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首页> 外文期刊>Journal of oceanography >Assessment of nitrogen loading from the Kiso-Sansen Rivers into Ise Bay using stable isotopes
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Assessment of nitrogen loading from the Kiso-Sansen Rivers into Ise Bay using stable isotopes

机译：使用稳定同位素评估从木曾三森河入伊势湾的氮负荷

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Concentrations of particulate organic nitrogen (PN), dissolved inorganic nitrogen (DIN), and their nitrogen isotope ratios (δ15N) in the Kiso-Sansen Rivers were determined from monthly observations over the course of a year to assess variations in the form and sources of riverine nitrogen discharged into Ise Bay. The δ15N values of NO3? observed in the Kiso-Sansen Rivers showed a logarithmic decreasing trend from 8 to 0‰, which varied with the river discharge, indicating mixing between point sources with high δ15N and non-point sources with low δ15N. The influence of isotope fractionation of in situ biogeochemical processes (mainly DIN assimilation by phytoplankton) on δ15N of NO3? was negligible, because sufficient concentrations of NH4+ for phytoplankton demand would inhibit the assimilation of NO3?. A simple relationship between river discharge and δ15N of NO3? showed that the fraction of total NO3? flux arising from point sources increased from 4.0–6.3% (1.1–1.8?tN?day?1) during higher discharge (>600?m3?s?1) to 30.2–48.3% (2.6–4.1?tN?day?1) during lower discharge (<300?m3?s?1). Riverine NO3? discharge from the Kiso-Sansen Rivers can explain 75% of the variations in surface NO3? at the head of Ise Bay over the year.
机译：根据一年中的每月观测，确定了木曾三森河中的颗粒有机氮（PN），溶解性无机氮（DIN）的浓度及其氮同位素比（δ15N），以评估其形态和来源的变化。河流氮排入伊势湾。 NO3δ的δ15N值在Kiso-Sansen河中观测到的对数呈从8到0‰的对数下降趋势，并随河流流量而变化，这表明高δ15N的点源与低δ15N的非点源之间混合。原位生物地球化学过程的同位素分馏（主要是浮游植物与DIN的同化作用）对NO3δ15N的影响。可以忽略不计，因为足够的浓度的NH4 +满足浮游植物的需求会抑制NO3？的吸收。河流流量与NO3δ15N之间的简单关系表明占总NO3的比例？在较高排放量（> 600？m3？s？1）期间，来自点源的通量从4.0-6.3％（1.1-1.8？tN？day？1）增加到30.2-44.8％（2.6-4.1？tN？day？1）。 ）在较低的排放量（<300？m3？s？1）中。河流NO3？木曾三森河的排放可以解释75％地表NO3的变化？一年来在伊势湾的首领。

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