Ling Xin, Xu Hui-Ping, Lu Guang-Hua
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Huan Jing Ke Xue. 2021 Jun 8;42(6):2868-2874. doi: 10.13227/j.hjkx.202011199.
To understand the effects of pharmaceuticals and personal care products (PPCPs) on nitrogen transformation in high-altitude rivers, we investigated the influence of the single and combined exposure of sulfamethoxazole (SMX) and 2-ethylhexyl-4-methoxycinnamate (EHMC) at different concentrations (0.01, 0.1, 1.0, 10, and 100 μg·L) on nitrification in the sediments of the Yarlung Zangbo River in sediment slurry experiments. All treatments significantly reduced nitrification rates, and the maximum inhibition rates induced by SMX and EHMC (alone and in combination) were 47%, 50%, and 66%, respectively. SMX significantly inhibited ammonia monooxygenase (AMO) activity in a concentration-dependent manner, with the inhibition rates ranging from 51% to 78%. The inhibitory effect of SMX combined with EHMC on AMO activity was similar to or stronger than that of SMX alone, and the inhibition rates ranged from 55% to 84%. All EHMC exposures also significantly inhibited AMO activity, but the inhibition rates decreased with an increase in EHMC concentrations. The gene abundance was significantly reduced in all the treatments, and SMX alone and in combination with EHMC induced stronger inhibitory effects than EHMC alone. SMX alone and in combination with EHMC significantly inhibited HAO activity, showing a similar concentration-effect relationship, but their combined exposure produced a stronger effect. SMX alone and in combination with EHMC also significantly decreased gene abundance in the sediments, and the maximum inhibition rates were 76% and 68%, respectively. Although exposure to higher concentrations of EHMC increased gene abundance and HAO activity, the notable decrease in nitrification rates in the sediments suggested that oxidation of ammonia to hydroxylamine catalyzed by AMO was the rate-limiting step in the nitrification process. The results also showed that PPCPs influence the activities of nitrifying communities in the sediments of high-altitude rivers and inhibit nitrification, and their coexistence further increases the pressure of nitrogen loading in aquatic ecosystems.
为了解药品和个人护理产品（PPCPs）对高海拔河流氮转化的影响，我们在沉积物悬液实验中研究了不同浓度（0.01、0.1、1.0、10和100 μg·L）的磺胺甲恶唑（SMX）和2-乙基己基-4-甲氧基肉桂酸酯（EHMC）单独及联合暴露对雅鲁藏布江沉积物中硝化作用的影响。所有处理均显著降低了硝化速率，SMX和EHMC（单独及联合）诱导的最大抑制率分别为47%、50%和66%。SMX以浓度依赖的方式显著抑制氨单加氧酶（AMO）活性，抑制率在51%至78%之间。SMX与EHMC联合对AMO活性的抑制作用与单独使用SMX相似或更强，抑制率在55%至84%之间。所有EHMC暴露也显著抑制AMO活性，但抑制率随EHMC浓度增加而降低。所有处理中 基因丰度均显著降低，单独的SMX及其与EHMC联合诱导的抑制作用比单独的EHMC更强。单独的SMX及其与EHMC联合显著抑制羟胺氧化酶（HAO）活性，呈现相似的浓度效应关系，但它们的联合暴露产生更强的效应。单独的SMX及其与EHMC联合也显著降低了沉积物中的 基因丰度，最大抑制率分别为76%和68%。尽管暴露于较高浓度的EHMC会增加 基因丰度和HAO活性，但沉积物中硝化速率的显著降低表明，AMO催化氨氧化为羟胺是硝化过程中的限速步骤。结果还表明，PPCPs影响高海拔河流沉积物中硝化群落的活性并抑制硝化作用，它们的共存进一步增加了水生生态系统中氮负荷的压力。
