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首页> 外文期刊>Estuarine Coastal and Shelf Science >Primary productivity and nitrogen assimilation with identifying the contribution of urea in Funka Bay, Japan
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Primary productivity and nitrogen assimilation with identifying the contribution of urea in Funka Bay, Japan

机译：日本Funka湾的初级生产力和氮同化，确定尿素的贡献

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Primary production is supported by utilization of several forms of nitrogen (N), such as nitrate, ammonium, and urea. Nevertheless, only few studies have measured the concentration and uptake of urea despite its importance as a nitrogenous nutrient for phytoplankton. We measured primary productivity monthly at four depths within the euphotic zone using a clean technique and the C-13 method by a 24 h in situ mooring incubation over a year in Funka Bay, a subarctic coastal area in Japan, to make better updated estimates (re-evaluation) of annual primary production. Nitrogenous (N) nutrient assimilation rates (nitrate, ammonium and urea) were also measured to elucidate the relative contributions of these nutrients to autotrophic production and to distinguish between new and regenerated production. The estimated annual primary production was 164 g C m(-2), which was 40-60% higher than the previously reported values in the bay. Use of a clean technique and more frequent measurement during the spring bloom may have contributed to the higher rates. The production during the spring bloom was 56.5 g C m(-2), accounting for 35% of the annual production. The maximum daily productivity occurred in the bloom at 1.4 g C m(-2) d(-1), which is one of the highest values among the world embayments. The annual primary production in the bay was classified as mesotrophic state based on the classification by Cloern et al. (2014). The assimilation rate of nitrate was maximal at 54 nmol N L-1 h(-1) during the bloom. During the post-bloom periods with nitrate depleted conditions, assimilation rates of ammonium and urea increased and accounted for up to 85% of the total N assimilation. The assimilation rate of urea was almost comparable to that of ammonium throughout the year. Taking urea into account, the f-ratio ranged from 0.15 under the nitrate-depleted conditions to 0.8 under the spring bloom conditions. These ratios were overestimated by 50% and 10%, respectively, if urea uptake was eliminated. We provide a valuable data for the primary production dataset in the world's ecosystems, and show that urea plays an important role in supporting regenerated production during late spring and summer. (C) 2015 Elsevier Ltd. All rights reserved.
机译：通过利用多种形式的氮（N）（例如硝酸盐，铵和尿素）来支持初级生产。然而，尽管尿素作为浮游植物的一种氮素营养很重要，但只有很少的研究测量了尿素的浓度和吸收。我们采用清洁技术和C-13方法，通过在日本亚北极沿海地区Funka湾进行了长达24小时的原位系泊孵化，在每月的四个深度处测量了一次生产力，以进行更好的更新估算（重新评估）的年度一次生产。还测量了氮（N）养分的同化率（硝酸盐，铵和尿素），以阐明这些养分对自养生产的相对贡献，并区分新养和再生养。估计的年度初级产量为164 g C m（-2），比海湾先前报告的值高40-60％。在春季开花期间使用清洁技术和更频繁地进行测量可能是造成较高比率的原因。春季开花期间的产量为56.5 g C m（-2），占年产量的35％。每天最大的生产力出现在花开时为1.4 g C m（-2）d（-1），这是世界范围内最高的值之一。根据Cloern等人的分类，该海湾的年度初级生产被分类为中营养状态。 （2014）。在开花期间，硝酸盐的同化率在54 nmol N L-1 h（-1）时最大。在硝酸盐耗尽的花后时期，铵和尿素的同化率增加，占氮吸收总量的85％。全年尿素的同化率几乎可与铵同化。考虑到尿素，f比率在硝酸盐耗尽条件下为0.15，在春季开花条件下为0.8。如果消除尿素吸收，则这些比率分别被高估了50％和10％。我们为世界生态系统中的初级生产数据集提供了有价值的数据，并表明尿素在支持春末夏初的再生生产中发挥着重要作用。 （C）2015 Elsevier Ltd.保留所有权利。

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