大沟蓄排工程对水体中氮磷浓度变化的影响

The effect of N and P concentration change under the main ditches storage and drainage project

为研究大沟蓄排水对农田地表水和地下水水体污染的缓解和控制作用,选取车辙沟不同断面的氮磷含量进行观测,分析了不同降雨量和施肥量对氮磷变化的影响,开展了不同指标的相关性分析,比较了2个观测年份氮磷含量的变化情况。结果表明:(1)地表水中TN浓度整体随降雨量的增大而升高;降雨充足时地下水中TN及NO_3^--N对施肥响应较为明显。(2)地表水pH变化与氮素含量有一定联系,TN、NO_3^--N和NO_2^--N间的相关性非常好;地下水中pH、水温与氮磷的相关性较弱,NH_4^+-N与NO_3^--N的转化难度较大,但与TP线性关系较强。(3)大沟蓄水工程能有效减缓在施肥过程中地表水磷素的流失,对降低汛期地下水中TN浓度也有积极的影响,另外一定程度上造成地下水中磷素的升高,在推广区的不同农业耕作灌溉时期要注意对总磷排放的控制。

In order to study the alleviated influence on the pollution of surface water and groundwater in farmland by the impoundment of main ditchs, the nitrogen and phosphorus contents at different sections of Chezhegou had been observed, the impact of fertilization and precipitation in different months on the change process of N and P concentrations was analyzed, and the correlation analysis among different indexes was carried out. The results showed that:(1) TN concentration in surface water increased with rainfall, TN and NO3^--N concentrations in groundwater had an obvious response with fertilization process under the condition of adequate rainfall.(2) In surface water, pH and nitrogen content existed a certain relationship, while TN, NO3^--N and NO2^--N had a good correlation. In contrast, pH and temperature had a weak correlation with nitrogen and phosphorus in groundwater, and NH4^+-N had a difficult conversation with NO3^--N but a strong linear relationship with TP.(3) The main ditches storage and drainage project could alleviate phosphorus loss effectively, while had a positive effect on reducing TN concentration in underwater in flood season. On the other hand, it had given a rise to phosphorus concentration in groundwater for a certain extent, so controlling TP discharge should be paid attention to during different farming and irrigation time in promotion area.