Abstract Despite the economic and political importance of the Persian Gulf and the vast amount of marine trade carried on, mainly in tanker traffic, chemical oceanographic properties of the area, particularly nutrients and chlorophyll a had been measured only a few times in the past (expeditions of the Research Vessels Meteor (1965), Atlantis II (1977), Umitaka-Maru (1993–1994), ROPME (2000, 2001 and 2006)) and no observations after 2006 (ROPME cruise) were taken. The present study aims to investigate the hydrographic characteristics, nutrients and chlorophyll a on 20 stations between 25° N and 27°N across the Persian Gulf and the Gulf of Oman during the PGE 1801 cruise in January 2018. Seawater samples were collected at the surface, 10 m, 25 m, 50 m, 75 m and upper depths, depending on each station's total depth (the deepest sample was taken at 180 m). The results showed that chlorophyll a is concentrated in the surface layer and decreases with increasing depth, which may be associated with a decrease in the phytoplankton population in the lower layers. The inflowing surface water is high in phosphate (0.74–1.10 μM) due to the north-east monsoon's upwelling. The N/P ratio was lower than the standard Redfield ratio of 16/1 suggesting nitrogenous nutrients as limiting elements. In nearly-enclosed basins with minimal exchanges with open oceans similar to the Persian Gulf, the primary production generally is limited by nitrogen. Nitrate was the highest and ammonium was the lowest in the Persian Gulf and Gulf of Oman waters. The results show the penetration of surface water with a salinity of 36.7 psu into the Persian Gulf which is carried along the Iranian Coast, gradually increasing in salinity to more than 38.2 psu.

中文翻译：

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波斯湾和阿曼湾的营养物质和叶绿素 a 的空间分布

摘要 尽管波斯湾在经济和政治上具有重要意义，并且进行了大量的海上贸易，主要是油轮运输，但该地区的化学海洋学特性，特别是营养物质和叶绿素 a 过去仅进行了几次测量（探险研究船 Meteor (1965)、Atlantis II (1977)、Umitaka-Maru (1993–1994)、ROPME (2000、2001 和 2006)) 和 2006 年之后没有观测（ROPME 巡航）。本研究旨在调查 2018 年 1 月 PGE 1801 巡航期间波斯湾和阿曼湾 25°N 至 27°N 之间的 20 个站点的水文特征、营养物质和叶绿素 a。 , 10 m, 25 m, 50 m, 75 m 及以上深度，取决于每个站点' s 总深度（最深的样本是在 180 m 处采集的）。结果表明，叶绿素a集中在表层，随着深度的增加而减少，这可能与下层浮游植物种群减少有关。由于东北季风的上升流，流入地表水的磷酸盐含量高（0.74-1.10 μM）。N/P 比低于 16/1 的标准 Redfield 比，表明含氮养分是限制元素。在与波斯湾类似的与开阔海洋交换最少的近乎封闭的盆地中，初级生产通常受到氮的限制。在波斯湾和阿曼湾水域，硝酸盐含量最高，铵盐含量最低。结果表明，地表水的渗透率为 36。