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首页> 外文期刊>Environmental Science & Technology >Enhancement and Inhibition of Denitrification by Fluid-Flow and Dissolved Oxygen Flux To Stream Sediments
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Enhancement and Inhibition of Denitrification by Fluid-Flow and Dissolved Oxygen Flux To Stream Sediments

机译：增强和抑制液流和溶解氧通量沉积物反硝化作用

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摘要

Microscale measurements of nitrate (NO_3~-) and dissolved oxygen (DO) concentrations in sediments were made in a laboratory channel under turbulent fluid-flow conditions to examine the effects of DO flux on denitrification rates. DO concentrations and flux within sediments increased with increasing velocity in the surface water. Under low fluid-flow conditions (shear stress velocity, u* < 0.23 cm s~(-1)), increasing velocity increased NO_3~- loss from the bulk flow. For high fluid-flow conditions (u* > 0.39 cm s~(-1)), increasing velocity inhibited NO3_3~-loss. Sediment cores were collected and sliced to measure the depth distribution of denitrifying biomass in sediments. Quantities of nirK and nirS genes were higher within the surface layer and decreased with depth in the sediments. Microscale concentration profiles of DO and NO_3~- revealed that denitrification occurs within a thin region just below the oxic-anoxic interface in sediments. The interplay of mass transfer and DO flux generated threshold conditions for NO_3~- loss by denitrification. These results suggest that for a given sediment and environmental conditions (chemical, physical, microbiological), there exists an optimal range in velocities for enhancing denitrification in aquatic systems.
机译：在湍流条件下，在实验室通道中对沉积物中的硝酸盐（NO_3〜-）和溶解氧（DO）浓度进行了微型测量，以研究DO通量对反硝化速率的影响。沉积物中的溶解氧浓度和通量随地表水中流速的增加而增加。在低流量条件下（剪切应力速度，u * <0.23 cm s〜（-1）），增加流速会增加整体流量中的NO_3〜-损失。对于高流量条件（u *> 0.39 cm s〜（-1）），增加流速会抑制NO3_3〜的损失。收集沉积岩心并切成薄片，以测量沉积物中反硝化生物量的深度分布。表层内nirK和nirS基因的数量较高，随着沉积物深度的增加而降低。 DO和NO_3〜-的微观浓度分布图表明，反硝化作用发生在沉积物中氧-氧-氧界面正下方的薄区域中。传质与溶解氧通量的相互作用产生了脱硝导致NO_3〜-损失的阈值条件。这些结果表明，对于给定的沉积物和环境条件（化学，物理，微生物学），存在用于增强水生系统反硝化作用的最佳速度范围。

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  • 来源
    《Environmental Science & Technology》 |2008年第1期|119-125|共页
  • 作者

    BEN L. OCONNOR; MIKI HONDZO;

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  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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