Long-term changes in pollutant load outflows and purification function in a paddy field watershed using a circular irrigation system.
Long-term changes in pollutant load outflows and purification function in a paddy field watershed using a circular irrigation system.
复制标题
DOI：
10.1016/j.watres.2005.08.034
复制
发表时间：
2006-02
期刊：
影响因子：
12.8
通讯作者：
I. Takeda;A. Fukushima
中科院分区：
文献类型：
--
作者：
I. Takeda;A. Fukushima
对采用循环灌溉系统的稻田流域进行了为期8年零7个月（1991年10月至2000年4月）的水质和水文长期调查。年降雨量在1270 ~ 2226 mm之间，灌溉用水量随降雨量的增加而减少。磷和化学需氧量（COD）浓度有下降的趋势，而氮浓度没有显着差异。总氮（T-N）、总磷（T-P）和COD的年输出负荷（灌溉期净输出负荷和非灌溉期输出负荷之和）分别为13.6 ~ 75.3kgha-1 yr-1、-3.55 ~2.21kgha-1 yr-1和-24.7 ~48.5kgha-1 yr-1。T-P和COD负荷均为负值，表明研究流域具有一定的净化功能。年污染物负荷的变化主要是由于水文水量（年降雨量或降雨量加上灌溉水）的T-N和COD负荷和部分T-P负荷。此外，净化功能有关的水力停留时间，研究流域允许足够的保留污染物净化磷和COD含量和部分氮含量。
A long-term investigation on the water quality and hydrology was carried out for 8 years and 7 months (from October 1991 to April 2000) in a paddy field watershed using a circular irrigation system. The annual amount of rainfall ranged from 1270 to 2226mm and it was found that the amount of irrigation water tended to decrease as rainfall increased. Phosphorus and chemical oxygen demand (COD) concentrations tended to decrease with the river flowing down, whereas nitrogen concentrations showed no significant difference. The annual outflow loads (sum of the net-outflow load during irrigation periods and the outflow load during non-irrigation periods) of total nitrogen (T-N), total phosphorus (T-P), and COD ranged from 13.6 to 75.3kgha−1yr−1, −3.55 to 2.21kgha−1yr−1, and −24.7 to 48.5kgha−1yr−1, respectively. The negative values for T-P and COD loads indicated that the study watershed performed a purification function. The change in annual pollutant loads was primarily attributed to the amount of hydrological water volumes (the annual amount of rainfall or that of rainfall plus irrigation water) for T-N and COD loads and partially for T-P load. In addition, the purification function was related to the hydraulic retention time, and the study watershed allows sufficient retention for pollutant purification for phosphorus and COD contents and partially for nitrogen content.