Key Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Jianghan Plain-Honghu Lake Station for Wetland Ecosystem Research, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430077, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei, Jianghan Plain-Honghu Lake Station for Wetland Ecosystem Research, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430077, China; School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430078, China.
Sci Total Environ. 2024 Nov 15;951:175745. doi: 10.1016/j.scitotenv.2024.175745. Epub 2024 Aug 24.
With increasing land resource constraints, wetlands, as ecological hotspots, are expected to enhance biogeochemical processes to mitigate nitrogen (N) pollution, particularly nitrate-nitrogen (NO-N). However, the interactions among bacteria, algae, and macrophytes in wetlands, which are crucial for N removal, remain largely unknown. This study explored how macrophyte coverage influences bacterial-algal interactions, shifting from mutualism to inhibition, thereby affecting N removal. Moderate coverage enhanced NO-N and total nitrogen (TN) removal (P < 0.05), which was correlated with increased microbial abundance (P < 0.05). This may have resulted from moderate algal photosynthesis, reduced physiological stress, and the expansion of ecological niches for microbes. Insufficient coverage promoted algal growth (chlorophyll-a > 31.8 μg·L), leading to increased competition for substrates and elevated pH, which further inhibited bacterial activity. Excessive coverage also inhibited bacterial activity by reducing illumination and oxidation-reduction potential. Consequently, insufficient and excessive coverage decreased N removal efficiencies by 2.7-15.7 % (NO-N) and 3.7-11.1 % (TN) while increasing methane emission potential by 1.4-6.9 times compared with moderate coverage. These findings offer insights into solving NO-N contamination using near-natural methods and balancing the ecological and practical considerations for small wetlands.
随着土地资源约束的加剧，湿地作为生态热点，有望增强生物地球化学过程，以减轻氮（N）污染，特别是硝酸盐氮（NO-N）。然而，湿地中对 N 去除至关重要的细菌、藻类和大型植物之间的相互作用在很大程度上仍不清楚。本研究探讨了大型植物覆盖度如何影响细菌-藻类相互作用，从共生关系转变为抑制关系，从而影响 N 的去除。适度的覆盖度增强了 NO-N 和总氮（TN）的去除（P<0.05），这与微生物丰度的增加（P<0.05）相关。这可能是由于适度的藻类光合作用增加、生理压力降低以及微生物生态位的扩大。覆盖度不足促进了藻类的生长（叶绿素-a>31.8μg·L），导致对基质的竞争增加和 pH 值升高，从而进一步抑制了细菌的活性。过度的覆盖度也通过减少光照和氧化还原电位来抑制细菌的活性。因此，与适度覆盖相比，不足和过度覆盖分别降低了 2.7-15.7%（NO-N）和 3.7-11.1%（TN）的 N 去除效率，同时甲烷排放潜力增加了 1.4-6.9 倍。这些发现为使用近自然方法解决 NO-N 污染以及平衡小型湿地的生态和实际考虑因素提供了思路。
