摘要
为探讨三江平原水田面源污染物氮的输出机制,通过不同尺度田间原位实验,研究了氮在水田-田埂-渠系系统侧渗输出过程中氮含量、田埂截留率及侧渗速率的变化规律,并对水田氮流失负荷进行了量化.结果表明,近沟渠田埂宽度对侧渗速率和截留氮素的能力影响明显.随田埂宽度的增加,侧渗速率降低,而田埂对氮素的截留能力增强,其中,田埂对氨氮(NH 4+-N)的截留率大于总氮(TN)和硝态氮(NO 3--N).控制氮流失的最佳田埂宽度建议达到80～130 cm,渠系深度150 cm.现有耕作模式下,三江平原单位面积水田侧渗流失的TN为11 kg.hm-2,占当年施肥总量的6.7%,侧渗是水田氮素输出的一个重要途径;而单位面积水田TN流失负荷为25.3 kg.hm-2,占施肥总量的15.3%,三江平原大规模旱田改为水田的农业面源污染不容忽视.
The present study aims to discuss the export mechanism for nonpoint source pollution of nitrogen from paddy field in Sanjiang Plain. Different scales of in-situ experiments were performed to study the concentrations of nitrogen,the intercepting ratio of bund to nitrogen,and the lateral seepage velocity during the export process of nitrogen in the field-bund-trench system. The annual export load of nitrogen was also quantified. The results showed that the width of near-trench bund affected the lateral seepage velocity and the intercepting ability of bund to nitrogen obviously. With the increasing of the width, the velocity decreased, however, the intercepting ability increased. The intercepting ratio of bund to ammonia nitrogen was bigger than that of total nitrogen and nitrate nitrogen. In order to control the nitrogen loss, the width of near-trench bund and the depth of trench were suggested to be at 80-130 cm and 150 cm, respectively. Under the current cultivation mode,the export load of total nitrogen from lateral seepage was 11 kg. hm^-2 ,accounting for 6. 7 perceflt of the total fertilizer applied,demonstrating that lateral seepage was an important pathway of nitrogen loss. And the export load of total nitrogen was about 25.3 kg＂ hm-2, accounting for 15.3 percent of the total fertilizer applied, the agricultural nonpoint source pollution of the large scale development of paddy fields in Sanjiang Plain should not be neglected.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2011年第1期108-112,共5页
Environmental Science
基金
中国科学院知识创新工程重要方向项目(KZCX2-YW-Q06-03)
国家自然科学基金项目(40901128)
关键词
侧渗
氮
负荷
面源污染
三江平原
lateral seepage
nitrogen
load
nonpoint source pollution
Sanjiang Plain
