为631.13 μg·（m²·s）^-1]，K_m变化范围为0.16~5.52 mg·L^-1（均值为1.46 mg·L^-1）.相关分析表明，S_w-amb与NO₃^--N_amb呈显著负相关、U_amb与NO₃^--N_amb呈极显著正相关，其它螺旋指标与NO₃^--N背景浓度的相关性均不明显；水文因素对NO₃^--N滞留影响也不显著，而沟渠槽道地貌特征指标Ф_w、Ф_A与大部分螺旋指标都呈显著相关性，表明槽道地貌特征对NO₃^--N滞留影响相对较为重要. 英文摘要 To investigate the whole-reach nitrate (NO₃^--N) uptake dynamics in a headwater agricultural stream, we performed five pulse tracer additions of a reactive solute (as KNO₃) and a conservative solute (as NaBr) in an agricultural drainage ditch in Hefei district, Chaohu Lake basin, from October 2016 to April 2017. The TASCC (tracer additions for spiraling curve characterization) approach and Michaelis-Menten (M-M) method were applied for the simulation of NO₃^--N uptake dynamics. Results showed that the ambient areal rate of total NO₃^--N uptake U_amb varied from 11.40 to 69.13 μg ·(m² ·s)^-1 with an average of 34.45 μg ·(m² ·s)^-1, and the ambient uptake velocity V_f-amb averaged 0.24 mm ·s^-1 and varied from 0.07 to 0.43 mm ·s^-1 across three well-mixed sub-reaches in the study. The ambient uptake length S_w-amb averaged 199.06 m with a range from 92.51 to 405.74 m, which was much smaller than the length of the drainage ditch (about 2.5 km), suggesting that the agricultural drainage ditch had a high potential for NO₃^--N retention. Generally, the M-M model fit the NO₃^--N uptake dynamics well, and the maximum uptake U_max ranged from 158 to 1280 μg ·(m² ·s)^-1 with a mean of 631.13 μg ·(m² ·s)^-1. The half saturation constant K_m ranged from 0.16 to 5.52 mg ·L^-1 with a mean of 1.46 mg ·L^-1. According to correlation analysis, S_w-amb was negatively correlated with NO₃^--N_amb, and U_ambwas significantly positively correlated with NO₃^--N_amb, while other nutrient spiraling metrics were not correlated with the NO₃^--N ambient concentration. Hydrological conditions had no distinct effect on the NO₃^--N retention, but both the width variability Ф_w and variability in cross-sectional area Ф_A were significantly correlated with most of the nutrient spiraling metrics, indicating that geomorphic features in the drainage ditch evidently impacted NO₃^--N uptake.

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