<br>氧化还原梯度如何潜在影响硝酸盐还原与硫循环：对以污水为主的河流潜流区氮循环的新见解,Science of the Total Environment

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氧化还原梯度如何潜在影响硝酸盐还原与硫循环：对以污水为主的河流潜流区氮循环的新见解
Science of the Total Environment ( IF 8.2 ) Pub Date : 2024-01-12 , DOI: 10.1016/j.scitotenv.2024.170070
Ziyi Wang ₁ , Longfei Wang ₁ , Yi Li ₁ , Yina Zou ₂ , Xing Hou ₃ , Linqiong Wang ₄

Affiliation

在接收废水处理厂污水的河流的潜流带 (HZ) 中，可变氧化还原梯度中的耦合 N 和 S 循环尚不清楚。以两条具有代表性的污水为主的河流作为模型系统，采用宏基因组方法来探索 HZ 的时空氧化还原分区和系统内的 N/S 循环过程。结果表明，硝酸盐还原是HZ 中基本的氮途径。有趣的是，DNRA与硫还原相结合，以及反硝化与硫氧化相结合分别在好氧区和缺氧区丰富。在缺氧区检测到较低的硝酸盐浓度（0-2.72 mg-N/L）和更丰富的反硝化（，）和硫氧化（，）相关基因。相反，在好氧区硝酸盐浓度（0.07–4.87 mg-N/L）以及参与硫还原（，）和DNRA（）的基因丰度更为丰富。因此，结果验证了在活性硫循环存在的情况下，限氧条件并没有抑制而是促进了反硝化过程。污水排放区和下游区域的基因编码序列相对丰度较高（相对于所有氮循环过程为3%~5%），充分证实了HZ能够减轻该地区的NO排放。通过共现网络分析揭示了功能关键类群。结构方程模型表明，N/S 循环基因受到功能关键类群的积极影响，尤其是 N 循环基因。功能性关键类群被证明是由氧化还原梯度驱动的，证明了它们在介导 N/S 循环过程中的积极作用。当氧化还原条件振荡时，对硝酸盐还原与硫循环的促进作用得到阐明，为减轻入流河流中的氮污染和温室气体排放提供了新的视角。

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How redox gradient potentially influences nitrate reduction coupled with sulfur cycling: A new insight into nitrogen cycling in the hyporheic zone of effluent-dominated rivers

The coupled N and S cycling in variable redox gradients in the hyporheic zone (HZ) of the rivers receiving effluents from wastewater treatment plants is unclear. Using two representative effluent-dominated rivers as model systems, a metagenome approach was employed to explore the spatiotemporal redox zonation of the HZ and the N/S cycling processes within the system. The results manifested that nitrate reduction represented the fundamental nitrogen pathway in the HZ. Interestingly, DNRA coupled with sulfur reduction, and denitrification coupled with sulfur oxidation were respectively abundant in the oxic and anoxic zone. Lower nitrate concentration (0–2.72 mg-N/L) and more abundant genes involved in denitrification (, ) and sulfur oxidation (, ) were detected in the anoxic zone. Contrarily, the nitrate concentration (0.07–4.87 mg-N/L) and the abundance of genes involved in sulfur reduction (, ) and DNRA () wer observed more abundant in the oxic zone. Therefore, the results verified the oxygen-limited condition did not suppress but rather facilitated the denitrification process in the presence of active S cycling. The high relative abundances of gene encoding sequence (3–5 % relative to all nitrogen-cycling processes) in both the effluent-discharging area and downstream area highly confirmed that HZ was capable of alleviating the NO emission in the region. The functional keystone taxa were revealed through co-occurrence network analysis. The structural equation model shows that the genes of N/S cycling were positively impacted by functional keystone taxa, especially the N cycling genes. Functional keystone taxa were proven driven by the redox gradient, demonstrating their positive roles in mediating N/S cycling processes. The promoting effect on nitrate reduction coupled with sulfur cycling was clarified when redox conditions oscillated, providing a new perspective on mitigating nitrogen pollution and greenhouse gas emissions in effluent-receiving rivers.

更新日期：2024-01-12

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