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首页> 外文期刊>Journal of plankton research >Inhibition kinetics of nitrate uptake by ammonium in size-fractionated oceanic phytoplankton communities: implications for new production and f-ratio estimates
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Inhibition kinetics of nitrate uptake by ammonium in size-fractionated oceanic phytoplankton communities: implications for new production and f-ratio estimates

机译：大小分离的海洋浮游植物群落中铵盐吸收硝酸盐的动力学：对新产量和产值比的影响

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摘要

Ammonium inhibition of nitrate uptake by natural phytoplankton communities was investigated in two size fractions (< 2 and > 2 mu m) in the northeast basin of the Atlantic Ocean. Kinetics of the inhibition process were assessed in surface waters by measuring nitrate uptake rates over a range of ammonium concentrations with N-15 tracer techniques. Extremely low levels of ammonium were shown to significantly inhibit nitrate uptake in both small and large fractions at all seven sampling stations. The half-inhibition constant was significantly lower and the maximum inhibition was generally higher in the < 2 mu m (K-i = 60 +/- 29 nmol L-1, I-max = 0.74 +/- 0.13) compared to the > 2 mu m size fractions (K-i = 132 +/- 72 nmol L-1, I-max = 0.67 +/- 0.12), demonstrating that the ammonium inhibition was more pronounced in the small size class. Based on the surface ammonium concentrations of the study area, inhibition kinetics parameters predict a mean reduction of nitrate uptake of 27.8% (+/- 12.6) for < 2 mu m fraction and of 16.5% (+/- 12.8) for > 2 mu m fraction which leads to a mean reduction of 20.8% (+/- 11.9) for the total community. The importance of the inhibition size specificity in regulating new production and the f-ratio is discussed.
机译：在大西洋东北盆地的两个大小部分（<2和> 2μm）中研究了天然浮游植物群落对铵盐吸收硝酸盐的抑制作用。通过使用N-15示踪技术测量一系列铵浓度范围内的硝酸盐吸收速率来评估地表水中抑制过程的动力学。在所有七个采样站中，极低水平的铵盐均会显着抑制大小部分的硝酸盐吸收。与> 2μm相比，在<2μm（Ki = 60 +/- 29 nmol L-1，I-max = 0.74 +/- 0.13）中，半抑制常数明显较低，而最大抑制率通常更高。 m大小的分数（Ki = 132 +/- 72 nmol L-1，I-max = 0.67 +/- 0.12），表明在小尺寸类别中，铵的抑制作用更为明显。根据研究区域的表面铵盐浓度，抑制动力学参数预测，<2微米级分的硝酸盐吸收平均降低量为27.8％（+/- 12.6），> 2微米级则平均降低16.5％（+/- 12.8）。 m分数导致整个社区平均减少20.8％（+/- 11.9）。讨论了抑制大小特异性在调节新产量和f比率中的重要性。

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