生物滞留系统中^(15)NO_3^-的迁移转化及丹麦草对此过程的影响研究

TRANSFER AND TRANSFORMATION OF ^(15)NO_3^- IN BIORETENTION AND EFFECT OF DANISH GRASS IN THE PROCESS

通过构建模拟试验,利用^(15)N同位素示踪技术研究^(15)NO_3^-在生物滞留系统中的迁移转化以及丹麦草对此过程的影响。结果表明:在处理组(植物组)中约79.6%的NO_3^-发生了转化,其中反硝化作用、硝酸盐异化还原为铵(DNRA)、微生物固定和植物吸收参与转化分别占所添加^(15)N的32.7%、10.4%、24.2%和12.3%;在对照组中,约60.5%的NO_3^-发生了转化,其中反硝化作用、DNRA作用和微生物固定参与转化部分分别占所添加^(15)N的21.6%、19.5%和19.4%。两组中,反硝化作用均为优势反应,其次是微生物的固定和DNRA作用。在处理组中,丹麦草的直接吸收对NO_3^-的去除起到一定作用,同时间接促进了反硝化作用和微生物固定,加快了生物滞留系统对NO_3^-的去除。

A simulation experiment was constructed by using ^15N isotope tracing technique,to research the transfer and transformation of 15NO3^-in the bioretention and effect of Danish grass on this process. The results suggested that in the treatment group（ planted group）,about 79. 6% of the exogenous ^15N was transformed,the percentage of exogenous nitrate nitrogen removed by denitrification,dissimilatory nitrate reduction to ammonium（ DNRA）,microorganism immobilization,and plant absorption was 32. 7%,10. 4%,24. 2%,and 12. 3%,respectively. While in the control group,about 60. 5% of the exogenous ^15N was transformed,and the percentage of exogenous nitrate nitrogen removed by denitrification,DNRA and microorganism immobilization,was 21. 6%,19. 5% and 19. 4% respectively,during the 20 days experiment. According to the test result,denitrification was the dominant pathway for nitrate nitrogen removal,followed by microorganism immobilization and DNRA. In the treatment group,the direct absorption of the Danish grass played a certain role in the removal of NO3^-;meanwhile,the denitrification effect and microorganism immobilization was promoted,and the removal of NO3^- from the bioretention was accelerated.