| 前期干旱天数对生物滞留系统除氮性能的影响 |
| 摘要点击 2911 全文点击 957 投稿时间：2020-05-07 修订日期：2020-07-16 |
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| 中文关键词 生物滞留系统 干湿交替 前期干旱天数(ADD) 除氮 氮还原酶 微生物群落 |
| 英文关键词 bioretention system alternate drying-rewetting antecedent dry days (ADD) nitrogen removal nitrogen reductases microbial community |
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| 中文摘要 |
| 生物滞留系统是海绵城市建设的优选设施之一，但其对氮素的去除特性受前期干旱天数（ADD）影响较大.通过设计不同ADD（1、2、3、5、7、12和22 d）条件，形成7种恒定干湿交替周期的生物滞留系统，研究ADD对氮素去除性能的影响，并根据不同ADD条件下氮还原酶和微生物种群的空间变化规律，分析ADD对生物滞留系统除氮过程的影响机制.结果表明，生物滞留系统对NH4+-N的去除受ADD影响不显著，但去除率会因填料水力渗透性能和植物生长状况的影响而呈现较大的波动性；当ADD从7 d增至22 d时，NO3--N和TN去除率随ADD的增加而减小.ADD在一定程度上影响土壤中硝酸还原酶（NaR）、亚硝酸还原酶（NiR）和羟胺还原酶（HyR）的空间分布；生物滞留系统中氮素转化过程受淹没层含水率调控，且NO3--N可通过淹没层中氮还原酶的次第催化还原作用发生硝酸盐异化还原成铵（DNRA），进而影响NH4+-N的去除.ADD会显著改变土壤微生物群落结构及其空间分布，影响系统对不同形态氮的综合去除能力.其中，较短ADD（1~5 d）条件下，具反硝化能力的Firmicutes为优势菌门，其优势菌属Clostridium_sensu_stricto_1还具有DNRA功能.结果证实，恒定干湿条件下ADD对生物滞留系统中氮素的去除能力、氮还原酶活性以及微生物种群结构空间变化存在一定的影响. |
| 英文摘要 |
| Bioretention systems have become an optimal technology during the construction of the sponge city, but its nitrogen removal performance can be affected by antecedent dry days (ADD). This study was designed to investigate the effects of different lengths of ADD (1,2,3, 5, 7, 12, and 22 d) on nitrogen removal performance using a series of laboratory-scale bioretention systems to form seven constant alternate drying-rewetting regimes. The influence mechanism was further investigated by analyzing the spatial distribution of nitrogen reductase activity and microbial community structure under different drying-rewetting regimes. The results showed that the ammonium removal efficiency was not significantly affected by ADD, while exhibiting high variation depending on the hydraulic permeability of the filler and plant growth conditions. The nitrate and total nitrogen removal efficiency decreased as the length of ADD increased form 7 d to 22 d. In addition, the spatial distribution of nitrate reductase (NaR), nitrite reductase (NiR), and hydroxylamine reductase (HyR) were affected by ADD to some extent. It was found that the soil moisture of submerged layer (SL) regulated the nitrogen processes. The nitrate dissimilatory reduction to ammonium (DNRA) can occur in the SL through secondary catalytic reduction by nitrogen reductases, thus affecting the removal of ammonium. The soil microbial community structure and its spatial distribution could be altered by ADD significantly, and the removal of multiple nitrogen species was partly affected. Thereinto, under shorter ADD values of 1, 2, 3, and 5 d, the dominant phylum was Firmicutes, a group of denitrifying microbes, and its dominant genus, Clostridium_sensu_stricto_1, also had the function of DNRA. The results of the study confirmed that ADD has a certain effect on the nitrogen removal capacity and nitrogen reductase activity, while resulting in spatial changes in the microbial community structure in the bioretention system under constant drying-rewetting conditions. |
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