| 农业排水沟渠硝态氮吸收动力学特征及相关性分析 |
| 摘要点击 1703 全文点击 591 投稿时间：2017-10-27 修订日期：2017-11-20 |
| 查看HTML全文
查看全文 查看/发表评论 下载PDF阅读器 |
| 中文关键词 排水沟渠 硝态氮吸收 养分螺旋指标 TASCC M-M方程 |
| 英文关键词 drainage ditch nitrate uptake nutrient spiraling metrics tracer additions for spiraling curve characterization (TASCC) Michaelis-Menten (M-M) model |
|
| 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Uamb和Vf-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Sw-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Umax变化范围为158~1280 μg·（m2·s）-1[均值为631.13 μg·（m2·s）-1]，Km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，Sw-amb与NO3--Namb呈显著负相关、Uamb与NO3--Namb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Фw、ФA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 Uamb 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 Vf-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 Sw-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 Umax ranged from 158 to 1280 μg ·(m2 ·s)-1 with a mean of 631.13 μg ·(m2 ·s)-1. The half saturation constant Km ranged from 0.16 to 5.52 mg ·L-1 with a mean of 1.46 mg ·L-1. According to correlation analysis, Sw-amb was negatively correlated with NO3--Namb, and Uambwas significantly positively correlated with NO3--Namb, 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 Фw and variability in cross-sectional area ФA were significantly correlated with most of the nutrient spiraling metrics, indicating that geomorphic features in the drainage ditch evidently impacted NO3--N uptake. |
|
|
|
