Stable carbon and nitrogen isotopic compositions of sinking particles in the northeast Japan Sea
Stable carbon and nitrogen isotopic compositions of sinking particles in the northeast Japan Sea
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DOI：
10.2343/geochemj.37.261
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发表时间：
2003-04
影响因子：
0.8
通讯作者：
T. Nakanishi;M. Minagawa
中科院分区：
文献类型：
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作者：
T. Nakanishi;M. Minagawa
1998年8月至1999年10月在日本海东北部进行了沉积物捕获实验和沉降有机颗粒的稳定碳和氮同位素分析，以确认浮游植物生产的季节变化和沉降颗粒的同位素组成之间的关系。部署在1090米的沉积物收集器成功地回收了记录有机颗粒沉降一年的样品。POC和总质量通量的增加表明，该地区每年有两次开花发生在秋末和初夏。结果表明，浮游植物δ 13 C和δ 15 N的季节变化可以用浮游植物同位素比值的一般规律来解释，说明浮游植物光合作用和硝酸盐吸收过程中同位素分馏的出现对浮游植物δ 13 C和δ 15 N的变化起着重要作用，并与混合层的营养盐供应和生产率密切相关。表层沉积物的δ 13 C和δ 15 N明显重于沉降颗粒，且其垂向变化趋势与前人的研究结果一致。通过对这种垂直趋势的分析，我们发现，由于沉降过程中的碳、氮同位素差异，沉降颗粒与表层沉积物之间的碳、氮同位素差异可能受到底部深度的限制，但也可能受到外来物质输入等区域因素的进一步影响。最后强调了这一因素对同位素代用指标在古海洋学研究中的应用意义。
A sediment trap experiment and stable carbon and nitrogen isotope analysis of sinking organic particles have been performed in the northeast Japan Sea from August 1998 to October 1999 in order to confirm the relationship between seasonal variability of phytoplankton production and the isotope composition of sinking particles. The sediment trap deployed at 1090 m has successfully recovered samples recording organic particles sinking for a year round. Increases of POC and total mass fluxes suggested that blooming occur twice a year in late autumn and early summer in this region. It was shown that the seasonal variation of δ13C and δ15N of sinking particles could be explained by the general pattern controlling isotope ratios of phytoplankton so that appearance of isotope fractionation on photosynthesis and nitrate uptake might play a most important role to change δ13C and δ15N of phytoplankton in tightly linked with nutrient supply and production rate in the mixed layer. The δ13C and δ15N of the surface sediment were significantly heavier than those of sinking particles and showed a consistent trend of vertical isotopic change with the results reported in previous works. Compiled such vertical trend we addressed that carbon and nitrogen isotopic discrimination between sinking particles and the surface sediment might be qualified by the bottom depth due to isotope discrimination in sinking process but further modification can occur by regional factors such as import of allochthonous substances. Finally we stress about the implication of such factor to apply isotopic proxies to paleoceanographic research.