用于防控菜地排水中氮磷污染的缓冲带技术初探

太湖地区菜地复种指数高、施肥量大,其排水中N、P浓度较高,容易造成受纳水体的富营养化,针对这一问题,在野外构建了不同宽度的缓冲带,分别研究了缓冲带适宜种植的植物以及缓冲带不同宽度条件下对菜地排水中各形态N、P的拦截效果。结果表明,与水稻、空心菜相比,狗牙根更适合作为缓冲带植物;随着缓冲带宽度的增加,缓冲带对菜地排水中各形态N、P的拦截效率在逐渐增加,但其拦截效率的增幅却在逐渐降低,综合考虑N、P拦截所应达到的效果指标和节约用地的原则,缓冲带的最佳宽度应设置为1.5 m,此时缓冲带对溶解态N、P的处理效率分别为30.3%和54.9%,对颗粒态N和P的去除效果分别达到91.2%和94.4%,对总N(颗粒态+溶解态)和总P(颗粒态+溶解态)的去除效果分别达到56.1%和85.9%,缓冲带宽度为1.5 m时菜地和缓冲带面积之比为100:11。

Pre-test of buffer zones for preventing nitrogen and phosphorus pollution from vegetable drainage

Due to high cropping index, high fertilization load and some other factors, the nitrogen and phosphorus concentrations in the drainage of vegetable fields were high, which was more likely to cause eutrophication to the receiving water bodies. In response to such problem, the experiment constructed the buffer zones, firstly explored the appropriate species of the interception plants in the buffer strip, and then studied the removal efficiency of different forms of nitrogen and phosphorus in the vegetable drainage of different widths of the buffer strip. The results showed that, compared with oryza sativa and ipomoea aquatica, cynodon dactylon was more suitable to be interception plants in the buffer zones; with the width of buffer zones increased, the removal efficiency of different forms of nitrogen and phosphorus in the vegetable drainage of the buffer zones increased, but the increase rate of the removal efficiency reduced gradually. When the target removal efficiency of nitrogen and phosphorus and the principle of land conservation were considered, the optimal width of buffer zones should be set to be 1.5 m, while the vegetable land area and buffer zones area ratio was 100:11.