Yao Lu, Chen Chengrong, Liu Guihua, Li Feng, Liu Wenzhi
Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences Lumo Road No. 1, Wuchang District Wuhan 430074 PR China
Australian Rivers Institute and Griffith School of Environment, Griffith University Nathan 4111 Australia.
RSC Adv. 2018 Jan 9;8(4):1875-1883. doi: 10.1039/c7ra11956a. eCollection 2018 Jan 5.
Sediment nitrification plays a vital role in nitrogen (N) biogeochemical cycling and ecological function of an aquatic ecosystem. The relative importance of environmental factors and nitrifying microbial communities in regulating sediment nitrification process has received less attention, especially in aquatic habitats where high N loads are frequently detected. Here, we report the potential nitrification rates of 35 sediment samples from 10 shallow lakes in the Yangtze River basin. The diversity and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were quantified using archaeal and bacterial genes. The results showed that there was no significant difference in sediment nitrification rates among sites of different trophic state. The nitrification rates were positively related to water chlorophyll-a, sediment N and carbon levels, but not significantly associated with diversity and abundance of ammonia-oxidizing microorganisms and submerged plants. Interestingly, the abundance and diversity of sediment AOB but not AOA communities were significantly influenced by trophic state. In addition, AOB communities were more sensitive to changes in local environments and catchment land uses than the AOA communities. Using path analysis, we found that 55-60% of the indirect effect of catchment land uses on nitrification rates was mediated sediment N content. Our findings suggest that, although nitrification is a microbial process, variation in sediment nitrification rates in Yangtze lakes is mainly explained by abiotic factors but not by microbial abundance and diversity.
沉积物硝化作用在水生生态系统的氮生物地球化学循环和生态功能中起着至关重要的作用。环境因素和硝化微生物群落对沉积物硝化过程的相对重要性较少受到关注，特别是在经常检测到高氮负荷的水生生境中。在此，我们报告了长江流域10个浅水湖泊中35个沉积物样本的潜在硝化速率。利用古菌和细菌基因对氨氧化古菌（AOA）和细菌（AOB）的多样性和丰度进行了定量分析。结果表明，不同营养状态的站点间沉积物硝化速率无显著差异。硝化速率与水体叶绿素a、沉积物氮和碳含量呈正相关，但与氨氧化微生物和沉水植物的多样性和丰度无显著关联。有趣的是，沉积物AOB群落的丰度和多样性而非AOA群落受营养状态的显著影响。此外，与AOA群落相比，AOB群落对当地环境和集水区土地利用变化更为敏感。通过路径分析，我们发现集水区土地利用对硝化速率的间接影响中有55%-60%是由沉积物氮含量介导的。我们的研究结果表明，尽管硝化作用是一个微生物过程，但长江湖泊沉积物硝化速率的变化主要由非生物因素而非微生物丰度和多样性来解释。
