Inorganic and Organic Nitrogen Uptake by Phytoplankton and Bacteria in Hong Kong Waters
Inorganic and Organic Nitrogen Uptake by Phytoplankton and Bacteria in Hong Kong Waters
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DOI：
10.1007/s12237-011-9433-3
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发表时间：
2011
影响因子：
2.7
通讯作者：
Xiangcheng Yuan;P. Glibert;Jie Xu;Hao Liu;Mianrun Chen;Hongbin Liu;K. Yin;P. Harrison
中科院分区：
文献类型：
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作者：
Xiangcheng Yuan;P. Glibert;Jie Xu;Hao Liu;Mianrun Chen;Hongbin Liu;K. Yin;P. Harrison
2008年夏季，在香港亚热带沃茨的四个对比环境中，测量了无机氮（NO3-和NH 4+）和有机氮（尿素、甘氨酸和谷氨酸）的吸收速率，并间接估计了细菌对总氮的吸收。此外，在东部沃茨，几天的降雨对氮吸收速率的影响进行了研究。虽然香港沃茨的氮主要以空气中的NO3-形式存在，但浮游植物吸收的氮主要形式通常是NH 4+和有机氮，包括尿素和氨基酸，而不是NO3-。因此，由于NO3−吸收量低，NO3−的周转时间很长（100天），大部分NO3−显然被离岸输送到更深的陆架沃茨。在NH 4+无法检测到的东部沃茨，NO3−吸收率与浮游植物细胞大小呈正相关。与此相反，谷氨酸吸收的潜在速率与浮游植物的大小呈负相关。在较小的尺寸级（0.7-2.8 μm）的氮吸收速率的影响较小的降雨事件，和较小的浮游植物似乎超过了较大的细胞在几天的降雨后。降雨后，大于8 μm的部分的表面（PN）特定氮吸收速率从0.02下降到0.0001 h-1，而较小的部分仅显示出一到三倍的下降。相反，细菌的生产和氮的吸收不受降雨事件的影响，细菌的氮吸收占总的浮游植物的氮吸收的10-60%。
Measurements of uptake rates of inorganic (NO3−and NH4+) and organic (urea, glycine, and glutamic acid) N, and indirect estimates of total N uptake by bacteria, were made in four contrasting environments in sub-tropical Hong Kong waters in summer of 2008. In addition, the effects of several days of rain on N uptake rates were studied in eastern waters. Although ambient NO3−was the dominant form of N in Hong Kong waters, the dominant N form taken up by phytoplankton was usually NH4+and organic N, including urea and amino acids, rather than NO3−. Hence, because of the low NO3−uptake, there was a long turnover time for NO3−(100 days), and most of the NO3−was apparently transported offshore into deeper shelf waters. In eastern waters where NH4+was undetectable, NO3−uptake rates were positively correlated with phytoplankton cell size. In contrast, potential rates of glutamic acid uptake were negatively correlated with phytoplankton size. N uptake rates in the smaller size fraction (0.7–2.8 μm) were less affected by the rain event, and smaller phytoplankton appeared to outcompete larger cells after several days of rain. The surface (PN)-specific N uptake rates in the >8-μm fraction decreased from 0.02 to 0.0001 h−1, while the smaller fraction only exhibited a one- to threefold decrease after the rainfall. In contrast, bacterial production and N uptake were not affected by the rain event, and bacteria N uptake accounted for 10–60% of the total N uptake by phytoplankton.