Spatial and Seasonal Variations of Stable Isotope Ratios of Particulate Organic Carbon and Nitrogen in the Surface Water of the Kuroshio
Spatial and Seasonal Variations of Stable Isotope Ratios of Particulate Organic Carbon and Nitrogen in the Surface Water of the Kuroshio
复制标题
黑潮表层水中颗粒有机碳和氮稳定同位素比的时空变化
DOI：
10.1029/2021jc017175
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Ono Tsuneo
中科院分区：
文献类型：
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作者：
Kodama Taketoshi;Nishimoto Atsushi;Horii Sachiko;Ito Daiki;Yamaguchi Tamaha;Hidaka Kiyotaka;Setou Takashi;Ono Tsuneo
2008年至2019年，对黑潮附近海域真光层颗粒有机质中碳、氮(δ13C和δ15N)的季节稳定同位素比值进行了研究。δ13C和δ15N在黑潮北缘划分的近岸和近海海域具有明显的季节性。季节平均δ13C在夏季最高(沿海和近海分别为−23.2%±11.1‰和−23.7%±11.1‰)，冬季最低(沿海和近海分别为−24.6%±10.8‰和−25.0%±0.90‰)。季节平均δ15N表现出不同的空间变异。δ-15N值以沿海地区冬季最低(1·0±1·9‰)，其余3个季节均升高至接近水平(∼3‰)。反之，近海海域δ15N从春季(2.5m±11.5‰)减少到夏季(1.2m±1.7m‰)。δ15N的这些空间和季节差异在广义线性模型和广义加性模型中显著，表明用于生物生产的氮源在沿海和近海以及季节之间是不同的。来自较深水域和河流的硝酸盐是沿海地区全年新生产的主要来源。夏季近岸海域大气沉降和固氮贡献较大，而冬季、春季和秋季近岸海域硝酸盐主要来源于深水。
Seasonal stable isotope ratios of carbon and nitrogen (δ13C and δ15N) in the particulate organic matter (POM) of the euphotic layer were investigated around the Kuroshio from 2008 to 2019 (n= 474). Significant seasonality in POM δ13C and δ15N were observed in the coastal and offshore areas divided by the northern edge of the Kuroshio. Seasonal mean δ13C was highest during the summer (−23.2 ± 1.1‰ and −23.7 ± 1.1‰ in coastal and offshore areas, respectively) and lowest during the winter (−24.6 ± 0.8‰ and −25.0 ± 0.9‰ in coastal and offshore areas, respectively) in both areas. Seasonal mean δ15N exhibited different spatial variations. The mean δ15N value in the coastal area was the lowest during the winter (1.0 ± 1.9‰) and increased to a similar level (∼3‰) during the other three seasons. In contrast, δ15N in the offshore area near the surface decreased from the spring (2.5 ± 1.5‰) to the summer (1.2 ± 1.7‰). These spatial and seasonal differences in δ15N are significant in generalized linear models and the generalized additive models, and suggest that the nitrogen sources used in biological production differ between coastal and offshore areas and between seasons. Nitrate originating in deeper water and rivers is the main sources used for new production throughout the year in the coastal area. Contributions from atmospheric deposition and nitrogen fixation are significant in the offshore area during the summer, while nitrate originating in deeper water is main during winter, spring, and fall in the offshore area.