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<p>Salman Bay (lagoon) is located north of Jeddah City, eastern cost of the Red Sea. It is currently experiencing brine conditions due to the shallowing of its outlet channel, but with a natural condition. Therefore, its latest sedimentary archive could provide an opportunity to study the late Holocene climatic events in a tropical region, such as the Little Ice Age (LIA) and Medieval Warm Period (MWP), which prevailed the Northern Hemisphere. A sediment core (SALM1, 2.9&#xa0;m long) was recovered from the intertidal–supratidal area in the southern part of the site to reveal the lagoon’s development during the last 5&#xa0;ka and linking this with the environmental and climatic conditions that prevailed during the period of deposition of this section. Sediment dating was by five AMS <sup>14</sup>C age-dating points backed up by investigations of metal concentrations, geochemical parameters and sediment granulometry in 70 samples from the sediment core. The frequency distribution of these data and statistical analyses enabled this core to be divided into five intervals as: before 1500 BC, 1500‒200 BC, 200 BC‒AD 1500, AD 1500‒1850 and AD 1850‒to the present (2017). In the lower part of the core (before 200 BC), normal salinity metals (Ca, Na, Mg, Sr, K, B and Bi) precipitated under warm and dry climate with stable environmental conditions, and showing redox frontal conditions at around 3000 BC. During 200 BC‒AD 1500, B, Bi and Cd showed the lowest mean values of 56, 6, 0.7&#xa0;mg/kg, whereas Li, Ga, and Co increased to the high mean values of 70, 160, 9&#xa0;mg/kg indicating the start of high evaporative conditions coeval with the warming in the Medieval Period (MWP). This allowed more production of aragonite and mollusc shells which are more favorable sites for Sr rather than Mg. Results also indicated that the Little Ice Age (LIA) period (AD 1500‒1850) started and ended abruptly and it was an interval of near sterilization due to high salinity that has continued to the present. Sediments of the most recent period (1850–2017) consisted of evaporites and thick algal mats that lead to the cessation of CaCO<sub>3</sub> production and a decrease in metals precipitation.</p> Graphical abstract <p></p>

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Elemental variations in response to environmental and climatic changes in a sediment core spanning the last 5 ka from Salman Bay, eastern Red Sea coast

  • 期刊论文

  • 发表日期：

    2025年6月10日

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  • Mohammed I. Orif,
  • Ramadan H. Abu-Zied

摘要

Salman Bay (lagoon) is located north of Jeddah City, eastern cost of the Red Sea. It is currently experiencing brine conditions due to the shallowing of its outlet channel, but with a natural condition. Therefore, its latest sedimentary archive could provide an opportunity to study the late Holocene climatic events in a tropical region, such as the Little Ice Age (LIA) and Medieval Warm Period (MWP), which prevailed the Northern Hemisphere. A sediment core (SALM1, 2.9 m long) was recovered from the intertidal–supratidal area in the southern part of the site to reveal the lagoon’s development during the last 5 ka and linking this with the environmental and climatic conditions that prevailed during the period of deposition of this section. Sediment dating was by five AMS 14C age-dating points backed up by investigations of metal concentrations, geochemical parameters and sediment granulometry in 70 samples from the sediment core. The frequency distribution of these data and statistical analyses enabled this core to be divided into five intervals as: before 1500 BC, 1500‒200 BC, 200 BC‒AD 1500, AD 1500‒1850 and AD 1850‒to the present (2017). In the lower part of the core (before 200 BC), normal salinity metals (Ca, Na, Mg, Sr, K, B and Bi) precipitated under warm and dry climate with stable environmental conditions, and showing redox frontal conditions at around 3000 BC. During 200 BC‒AD 1500, B, Bi and Cd showed the lowest mean values of 56, 6, 0.7 mg/kg, whereas Li, Ga, and Co increased to the high mean values of 70, 160, 9 mg/kg indicating the start of high evaporative conditions coeval with the warming in the Medieval Period (MWP). This allowed more production of aragonite and mollusc shells which are more favorable sites for Sr rather than Mg. Results also indicated that the Little Ice Age (LIA) period (AD 1500‒1850) started and ended abruptly and it was an interval of near sterilization due to high salinity that has continued to the present. Sediments of the most recent period (1850–2017) consisted of evaporites and thick algal mats that lead to the cessation of CaCO3 production and a decrease in metals precipitation.

Graphical abstract