沟渠及塘堰湿地系统对稻田氮磷污染的去除试验

Experiments on Removal Effects of Ditch-Pond Wetland System on N and P Pollutants from Paddy Field

为研究原位状态下灌区沟渠及塘堰湿地系统对稻田氮磷污染的去除效应和规律,在湖北省漳河灌区选取农沟～斗沟尺度的3段典型排水沟渠和一处塘堰,分别于2009—2010年5—9月水稻生育期在沟渠和塘堰进出水口采集水样进行氮磷浓度化验分析。结果表明,灌区农沟～斗沟尺度典型排水沟渠对总氮、硝态氮、铵态氮、总磷整体去除率分别为44.6%、9.9%、37.3%、35.1%;塘堰对总氮、硝态氮、铵态氮、总磷的平均去除率分别为15.2%、15.6%、30.2%、-6.5%。典型沟渠和塘堰对氮磷污染的去除表现出一定的抗冲击自修复性。原位条件下,由于排水沟中水力停留时间都不长,使得种植不同植被的沟段之间对氮磷的去除效应差异性不明显。塘堰湿地系统中植被的选育及其管理对去除稻田排水氮磷污染具有重要意义。

In order to study removal effect and laws of irrigation area ditch-pond wetlands system to paddy drainage water nitrogen and phosphorus pollutants under natural condition, three typical drainage ditches and one pond at the scale from field ditch to lateral ditch were selected in Zhanghe Irrigation System, Hubei Province. Water samples at inlet and outlet of the ditches and pond were collected for nitrogen and phosphorus analysis during the whole rice growing season from May to September in 2009 and 2010. The results show that the average total re- moval rates from field ditch to lateral ditch on total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus in drainage water from paddy field were 44.6%, 9.9%, 37.3% and 35.1%, respectively; and the average removal rates of typical pond on total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus in drainage water were 15.2%, 15.6%, 30.2% and -6.5%, respectively. The experiment also showed certain anti-impact and self-repairing effects of the wetland system to nitrogen and phosphorus pollutants. Generally the removal rate was significant in the earlier growing stage of paddy rice, then decreased or even appeared negative value in the middle, and finally recovers in the later growing stage. In natural condition, the hydraulic retention time（HRT） of each ditch was not long enough, which made the difference of removal effect on nitrogen and phosphorus pollutants between different ditches not significant. The pond＇s removal effect on paddy drainage water nitrogen and phosphorus pollutants in 2009 when it was planted with pollen typhae were better than that in 2010 without pollen typhae in the pond. The cultivation of vegetation and its management of ditches-pond wetland system is of great significance to remove drainage water nitrogen and phosphorus pollutants from paddy field.