太湖地区高效除氮浮萍品种的筛选及其除氮机理的初步研究

农业面源污染是引起太湖水体富营养化的重要因素，而植物生态工程技术在面源污染的治理中起到了很大的作用。本文调查和收集了太湖地区13个稻田浮萍种质资源，研究了不同浮萍品种对低浓度稻田排水中氮（N）素的去除效果及其初步除N机理。结果表明，在实验营养条件下，4种浮萍品种中紫背浮萍（Spirodela polyrrhiza）具有最高的N去除效率，其次是少根紫萍（Spirodela oligorrhiza）或稀脉浮萍（Lemna perpusilla），而除N效果最低的品种是青萍（Lemna minor）。供试材料对水体中总N的去除率范围为57.3% ~ 85.2%，其中紫背浮萍HZ1具有最高的去除效果，15天后总N去除率可达到85%，青萍WX3去除效果最低，15天后去除率仅为57%。两个浮萍品种进行比较发现，HZ1生物量增长速度慢，鲜重和干重平均倍增时间分别为7.96天和7.82天，而WX3的鲜重和干重倍增时间分别为5.20天和4.73天。另一方面，HZ1和WX3的含N量分别为4.9% 和5.7%。由此可以推知，紫背浮萍HZ1高效除N的主要机理不是通过生物体吸收，而更可能是微生物或化学作用共同引起。

Screening Duckweed(Lemnaceae)Species for Efficient Removal of Water-Body's Nitrogen in the Tai Lake Region and Preliminary Study on Nitrogen Removal Mechanism

Non-point agricultural sources are the major cause of water eutrophication in Tai Lake. Phyto-remediation techniques are playing an increasingly important role in non-point pollution research. This study compared nitrogen removal efficiency among different duckweed species growing in paddy field drainage water with low nitrogen concentrations in the Tai Lake region. Nitrogen removal efficiency declined in the order of Spirodela polyrrhiza > Spirodela oligorrhiza, Lemna perpusilla > Lemna minor, total nitrogen removal efficiency among the duckweed species in this study ranged from 57.3% to 85.2%. The removal efficiency in 15 days of HZ1 was highest (85.2%) while WX3 was 57.3%. The biomass production rates of WX3 were higher than that of HZ1, the doubling time of fresh and dry weights were 5.20 days and 4.73 days for WX3 but 7.96 days and 7.82 days for HZ1, respectively. The nitrogen contents were 4.9% and 5.7% in HZ1 and WX3, respectively, however the nitrogen removal efficiency of HZ1 was significantly higher than that of WX3. It suggests that nitrogen removal from water is due to microbial or chemical processes rather than bioaccumulation.