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首页> 外文期刊>Journal of oceanography >Total organic carbon and nitrogen contents in surface sediments of Harima Nada, eastern Seto Inland Sea, Japan: a comparison under two different trophic states
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Total organic carbon and nitrogen contents in surface sediments of Harima Nada, eastern Seto Inland Sea, Japan: a comparison under two different trophic states

机译：日本濑户内海东部Harima Nada表层沉积物中总有机碳和氮含量：两种不同营养状态下的比较

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摘要

Phytoplankton abundance in the surface waters of Harima Nada, eastern Seto Inland Sea of Japan, decreased after around the late 1970s following a reduction of terrestrial phosphorous inputs, and relatively low levels persisted thereafter. This symptom of de-eutrophication in recent decades might have reduced organic matter storage in surficial sediments. To test this possibility, we examined total organic carbon (TOC) and nitrogen (TN) contents of Harima Nada sediments in 2011, and compared the results to past data from more eutrophic states. In 2011, the TOC and TN varied horizontally within the basin, in relation to physicochemical properties (water and mud content) and phytoplankton remnants (pheo-pigments) of the sediments. These horizontal patterns were fundamentally similar to those of the early 1980s (1982-1983), although discrepancies between the periods were observed in some areas. Differences of mean TOC and TN in the 0-2 cm layer at 63 stations from 1982-1983 to 2011 were consequently ＜10 %. Hence, the recent de-eutrophication in Harima Nada was associated with little overall change of TOC and TN storage in the sediment. In Harima Nada, changes in water clarity and particle size composition of the sediment seem to have occurred during recent decades. The aforementioned paradoxical phenomenon may therefore be explained by factors that are affected by these environmental changes. Such factors include the ratio of export flux to the seafloor to phytoplankton production, phytoplankton biomass and production in the entire euphotic zone, and accumulation rate of surface sediment.
机译：在日本濑户内海东部播磨的表层水域，浮游植物的丰度在1970年代后期由于陆上磷的输入减少而下降，此后一直保持相对较低的水平。近几十年来这种富营养化的症状可能减少了表层沉积物中有机物的存储。为了测试这种可能性，我们检查了2011年Harima Nada沉积物的总有机碳（TOC）和氮（TN）含量，并将结果与​​富营养化状态的以往数据进行了比较。 2011年，流域内TOC和TN的水平与沉积物的理化性质（水和泥浆含量）和浮游植物残余物（浅色色素）有关。这些水平模式从根本上类似于1980年代初期（1982-1983年）的水平模式，尽管在某些地区发现了不同时期之间的差异。因此，从1982-1983年到2011年，在63个站点的0-2 cm层中，平均TOC和TN的差异小于＜10％。因此，最近在Harima Nada的富营养化与沉积物中TOC和TN储存的总体变化几乎没有关系。在Harima Nada，近几十年来似乎发生了水的净度和沉积物颗粒大小组成的变化。因此，上述矛盾现象可以由受这些环境变化影响的因素来解释。这些因素包括：出口通向海底的通量与浮游植物产量的比率，浮游植物生物量和整个富营养区的产量以及表层沉积物的积累率。

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