Iron and silicic acid concentrations together regulate Si uptake in the equatorial Pacific Ocean
Iron and silicic acid concentrations together regulate Si uptake in the equatorial Pacific Ocean
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DOI：
10.4319/lo.2008.53.3.0875
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发表时间：
2008-05
影响因子：
4.5
通讯作者：
M. Brzezinski;C. Dumousseaud;J. Krause;C. Measures;D. M. Nelson
中科院分区：
文献类型：
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作者：
M. Brzezinski;C. Dumousseaud;J. Krause;C. Measures;D. M. Nelson
在110°W和140° W之间的赤道太平洋上升流区的两次航行中，考察了添加Si和Fe对磷酸吸收速率的影响。硅的最大吸收速率（Vmax）与平均值0.026 ± 0.007 h−1（n = 29）高度一致，这意味着硅藻的最大生长速率约为0.6 d−1。硅吸收的半饱和常数（KS）也显示出很小的变化，平均值为1.7 ± 0.7 mmol L−1 Si（OH）4。没有生态显着的空间或时间模式，无论是Vmax或KS观察。在环境强酸浓度（Vamb）下的Si吸收速率与Vmax的比较表明，环境[Si（OH）4]将Vamb限制到Vmax的平均63% ± 13%。Fe的添加也引起了Vmax和Vamb的显着增加，表明Si的吸收速率也受到环境[Fe]的调节。Fe添加物对KS有不同的影响，但它们始终增加了Vmax和动力学曲线的初始斜率（Vmax：KS），因此硅藻组合物在低浓度下吸收Si（OH）4的能力。添加Fe或Si使Si吸收速率分别增加87% ± 59%和69% ± 31%，表明这两种元素在限制原位Si吸收速率方面的作用几乎相等。当同时添加Si和Fe时，观察到Si吸收速率的最大平均增加172% ± 43%，这意味着Si和Fe一起限制Si吸收速率几乎三倍。
The effects of added Si and Fe on the rate of silicic acid uptake were examined during two cruises to the equatorial Pacific upwelling zone between 110°W and 140°;W. Maximum uptake rates of Si (Vmax) were highly consistent with a mean of 0.026 ± 0.007 h−1(n = 29), implying maximum diatom growth rates of ~0.6 d−1. Half‐saturation constants for Si uptake (KS) also showed little variance, averaging 1.7 ± 0.7 mmol L−1 Si(OH)4. No ecologically significant spatial or temporal patterns for either Vmax or KS were observed. Comparison of Si uptake rates at the ambient silicic acid concentration (Vamb) with Vmax indicated that the ambient [Si(OH)4] restricted Vamb to an average of 63% ± 13% of Vmax. Fe additions also caused significant increases in both Vmax and Vamb, indicating that the rate of Si uptake was also regulated by the ambient [Fe]. Fe additions had a variable effect on KS, but they consistently increased both Vmax and the initial slope of the kinetic curve (Vmax :KS), and thus the diatom assemblages’ ability to take up Si(OH)4 at low concentrations. Added Fe or Si increased Si uptake rates by 87% ± 59% and 69% ± 31%, respectively, indicating nearly equal roles for the two elements in limiting rates of Si uptake in situ. The largest average increase in Si uptake rates, 172% ± 43%, was observed when both Si and Fe were added, implying that together Si and Fe restricted Si uptake rates by almost a factor of three.