螺-草水质净化系统氮素环境归趋的实验研究

Experimental Study on the Environmental Fate of Nitrogen in Snail-Macrophyte Ecosystem for Water Purification

通过构建螺-草模拟系统并利用稳定同位素示踪技术研究池塘螺-草水质净化系统中氮素的环境归趋,结果表明,以底泥为基质的螺-草系统中,实验结束后苦草湿重增加了580%,分株数增加了6.6株,苦草根部吸收储存了1.07%的15N,苦草茎叶吸收储存了7.74%的15N,环棱螺吸收储存较少,只占0.06%,底泥滞留了5.73%的15N.结果分析表明:螺-草水质净化系统中苦草对水体中溶解态氮的吸收较少,沉积物是苦草生长的主要营养源;水体中氨氮主要通过沉积物-水界面进行迁移转化,大部分被苦草根系吸收利用转化为生物体,少部分通过硝化/反硝化作用去除,其余则滞留于沉积物;苦草是系统中氮素去除的最终载体,环棱螺的存在通过促进苦草生长及加强泥-水界面硝化和反硝化作用来加快系统中氮素的去除.因此,在养殖的不同阶段合理配置螺-草结构是整个养殖过程中水质调控的关键.

A snail-macrophyte simulation system was built and isotope tracer technique was adopted to study the environmental fate of nitrogen in snail-macrophyte purification system,the results showed that： Vallisneria spiralis increased its wet weight by 580% and its number by 6.6 ramets,moreover,Vallisneria spiralis absorbed 1.07% 15 N by the roots and 7.74% by stems and leaves,while Bellamya only absorbed 0.06%.And 5.73% 15 N was retained in the sediment.Through analyzing of the results,it indicated that： in such simulation system,sediment was the main nutrition source for the growth of Vallisneria spiralis,which absorbed only few dissolved nitrogen from water;ammonium nitrogen in water was transformed mainly in the sediment-water interface,most of which was absorbed by Vallisneria spiralis,a small amount was removed through nitrification and denitrification,and the rest was kept by sediment;Vallisneria spiralis was final vector for removing nitrogen in the system,and Bellamya could also boost the growth of Vallisneria spiralis and strengthen the processes of nitrification and denitrification,thus promoting the nitrogen removal from the system indirectly.So,during the period of culture,rational allocation of snail-macrophyte structure in different stages plays an important role in controlling water quality in ponds.